Optical devices, projectors, and imaging devices

Abstract

To make optical devices more compact. [Solution] The optical device 50 comprises a first reflective surface 4a having power, a second reflective surface 4b having power and positioned on the enlarged side of the first reflective surface 4a, and a first optical element 42a positioned on the enlarged side of the second reflective surface 4b. The first optical element 42a has a first transmissive surface 5a arranged sequentially from the contraction side to the enlargement side, a third reflective surface 4c having a concave shape that reflects light inside the first optical element 42a, and a second transmissive surface 5b different from the first transmissive surface 5a. At least one of the first transmissive surface 5a, the third reflective surface 4c, and the second transmissive surface 5b has power and comprises an aperture diaphragm positioned on the first reflective surface and a first light absorbing member that absorbs light passing outside the first reflective surface.

Description

[Technical Field]

[0001] The present invention relates to an optical device, and to a projector and imaging device equipped with an optical device. [Background technology]

[0002] Projection lenses that utilize many spherical lenses and some aspherical lenses as projection optical systems for projectors are known (Patent Document 1). These projection lenses correct various aberrations, including chromatic aberration, using a large number of lenses.

[0003] A reflective imaging optical system that makes extensive use of free-form surface mirrors is known as an imaging optical system used in projectors and the like (Patent Document 2). This imaging optical system enables projection at high elevation angles using a large number of mirrors and is also compactly configured in the lateral direction. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2015-014677 [Patent Document 2] Japanese Patent Publication No. 2003-043360 [Overview of the project] [Problems that the invention aims to solve]

[0005] In the projection lens described in Patent Document 1, not only does the number of lenses increase and the overall length of the lens increase, but because the lenses are arranged in one direction, it becomes difficult to project at high elevation angles, and the freedom of product layout is reduced.

[0006] In imaging optical systems that utilize multiple reflective surfaces, as described in Patent Document 2, the mirrors, excluding the first and last, must be positioned so that the light directed towards the mirror and the light reflected by that mirror do not spatially interfere with each other. This imposes constraints on the relationship between the reflection angle at each mirror, the distance between mirrors, and the diameter of the light beam at each mirror, resulting in a larger overall optical system. Furthermore, focusing on the aperture, which determines the brightness of the light rays that can be captured by the imaging optical system, it is located between the second and third mirrors. However, it can be confirmed that the aperture interferes not only with the light rays traveling from the second to the third mirror, but also with the light rays reflected by the first mirror, and further with the light rays reflected by the third mirror and heading toward the fourth mirror. When actually commercializing the imaging optical system of Patent Document 2, the aperture position needs to be reviewed. [Means for solving the problem]

[0007] An optical device in one aspect of the present invention comprises a first reflective surface having power, a second reflective surface having power positioned on the enlarged side of the first reflective surface, a first optical element positioned on the enlarged side of the second reflective surface and arranged sequentially from the contraction side to the enlargement side, having a first transmissive surface, a third reflective surface having power and a concave shape, and a second transmissive surface different from the first transmissive surface, an aperture diaphragm positioned on the first reflective surface, and a first light absorbing member that absorbs light passing outside the first reflective surface.

[0008] In one aspect of the present invention, the projector comprises the optical device described above and an image forming unit that forms an image on the reduced-side conjugate surface of the optical device.

[0009] An imaging device in one aspect of the present invention comprises the optical device described above and an image sensor disposed on the conjugate surface of the optical device on the reduction side. [Brief explanation of the drawing]

[0010] [Figure 1] This diagram illustrates the structure of a projector incorporating the optical device of the first embodiment. [Figure 2] This diagram shows the projection state of the optical device onto the screen. [Figure 3]It is a cross-sectional view for explaining the optical device or projection optical system of Example 1. [Figure 4] It shows the lateral aberration characteristics of the projection optical system of Example 1. [Figure 5] It shows the lateral aberration characteristics of the projection optical system of Example 1. [Figure 6] It is a diagram for explaining the relationship between the display surface and the projection surface of Example 1. [Figure 7] It is a diagram for explaining a modified example of the optical device of the first embodiment. [Figure 8] It is a cross-sectional view for explaining the optical device or projection optical system of the second embodiment. [Figure 9] It shows the lateral aberration characteristics of the projection optical system of Example 2. [Figure 10] It shows the lateral aberration characteristics of the projection optical system of Example 2. [Figure 11] It is a diagram for explaining the relationship between the display surface and the projection surface of Example 2. [Figure 12] It is a diagram for explaining a modified example of the optical device of the second embodiment. [Figure 13] It is a diagram for explaining another modified example of the optical device of the second embodiment. [Figure 14] It is a diagram for explaining the structure of an imaging device incorporating the optical device of the third embodiment.

[0011] 〔First Embodiment〕 Hereinafter, referring to the drawings, an optical device according to the first embodiment of the present invention and a projector incorporating the same will be described.

[0012] FIG. 1 is a diagram for explaining the structure of a projector 2 incorporating an optical device 50 according to the first embodiment. As shown in FIG. 1, the projector 2 includes an optical system portion 60 that projects image light and a circuit device 80 that controls the operation of the optical system portion 60. The optical system portion 60 has an image display device 20 that displays image light or video light and a projection optical system 40 that projects the image light onto a screen SC (see FIG. 2).

[0013] The image display device 20 includes a light source device 10, a separation optical system 20a, an image forming unit 20b, and a prism PR. In this embodiment, the optical device 50 is a projection optical device 51, which is a combination of the prism PR and the projection optical system 40.

[0014] The light source device 10 emits light including R light, G light, and B light in a uniform state. The light source device 10 includes a light source lamp, such as ultra-high pressure mercury, a two-stage integrator lens having a plurality of lens elements arranged in an array, a polarization conversion element that converts the light that has passed through the two-stage integrator lens into a predetermined linear polarization, and a superposition lens that superimposes the illumination light emitted from the later integrator lens onto the display areas of the liquid crystal panels 29R, 29G, and 29B.

[0015] The separation optical system 20a separates the light emitted from the light source device 10 into three colors: R, G, and B. The separation optical system 20a includes a first dichroic mirror 21, a second dichroic mirror 22, relay lenses 23 and 24, reflective mirrors 25, 26, and 27, and field lenses 28R, 28G, and 28B. The image forming unit 20b includes liquid crystal panels 29R, 29G, and 29B, which are light modulation elements OM.

[0016] The first dichroic mirror 21 reflects the red light incident from the light source device 10 and transmits the green and blue light. The red light reflected by the first dichroic mirror 21 passes through the reflective mirror 25 and the field lens 28R before entering the liquid crystal panel 29R. The liquid crystal panel 29R modulates the red light according to the image signal to form an image of red color.

[0017] The second dichroic mirror 22 reflects the green light from the first dichroic mirror 21 and transmits the blue light. The green light reflected by the second dichroic mirror 22 passes through the field lens 28G and enters the liquid crystal panel 29G. The liquid crystal panel 29G modulates the green light according to the image signal to form a green-colored image. The blue light that has passed through the second dichroic mirror 22 passes through the relay lenses 23, 24, the reflection mirrors 26, 27, and the field lens 28B and enters the liquid crystal panel 29B. The liquid crystal panel 29B modulates the blue light according to the image signal to form a blue-colored image.

[0018] The liquid crystal panels 29R, 29G, and 29B, which are the image forming units 20b, form an image on their display surfaces, that is, on the reduced conjugate plane RC of the projection optical system 40 (see Figure 3).

[0019] The prism PR is, for example, a cross dichroic prism 31. The cross dichroic prism 31 is a prism for photosynthesis, which synthesizes the light modulated by each liquid crystal panel 29R, 29G, and 29B to form image light, which is then directed to the projection optical system 40.

[0020] The projection optical system 40 is a projection lens that projects the image light, which is modulated by each liquid crystal panel 29R, 29G, and 29B and combined by the cross dichroic prism 31, onto the screen SC (see Figure 2).

[0021] The circuit device 80 includes an image processing unit 81 to which an external image signal IS such as a video signal is input, a display drive unit 82 that drives liquid crystal panels 29R, 29G, and 29B provided in the optical system section 60 based on the output of the image processing unit 81, a lens drive unit 83 that adjusts the state of the projection optical system 40 by operating a moving mechanism AN provided in the projection optical system 40, and a main control unit 88 that comprehensively controls the operation of these circuit sections 81, 82, 83, etc.

[0022] The image processing unit 81 converts the input external image signal IS into an image signal that includes the gradation of each color. The image processing unit 81 can also perform various image processing operations on the external image signal IS, such as distortion correction and color correction.

[0023] The display drive unit 82 can operate the liquid crystal panels 29R, 29G, and 29B based on the image signal output from the image processing unit 81, and can form an image on the liquid crystal panels 29R, 29G, and 29B that corresponds to the image signal or an image that has been processed therefrom.

[0024] The lens drive unit 83 operates under the control of the main control unit 88 and adjusts the focus of the projection optical system 40 by appropriately moving the lens 41 constituting the projection optical system 40 or optical device 50 along the optical axis OA of the device using the moving mechanism AN. Here, the optical axis OA of the device is the axis passing through the center of the lens 41 in the optical device 50, or the central axis OX passing through the center of the conjugate plane RC on the reduction side (see Figure 3). The moving mechanism AN includes, for example, an actuator.

[0025] The lens drive unit 83 can be omitted. In this case, the lens 41 may be manually moved using a mechanical mechanism including a cam mechanism as the moving mechanism AN, and the focus of the projection optical system 40 may be adjusted.

[0026] The optical device 50 will be described in detail below with reference to Figures 2 and 3. Figure 2 shows the projection state of the optical device 50 onto the screen SC. Figure 3 is a diagram illustrating the configuration of the optical device 50 and the light rays. Note that the optical device 50 illustrated in Figure 3 has the same configuration as the optical device 50 of Example 1, which will be described later.

[0027] As shown in Figure 2, the optical device 50 comprises a prism PR and a projection optical system 40. The optical device 50 projects the image formed on the display surface 2a or projection surface of the image forming unit 20b onto the projection surface 2b of the screen SC. In other words, the image light ML emitted from the display surface 2a of the image forming unit 20b passes through the prism PR and the projection optical system 40 and is incident on the projection surface 2b of the screen SC. Here, a prism PR corresponding to the cross dichroic prism 31 in Figure 1 is positioned between the projection optical system 40 and the image forming unit 20b.

[0028] As shown in Figure 3, the projection optical system 40 of the optical device 50 comprises a lens 41, an internal reflective element 42, and a mirror element 43. The projection optical system 40 is an eccentric or off-axis optical system, and the optical axis OA of the device, which extends along the optical path through the center of the image forming unit 20b, is arranged along a plane of symmetry parallel to the YZ plane. In other words, the projection optical system 40 is asymmetric with respect to the vertical Y direction and symmetric with respect to the YZ plane. The projection optical system 40 of the optical device 50 comprises, as a general set of components, a first reflective surface 4a having power, a second reflective surface 4b having power and positioned on the enlarged side of the first reflective surface 4a, and a first optical element 42a having a first transmissive surface 5a, a third reflective surface 4c having a concave shape that reflects light internally, and a second transmissive surface 5b different from the first transmissive surface 5a, which are positioned on the enlarged side of the second reflective surface 4b and arranged sequentially from the reduction side to the enlargement side. Furthermore, the projection optical system 40 includes a third optical element 42c having a fourth reflective surface 4d positioned on the expanding side of the second reflective surface 4b in the optical path between the second reflective surface 4b and the first optical element 42a, and a fifth reflective surface 4e positioned between the fourth reflective surface 4d and the first transmissive surface 5a. Here, the third reflective surface 4c has positive power, and the fourth reflective surface 4d is spatially positioned on the contracting side conjugate surface RC side than the first reflective surface 4a and the third reflective surface 4c. As will be described in detail later, the first optical element 42a and the third optical element 42c are included in the internal reflective element 42. The internal reflective elements 42 and mirror elements 43 constituting the projection optical system 40 are held by the lens barrel member 49 and aligned with each other.

[0029] Lens 41 is a positive lens positioned between the retraction-side conjugate surface RC and the first reflective surface 4a of the optical device 50 or projection optical system 40. This allows the retraction side of the optical device 50 to be made telecentric. It also suppresses the spread of the light beam, allowing the entire optical system of the optical device 50 to be miniaturized. Note that telecentricity includes the case where the principal ray is approximately parallel to the optical axis OA of the device. Lens 41 can be moved along the lens optical axis OA2 or the central axis OX of the retraction-side conjugate surface RC by the movement mechanism AN. This enables a focusing function in the optical device 50.

[0030] The internal reflective element 42 has a first optical element 42a, a second optical element 42b, and a third optical element 42c. The first optical element 42a, the second optical element 42b, and the third optical element 42c are an integrated internal reflective element 42. The internal reflective element 42 is an internal reflective type refractive optical element that has both internal reflection and refraction functions in a single element. Since the first to third optical elements 42a to 42c are an integrated component, that is, composed of the same element, cost reduction and improved assembly accuracy can be achieved. As will be described in detail later, the internal reflective element 42 has one or more reflective surfaces that are internal reflective surfaces W1. The internal reflective element 42 is formed from a light-transmitting material. Examples of light-transmitting materials include resin and glass. The light-transmitting material is formed, for example, by molding.

[0031] The first optical element 42a is positioned on the magnifying or upper side of the internal reflective element 42. The first optical element 42a has a first transmissive surface 5a, a third reflective surface 4c having a concave shape in the direction of the incident light ray, and a second transmissive surface 5b different from the first transmissive surface 5a, arranged sequentially from the reduction side to the magnification side. In other words, in the first optical element 42a, and by extension the internal reflective element 42, the final reflective surface on the magnification side has a concave shape. The third reflective surface 4c is an internal reflective surface W1 that reflects or reflects light from the back surface inside the first optical element 42a. Because the first optical element 42a has a first transmissive surface 5a and a second transmissive surface 5b, the transmissive surface through which the incident light passes (incident surface) and the transmissive surface through which the emitted light passes (exit surface) are located in different regions of the first optical element 42a. This makes it possible to improve optical performance by giving separate functions to the first transmission surface 5a, which is the incident surface of the first optical element 42a, and the second transmission surface 5b, which is the exit surface.

[0032] A boundary, not shown, is provided between the first transmissive surface 5a and the second transmissive surface 5b, specifically a linear or strip-shaped boundary in which the curvature, etc., changes discontinuously. This boundary may be provided with a light-absorbing member to suppress the leakage of incident or reflected light to the first optical element 42a into an optical path outside the specified path and back into the specified optical path from another location.

[0033] At least one of the first transmitting surface 5a, the third reflecting surface 4c, and the second transmitting surface 5b has power. In this embodiment, the first transmitting surface 5a, the third reflecting surface 4c, and the second transmitting surface 5b have positive power. This makes it possible to utilize the refractive power of the first transmitting surface 5a and the second transmitting surface 5b that are close to the third reflecting surface 4c, which facilitates ray control and is advantageous for miniaturizing and improving the performance of the optical device 50. The positive or negative sign of the power of the first transmitting surface 5a, the third reflecting surface 4c, and the second transmitting surface 5b can be changed as appropriate, but it is preferable that the third reflecting surface 4c and the second transmitting surface 5b have positive power.

[0034] In the optical device 50, an intermediate image is formed between the first transmission surface 5a and the third reflection surface 4c. In other words, the intermediate image is formed within the first optical element 42a. As a result, the intermediate image is formed in the optical path on the reduced side of the third reflection surface 4c, and by re-imaging the intermediate image with the concave third reflection surface 4c, it becomes possible to shorten the focal length.

[0035] The second optical element 42b is positioned on the reduced side or below the internal reflective element 42. The second optical element 42b has a first reflective surface 4a and a third transmissive surface 5c. The third transmissive surface 5c transmits both incident light incident on the first reflective surface 4a and reflected light reflected by the first reflective surface 4a. By having the incident and exit rays to the second optical element 42b pass through the third transmissive surface 5c, which is the same refractive surface W3, ray control that is not possible with surface reflection becomes possible, and optical performance can be improved in a space-saving manner.

[0036] A first aperture diaphragm ST1 is positioned on the first reflective surface 4a. The first aperture diaphragm ST1 is attached to the first reflective surface 4a and is formed outside the effective light-passing region of the first reflective surface 4a so as to surround the effective light-passing region of the first reflective surface 4a. The first aperture diaphragm ST1 absorbs light that passes outside the effective light-passing region of the first reflective surface 4a. In particular, when the optical device 50 is used as a projection optical device 51, the light emitted from the liquid crystal panel 29G or the like, which is a display device, is restricted by the first aperture diaphragm ST1 in the initial stages of the optical system, thereby preventing unnecessary diffuse reflection from occurring within the optical system of the optical device 50.

[0037] A second aperture diaphragm ST2 is positioned on the third transmissive surface 5c. The second aperture diaphragm ST2 is attached to the third transmissive surface 5c and is a second light absorbing member AB02 formed outside the effective light ray passage region of the third transmissive surface 5c so as to surround the effective light ray passage region of the third transmissive surface 5c. The second aperture diaphragm ST2 absorbs light that passes outside the effective light ray passage region of the third transmissive surface 5c. By providing the second aperture diaphragm ST2, that is, by providing an aperture function on the incident side of the internally reflective second optical element 42b having the first reflective surface 4a, light ray control at this aperture position, i.e., a position close to the light source, becomes easier, which is advantageous for improving optical performance.

[0038] The third optical element 42c is positioned in the internal reflective element 42 between the first optical element 42a and the second optical element 42b. The third optical element 42c has a fourth reflective surface 4d positioned on the enlarged side of the second reflective surface 4b of the mirror element 43, which will be described later.

[0039] The first light absorbing member AB01 is widely positioned on the inner surface of the lens barrel member 49, facing the back surface 6a, which is the surface opposite to the fourth reflective surface 4d, and the upper and lower regions in the Y-direction or vertical direction, so as to cover these areas. This absorbs image light ML and the like that would pass outside the first reflective surface 4a. In other words, it can block unwanted light that would pass outside the first reflective surface 4a and the third reflective surface 4c and cause stray light, such as image light ML reflected by the first reflective surface 4a and the third reflective surface 4c. Such unwanted light includes not only image light ML that leaks into unintended, non-specified optical paths and propagates through the inner surface of the inner reflective element 42, such as image light ML that is reflected near the back surface 6a of the first reflective surface 4a and deviates from the first transmitting surface 5c, and image light ML that is incident on the back surface 6a near the first reflective surface 4a and the third reflective surface 4c and transmitted or reflected there, but also unintended ambient light. Examples of materials for the first light-absorbing member AB01 include light-absorbing paints or other substances, and light-shielding films.

[0040] Furthermore, in the third optical element 42c, a third light-absorbing member AB3 for preventing stray light may be provided around the fourth reflective surface 4d.

[0041] The mirror element 43 is spatially positioned in the -Z direction relative to the internal reflective element 42, that is, on the contraction-side conjugate plane RC side. The mirror element 43 has a second reflective surface 4b and a fifth reflective surface 4e. The second and fifth reflective surfaces 4b and 4e are surface reflective surfaces W4 that reflect incident light off the surface of the mirror element 43. The second and fifth reflective surfaces 4b and 4e face the internal reflective element 42 at a position closer to the center, avoiding the upper and lower ends of the internal reflective element 42. In other words, the second and fifth reflective surfaces 4b and 4e are spatially positioned on the contraction-side conjugate plane RC side relative to the third reflective surface 4c. The second reflective surface 4b is spatially positioned on the lower side of the optical device 50, that is, on the contraction side. Furthermore, the second reflective surface 4b is positioned between the third transmission surface 5c and the fourth reflective surface 4d in the optical path. The fifth reflective surface 4e is positioned on the upper side of the optical device 50, that is, on the expansion side. Furthermore, the fifth reflective surface 4e is positioned between the fourth reflective surface 4d and the first transmissive surface 5a in the optical path. The mirror element 43 is integrally formed such that the fifth and second reflective surfaces 4e and 4b are arranged vertically. This makes it possible to miniaturize and reduce the cost of the optical system of the optical device 50. The substrate of the mirror element 43 is made of, for example, resin, metal, etc.

[0042] A stepped boundary is provided between the second reflective surface 4b and the fifth reflective surface 4e.

[0043] Focusing on the optical surfaces of the internal reflective element 42 and the mirror element 43, the optical device 50 has, in the optical path, a third transmitting surface 5c, a first reflecting surface 4a, a third transmitting surface 5c, a second reflecting surface 4b, a fourth reflecting surface 4d, a fifth reflecting surface 4e, a first transmitting surface 5a, a third reflecting surface 4c, and a second transmitting surface 5b, in the order from the reduction side to the expansion side. In the optical device 50, the image light ML is reflected five times. By providing the optical device 50 with a plurality of reflecting surfaces 4a to 4e in a direction that projects magnified with respect to the central axis OX of the reduction-side conjugate surface RC, which is the reduction-side imaging surface, the reflection angle can be minimized and a decrease in optical performance can be suppressed.

[0044] Furthermore, when focusing on the optical surface of the internal reflective element 42 in a cross-sectional view, the third transmissive surface 5c, the fourth transmissive surface 4d, the first transmissive surface 5a, and the second transmissive surface 5b are arranged on the side of the internal reflective element 42 that is the conjugate surface RC, i.e., the side of the second reflective surface 4b. On the opposite side of the internal reflective element 42 from the conjugate surface RC, i.e., the side of the first reflective surface 4a, the back surface 6a and the third reflective surface 4c are arranged. In this way, in the projection optical system 40 of the embodiment, the internal reflective surface W1, the surface reflective surface W2, and the refractive surface W3 can be arranged three-dimensionally on the internal reflective element 42 while maintaining their functions. Specifically, they can be arranged side by side in the vertical Y direction and placed close together, while being appropriately spaced apart in the front-to-back Z direction, which is advantageous for miniaturization. Specifically, the internal reflective surface W1 corresponds to the first and third reflective surfaces 4a and 4c. The surface reflective surface W2 corresponds to the fourth reflective surface 4d. The refractive surface W3 corresponds to the first to third transmission surfaces 5a to 5c.

[0045] In the internal reflective element 42, the internal reflective surface W1 and the surface reflective surface W2 may have a thin metal film such as aluminum or silver formed on their surface, or a dielectric multilayer film formed on their surface. The refractive surface W3 has an anti-reflective film formed on its surface. On the contraction side conjugate surface RC of the internal reflective element 42, the surface reflective surface W2 and the refractive surface W3 are provided on a continuous surface, and the reflective film constituting the surface reflective surface W2 and the anti-reflective film constituting the refractive surface W3 are formed in corresponding regions.

[0046] In the mirror element 43, the surface reflective surface W4 may be a reflective surface with a thin metal film such as aluminum or silver formed on its surface, or a reflective surface with a dielectric multilayer film formed on its surface.

[0047] The optical path of the optical device 50 will be described below. Image light from the image forming unit 20b passes through the prism PR and lens 41 and enters the third transmission surface 5c of the internal reflection element 42. The light that has passed through the third transmission surface 5c is refracted as appropriate and internally reflected by the first reflection surface 4a. The light reflected by the first reflection surface 4a passes through the third transmission surface 5c again. The light emitted from the third transmission surface 5c and refracted as appropriate is reflected by the second reflection surface 4b of the mirror element 43. The light reflected by the second reflection surface 4b is surface-reflected by the fourth reflection surface 4d of the internal reflection element 42 and reflected by the fifth reflection surface 4e of the mirror element 43. The light reflected by the fifth reflection surface 4e enters the first transmission surface 5a of the internal reflection element 42. The light that has passed through the first transmission surface 5a is refracted as appropriate and internally reflected by the third reflection surface 4c. Light reflected by the third reflective surface 4c passes through the second transmissive surface 5b, which is different from the first transmissive surface 5a. The light emitted from the second transmissive surface 5b and refracted as appropriate is projected onto the screen SC (see Figure 2).

[0048] The optical device 50 described above comprises a first reflective surface 4a having power, a second reflective surface 4b having power and positioned on the enlarged side of the first reflective surface 4a, and a first optical element 42a positioned on the enlarged side of the second reflective surface 4b. The first optical element 42a has a first transmissive surface 5a arranged sequentially from the contraction side to the enlargement side, a third reflective surface 4c having a concave shape that reflects light inside the first optical element 42a, and a second transmissive surface 5b different from the first transmissive surface 5a. At least one of the first transmissive surface 5a, the third reflective surface 4c, and the second transmissive surface 5b has power.

[0049] In the optical device 50 described above, by utilizing the refractive power of the first and second transmission surfaces 5a and 5b, which are close to the third reflection surface 4c, which is the inner reflection surface W1 of the first optical element 42a, ray control becomes easier, which is advantageous for miniaturization and high performance. Furthermore, the first and second transmission surfaces 5a and 5b can be given different functions to the incident and exit surfaces of the first optical element 42a, thereby improving optical performance. In addition, by making the third reflection surface 4c the inner reflection surface W1, the third reflection surface 4c can be made smaller, and the entire optical system can be miniaturized. As a result of the above, the optical device 50 can be made shorter in focal length and miniaturized.

[0050] Conventionally, when a projection optical system is composed solely of refractive elements, the number of lenses increases to correct for the spherical shape of the lenses and chromatic aberration, resulting in a linear projection lens with a long overall length. In contrast, the optical device 50 of the present invention can realize a three-dimensional optical system by utilizing multiple reflective surfaces and multiple refractive surfaces. Furthermore, since the internal reflective element 42 utilizes a molded reflective surface, it is not limited to a spherical shape, and by effectively utilizing the correction function of aspherical or free-form shapes on each surface, a projection system can be realized with a small number of surfaces and parts. As a result, the overall length of the optical system (i.e., the dimension in the Z direction) can be shortened, and a configuration in which the image is folded back towards the image forming unit 20b can be realized. In particular, when the focal length is shortened, the main body of the device can be placed near the screen SC, realizing a user-friendly projection configuration.

[0051] Furthermore, if the projection optical system is constructed using only surface reflective elements, as in conventional methods, the projection optical system becomes a large optical system with a large number of reflective surfaces. In contrast, the optical device 50 of the present invention uses an internal reflective element 42, which is an internal reflective type refractive optical element, and by utilizing the refractive effect at the transmission interface, the number of reflective surfaces can be reduced, thereby realizing a compact optical system.

[0052] In particular, by making the final reflective surface on the magnification side, specifically the third reflective surface 4c, a concave shape, the intermediate image formed in front of the third reflective surface 4c can be magnified and projected, thereby achieving wide-angle projection. Furthermore, by providing the first aperture diaphragm ST1 on the first reflective surface, specifically the first reflective surface 4a, from the image forming unit 20b, and providing the first light absorbing member AB01 behind or around it, unwanted light can be blocked at an early stage, enabling the realization of a compact optical system. By providing the first reflective surface 4a with the first aperture diaphragm ST1 on the internal reflective element 42, and providing the second light absorbing member AB02 on the third transmissive surface 5c in front of it, it becomes possible to control the light rays near the diaphragm position corresponding to the aperture position of the target optical element, enabling the realization of a relatively bright optical system.

[0053] Furthermore, the optical device 50 can be made into a single component by arranging the optical elements or optical surfaces together in the vertical direction and connecting each element. Since the shapes of multiple surfaces can be manufactured at once by integral molding of the optical elements, it is possible to realize an optical system that reduces the number of parts while ensuring assembly accuracy.

[0054] As described above, the optical device 50 is a compact device that is bright, produces high image quality, and has a wide angle of view.

[0055] The projector 2 described above comprises the optical device 50 and an image forming unit 20b that forms an image on the reduction-side conjugate surface RC of the optical device 50. This makes it possible to miniaturize the projector 2 equipped with the optical device 50.

[0056] [Examples] The following describes an embodiment of the optical device 50.

[0057] In the following examples, including Example 1, the displacement z of the surface on an aspherical surface is determined by the following polynomial (aspherical equation). TIFF2026109014000002.tif16166 However, c: Curvature (1 / R) h: Height from the optical axis k: Conic coefficient Ai: i-th order aspherical coefficients

[0058] The displacement z of a surface in an XY polynomial surface is determined by the following polynomial. TIFF2026109014000003.tif16166 However, c: Curvature (1 / R) k: Conic coefficient C mn :monomial x m y n coefficient r: Radial distance (r = √(x 2 +y 2 ))

[0059] (Example 1) Table 1 shows the optical surface data for Example 1. The terms used in Table 1 and the following tables are defined below. Surface number 1 refers to the reducing conjugate surface RC, and the last surface number refers to the expanding conjugate surface MC. "TC" means to refer to the eccentricity setting table. Data for surface numbers that do not correspond to the optical elements shown in Figure 3 are dummy data. SuNo: Face Number SuTy: Surface type Mt:Material SuFu: Surface function (refractory or reflective) SP: Spherical NP: Aspherical XY-FS:XY polynomial surface INF:Infinity OM1:SBSL7_OHARA OM2: Refractive index; 1.516745, Abbe number; 67.43 OM3:Z-330R DK: Refractive surface RH: Reflective surface R: Paraxial radius of curvature (unit: mm) D: Axis clearance (unit: mm) Ar: Aperture radius (unit: mm)

[0060] [Table 1] SuNo SuTy RD Mt SuFu Ar 1 SP INF 9.5000 DK 7.5472 2 SP INF 25.9100 OM1 DK 9.2096 3 SP INF 0.1000 DK 12.3490 4 NP 28.8770 6.9428 OM2 DK 12.8011 5 NP 47.6057 1.4383 DK 13.0167 6 SP INF TC DK 13.4207 7 NP -94.0326 TC OM3 DK 56.3488 8 NP -118.4506 TC OM3 RH 24.6180 9 NP -94.0326 TC DK 61.1608 10 XY-FS -96.6316 TC RH 34.1892 11 XY-FS 116.8783 TC RH 70.2483 12 XY-FS 291.7526 TC RH 58.1977 13 NP 41.5495 TC OM3 DK 40.5669 14 NP -63.1738 TC OM3 RH 25.6137 15 NP 24.5897 TC DK 24.1499 16 SP INF 0.0000 DK 112.8491 17 SP INF -608.6860 DK 112.8491 18 SP INF 0.0000 DK 998.8233

[0061] Table 2 shows the eccentricity settings for Example 1. The terms used in Table 2 and the following tables are defined below. The X-axis is the axis perpendicular to the plane of the paper, with the depth direction being positive. α rotation is the clockwise rotation around the X-axis when observed in the +X direction. The unit of distance is mm, and the unit of angle is °. Ec: Eccentricity XEc:X eccentricity YEc: Y-eccentricity ZEc:Z eccentricity αRo: α rotation Nr: Normal N / A: None DC & RE: Decenter and Return

[0062] [Table 2] CoNo Ec XEc YEc ZEc αRo 1 nr - - - - 2 N / A - - - - 3 N / A - - - - 4 N / A - - - - 5 N / A - - - - 6 dc & re - - 3.0000 - 7 dc & re - -37.3662 30.9474 -40.3930 8 dc & re - -4.1776 80.0000 -11.8012 9 dc & re - -37.3662 30.9474 -40.3930 10 dc & re - 46.7505 0.0000 15.4661 11 dc & re - -2.8256 62.0106 20.7235 12 dc & re - 81.6189 0.0000 -5.6859 13 dc & re - 100.5863 34.3353 1.4988 14 dc & re - 100.5863 80.0000 1.4988 15 dc & re - 100.5863 34.3353 1.4988 16 nr - - 80.0000 -

[0063] Table 3 shows the aspherical data for Example 1. The terms used in Table 3 and the following tables are defined below. Each item in the table is written in two rows. In Table 3 and the following tables, powers of 10 (e.g., 1.00 × 10) +18 This is expressed using E (for example, 1.00E+18). A: 4th aspheric coefficient B: 6th aspheric coefficient C: 8th aspheric coefficient [Table 3] SuNo 4 5 7 8 9 13 14 15 R 28.8770 47.6057 -94.0326 -118.4506 -94.0326 41.5495 -63.1738 24.5897 k 0 0 -4.56456798 -0.806373821 -4.56456798 -1.130497264 -1.223810266 0.0163858628 A -2.33958E-05 -8.62465E-06 -6.59366E-07 -6.44513E-08 -6.59366E-07 1.92800E-06 1.79185E-06 1.62137E-06 B -1.74199E-08 -2.81549E-08 5.14391E-11 -2.99274E-12 5.14391E-11 -6.00051E-10 -2.33459E-10 1.06802E-09 C -2.50049E-11 7.67102E-12 -6.52695E-15 1.45230E-15 -6.52695E-15 -3.50419E-15 -2.98931E-13 1.23508E-11

[0064] Table 4 shows the XY polynomial surface data of Example 1. In Table 4 and the following tables, C-xmyn is the coefficient C of the term of x m y n (where m and n are integers greater than or equal to 0) mn means. When m and n are 0, or x m or y n is 1 and not shown.

[0065] [Table 4] SuNo 10 11 12 R -96.6316 116.8783 291.7526 k -0.0772 0.7438 16.6250 C-x4 -2.90007E-07 1.06165E-06 1.05110E+01 C-x2y2 -5.09409E-08 -2.36731E-06 1.84650E+01 C-y4 -1.67407E-07 -2.56278E-07 7.90174E+00 C-x6 9.59623E-10 -4.03104E-10 -1.02890E+01 C-x4y2 3.17737E-10 1.51031E-10 -2.47269E+01 C-x2y4 2.14788E-10 5.34443E-10 -2.43574E+01 C-y6 1.04278E-10 -9.22891E-11 -6.86895E+00 C-x8 2.58292E-13 -7.24293E-13 6.67097E+00 C-x6y2 -1.46208E-12 1.64145E-13 2.55089E+01 C-x4y4 -2.13827E-13 -9.37039E-14 3.24116E+01 C-x2y6 -2.19981E-13 -4.83831E-14 2.12806E+01 C-y8 -5.24404E-14 1.92004E-14 3.70168E+00 C-x10 0 1.86064E-15 7.98339E-01 C-x8y2 0 -1.3112E-16 -1.53734E+01 C-x6y4 0 2.60133E-17 -2.31288E+01 C-x4y6 0 7.50031E-18 -2.05257E+01 C-x2y8 0 3.65135E-19 -1.08005E+01 C-y10 0 -1.46754E-18 -1.36452E+00

[0066] Figure 3 is a cross-sectional view of the optical device 50 of Example 1.

[0067] The optical device 50 includes a prism PR, a lens 41, an internal reflective element 42, and a mirror element 43. The internal reflective element 42 is an integrated unit comprising a first optical element 42a, a second optical element 42b, and a third optical element 42c. The third optical element 42c is positioned between the first optical element 42a and the second optical element 42b. The mirror element 43 is positioned opposite the internal reflective element 42.

[0068] The first optical element 42a has a first transmission surface 5a, a third reflection surface 4c, and a second transmission surface 5b. The third reflection surface 4c is a concave inner reflection surface W1. In the first optical element 42a, the refractive surfaces W3 through which incident and reflected light pass are different optical surfaces for the first transmission surface 5a and the second transmission surface 5b. The first transmission surface 5a, the third reflection surface 4c, and the second transmission surface 5b have positive power.

[0069] The second optical element 42b has a first reflective surface 4a and a third transmissive surface 5c. The first reflective surface 4a is a concave inner surface reflective surface W1. In the second optical element 42b, the refractive surface W3 through which incident light and reflected light pass is a single third transmissive surface 5c, which is a common optical surface. A first aperture diaphragm ST1 is positioned on the first reflective surface 4a. A second aperture diaphragm ST2 is positioned on the third transmissive surface 5c.

[0070] The third optical element 42c has a fourth reflective surface 4d, which is the surface reflective surface W2. The back surface 6a, which is the surface opposite to the fourth reflective surface 4d, is generally smooth but is not an optical surface. Opposite the back surface 6a, etc., a first light absorbing member AB01 is widely arranged inside the lens barrel member 49 to cover the back surface 6a, etc., in order to prevent stray light.

[0071] The mirror element 43 has a second reflective surface 4b, which is the surface reflective surface W4, and a fifth reflective surface 4e, which is also the surface reflective surface W4. The second and fifth reflective surfaces 4b and 4e are integrated.

[0072] The optical device 50 has, in the optical path, a third transmissive surface 5c, a first reflective surface 4a, a third transmissive surface 5c, a second reflective surface 4b, a fourth reflective surface 4d, a fifth reflective surface 4e, a first transmissive surface 5a, a third reflective surface 4c, and a second transmissive surface 5b, in the order from the reduction side to the expansion side. In the internal reflective element 42, the third transmissive surface 5c, the fourth reflective surface 4d, the first transmissive surface 5a, and the second transmissive surface 5b are arranged on the reduction side conjugate surface RC side, that is, on the second reflective surface 4b side. On the opposite side of the internal reflective element 42 from the reduction side conjugate surface RC, that is, on the first reflective surface 4a side, the first reflective surface 4a, the back surface 6a, and the third reflective surface 4c are arranged.

[0073] Figures 4 and 5 show the lateral aberration characteristics of the optical device 50 or projection optical system 40 of Example 1. Figure 6 is a diagram illustrating the relationship between the display surface 2a of the liquid crystal panel 29G and the projection surface 2b of the screen SC of Example 1. In the upper part of Figure 6, the ● marks indicate the position of light rays on the display surface 2a, and in the lower part of Figure 6, the ● marks indicate the position of light rays on the projection surface 2b. The coordinates shown in Figure 6 are based on the center of the display surface 2a or the center of the projection surface 2b. Since the light ray positions are symmetrical, the lateral aberration diagram shows the characteristics of nine points on one side corresponding to the coordinates on the display surface 2a.

[0074] The optical device 50 of the first embodiment shown in Figure 3, etc., is not limited to the illustrated structure, and various modifications are possible within the scope of the gist of the invention.

[0075] As shown in Figure 7, the first light absorbing member AB01 is not limited to being provided on the inner surface of the lens barrel member 49 at a distance from the inner surface reflecting element 42, but may also be attached to the back surface 6a so as to cover the entire back surface 6a sandwiched between the first reflecting surface 4a and the third reflecting surface 4c.

[0076] The first reflective surface 4a may be a surface reflective surface, in which case the third transmissive surface 5c is omitted.

[0077] [Second Embodiment] The optical apparatus of the second embodiment will now be described. Note that the optical apparatus of the second embodiment is a modified version of the optical apparatus of the first embodiment, and the parts common to both embodiments will not be described.

[0078] Figure 8 shows the configuration and ray diagram of the optical device 50. Note that the optical device 50 illustrated in Figure 8 has the same configuration as the optical device 50 of Embodiment 2 described later.

[0079] As shown in Figure 8, in this embodiment, the mirror element 43 has a second reflective surface 4b as one surface reflective surface W4. Also, the optical device 50 does not have a third optical element 42c as shown in Figure 3, etc. Furthermore, although the details will be described later, the lens 41 is eccentric. Because the lens 41 is eccentric, in the example of Figure 8, the lens 41 has a circular lens shape, but only the upper half into which the light rays are incident.

[0080] The internal reflective element 42 has a first optical element 42a and a second optical element 42b.

[0081] The first optical element 42a has a first transmissive surface 5a, a third reflective surface 4c which is an internal reflective surface W1, and a second transmissive surface 5b. The second optical element 42b has a first reflective surface 4a which is a surface reflective surface W2. A first aperture diaphragm ST1 is positioned on the first reflective surface 4a.

[0082] The first light absorbing member AB01 is positioned on the inner surface 6a of the lens barrel member 49, opposite to the step at the boundary between the first reflective surface 4a and the first transmissive surface 5a, and facing the upper and lower regions in the Y-direction or vertical direction. The first light absorbing member AB01 suppresses optical path interference between the light reflected by the first reflective surface 4a and the light reflected by the third reflective surface 4c, that is, it prevents light from leaking into an unspecified optical path and returning to the specified optical path from another location. This makes it possible to block unwanted light that causes stray light, such as image light ML that leaks into an unintended unspecified optical path and propagates through the inner surface of the inner reflective element 42, etc., for example, when image light ML reflected by the first reflective surface 4a is reflected by the third reflective surface 4c without passing through the second reflective surface 4b.

[0083] As illustrated in Figure 8, a fourth light-absorbing member AB4 may be provided at the boundary between the first transmissive surface 5a and the second transmissive surface 5b to suppress incident or reflected light to the first optical element 42a from leaking into an unspecified optical path and returning to the specified optical path from another location.

[0084] Since the mirror element 43 consists only of the second reflective surface 4b, it can be miniaturized.

[0085] The optical axis OA2 of lens 41 is shifted on the opposite side of the enlargement-side conjugate plane MC (see Figure 2) corresponding to the screen SC, relative to the center of the display device (specifically, the liquid crystal panel 29G, etc.), the display surface 2a, or the center of the reduction-side conjugate plane RC. The optical axis OA2 of lens 41 is defined by the axis connecting the centers of the spheres of the incident and exit surfaces of lens 41. In other words, lens 41 is shifted downward, or in the -Y direction, in the vertical direction which is the Y direction perpendicular to the central axis OX passing through the center of the reduction-side conjugate plane RC or the reduction-side image plane. This allows the position of the first reflective surface 4a to be placed on the lower side, opposite to the enlargement-side conjugate plane MC or the enlargement-side image plane, relative to the central axis OX of the reduction-side conjugate plane RC, and the height of the optical system positioned above the first reflective surface 4a can be reduced.

[0086] In the above, focusing on the optical surface of the internal reflective element 42, the optical device 50 has, in the optical path, a first reflective surface 4a, a second reflective surface 4b, a first transmitting surface 5a, a third reflective surface 4c, and a second transmitting surface 5b, in the order from the reduction side to the expansion side. In the optical device 50, the image light is reflected three times.

[0087] (Example 2) Table 5 shows the optical surface data for Example 2. The terms used in Table 5 are defined below. OM1=SBSL7_OHARA OM3=Z-330R OM6 = refractive index; 1.487490, Abbe number; 70.41 [Table 5] SuNo SuTy RD Mt SuFu Ar 1 SP INF 9.5000 DK 7.5472 2 SP INF 25.9100 OM1 DK 9.7316 3 SP INF 2.0000 DK 13.7947 4 SP INF 1.7952 DK 29.5718 5 NP -305.9334 4.4443 OM6 DK 29.8081 6 NP -106.1521 0.1000 DK 29.9102 7 SP INF TC DK 30.0793 8 XY-FS -153.7023 TC RH 34.0569 9 XY-FS -76.1137 TC RH 51.6330 10 NP 42.5040 TC OM3 DK 45.1329 11 XY-FS -57.3718 TC OM3 RH 53.8924 12 NP 350.6869 TC DK 48.1930 13 SP INF TC DK 169.8454 14 SP INF -428.0000 DK 169.8454 15 SP INF 0.0000 DK 773.3410

[0088] Table 6 shows the eccentricity settings for Example 2. [Table 6] CoNo Ec XEc YEc ZEc αRo 1 nr - - - - 2 N / A - - - - 3 N / A - - - - 4 nr - -20.3152 - - 5 N / A - - - - 6 N / A - - - - 7 dc & re - - 3.0000 - 8 dc & re - - 119.4592 -16.1328 9 dc & re - 93.4176 0.0000 36.2218 10 dc & re - 93.2930 52.2173 -8.1585 11 dc & re - 125.7550 117.3741 32.8682 12 dc & re - 93.2930 52.2173 -14.6886 13 nr - - 52.2173 - 14 dc & re - - - - 15 N / A - - - -

[0089] Table 7 shows the aspherical data for Example 2. The terms used in Table 7 are defined below. A: Fourth-order aspherical coefficients B: Sixth-order aspherical coefficients C: 8th-order aspherical coefficient D: 10th-order aspherical coefficient [Table 7] SuNo 5 6 10 12 R -0.0033 -0.0094 0.0235 0.0029 k -3.059334E+02 -1.061521E+02 4.250405E+01 3.506869E+02 A 0.000000E+00 0.000000E+00 -3.232399E-01 4.502167E+01 B 2.767998E-06 1.772463E-06 -1.711107E-06 2.614078E-06 C -1.877724E-09 -1.464826E-09 5.830137E-10 -6.789367E-10 D 4.69008E-13 2.98425E-13 -1.64402E-13 1.55824E-13

[0090] Table 8 shows the XY polynomial surface data for Example 2. [Table 8] SuNo 8 9 11 R -153.7022973 -76.11373632 -57.37178972 k -1.75E+00 -7.84E-01 -9.13E-01 C-x4 -6.14447E-08 -5.04573E-07 5.97035E-07 C-x2y2 -1.22579E-07 3.84921E-09 -3.71172E-06 C-y4 -6.15013E-08 -1.97105E-06 -2.14479E-07 C-x6 -2.24865E-13 -9.47912E-10 -1.74977E-09 C-x4y2 -1.57103E-12 6.46022E-10 -2.12943E-10 C-x2y4 -1.33344E-12 1.71838E-10 4.27392E-10 C-y6 -4.48952E-13 4.56109E-10 -2.64272E-10 C-x8 -6.52794E-17 8.18747E-13 1.26535E-12 C-x6y2 1.80997E-16 2.97945E-13 1.57809E-12 C-x4y4 1.7432E-16 -2.73843E-13 4.5708E-13 C-x2y6 -5.70596E-17 -5.6652E-14 1.80449E-13 C-y8 -6.55454E-18 -4.82723E-14 6.16036E-14

[0091] Figure 8 is a cross-sectional view of the optical device 50 of Example 2.

[0092] The optical device 50 includes a prism PR, a lens 41, an internal reflective element 42, and a mirror element 43. The internal reflective element 42 is an integrated first optical element 42a and a second optical element 42b. The mirror element 43 is positioned opposite the internal reflective element 42.

[0093] The first optical element 42a has a third reflective surface 4c, a first transmissive surface 5a, and a second transmissive surface 5b. The third reflective surface 4c is a concave inner surface reflective surface W1. In the first optical element 42a, the refractive surfaces W3 through which incident and reflected light pass are different for the first transmissive surface 5a and the second transmissive surface 5b. The first transmissive surface 5a, the third reflective surface 4c, and the second transmissive surface 5b have positive power.

[0094] The second optical element 42b has a first reflective surface 4a. The first reflective surface 4a is a concave surface reflective surface W2. A first aperture diaphragm ST1 is positioned on the first reflective surface 4a. A first light absorbing member AB01 is provided on the back surface 6a of the lens barrel member 49, facing the back surfaces of the first reflective surface 4a and the third reflective surface 4c.

[0095] The mirror element 43 has a second reflective surface 4b which is the surface reflective surface W4.

[0096] The optical device 50 has a first reflective surface 4a, a second reflective surface 4b, a first transmitting surface 5a, a third reflective surface 4c, and a second transmitting surface 5b in the optical path, in the order from the reduction side to the expansion side. The first reflective surface 4a, the first transmitting surface 5a, and the second transmitting surface 5b are arranged on the reduction side conjugate surface RC side of the internal reflective element 42, that is, on the second reflective surface 4b side. The third reflective surface 4c is arranged on the opposite side of the reduction side conjugate surface RC of the internal reflective element 42, that is, on the opposite side of the first reflective surface 4a.

[0097] Figures 9 and 10 show the lateral aberration characteristics of the optical device 50 or projection optical system 40 of Example 2. Figure 11 is a diagram illustrating the relationship between the display surface 2a of the liquid crystal panel 29G and the projection surface 2b of the screen SC of Example 2.

[0098] The optical device 50 of the second embodiment shown in Figure 8, etc., is not limited to the illustrated structure and can be modified in various ways within the scope of the gist of the invention.

[0099] As shown in Figure 12, the first light absorbing member AB01 is not limited to being provided on the inner surface of the lens barrel member 49 spaced apart from the inner surface reflecting element 42, but may also be arranged to lie along the step between the first transmitting surface 5a and the first reflecting surface 4a.

[0100] As shown in Figure 13, the first light-absorbing member AB01 may be attached to the back surface 6a so as to cover the entire back surface 6a that extends downward from the lower end of the third reflective surface 4c.

[0101] The first reflective surface 4a may also be a back surface reflective surface, in which case a third transmissive surface 5c, as shown in Figure 3, is added.

[0102] [Third Embodiment] The optical apparatus of the third embodiment will be described below. Note that the optical apparatus of the third embodiment is a partial modification of the optical apparatus of the first embodiment, and the parts common to the optical apparatus of the first embodiment will not be described.

[0103] Figure 14 is a diagram illustrating a camera 102 incorporating an optical device 150 according to the third embodiment. As shown in Figure 14, the camera 102 includes an optical system portion 60 that images the subject OB, and a circuit device 80 that controls the operation of the optical system portion 60. The optical system portion 60 includes an imaging optical system 140 that forms an image of the subject OB, and an image detection device 120 that detects the image.

[0104] The image detection device 120 has an image sensor 129. The image sensor 129 is positioned on the reduction-side conjugate surface RC of the optical device 150. In this embodiment, the optical device 150 is an imaging optical device 151. The optical device 150 illustrated in Figure 14 has the same configuration as the optical device 50 of Example 1 (see Figure 3, etc.). Alternatively, the optical device 150 may be the optical device 50 of Example 2 (see Figure 9, etc.). The imaging optical device 151 is obtained by omitting the prism PR that constitutes the optical device 50 of Examples 1 and 2, or by replacing it with a cover glass that is not shown.

[0105] The optical device 150 forms an image of the subject OB using the imaging optical system 140 and acquires the image detected by the imaging surface 2c of the image sensor 129.

[0106] [Other matters] The structure described above is an example, and can be modified in various ways as long as similar functionality can be achieved.

[0107] For example, in each embodiment, the optical device 50 may have one or more substantially powerless lenses added to it.

[0108] Furthermore, the optical device 50 can project images not only formed by the liquid crystal panels 29R, 29G, and 29B, but also images formed by optical modulation elements such as digital micromirror devices.

[0109] Furthermore, the second light-absorbing member AB02, i.e., the second aperture diaphragm ST2, may be omitted.

[0110] The optical devices 50 and 150 can be incorporated not only into projectors 2, but also into head-up displays, in-vehicle projection systems, and the like.

[0111] [Summary of this disclosure] A summary of this disclosure is provided below.

[0112] (Note 1) A first reflective surface that possesses power, A second reflective surface having power is positioned on the enlarged side of the first reflective surface, A first optical element having a first transmissive surface, a third reflective surface with a concave shape and power, and a second transmissive surface different from the first transmissive surface, arranged in order from the contraction side toward the enlargement side of the second reflective surface, An aperture diaphragm positioned on the first reflective surface, A first light absorbing member that absorbs light passing outside the first reflective surface, Equipped with, optical equipment. The first and second transmitting surfaces allow the incident and exit surfaces of the first optical element to have different functions, thereby improving optical performance. Furthermore, by making the third reflecting surface an internal reflecting surface, the size of the third reflecting surface can be reduced, allowing for miniaturization of the entire optical system. As a result, it is possible to achieve a shorter focal length for the optical device and to miniaturize the optical device. Moreover, by providing an aperture diaphragm function to the internally reflective second optical element having the first reflecting surface, ray control at the diaphragm position becomes easier, which is advantageous for improving optical performance. In addition, the first light absorbing member can block unwanted light that passes outside the first and third reflecting surfaces and causes stray light, such as image light reflected by the first and third reflecting surfaces.

[0113] (Note 2) In the optical apparatus described in Appendix 1, The second optical element further comprises the first reflective surface and a third transmissive surface through which both incident light incident on the first reflective surface and reflected light reflected by the first reflective surface are transmitted. The third transparent surface has power, The aperture diaphragm is positioned on the first reflective surface of the second optical element, optical equipment. By having the incident and exiting light rays pass through the third transmission surface, which is the same refractive surface, it becomes possible to control the light rays in a way that is not possible with surface reflection, thereby improving optical performance in a space-saving manner.

[0114] (Note 3) In the optical apparatus described in Appendix 2, The device further comprises a second light-absorbing member that absorbs light passing outside the effective light-transmitting region of the third transmissive surface through which the light reflected by the first reflective surface is transmitted. optical equipment. By having the incident and exiting light rays of the second optical element pass through a third transmission surface, which is the same refractive surface, light ray control that is not possible with surface reflection becomes possible, and optical performance can be improved in a space-saving manner. Furthermore, by adding an aperture function to the internal reflection type second optical element having a first reflective surface, light ray control at the aperture position becomes easier, which is advantageous for improving optical performance.

[0115] (Note 4) In the optical apparatus described in either Appendix 2 or 3, The first optical element and the second optical element are an integrated internal reflective element. optical equipment. As a result, since the first and second optical elements are composed of the same element, cost reduction and improved assembly accuracy can be achieved.

[0116] (Note 5) In an optical device described in any one of the appendices 1 to 4, An intermediate image is formed between the first transmission surface and the third reflection surface. optical equipment. This creates an intermediate image in the optical path on the reduced side of the concave third reflecting surface, and by re-imaging this intermediate image with the third reflecting surface, it becomes possible to shorten the focal length.

[0117] (Note 6) In an optical device described in any one of the appendices 1 to 5, The first and second transparent surfaces have power. optical equipment.

[0118] (Note 7) In an optical device described in any one of the appendices 1 to 6, The system further comprises a positive lens positioned between the conjugate surface on the reduction side and the first reflective surface. optical equipment. This allows for telecentricity on the reduction side. Furthermore, it suppresses the spread of the light beam, enabling miniaturization of the entire optical system.

[0119] (Note 8) In an optical device described in any one of the appendices 1 to 6, The system further comprises a positive lens positioned between the conjugate plane on the reduction side and the first reflective surface, The optical axis of the aforementioned lens is shifted to the opposite side of the conjugate plane from the center of the conjugate plane on the reducing side, relative to the conjugate plane on the expanding side. optical equipment. This not only suppresses the spread of the light beam and allows for a miniaturization of the entire optical system, but also allows the position of the first reflecting surface to be placed on the lower side, opposite to the enlargement-side conjugate surface, relative to the central axis of the reduction-side conjugate surface, thereby reducing the height of the optical system positioned above the first reflecting surface.

[0120] (Note 9) An optical device described in any one of the appendices 1 to 8, The optical device comprises an image forming unit that forms an image on the reduced-side conjugate surface, Equipped with, projector. This makes it possible to miniaturize projectors equipped with optical devices while suppressing the generation of stray light.

[0121] (Note 9) An optical device described in any one of the appendices 1 to 8, An image sensor arranged on the reduced conjugate surface of the optical device, Equipped with, Imaging device. This makes it possible to miniaturize imaging devices equipped with optical devices while suppressing the generation of stray light. [Explanation of Symbols]

[0122] 2...Projector, 2a...Display surface, 2b...Projection surface, 2c...Imaging surface, 4a~4e...Reflective surface, 5a~5c...Transmitting surface, 10...Light source device, 20...Image display device, 20a...Separation optical system, 20b...Image forming unit, 29R,29G,29B...Liquid crystal panel, 31...Cross dichroic prism, 40...Projection optical system, 41...Lens, 42,142,145...Internal reflection element, 42a,42b,42c...Optical element, 43...Mirror element, 49...Lens barrel member, 50...Optical device, 51...Projection optical device, 60...Optical system part, 80...Circuit device, 102 ...camera, 120...image detection device, 129...image sensor, 140...imaging optical system, 150...optical device, 151...imaging optical device, AB01...first light absorbing member, AB02...second light absorbing member, AB3...third light absorbing member, AB4...fourth light absorbing member, AN...moving mechanism, MC...magnifying conjugate surface, OA...device optical axis, OA2...lens optical axis, OB...subject, OM...light modulation element, OX...central axis, PR...prism, RC...reducing conjugate surface, SC...screen, ST1,ST2...aperture diaphragm, W1...internal reflective surface, W2,W4...surface reflective surface, W3...refracting surface

Claims

1. A first reflective surface that possesses power, A second reflective surface having power is positioned on the enlarged side of the first reflective surface, A first optical element having a first transmissive surface, a third reflective surface with a concave shape and power, and a second transmissive surface different from the first transmissive surface, arranged in order from the contraction side toward the enlargement side of the second reflective surface, An aperture diaphragm positioned on the first reflective surface, A first light absorbing member that absorbs light passing outside the first reflective surface, Equipped with, optical equipment.

2. In the optical apparatus described in claim 1, The second optical element further comprises the first reflective surface and a third transmissive surface through which both incident light incident on the first reflective surface and reflected light reflected by the first reflective surface are transmitted. The third transparent surface has power, The aperture diaphragm is positioned on the first reflective surface of the second optical element. optical equipment.

3. In the optical apparatus described in claim 2, The device further comprises a second light-absorbing member that absorbs light passing outside the effective light-transmitting region of the third transmissive surface through which the light reflected by the first reflective surface is transmitted. optical equipment.

4. In the optical apparatus described in claim 2, The first optical element and the second optical element are an integrated internal reflective element. optical equipment.

5. In the optical apparatus according to any one of claims 1 to 4, An intermediate image is formed between the first transmission surface and the third reflection surface. optical equipment.

6. In the optical apparatus according to any one of claims 1 to 4, The first and second transparent surfaces have power. optical equipment.

7. In the optical apparatus according to any one of claims 1 to 4, The system further comprises a positive lens positioned between the conjugate surface on the reduction side and the first reflective surface. optical equipment.

8. In the optical apparatus according to any one of claims 1 to 4, The system further comprises a positive lens positioned between the conjugate surface on the reduction side and the first reflective surface, The optical axis of the aforementioned lens is shifted to the opposite side of the conjugate plane from the center of the conjugate plane on the reducing side, relative to the conjugate plane on the expanding side. optical equipment.

9. The optical apparatus according to claim 1, The optical device comprises an image forming unit that forms an image on the reduced-side conjugate surface, Equipped with, projector.

10. The optical apparatus according to claim 1, An image sensor arranged on the reduced conjugate surface of the optical device, Equipped with, Imaging device.

Images