Projection optical system and projection type display device

Abstract

The utility model provides a small projection optical system capable of projecting a bright and large projection image from the vicinity of a screen, and a projection type display device provided with the projection optical system. The projection optical system projects an image displayed on the display surface of the display element on the reduction side onto the projection surface on the enlargement side, does not include a reflective surface having refractive power, and includes at least one optical path deflection surface in the optical path, the optical path deflection surface bending the optical path by 90 degrees. [sigma] THe is the sum of the thicknesses of all optical elements on the optical axis from the lens surface closest to the magnification side of the projection optical system to the lens surface closest to the reduction side of the projection optical system, Imax is the height of the optical axis of the maximum effective light from the display surface, and f is the focal length of the projection optical system. The projection optical system satisfies sigma THe < 70 mm and 1.7 < Imax / f.

Description

Technical Field

[0001] The technology of the present invention relates to a projection optical system and a projection display device. Background Art

[0002] As optical systems applicable to projection display devices, optical systems described in Patent Documents 1 and 2 listed below are known.

[0003] Patent Document 1: Japanese Patent No. 6939469

[0004] Patent Document 2: Japanese Patent Application Publication No. 2022-124901

[0005] A projection optical system capable of projecting a large screen from near a screen is required. In order to project a large screen, a bright projection display device is required. In addition, a projection display device that is small and highly portable is required so that projection can be performed in various places. Summary of the invention

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a small projection optical system capable of projecting a bright and large projection image from near a screen, and a projection type display device including the projection optical system.

[0007] One embodiment of the present invention is a projection optical system for projecting an image displayed on a display surface of a display element on a reduction side onto a projection surface on an enlargement side, wherein the projection optical system does not include a reflection surface having optical focal power, and includes at least one optical path deflection surface for bending the optical path by 90 degrees in an optical path of the projection optical system, and when the sum of the thicknesses on the optical axis of all optical elements included in the range from the lens surface of the projection optical system closest to the enlargement side to the lens surface of the projection optical system closest to the reduction side is set to ∑THe, the height of the optical axis of the maximum effective light on the display surface is set to Imax, the focal length of the projection optical system is set to f, when the projection optical system is a variable magnification optical system, f is set to a value at the wide-angle end, and mm is set to millimeters as a unit of length, the following conditional expressions (1) and (2) are satisfied:

[0008] ∑THe<70mm (1)

[0009] 1.7<Imax / |f| (2).

[0010] The projection optical system of the above aspect preferably satisfies at least one of the following conditional expressions (1-1) and (2-1):

[0011] 30mm<∑THe<70mm (1-1)

[0012] 2<Imax / |f|<3.5 (2-1).

[0013] The projection optical system of the above-mentioned method preferably includes only two optical path deflection surfaces in the optical path of the projection optical system, and when the distance on the optical axis from the optical path deflection surface on the magnification side to the optical path deflection surface on the reduction side is set to d1, the distance on the optical axis from the optical path deflection surface on the reduction side to the lens surface of the projection optical system closest to the reduction side is set to d2, and when the projection optical system is a variable magnification optical system, d1 and d2 are set to values ​​at the wide-angle end, the following conditional expressions (3) and (4) are satisfied:

[0014] d1<70mm (3)

[0015] d2<100mm (4).

[0016] The projection optical system of the above aspect preferably satisfies at least one of the following conditional expressions (3-1) and (4-1) in addition to satisfying conditional expressions (3) and (4).

[0017] 10mm<d1<50mm (3-1)

[0018] 20mm<d2<75mm (4-1).

[0019] When the longest diameter of the largest area capable of displaying an image on the display element is DL, the projection optical system of the above-mentioned embodiment preferably satisfies the conditional expression (5) represented by the following:

[0020] Imax / DL<0.78 (5)

[0021] It is more preferable to satisfy the conditional formula (5-1) represented by the following:

[0022] 0.65<Imax / DL<0.72 (5-1).

[0023] When the height of the optical axis of the maximum effective light on the projection surface is set to Ymax, the paraxial image magnification of the projection optical system when the magnification side is set to the object side and the reduction side is set to the image side is set to β, and when the projection optical system is a variable magnification optical system, β is set to a value at the wide-angle end, the projection optical system of the above-mentioned method preferably satisfies the conditional expression (6) represented by the following,

[0024] -0.05<(Imax-β×Ymax) / (β×Ymax)<0.05 (6)

[0025] It is more preferable to satisfy the conditional formula (6-1) represented by the following:

[0026] -0.03<(Imax-β×Ymax) / (β×Ymax)<0.03 (6-1).

[0027] When the sum of the thicknesses on the optical axis of all optical elements having optical power included from the lens surface closest to the magnification side of the projection optical system to the lens surface closest to the reduction side of the projection optical system is set as ∑THpw, and the sum of the thicknesses on the optical axis of all optical elements having optical power included from the lens surface closest to the magnification side of the projection optical system to the lens surface closest to the reduction side of the projection optical system and having a refractive index of 1.8 or more with respect to the d-line is set as ∑TH18, the projection optical system of the above-described embodiment preferably satisfies the conditional expression (7) represented by the following:

[0028] 0.27<∑TH18 / ∑THpw<0.5 (7)

[0029] It is more preferable to satisfy the conditional formula (7-1) represented by the following:

[0030] 0.3<∑TH18 / ∑THpw<0.4 (7-1).

[0031] Preferably, the intermediate image is formed inside the projection optical system.

[0032] The projection optical system of the above aspect preferably includes only two optical path deflection surfaces in the optical path of the projection optical system, and an intermediate image is formed in the optical path between the optical path deflection surface on the magnification side and the surface adjacent to the reduction side of the optical path deflection surface on the reduction side.

[0033] The aperture diaphragm is included on the reduction side of the intermediate image, and the real image of the aperture diaphragm exists inside the projection optical system on the magnification side of the intermediate image. The position where the light rays emitted from the outermost periphery of the effective image circle on the reduction side and passing through the center of the aperture diaphragm toward the magnification side intersect the optical axis on the magnification side of the intermediate image is set to Enp(Imax), and the position of the paraxial image of the aperture diaphragm is set to Fnp(0).

[0034] The air conversion distance on the optical axis from Enp(0) to Enp(Imax) is set to DifE, and the sign of DifE is set to positive for the distance on the reduction side and negative for the distance on the magnification side based on Enp(0). When the projection optical system is a variable magnification optical system, when DifE is set to a value at the wide-angle end, the projection optical system of the above-mentioned method preferably satisfies the conditional expression (8) represented by the following:

[0035] -3<DifE / Imax<-0.2 (8)

[0036] It is more preferable to satisfy the conditional formula (8-1) represented by the following:

[0037] -2.5<DifE / Imax<-0.5 (8-1).

[0038] The lens closest to the magnification side may be configured to have a rotationally symmetrical shape with a portion thereof missing.

[0039] At least one of the light path deflecting surfaces may be a surface of a reflector. At least one of the light path deflecting surfaces may be a surface of a prism.

[0040] Another aspect of the present invention is a projection display device including the projection optical system of the above aspect.

[0041] In addition, the term "including to" in this specification means that, in addition to the constituent elements listed above, it may also include: a lens that essentially has no refractive power; optical elements other than lenses such as an aperture, a mask, a filter, a cover glass, a plane mirror and a prism; and mechanical parts such as a lens flange, a lens barrel, an imaging element and a hand shake correction mechanism.

[0042] A composite aspheric lens (a lens (e.g., a spherical lens) and a film having an aspheric shape formed on the lens are integrated to function as a single aspheric lens as a whole) is used as a single lens and is not considered a cemented lens. Unless otherwise specified, the sign of the refractive power and the surface shape associated with the lens including the aspheric surface use the sign of the refractive power and the surface shape of the paraxial region. Unless otherwise specified, the "distance on the optical axis" used in the conditional expression is a geometric distance. The "focal length" used in the conditional expression is the paraxial focal length. The value used in the conditional expression is the value when the d line is used as a reference. The "mm" used in the conditional expression is millimeters, which is the unit of length.

[0043] The "d line", "C line" and "F line" described in this specification are clear lines, and the wavelength of the d line is considered to be 587.56 nm (nanometers), the wavelength of the C line is considered to be 656.27 nm (nanometers), and the wavelength of the F line is considered to be 486.13 nm (nanometers).

[0044] Effects of the Invention

[0045] According to the present invention, it is possible to provide a small-sized projection optical system capable of projecting a bright and large projection image from near a screen, and a projection type display device including the projection optical system. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is a cross-sectional view corresponding to the projection optical system of Example 1, showing the structure of the projection optical system involved in one embodiment and light beams.

[0047] Figure 2 It is a diagram showing examples of Imax and DL.

[0048] Figure 3 In the expansion Figure 1 In the cross-sectional view of the optical path of the projection optical system, a diagram showing Enp(0) and Enp(Imax) is shown.

[0049] Figure 4 exist Figure 3 A partial enlarged view of shows the DifE diagram.

[0050] Figure 5 middle, Figure 5 (A) Figure 5 (B) and Figure 5 (C) is a diagram showing an example of the shape of a lens in which a part of the rotationally symmetric shape is missing.

[0051] Figure 6 1 and 2 are diagrams showing various aberrations of the projection optical system of Example 1.

[0052] Figure 7 It is a cross-sectional view showing the structure of the projection optical system and light beams of Example 2.

[0053] Figure 8 1 and 2 are diagrams showing various aberrations of the projection optical system of Example 2.

[0054] Fig. 9 It is a cross-sectional view showing the structure of the projection optical system and the light beam of Example 3.

[0055] Fig.10 It means expansion Fig. 9 The structure of the optical path of the projection optical system and the cross-sectional view of the light beam.

[0056] Fig.11 1 and 2 are diagrams showing various aberrations of the projection optical system of Example 3.

[0057] Fig.12 It is a cross-sectional view showing the structure of the projection optical system and the light beam of Example 4.

[0058] Fig.13 These are various aberration diagrams of the projection optical system of Example 4.

[0059] Fig.14 It is a cross-sectional view showing the structure of the projection optical system and the light beam of Example 5.

[0060] Fig.15 These are various aberration diagrams of the projection optical system of Example 5.

[0061] Fig.16 It is a cross-sectional view showing the structure of the projection optical system and the light beam of Example 6.

[0062] Fig.17These are various aberration diagrams of the projection optical system of Example 6.

[0063] Fig.18 It is a schematic structural diagram of a projection display device according to one embodiment.

[0064] Fig.19 It is a schematic structural diagram of a projection display device according to another embodiment.

[0065] Fig. 20 It is a schematic structural diagram of a projection display device according to still another embodiment.

[0066] Explanation of symbols

[0067] 2-light, 10-optical system for projection, 11a~11c-transmission type display element, 12-dichroic mirror, 13-dichroic mirror, 14-cross dichroic prism, 15-light source, 16a~16c-condensing lens, 18a~18c-total reflection mirror, 21a~21c-DMD element, 24a~24c-TIR prism, 25-polarized light separation prism, 61-light source, 62-color wheel, 63-light guiding optical system, 64-DMD element, 65-TIR prism, 66-optical system for projection, 67-screen, 100-projection type display device, 105-screen, 200-projection type display device, 205-screen, 210-optical system for projection, 215-light source, 600-projection display device, d1-distance, d2-distance, DA-maximum display area, DifE-air conversion distance, DL-longest diameter, Enp(0)-position, Enp(Imax)-position, IC-effective image circle, Imax-height, L1~L21-lens, MI-intermediate image, Mr1-reflector, Mr2-reflector, PP-optical component, Pr-prism, R1-reflecting surface, R2-reflecting surface, Scr-screen, Sim-display surface, St-aperture aperture, Ymax-height, Z-optical axis. DETAILED DESCRIPTION

[0068] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0069] Figure 1 , a cross-sectional view of a structure of a projection optical system and a light beam according to an embodiment of the present invention is shown. Figure 1 In FIG. 1 , as light beams, an axial light beam and a light beam with a maximum viewing angle are shown. Figure 1 The example shown corresponds to the projection optical system of Example 1 described later.

[0070] exist Figure 1In the figure, an example is shown in which an optical system for projection is assumed to be mounted on a projection-type display device and an optical component PP and a display surface Sim of a light valve are arranged on the reduction side of the projection optical system. The light valve is a display element that outputs an optical image, and the optical image is displayed on the display surface Sim in the form of an image. As the light valve, for example, an image display element such as a liquid crystal display element or a DMD (digital micromirror device: registered trademark) can be used. The optical component PP is a component that is assumed to be a filter, a cover glass, a color synthesis prism, etc. The optical component PP is a component that does not have a refractive power. The material, length, and number of parts of the optical component PP can be appropriately changed, and a structure in which the optical component PP is omitted is also possible.

[0071] The projection optical system is, for example, mounted on a projection type display device and projects the image of the display surface Sim of the display element displayed on the reduction side onto the projection surface on the magnification side. In the projection type display device, a light beam given image information on the display surface Sim is incident on the projection optical system via an optical component PP, and is projected onto the screen Scr as the projection surface by the projection optical system. That is, the display surface Sim and the screen Scr are located at optically conjugate positions. The display surface Sim corresponds to the conjugate surface on the reduction side, and the screen Scr corresponds to the conjugate surface on the magnification side. In addition, in this specification, the "screen Scr" means the object on which the projection image formed by the projection optical system is projected. As the screen Scr, in addition to a dedicated screen, it can also be a wall surface, a floor surface, a ceiling, and an outer wall of a building in a room.

[0072] Furthermore, in the description of this specification, the "magnification side" means the screen Scr side on the optical path, and the "reduction side" means the display surface Sim side on the optical path. In this specification, the "magnification side" and the "reduction side" are determined along the optical path. Furthermore, "adjacent" in relation to the arrangement of the constituent elements means adjacent as the arrangement order on the optical path. In the following, in order to avoid redundant descriptions, "from the magnification side toward the reduction side along the optical path in sequence" is sometimes described as "from the magnification side toward the reduction side in sequence".

[0073] As an example, Figure 1 The projection optical system includes lenses L1 to L12, a reflector Mr1, a lens L13, a reflector Mr2, lenses L14 to L17, an aperture stop St, and lenses L18 to L21 in order from the magnification side to the reduction side along the optical path. Figure 1 The aperture stop St shown indicates the position in the optical axis direction, and does not indicate the size or shape.

[0074] The reflectors Mr1 and Mr2 are optical path deflection components that bend the optical path. The reflector Mr1 has a planar reflective surface R1. The reflector Mr2 has a planar reflective surface R2. The reflective surfaces R1 and R2 are surfaces without optical power. The optical path is bent 90 degrees on the reflective surfaces R1 and R2, respectively.

[0075] The projection optical system of the present invention is configured to not include a reflective surface with optical power. Usually, in a projection optical system including a reflective surface with optical power, a light beam near the optical axis reflected by the reflective surface is shielded by the projection type display device and cannot be used in the formation of a projection image. Therefore, in order to avoid this shielding, it is configured to displace the center position of the image of the display surface Sim from the optical axis Z of the projection optical system, and the displacement amount is mostly increased. Therefore, in a projection optical system including a reflective surface with optical power, the size of the reflective surface with optical power tends to become larger, and thus it is not easy to miniaturize. In contrast, the projection optical system of the present invention does not include a reflective surface with optical power, so the light beam near the optical axis can also be used in the formation of a projection image, and even in the case of the above-mentioned displacement, the displacement amount can be reduced. By reducing the displacement amount, the miniaturization of each optical element can be achieved, and thus the miniaturization of the optical system as a whole can be achieved.

[0076] The projection optical system of the present invention includes at least one optical path deflection surface that bends the optical path by 90 degrees in the optical path of the projection optical system. The optical system can be compactly constructed by bending the optical path, so it can contribute to miniaturization. In addition, the above-mentioned "90 degrees" includes the actual allowable error in the technical field to which the technology of the present invention belongs. The error can be set within the range of more than -1 degree and less than +1 degree, for example.

[0077] At least one of the light path deflection surfaces may be a surface of a reflector. In this case, it is beneficial to reduce weight. The reflector may be a metal reflector or a dielectric multilayer reflector. At least one of the light path deflection surfaces may be a surface of a prism. In this case, it is beneficial to ensure performance during assembly. The surface of the prism formed by the reflective film may be used as the light path deflection surface, or the surface of the prism may be used as the light path deflection surface by utilizing total reflection.

[0078] Figure 1 The projection optical system of the example includes two light path deflection surfaces that bend the light path by 90 degrees. Figure 1 In the example, the reflecting surface R1 and the reflecting surface R2 correspond to the light path deflecting surfaces.

[0079] The projection optical system of the present invention preferably forms an intermediate image MI inside the projection optical system. When the focal length of the projection optical system is shortened to achieve a wide angle, if the back focal length required in the projection optical system is to be ensured and the required optical performance is to be achieved, the lens on the magnification side tends to become huge. By setting the relay optical system in which the intermediate image MI is formed inside, the back focal length of the optical system closer to the magnification side than the intermediate image MI can be shortened, and the lens diameter on the magnification side can be reduced, which is conducive to miniaturization.

[0080] exist Figure 1 In the example of FIG. 1 , an intermediate image MI is formed between the lens L13 and the reflector Mr2. The image on the display surface Sim, the intermediate image MI, and the projected image on the screen Scr are in an optically conjugate relationship. Figure 1 In FIG. 1 , an intermediate image MI is conceptually shown by a dotted line. Figure 1 The shape of the middle like MI is not accurate.

[0081] When the projection optical system includes only two optical path deflection surfaces in its optical path, it is preferred to form an intermediate image MI in the optical path between the optical path deflection surface on the magnification side and the surface adjacent to the reduction side of the optical path deflection surface on the reduction side. In this case, it is advantageous to suppress the size of the projection optical system in two directions perpendicular to each other. The “two directions perpendicular to each other” mentioned here are, for example, Figure 1 up and down directions and left and right directions.

[0082] Next, the preferred structure and the achievable structure related to the conditional formula of the projection optical system of the present invention are described. In the following description of the conditional formula, in order to avoid redundant description, the same symbols are used for the parts with the same definition, and the repeated description of the symbols is omitted. And, in order to avoid redundant description, the "projection optical system of the present invention" is also referred to as the "projection optical system".

[0083] The projection optical system preferably satisfies the following conditional formula (1). Here, the sum of the thicknesses on the optical axis of all optical elements included in the lens surface closest to the magnification side of the projection optical system to the lens surface closest to the reduction side of the projection optical system is set to ∑THe. In the case where optical elements other than lenses, such as prisms, are arranged from the lens surface closest to the magnification side of the projection optical system to the lens surface closest to the reduction side of the projection optical system, the above-mentioned "all optical elements" also include the prism. By not being above the upper limit of conditional formula (1), the transmittance caused by the internal absorption of the material of the optical element of the projection optical system will not be too low, so it is easy to ensure the brightness of the optical engine. The projection optical system of the present invention more preferably satisfies the following conditional formula (1-1). By not being below the lower limit of conditional formula (1-1), the thickness of each optical element will not become too thin, so it is easy to perform aberration correction on the ultra-wide-angle optical system, especially the correction of distortion aberration and the correction of field curvature.

[0084] ∑THe<70mm (1)

[0085] 30mm<∑THe<70mm (1-1)

[0086] The projection optical system preferably satisfies the following conditional formula (2). Here, the height of the optical axis Z of the maximum effective light from the display surface Sim is set to Imax. The focal length of the projection optical system is set to f. When the projection optical system is a variable magnification optical system, f is set to the value under the wide-angle end. The effective light is the light used in the formation of the projection image. The maximum effective light is the light farthest from the optical axis Z in the radial direction among the light used in the formation of the projection image. When the reduction side is set to the image side, the above-mentioned height Imax is the maximum image height of the projection optical system. By not being below the lower limit of conditional formula (2), a large-screen projection image can be projected in a state where the distance between the projection optical system and the screen Scr is short. In order to obtain better characteristics, the projection optical system more preferably satisfies the following conditional formula (2-1). By not being above the upper limit of conditional formula (2-1), it is easy to take into account both the miniaturization and projection performance of the projection type display device.

[0087] 1.7<Imax / |f| (2)

[0088] 2<Imax / |f|<3.5 (2-1)

[0089] In the case where the projection optical system includes only two light path deflection surfaces in its light path, the projection optical system preferably satisfies the following conditional expression (3). Here, the distance on the optical axis from the light path deflection surface on the magnification side to the light path deflection surface on the reduction side is set to d1. In the case where the projection optical system is a variable magnification optical system, the distance d1 is set to a value at the wide-angle end. By not exceeding the upper limit of conditional expression (3), the direction of the distance d1 (in the Figure 1 In the case where the direction of the distance d1 is set as the thickness direction of the projection display device, it is conducive to the thinning of the projection display device. In order to obtain better characteristics, the projection optical system more preferably satisfies the following conditional formula (3-1). By not being below the lower limit of the conditional formula (3-1), the interference between the projection display device body and the projected image can be suppressed, and the interference between the optical element from the optical element closest to the magnification side to the optical path deflection surface on the magnification side and the optical element from the display element to the optical path deflection surface on the reduction side can be suppressed.

[0090] d1<70mm (3)

[0091] 10mm<d1<50mm (3-1)

[0092] In the case where the projection optical system includes only two light path deflection surfaces in its light path, the projection optical system preferably satisfies the following conditional expression (4). Here, the distance on the optical axis from the light path deflection surface on the reduction side to the lens surface of the projection optical system closest to the reduction side is set to d2. In the case where the projection optical system is a variable magnification optical system, the distance d2 is set to a value below the wide-angle end. By not exceeding the upper limit of conditional expression (4), the direction of the distance d2 (in Figure 1 The projection optical system in the left and right directions (in the middle, left and right directions) is long, so it is easy to miniaturize. When the direction of the distance d2 is set to the direction parallel to the setting surface of the projection type display device, it is beneficial to make the area required in the setting of the projection type display device smaller. In order to obtain better characteristics, the projection optical system more preferably satisfies the following conditional formula (4-1). By not being below the lower limit of the conditional formula (4-1), the total length of the optical system can be shortened without excessively, so it is beneficial to correct the field curvature when widening the angle.

[0093] d2<100mm (4)

[0094] 20mm<d2<75mm (4-1)

[0095] When the projection optical system includes only two light path deflection surfaces in its light path, the projection optical system preferably satisfies conditional expressions (3) and (4). By satisfying conditional expressions (3) and (4), the projection optical system can promote the miniaturization of the projection type display device. In addition, for further miniaturization and good characteristics, the projection optical system is more preferably, on the basis of satisfying conditional expressions (3) and (4), satisfying at least one of conditional expressions (3-1) and (4-1).

[0096] The projection optical system preferably satisfies the following conditional formula (5). Here, the longest diameter of the maximum area in the display element that can display an image is set to DL. By not being above the upper limit of conditional formula (5), the overall enlargement of the optical system can be suppressed, and in particular, the enlargement of the lens on the magnification side can be suppressed, so it is easy to miniaturize. In order to obtain better characteristics, the projection optical system more preferably satisfies the following conditional formula (5-1). By not being below the lower limit of conditional formula (5-1), it is easy to prevent the projection image from being shielded by the projection display device body.

[0097] Imax / DL<0.78 (5)

[0098] 0.65<Imax / DL<0.72 (5-1)

[0099] DL is described below. In the following description of DL, for ease of explanation, "the maximum area in the display element that can display an image" is referred to as the maximum display area. DL in this specification refers to a value that is twice the distance between the center of gravity of the maximum display area and the point in the maximum display area that is farthest from the center of gravity in a plane perpendicular to the optical axis Z. For example, when the maximum display area is a rectangle, the length of the diagonal of the rectangle is DL. For example, when the maximum display area is a perfect circle, the diameter of the perfect circle is DL. For example, when the maximum display area is an ellipse, the major diameter of the ellipse is DL.

[0100] As an example, Figure 2 In FIG. 1 , a rectangular maximum display area DA and a longest diameter DL of the maximum display area DA are shown. Figure 2 In the example shown in FIG. 1 , the diagonal length of the maximum area DA is equal to the longest diameter DL. Figure 2 It is a diagram on a plane perpendicular to the optical axis Z, and also shows the effective image circle IC on the reduction side and the height Imax as an example.

[0101] The projection optical system preferably satisfies the following conditional formula (6). Here, the height of the optical axis Z of the maximum effective light from the projection surface is set to Ymax. The paraxial image magnification of the projection optical system in the case where the magnification side is set to the object side and the reduction side is set to the image side is set to β. And, in the case where the projection optical system includes a variable magnification optical system, β is set to the value at the wide-angle end. In the case where the magnification side is set to the object side, the above-mentioned height Ymax is the maximum object height of the projection optical system. In a projection-type display device, it is required to project a projection image without deformation at the eye level. By satisfying conditional formula (6), distortion aberration can be suppressed, so it can correspond to the above requirements. In order to obtain better characteristics, the projection optical system more preferably satisfies the following conditional formula (6-1).

[0102] -0.05<(Imax-β×Ymax) / (β×Ymax)<0.05 (6)

[0103] -0.03<(Imax-β×Ymax) / (β×Ymax)<0.03 (6-1)

[0104] The projection optical system preferably satisfies the following conditional expression (7). Here, the sum of the thicknesses on the optical axis of all optical elements with optical power included from the lens surface closest to the magnification side of the projection optical system to the lens surface closest to the reduction side of the projection optical system is set to ∑THpw. Among the optical elements with optical power included from the lens surface closest to the magnification side of the projection optical system to the lens surface closest to the reduction side of the projection optical system, the sum of the thicknesses on the optical axis of all optical elements with a refractive index of 1.8 or more relative to the d-line is set to ∑TH18. By not being below the lower limit of conditional expression (7), the proportion of optical elements with a refractive index of 1.8 or more relative to the d-line among all the above-mentioned optical elements with optical power will not be too low, so it is beneficial to achieve miniaturization and good correction of various aberrations such as spherical aberration. Among them, most optical materials with a refractive index of 1.8 or more relative to the d-line have low transmittance. Therefore, by not being above the upper limit of conditional expression (7), the above proportion will not be too high, so the reduction in transmittance can be suppressed. As a result, it is beneficial to ensure the brightness of the optical engine. In order to obtain better characteristics, the projection optical system more preferably satisfies the following conditional expression (7-1).

[0105] 0.27<∑TH18 / ∑THpw<0.5 (7)

[0106] 0.3<∑TH18 / ∑THpw<0.4 (7-1)

[0107] When the intermediate image MI is formed inside the projection optical system, the projection optical system includes an aperture stop St on the reduction side of the intermediate image MI, and a real image of the aperture stop St exists inside the projection optical system on the magnification side of the intermediate image MI. The projection optical system preferably satisfies the following conditional expression (8). Here, the position where the light rays emitted from the outermost periphery of the effective image circle on the reduction side and passing through the center of the aperture stop St toward the magnification side intersect with the optical axis Z on the magnification side of the intermediate image MI is set to Enp (Imax). The position of the paraxial image of the aperture stop St inside the projection optical system on the magnification side of the intermediate image MI is set to Enp (0). Position Enp (Imax) and position Enp (0) are positions in the optical axis direction. The air conversion distance on the optical axis from position Enp (0) to position Enp (Imax) is set to DifE. The sign of the above-mentioned air conversion distance DifE is based on position Enp (0), with the distance on the reduction side being positive and the distance on the magnification side being negative. When the projection optical system is a variable magnification optical system, the air conversion distance DifE is set to a value at the wide-angle end. By not being below the lower limit of conditional formula (8), it is beneficial to shorten the total length of the projection optical system. By not being below the lower limit of conditional formula (8), it is possible to suppress the enlargement of the diameter of the lens closest to the magnification side. In order to obtain better characteristics, the projection optical system preferably satisfies the following conditional formula (8-1).

[0108] -3<DifE / Imax<-0.2 (8)

[0109] -2.5<DifE / Imax<-0.5 (8-1)

[0110] As an example, Figure 3 and Figure 4 In Figure 1 In the projection optical system, the position Enp(Imax) and the position Enp(0) are used. Figure 3 2 shows a diagram in which the optical path is expanded so as to become a linear optical path. Figure 4 In FIG. 1 , a partial enlarged view including the position Enp(Imax) and the position Enp(0) is shown, and the air conversion distance DifE is also shown. As an example, in Figure 1 In the projection optical system, there are positions Enp(Imax) and Enp(0) between lens L7 and lens L8. Figure 3 and Figure 4 In FIG. 1 , the position Enp(Imax) and the position Enp(0) are indicated by dotted lines and two-dot chain lines, respectively, and the light ray 2 emitted from the outermost periphery of the effective image circle on the reduction side and passing through the center of the aperture stop St toward the magnification side is indicated by a single-dot chain line.

[0111] The projection optical system of the present invention preferably includes three negative lenses in sequence along the optical path from the most magnifying side to the reducing side. In this case, it is advantageous to achieve a wider angle. In order to achieve a wider angle, the projection optical system of the present invention preferably includes four negative lenses in sequence along the optical path from the most magnifying side to the reducing side.

[0112] In the projection optical system of the present invention, the second and third lenses from the magnification side are preferably negative meniscus lenses with the convex surface facing the magnification side. In this case, it is advantageous to achieve both wide angle and good aberration correction.

[0113] In the projection optical system of the present invention, the lens closest to the intermediate image MI on the optical axis is preferably a positive lens. In the case of such a configuration, it is advantageous for miniaturization.

[0114] The projection optical system of the present invention is preferably configured telecentrically on the reduced side. In recent years, the so-called pixel shifting method, which is to shift pixels to achieve a resolution of 2 or 4 times the number of pixels of a display element in order to realize a small and high-definition projection display device, is increasing, and a telecentric optical system is preferably used for the purpose of ensuring the resolution at this time.

[0115] In addition, the above-mentioned "the reduction side is configured in a telecentric manner" includes the error actually allowed in the technical field to which the technology of the present invention belongs. Regarding the error, for example, when tracing light from the magnification side to the reduction side, the angle between the main light incident on the display surface Sim and the optical axis Z can be within the range of more than -3 degrees and less than +3 degrees. In a system that does not include the aperture stop St, when the light beam is observed in the direction from the magnification side toward the reduction side, the telecentricity can be judged by replacing the main light beam with the angular bisector of the upper maximum light beam and the lower maximum light beam in the cross section of the light beam focused on the point on the display surface Sim.

[0116] The lens closest to the magnification side of the projection optical system of the present invention can be configured to have a shape in which a part of the rotationally symmetrical shape is missing. Generally, in a projection optical system that projects a wide-angle image, the effective diameter of the lens closest to the magnification side becomes the largest. Therefore, in the lens closest to the magnification side whose lens diameter is likely to become the largest in the projection optical system, the part that is not used for the formation of the projection image is made into a missing part, so that miniaturization can be achieved. Figure 1 The lens L1 has a shape where a portion of the rotationally symmetrical shape is missing below the optical axis Z, and Figure 1 The missing portion is indicated by a dotted line.

[0117] Figure 5 (A) Figure 5 (B) and Figure 5 (C) shows an example of the shape of a lens in which a part of the rotationally symmetrical shape is missing, on a plane perpendicular to the optical axis Z. Figure 5 (A) Figure 5 (B) and Figure 5 The example (C) is a non-circular shape on the plane perpendicular to the optical axis Z. By setting it to such a non-circular shape, it is possible to achieve miniaturization and lightness. In addition, the shape of a lens that lacks a rotationally symmetrical shape is not limited to Figure 5 (A) Figure 5 (B) and Figure 5 The example shown in (C) may also be in other shapes.

[0118] The projection optical system of the present invention preferably includes a focus group that moves along the optical axis Z when focusing. The focus group performs focusing by moving along the optical axis Z. The focus group is not limited to a structure including a plurality of lenses, and may also be a structure including only one lens. Figure 1 In the example, the focusing group includes lenses L4 to L6. Figure 1 The brackets below the lenses L4 to L6 and the double arrows in a direction parallel to the optical axis Z indicate that the lenses L4 to L6 constitute a focusing group.

[0119] The above-mentioned preferred structures and available structures, including structures related to the conditional expressions, can be arbitrarily combined, and preferably, they can be appropriately and selectively adopted according to the required specifications. Various modifications can be made within the scope of the technical purpose of the present invention. For example, in the technology of the present invention, the number of lenses and the shape of the lenses included in the projection optical system can be different from those in the present invention. Figure 1 Different from the example of Figure 1 The examples are different.

[0120] As an example, a preferred embodiment of the present invention is a projection optical system that projects an image displayed on a display surface Sim of a display element on a reduction side onto a projection surface on an enlargement side, wherein the projection optical system does not include a reflective surface having optical focal length, includes at least one optical path deflection surface that bends the optical path by 90 degrees in the optical path of the projection optical system, and satisfies the above-mentioned conditional expressions (1) and (2).

[0121] Next, embodiments of the projection optical system of the present invention are described with reference to the accompanying drawings. In addition, the reference symbols marked on the cross-sectional views of each embodiment are used independently for each embodiment to avoid the complication of the description and drawings caused by the increase in the number of digits of the reference symbols. Therefore, even if the same reference symbols are marked in the drawings of different embodiments, they are not necessarily the same structures.

[0122] [Example 1]

[0123] The structure of the projection optical system and the cross-sectional view of the light beam of Example 1 are shown in Figure 1, its illustration method and structure are as described above, so some repeated descriptions are omitted here. The projection optical system of Example 1 includes lenses L1~L12, reflector Mr1, lens L13, reflector Mr2, lenses L14~L17, aperture diaphragm St and lenses L18~L21 in sequence along the optical path from the magnification side to the reduction side. Reflector Mr1 and reflector Mr2 have a reflecting surface R1 and a reflecting surface R2, respectively. Reflecting surface R1 and reflecting surface R2 are surfaces without optical focal power, and respectively act as optical path deflection surfaces that bend the optical path 90 degrees. The intermediate image MI near the optical axis is formed between lens L13 and reflector Mr2. The focusing group includes lenses L4~L6.

[0124] Regarding the projection optical system of Example 1, basic lens data is shown in Table 1, specifications are shown in Table 2, variable surface intervals are shown in Table 3, and aspheric surface coefficients are shown in Table 4.

[0125] The table of basic lens data is as follows. The Sn column shows the face number when the face closest to the magnification side is the first face and the face number increases one by one toward the reduction side. The r column shows the radius of curvature of each face. The d column shows the face spacing on the optical axis between each face and the face adjacent to it on the reduction side. The nd column shows the refractive index of each component with respect to the d-line. The vd column shows the d-line reference dispersion coefficient of each component.

[0126] In the table of basic lens data, the sign of the curvature radius of the surface with the protruding shape facing the magnification side is set to positive, and the sign of the curvature radius of the surface with the protruding shape facing the reduction side is set to negative. In the column of surface number, the terms (R1), (R2) and (St) are recorded respectively for the surface corresponding to the optical path deflection surface on the magnification side, the surface corresponding to the optical path deflection surface on the reduction side, and the surface corresponding to the aperture stop St. In the table of basic lens data, the symbol DD[] is used for the variable surface interval during focusing, and the surface number on the magnification side of the interval is marked in [] and recorded in the D column.

[0127] Table 2 shows the absolute value of focal length |f|, back focus Bf at air conversion distance, F value FNo., maximum full angle of view 2ω, and Imax and DL used in the above conditional expressions based on the d-line reference. The [°] in the 2ω column indicates that the unit is degree.

[0128] Table 3 shows the variable surface spacing at each projection distance. The projection distance is the distance from the magnification side conjugate plane (at Figure 1 In the figure, it corresponds to the distance on the optical axis from the screen (Scr) to the lens surface closest to the magnification side.

[0129] In the basic lens data, the surface number of the aspheric surface is marked with an *, and the value of the paraxial curvature radius is recorded in the curvature radius column of the aspheric surface. In Table 4, the surface number of the aspheric surface is shown in the Sn row, and the numerical values ​​of the aspheric coefficients of each aspheric surface are shown in the KA and Am (m = 3, 4, 5, 6, ..., 20) rows. The "E±n" (n: integer) numerical values ​​of the aspheric coefficients in Table 4 represent "×10 ±n KA and Am are aspherical coefficients in the aspherical formula represented by the following formula.

[0130] Zd=C×h 2 / {1+(1-KA×C 2 ×h 2 ) 1 / 2 )+∑Am×h m

[0131] in,

[0132] Zd: depth of aspheric surface (the length of the perpendicular line from a point on the aspheric surface at height h to a plane tangent to the vertex of the aspheric surface and perpendicular to the optical axis Z);

[0133] h: height (the distance from the optical axis Z to the lens surface);

[0134] C: the reciprocal of the paraxial curvature radius;

[0135] KA, Am: Aspheric coefficients,

[0136] Σ in the aspherical expression represents the sum related to m.

[0137] In the data of each table, degrees are used as the unit of angle and mm (millimeter) is used as the unit of length. Since the optical system can be used at a magnified or reduced scale, other appropriate units may be used. In addition, the values ​​rounded to a specified number of digits are recorded in each table shown below.

[0138] [Table 1]

[0139] Example 1

[0140] Sn r d nd νd *1 -7.7516 1.7068 1.53158 55.08 *2 -16.8703 3.1884 3 32.753 1.1855 1.87267 40.68 4 17.672 4.0512 5 30.2205 0.9480 1.77304 50.6 6 11.6701 DD[6] 7 27.2539 0.9731 1.73253 54.75 8 8.36 12.0642 9 -11.4687 1.0426 1.60597 63.65 10 -22.8454 1.0149 11 443.109 2.6806 1.79309 30.73 12 -16.2305 DD

[12] 13 26.9364 1.9602 1.55032 75.5 14 174.3084 12.3004 15 26.3927 4.9222 1.55032 75.5 16 -15.3855 0.8514 1.74938 27.63 17 -81.7619 1.5272 18 1078.619 0.8715 1.90992 19.55 19 12.1557 7.9766 1.57144 71.61 20 -24.4623 0.1203 *21 -33.9121 2.2226 1.51007 56.24 *22 -13.8766 2.8600 23(R1) ∞ 12.5000 24 51.7002 5.2897 1.90632 36.88 25 -51.0049 20.0000 26(R2) ∞ 4.0150 *27 -12.9555 2.5000 1.51007 56.24 *28 -13.3724 10.1500 29 43.1681 5.4010 1.90999 32.52 30 -675.2912 0.7640 31 121.7484 2.9801 1.84975 42.93 32 -14.704 0.9006 1.90988 19.51 33 -34.2693 3.5400 34(St) ∞ 3.2516 35 -10.2131 0.9745 1.72466 45.14 36 47.5455 0.4973 37 46.8467 6.3713 1.43875 94.66 38 -13.9681 0.1922 39 284.1914 3.4386 1.497 81.61 40 -18.8412 0.3189 41 23.2703 2.5917 1.81425 43.55 42 413.3913 3.0000 43 ∞ 3.0000 1.5168 64.2 44 ∞ 0.5000 45 ∞ 15.0000 1.67003 47.2 46 ∞

[0141] [Table 2]

[0142] Example 1

[0143] |f| 1.94 Bf 16.03 FNo. 2.01 2ω[°] 144.0 Imax 6.00 DL 8.47

[0144] [Table 3]

[0145] Example 1

[0146] Projection distance 0.212m 0.160m 0.570m DD[6] 4.69 4.58 4.42 DD

[12] 1.31 1.43 1.59

[0147] [Table 4]

[0148] Example 1

[0149] Sn 1 2 21 22 KA -5.3037636E-01 -2.5343639E+00 -2.9823754E+00 6.9099676E-01 A3 9.7252460E-03 1.2084856E-02 -5.1135101E-05 -2.3181216E-04 A4 -4.7287937E-05 -2.1800900E-03 -5.8484664E-05 1.6688743E-04 A5 -1.1508528E-04 6.3139370E-04 6.7000474E-06 1.4903703E-05 A6 6.7066446E-06 -1.2252415E-04 1.8933588E-05 -9.4351586E-07 A7 4.7217042E-07 1.1076074E-05 -3.4243928E-06 1.2747422E-06 A8 -4.9193207E-08 -2.0401544E-07 -7.1695828E-07 -3.2248374E-07 A9 -8.7426127E-10 -3.6920347E-08 1.6400171E-07 -5.8012287E-08 A10 1.9670568E-10 2.3706250E-09 1.7515406E-08 1.7175837E-08 A11 -9.4217611E-13 -4.3818288E-11 -4.5219664E-09 1.1356033E-09 A12 -4.6081874E-13 3.5346778E-12 -2.9571009E-10 -4.3718411E-10 A13 7.8878559E-15 -1.8101326E-13 8.0529786E-11 -1.1452888E-11 A14 6.4046511E-16 -1.4675971E-14 3.0363251E-12 6.3870807E-12 A15 -1.6296562E-17 2.2328470E-16 -9.0135951E-13 5.6089147E-14 A16 -4.8431647E-19 1.5346074E-16 -1.3745307E-14 -5.5108511E-14 A17 1.5896934E-20 -1.1629984E-17 5.6733630E-15 -8.7340930E-17 A18 1.3568197E-22 3.4132586E-19 -1.7436817E-17 2.6344800E-16 A19 -6.2843094E-24 -3.8578104E-21 -1.5118758E-17 -1.1763911E-19 A20 2.1703737E-26 4.1060027E-24 2.6664058E-19 -5.4073652E-19

[0150] Sn 27 28 KA 8.9138696E-01 1.0585809E+00 A3 -2.0011122E-04 -1.0972481E-05 A4 3.2017721E-04 1.7063148E-04 A5 4.0775679E-05 1.0130712E-05 A6 -2.5576398E-05 2.0124585E-06 A7 3.3183437E-06 -1.5187772E-06 A8 7.3469520E-07 2.3441228E-08 A9 -2.0598307E-07 7.5368116E-08 A10 -5.3819603E-09 -6.0001978E-09 A11 5.0799773E-09 -1.7021962E-09 A12 -1.4684862E-10 1.7636348E-10 A13 -6.8267518E-11 2.1375544E-11 A14 3.9359331E-12 -2.4269602E-12 A15 5.2358440E-13 -1.5535100E-13 A16 -4.0216062E-14 1.8076928E-14 A17 -2.1537929E-15 6.1485680E-16 A18 1.9696372E-16 -7.0779097E-17 A19 3.6889344E-18 -1.0289849E-18 A20 -3.8233130E-19 1.1484581E-19

[0151] Figure 6 , various aberration diagrams of the projection optical system of Example 1 are shown when the projection distance is 0.25 m (meter). Figure 6 In the figure, spherical aberration, astigmatism, distortion aberration and lateral chromatic aberration are shown in order from the left. In the spherical aberration diagram, aberrations related to the d-line, C-line and F-line are shown with solid lines, long dashed lines and short dashed lines, respectively. In the astigmatism diagram, aberrations related to the d-line in the sagittal direction are shown with solid lines, and aberrations related to the d-line in the meridional direction are shown with short dashed lines. In the distortion aberration diagram, aberrations related to the d-line are shown with solid lines. In the lateral chromatic aberration diagram, aberrations related to the C-line and F-line are shown with long dashed lines and short dashed lines, respectively. In the spherical aberration diagram, the value of the F value is shown on the back side of "FNo.=". In the other aberration diagrams, the value of the maximum half viewing angle is shown on the back side of "ω=".

[0152] Unless otherwise specified, the symbols, meanings, recording methods and illustration methods of the data related to the above-mentioned embodiment 1 and the modified example are also basically the same in the following embodiments, so repeated descriptions are omitted below. In addition, the illustration of the screen Scr is omitted in the cross-sectional views of the following embodiments.

[0153] [Example 2]

[0154] The structure of the projection optical system and the cross-sectional view of the light beam of Example 2 are shown in FIG. Figure 7 . The projection optical system of Example 2 includes lenses L1 to L7, a reflector Mr1, lenses L8 to L11, a reflector Mr2, lenses L12 to L14, an aperture stop St and lenses L15 to L17 in order from the magnification side to the reduction side along the optical path. The reflector Mr1 and the reflector Mr2 have a reflection surface R1 and a reflection surface R2, respectively. The reflection surface R1 and the reflection surface R2 are surfaces without optical power, and function as optical path deflection surfaces that bend the optical path by 90 degrees, respectively. The intermediate image MI near the optical axis is formed between the reflector Mr2 and the lens L12. The focusing group includes a lens L5.

[0155] Regarding the projection optical system of Example 2, basic lens data are shown in Table 5, specifications are shown in Table 6, variable surface spacing is shown in Table 7, aspheric coefficients are shown in Table 8, and various aberration diagrams are shown in Table 9. Figure 8 Each aberration diagram is data when the projection distance is 0.279 m (meter).

[0156] [Table 5]

[0157] Example 2

[0158] Sn r d nd νd *1 -5.7999 2.8500 1.53158 55.08 *2 -10.5678 1.3540 3 17.1772 0.8550 1.80420 46.50 4 10.1112 2.6435 5 16.9718 0.7410 1.83481 42.72 6 7.4706 2.3631 7 17.1134 0.7410 1.83481 42.72 8 6.6990 DD[8] 9 -7.0514 5.9999 1.48749 70.44 10 -12.1244 DD

[10] 11 -39.6305 1.6555 1.80518 25.46 12 -19.0871 0.8767 13 20.5428 2.7849 1.48749 70.44 14 -37.7318 11.3542 15(R1) ∞ 8.8409 16 22.4979 4.7620 1.65160 58.54 17 -11.2035 0.7410 1.84666 23.78 18 12.4016 7.3754 1.59282 68.62 19 -17.6485 0.4991 *20 -1792.1148 1.8525 1.51007 56.24 *21 -41.6857 11.1502 22(R2) ∞ 9.1935 23 29.9833 4.0224 1.92286 20.88 24 -71.0186 22.1206 25 33.1434 1.5009 1.92286 20.88 26 11.2287 0.0291 27 11.2848 3.0953 1.49700 81.54 28 -17.8065 2.4644 29(St) ∞ 7.7701 30 33.5893 0.5191 1.90366 31.31 31 16.1638 0.0290 32 16.2509 5.0905 1.49700 81.54 33 -24.9533 4.8414 34 46.5654 2.3594 1.92286 20.88 35 -39.7011 6.0029 36 ∞ 15.0000 1.67003 47.20 37 ∞ 3.0000 1.48749 70.44 38 ∞

[0159] [Table 6]

[0160] Example 2

[0161] |f| 2.67 Bf 16.98 FNo. 2.00 2ω[°] 127.8 Imax 5.6 DL 8.47

[0162] [Table 7]

[0163] Example 2

[0164] Projection distance 0.279m 0.200m 0.570m DD[8] 6.59 6.47 6.74 DD

[10] 1.14 1.26 0.99

[0165] [Table 8]

[0166] Example 2

[0167] Sn 1 2 20 21 KA -3.3439740E+00 -4.9999906E+00 8.6597976E-06 -5.0000076E+00 A3 7.5963127E-03 6.2382908E-03 0.0000000E+00 0.0000000E+00 A4 -6.2933714E-04 9.4619045E-04 -1.3935446E-04 -3.0165687E-05 A5 3.3002673E-05 -1.0324457E-04 6.3786367E-06 -5.7210965E-06 A6 2.4049042E-06 -1.8466450E-05 -3.1057789E-06 2.3901562E-06 A7 -1.5156180E-06 2.7557481E-06 1.5873508E-07 -1.4652229E-06 A8 1.8613445E-07 9.1798158E-08 4.6083294E-08 2.4761229E-07 A9 2.1197178E-09 -2.7161239E-08 -3.1988785E-09 1.0739295E-08 A10 -1.9323861E-09 -2.8647355E-11 -1.7920935E-10 -5.4102545E-09 A11 8.2845667E-11 1.4908754E-10 1.9186998E-11 1.4432424E-10 A12 7.5625915E-12 -2.2598490E-12 1.4548501E-13 5.0780320E-11 A13 -6.0619046E-13 -4.6582204E-13 -5.6894702E-14 -2.4793687E-12 A14 -1.0034491E-14 1.1546269E-14 7.1519653E-16 -2.6226970E-13 A15 1.8404401E-15 8.2855999E-16 9.1070110E-17 1.3771357E-14 A16 -1.2987901E-17 -2.6019640E-17 -2.0563259E-18 7.8162792E-16 A17 -2.6612625E-18 -7.8297502E-19 -7.5306547E-20 -3.3898186E-17 A18 4.9934663E-20 2.8564582E-20 2.0938507E-21 -1.2720420E-18 A19 1.5066095E-21 3.0485035E-22 2.5239576E-23 3.1406171E-20 A20 -3.8812505E-23 -1.2412568E-23 -7.6932272E-25 8.8156419E-22

[0168] [Example 3]

[0169] The structure of the projection optical system and the cross-sectional view of the light beam of Example 3 are shown in FIG. Fig. 9 . Fig.10 In the figure, the optical path of the projection optical system of Example 3 is unfolded in a manner that the optical path is linear. The projection optical system of Example 3 includes lenses L1 to L10, a prism Pr, lenses L11 to L13, an aperture stop St and lenses L14 to L16 in order along the optical path from the magnification side to the reduction side. The prism Pr is an optical path deflecting component that bends the optical path. The prism Pr has two reflecting surfaces R1 and a reflecting surface R2. The reflecting surface R1 and the reflecting surface R2 are surfaces without optical power, and they each function as an optical path deflecting surface that bends the optical path 90 degrees. The intermediate image MI near the optical axis is formed between the reflecting surface R1 and the reflecting surface R2. The focusing group includes lens L5. Lenses L1 to L4 have a rotationally symmetrical shape in which a portion of the shape is missing. In Fig. 9 In the figure, the missing part is omitted. Fig.10 In FIG. 1 , the missing portion is indicated by a dotted line.

[0170] Regarding the projection optical system of Example 3, basic lens data are shown in Table 9, specifications are shown in Table 10, variable surface spacing is shown in Table 11, aspheric coefficients are shown in Table 12, and various aberration diagrams are shown in Table 13. Fig.11 Each aberration diagram is data when the projection distance is 0.237 m (meter).

[0171] [Table 9]

[0172] Example 3

[0173] Sn r d nd νd *1 -2.7074 2.7009 1.53158 55.08 *2 -4.6051 1.1206 3 17.3412 0.6000 1.88300 40.80 4 8.8746 2.0244 5 13.0764 0.5200 1.83481 42.72 6 6.6804 2.0960 7 15.3345 0.5200 1.80420 46.50 8 5.5790 DD[8] 9 -8.0396 2.7848 1.48749 70.44 10 -10.6056 DD

[10] 11 23.4951 1.4299 1.86966 20.02 12 -38.8123 10.3200 *13 36.8740 2.2306 1.58313 59.38 *14 -13.1049 0.5000 15 30.6928 3.1547 1.62041 60.34 16 -9.0909 0.5200 1.84666 23.78 17 9.0909 4.2588 1.59282 68.62 18 -12.5000 0.5000 19 ∞ 3.0000 1.56883 56.04 20(R1) ∞ 9.4479 1.56883 56.04 21 ∞ 9.4479 1.56883 56.04 22(R2) ∞ 3.0000 1.56883 56.04 23 ∞ 0.5000 24 229.6278 6.0009 1.92286 20.88 25 -16.7650 14.6796 26 20.0193 0.5192 1.92286 20.88 27 7.3590 0.0305 28 7.3819 2.5814 1.49700 81.61 29 -17.2560 1.9988 30(St) ∞ 7.0488 31 2794.3293 0.5210 1.84666 23.78 32 16.9086 3.1116 1.49700 81.61 33 -13.5266 0.4005 34 23.7363 2.1195 1.92286 20.88 35 -32.1947 3.9260 36 ∞ 11.5000 1.67003 47.20 37 ∞ 3.0000 1.51680 64.20 38 ∞

[0174] [Table 10]

[0175] Example 3

[0176] |f| 1.59 Bf 12.78 FNo. 2.00 2ω[°] 135.6 Imax 4.05 DL 5.95

[0177] [Table 11]

[0178] Example 3

[0179] Projection distance 0.237m 0.200m 0.570m DD[8] 5.35 5.22 5.87 DD

[10] 1.49 1.63 0.97

[0180] [Table 12]

[0181] Example 3

[0182] Sn 1 2 13 14 KA -1.1492190E+00 -1.5679723E+00 1.0000000E+00 1.0000000E+00 A3 2.1787329E-02 1.3051107E-02 0.0000000E+00 0.0000000E+00 A4 -2.7011125E-03 1.4360349E-03 -6.3113968E-05 3.0386033E-04 A5 -6.0353022E-05 -2.5453309E-04 6.1227327E-05 -1.2411180E-04 A6 4.6770932E-05 -4.7389812E-05 -6.3290517E-06 8.8691496E-05 A7 -3.0265478E-06 8.3288248E-06 -1.8799049E-07 -2.4827126E-05 A8 -2.6721817E-07 3.5124788E-07 6.2992782E-08 1.8962299E-06 A9 3.7730970E-08 -1.1281585E-07 -9.2758147E-10 5.7497854E-07 A10 2.2131065E-10 2.0163857E-10 -2.5530269E-10 -1.1741712E-07 A11 -2.0836311E-10 8.3447784E-10 5.8268733E-12 -3.2792597E-09 A12 4.5458201E-12 -1.9953412E-11 5.4008618E-13 2.0150483E-09 A13 6.3529261E-13 -3.5053643E-12 -1.3904499E-14 -2.2211995E-11 A14 -2.3896232E-14 1.2922326E-13 -6.2725973E-16 -1.7393377E-11 A15 -1.0995134E-15 8.3763287E-15 1.7588689E-17 3.4594189E-13 A16 5.4655111E-17 -3.8165691E-16 3.7558372E-19 8.2540263E-14 A17 1.0066335E-18 -1.0622001E-17 -1.1611332E-20 -1.4771866E-15 A18 -6.1703477E-20 5.5298591E-19 -8.6267404E-23 -2.0583615E-16 A19 -3.7622718E-22 5.5477107E-21 3.1438023E-24 2.1605043E-18 A20 2.8007492E-23 -3.1792714E-22 -3.5239343E-27 2.1134870E-19

[0183] [Example 4]

[0184] The structure of the projection optical system and the cross-sectional view of the light beam of Example 4 are shown in FIG. Fig.12 . The projection optical system of Example 4 includes lenses L1 to L12, a reflector Mr1, a lens L13, a reflector Mr2, lenses L14 to L17, an aperture stop St and lenses L18 to L21 in order from the magnification side to the reduction side along the optical path. The reflector Mr1 and the reflector Mr2 have a reflecting surface R1 and a reflecting surface R2, respectively. The reflecting surface R1 and the reflecting surface R2 are surfaces without optical focal power, and function as optical path deflection surfaces that bend the optical path by 90 degrees, respectively. An intermediate image MI near the optical axis is formed between the lens L13 and the reflector Mr2. The focusing group includes lenses L4 to L6. Lens L1 has a rotationally symmetrical shape in which a portion is missing. In Fig.12 In the figure, the missing part is omitted.

[0185] Regarding the projection optical system of Example 4, basic lens data are shown in Table 13, specifications are shown in Table 14, variable surface spacing is shown in Table 15, aspheric coefficients are shown in Table 16, and various aberration diagrams are shown in Table 17. Fig.13 Each aberration diagram is data when the projection distance is 0.212 m (meter).

[0186] [Table 13]

[0187] Example 4

[0188] Sn r d nd νd *1 -6.0386 1.3800 1.53158 55.08 *2 -13.1532 2.5200 3 25.7051 0.9010 1.89027 38.97 4 13.5893 3.1938 5 23.8806 0.9003 1.75099 52.9 6 9.0338 DD[6] 7 21.2414 0.9097 1.70576 56.21 8 6.5406 9.4252 9 -8.9597 0.8010 1.60903 63.23 10 -17.8627 1.0661 11 345.4634 2.1205 1.75914 28.86 12 -12.683 DD

[12] 13 20.9789 1.4241 1.54265 73.05 14 135.9828 9.2739 15 20.6194 3.9154 1.55995 70.78 16 -12.0273 0.8510 1.7297 28.52 17 -63.9899 0.9373 18 889.788 0.8709 1.90999 19.5 19 9.4957 6.7416 1.56854 69.45 20 -19.3015 0.1202 *21 -26.3897 1.7588 1.51007 56.24 *22 -10.8309 2.3000 23(R1) ∞ 9.7000 24 41.17 4.3686 1.90692 37.31 25 -40.3564 15.2000 26(R2) ∞ 3.5600 *27 -10.1283 2.0102 1.51007 56.24 *28 -10.436 7.8832 29 33.7634 4.2395 1.91 31.57 30 -525.9858 0.3794 31 95.4408 2.3912 1.83989 38.63 32 -11.4419 0.9097 1.91 19.5 33 -26.6763 2.0300 34(St) ∞ 3.7759 35 -7.9788 0.9993 1.70665 42.92 36 37.3445 0.4929 37 36.4101 4.6062 1.43875 94.66 38 -10.9175 0.1486 39 214.189 2.7583 1.46283 85.72 40 -14.2548 0.2060 41 18.1859 2.3827 1.78435 47.49 42 320.707 3.6612 43 ∞ 3.0000 1.5168 64.2 44 ∞ 0.8000 45 ∞ 11.5000 1.67003 47.2 46 ∞

[0189] [Table 14]

[0190] Example 4

[0191] |f| 1.52 Bf 12.51 FNo. 2.01 2ω[°] 143.4 Imax 4.6 DL 5.95

[0192] [Table 15]

[0193] Example 4

[0194] Projection distance 0.212m 0.160m 0.570m DD[6] 3.59 3.66 3.45 DD

[12] 0.89 0.82 1.04

[0195] [Table 16]

[0196] Example 4

[0197] Sn 1 2 21 22 KA -5.3037636E-01 -2.5343639E+00 -2.9823754E+00 6.9099676E-01 A3 1.6270757E-02 1.9815060E-02 2.4212140E-04 -3.6574163E-04 A4 -1.0017047E-04 -4.4923184E-03 -2.1056093E-04 4.3629416E-04 A5 -3.1987983E-04 1.6972467E-03 3.1604455E-05 9.1561452E-05 A6 2.3271436E-05 -4.2583755E-04 6.8789910E-05 -3.2021533E-05 A7 2.2624555E-06 4.8688328E-05 -2.3382285E-05 -1.7414613E-06 A8 -2.8317896E-07 -1.0131006E-06 -3.0531253E-06 1.4526095E-06 A9 -8.0637279E-09 -2.6697846E-07 1.9435975E-06 7.6842737E-09 A10 1.8885716E-09 1.9791958E-08 4.0548355E-08 -2.8321363E-08 A11 -1.1506337E-12 -4.9349200E-10 -8.6291254E-08 -4.4317839E-11 A12 -7.4431594E-12 7.2154900E-11 1.5271442E-09 -4.1855433E-10 A13 1.1810519E-13 -3.7324217E-12 2.3232477E-09 3.4898943E-11 A14 1.7661474E-14 -4.6593504E-13 -8.1509607E-11 3.2962867E-11 A15 -4.4482768E-16 8.2189761E-15 -3.8026097E-11 -1.3028270E-12 A16 -2.3599463E-17 6.5587356E-15 1.6656905E-12 -6.9951128E-13 A17 7.4302418E-19 -6.0672900E-16 3.4800776E-13 1.8393499E-14 A18 1.3687293E-20 2.2092523E-17 -1.6779179E-14 6.9493974E-15 A19 -4.9422537E-22 -3.2529157E-19 -1.3620466E-15 -9.4526861E-17 A20 6.6990816E-26 8.8883000E-22 6.8096255E-17 -2.7628051E-17

[0198] Sn 27 28 KA 8.9138696E-01 1.0585809E+00 A3 -1.0837632E-03 5.2253772E-05 A4 8.6290232E-04 2.4951778E-04 A5 2.7569186E-04 9.7327540E-05 A6 -1.2131281E-04 1.8696453E-05 A7 -4.1490383E-06 -1.6113029E-05 A8 7.0494169E-06 -8.0285068E-07 A9 -3.6292805E-07 1.1137690E-06 A10 -2.0133325E-07 -8.6613019E-09 A11 2.1375815E-08 -3.8996384E-08 A12 2.7315600E-09 1.1943157E-09 A13 -5.3166436E-10 7.7590414E-10 A14 -3.8039854E-12 -3.0613440E-11 A15 7.1639295E-12 -8.9327702E-12 A16 -3.7868484E-13 3.6975716E-13 A17 -5.1070056E-14 5.5652213E-14 A18 4.5535769E-15 -2.2030232E-15 A19 1.5108650E-16 -1.4564490E-16 A20 -1.7093201E-17 5.2013309E-18

[0199] [Example 5]

[0200] The structure of the projection optical system and the cross-sectional view of the light beam of Example 5 are shown in Fig.14 . The projection optical system of Example 5 includes lenses L1 to L11, a reflector Mr1, a lens L12, a reflector Mr2, lenses L13 to L15, an aperture stop St, and lenses L16 to L19 in order from the magnification side to the reduction side along the optical path. The reflector Mr1 and the reflector Mr2 have a reflecting surface R1 and a reflecting surface R2, respectively. The reflecting surface R1 and the reflecting surface R2 are surfaces without optical focal power, and function as optical path deflection surfaces that bend the optical path by 90 degrees, respectively. An intermediate image MI near the optical axis is formed between the reflector Mr1 and the lens L12. The focusing group includes lenses L7 to L8. Lens L1 has a rotationally symmetrical shape in which a portion is missing. In Fig.14 In the figure, the missing part is omitted.

[0201] Regarding the projection optical system of Example 5, basic lens data are shown in Table 17, specifications are shown in Table 18, variable surface spacing is shown in Table 19, aspheric coefficients are shown in Table 20, and various aberration diagrams are shown in Table 21. Fig.15 Each aberration diagram is data when the projection distance is 0.279 m (meter).

[0202] [Table 17]

[0203] Example 5

[0204] Sn r d nd νd *1 -6.1897 1.5275 1.53158 55.08 *2 -12.2632 5.3874 3 29.5729 1.1990 1.80182 47.66 4 7.9392 3.7304 5 29.5394 0.9009 1.76967 40.85 6 6.496 8.1757 7 -9.1115 1.2525 1.89918 28.19 8 -16.789 0.8331 9 148.9079 3.2679 1.69259 31.81 10 -13.1297 1.5832 11 24.0132 1.6051 1.90876 32.38 12 100.1081 DD

[12] 13 20.363 4.7795 1.50116 55.96 14 -12.4415 0.9238 1.81879 38.25 15 -65.3742 DD

[15] 16 10839.7416 0.9481 1.90703 19.82 17 9.8498 6.0478 1.66772 58.04 18 -18.1391 0.1751 *19 -19.0895 1.7010 1.51007 56.24 *20 -10.6107 6.0000 21(R1) ∞ 11.6444 22 40.9995 3.6659 1.78178 34.01 23 -38.9745 10.0000 24(R2) ∞ 5.5277 *25 -10.0994 1.9028 1.51007 56.24 *26 -10.8528 6.9070 27 32.784 8.0196 1.90744 32.31 28 -9.9442 0.9086 1.86891 21.64 29 -26.9438 4.9100 30(St) ∞ 2.6149 31 -7.1132 0.9010 1.7671 32.97 32 46.2487 0.4375 33 31.4496 3.3314 1.43875 94.66 34 -9.8754 0.7215 35 1212.356 3.0353 1.45657 86.68 36 -12.9526 1.7472 37 18.1408 2.9885 1.86867 40.5 38 1216.8816 3.6659 39 ∞ 3.0000 1.5168 64.2 40 ∞ 0.8000 41 ∞ 11.5000 1.67003 47.2 42 ∞

[0205] [Table 18]

[0206] Example 5

[0207] |f| 1.92 Bf 12.52 FNo. 2.01 2ω[°] 134.4 Imax 4.6 DL 5.95

[0208] [Table 19]

[0209] Example 5

[0210] Projection distance 0.279m 0.160m 0.570m DD

[12] 8.93 8.75 9.06 DD

[15] 0.42 0.60 0.29

[0211] [Table 20]

[0212] Example 5

[0213] Sn 1 2 19 20 KA -5.4212575E-01 -2.5807402E+00 -3.0969300E+00 7.3830461E-01 A3 1.6231168E-02 1.9719166E-02 2.5457963E-04 -6.5046904E-04 A4 -1.1164576E-04 -4.4910547E-03 -5.7011782E-05 6.0004450E-04 A5 -3.1840830E-04 1.7036792E-03 -3.0385024E-05 1.3712788E-04 A6 2.3566627E-05 -4.2582932E-04 4.9633876E-05 -7.2754087E-05 A7 2.2355903E-06 4.8483906E-05 -1.2860558E-05 -4.2915933E-06 A8 -2.8704557E-07 -1.0141317E-06 -1.3334230E-06 6.1873243E-06 A9 -7.7930333E-09 -2.6344462E-07 1.1122937E-06 1.2525411E-08 A10 1.9178805E-09 1.9814092E-08 -6.8894109E-08 -3.3010275E-07 A11 -2.7639256E-12 -5.2931324E-10 -4.9203875E-08 5.4806538E-09 A12 -7.5788782E-12 7.1915184E-11 6.2816434E-09 1.1045434E-08 A13 1.2393581E-13 -3.5133975E-12 1.3324310E-09 -2.2341273E-10 A14 1.8049724E-14 -4.6445031E-13 -2.1623014E-10 -2.3436205E-10 A15 -4.5737485E-16 7.4241624E-15 -2.2251815E-11 4.0853827E-12 A16 -2.4265536E-17 6.5534203E-15 4.0097625E-12 3.0596290E-12 A17 7.5780936E-19 -6.0515290E-16 2.0960004E-13 -3.6454711E-14 A18 1.4311052E-20 2.2102762E-17 -3.9304010E-14 -2.2335771E-14 A19 -5.0156804E-22 -3.2660689E-19 -8.4573784E-16 1.2610760E-16 A20 -1.7577761E-25 8.8061201E-22 1.5915707E-16 6.9509061E-17

[0214] Sn 25 26 KA 9.8920631E-01 9.5588928E-01 A3 -5.7797078E-04 1.5272970E-04 A4 4.8886916E-04 2.4674531E-04 A5 2.6883232E-04 5.8061799E-05 A6 -6.8461300E-05 2.3318454E-05 A7 -1.0880951E-05 -1.1045181E-05 A8 4.0399249E-06 -1.4081052E-06 A9 2.4638223E-07 7.7223797E-07 A10 -1.2929394E-07 2.5735188E-08 A11 -3.1453878E-09 -2.5796972E-08 A12 2.7224982E-09 1.3584844E-10 A13 1.0874429E-11 4.7609295E-10 A14 -4.0691470E-11 -1.1651921E-11 A15 3.2911318E-13 -4.9926000E-12 A16 4.1999308E-13 1.7183120E-13 A17 -5.0040903E-15 2.7966422E-14 A18 -2.6200751E-15 -1.0872754E-15 A19 2.1933497E-17 -6.5200616E-17 A20 7.2515032E-18 2.5816961E-18

[0215] [Example 6]

[0216] The structure of the projection optical system and the cross-sectional view of the light beam of Example 6 are shown in FIG. Fig.16 . The projection optical system of Example 6 includes lenses L1 to L7, a reflector Mr1, lenses L8 to L11, a reflector Mr2, lenses L12 to L14, an aperture stop St and lenses L15 to L17 in order from the magnification side to the reduction side along the optical path. The reflector Mr1 and the reflector Mr2 have a reflection surface R1 and a reflection surface R2, respectively. The reflection surface R1 and the reflection surface R2 are surfaces without optical power, and function as optical path deflection surfaces that bend the optical path by 90 degrees, respectively. The intermediate image MI near the optical axis is formed between the reflector Mr2 and the lens L12. The focusing group includes a lens L5.

[0217] Regarding the projection optical system of Example 6, basic lens data are shown in Table 21, specifications are shown in Table 22, variable surface spacing is shown in Table 23, aspheric coefficients are shown in Table 24, and various aberration diagrams are shown in Table 25. Fig.17 Each aberration diagram is data when the projection distance is 0.279 m (meter).

[0218] [Table 21]

[0219] Example 6

[0220] Sn r d nd νd *1 -3.1042 2.0000 1.53158 55.08 *2 -4.9904 1.1202 3 16.9729 0.6000 1.80420 46.50 4 8.2687 2.1019 5 15.6152 0.5200 1.83481 42.72 6 6.2507 1.8185 7 13.4058 0.5200 1.83481 42.72 8 6.1342 DD[8] 9 -7.4459 5.2194 1.48749 70.44 10 -12.2000 DD

[10] 11 -139.0858 1.5211 1.80518 25.46 12 -19.4323 12.2047 13 47.1498 2.0584 1.48749 70.44 14 -20.1123 7.0116 15(R1) ∞ 7.6195 16 23.6191 4.2242 1.65160 58.54 17 -11.5363 0.5200 1.84666 23.78 18 10.9887 5.6320 1.59282 68.62 19 -16.3340 0.4991 *20 -27.8027 1.3000 1.51007 56.24 *21 -17.0997 9.9089 22(R2) ∞ 7.8848 23 25.9270 5.7087 1.92286 20.88 24 -43.7883 14.8380 25 15.0977 1.5009 1.92286 20.88 26 5.9271 0.0272 27 5.8926 2.6124 1.49700 81.54 28 -12.4106 0.1991 29(St) ∞ 7.4969 30 -58.2598 0.5191 1.90366 31.31 31 18.7887 0.0292 32 19.4593 3.4046 1.49700 81.54 33 -11.7989 0.3992 34 29.0187 2.4628 1.92286 20.88 35 -23.2056 4.0942 36 ∞ 11.5000 1.67003 47.20 37 ∞ 3.0000 1.48749 70.44 38 ∞

[0221] [Table 22]

[0222] Example 6

[0223] |f| 1.87 Bf 12.98 FNo. 2.00 2ω[°] 130.0 Imax 4.12 DL 5.95

[0224] [Table 23]

[0225] Example 6

[0226] Projection distance 0.279m 0.200m 0.570m DD[8] 5.27 5.11 5.47 DD

[10] 1.35 1.51 1.16

[0227] [Table 24]

[0228] Example 6

[0229] Sn 1 2 20 21 KA -2.6702442E+00 -4.9999915E+00 8.5729145E-06 -5.0000083E+00 A3 1.2156820E-02 9.2572567E-03 0.0000000E+00 0.0000000E+00 A4 -1.1834866E-03 1.9758909E-03 -4.5871017E-04 -3.1743254E-04 A5 9.1446504E-05 -2.4760050E-04 2.2974253E-04 1.0769405E-04 A6 1.6395248E-06 -7.7718019E-05 -5.6226455E-05 -3.2625021E-06 A7 -6.5379047E-06 1.3469108E-05 8.8604609E-07 -8.9147473E-06 A8 1.2224325E-06 7.1926034E-07 2.0122113E-06 1.9245530E-06 A9 3.9602062E-09 -2.4277594E-07 -2.0658137E-07 1.2834428E-07 A10 -2.0235316E-08 -2.5492954E-10 -2.0513404E-08 -5.9137047E-08 A11 1.2484023E-09 2.4421384E-09 3.9396178E-09 8.1915616E-10 A12 1.2805691E-10 -6.0707450E-11 2.3023283E-11 8.5238777E-10 A13 -1.4584400E-11 -1.4010703E-11 -3.4558414E-11 -3.7559196E-11 A14 -2.4296295E-13 5.5250415E-13 9.4538230E-13 -6.9265741E-12 A15 7.3530865E-14 4.5776482E-14 1.6055639E-13 3.6526216E-13 A16 -9.3157209E-16 -2.2310078E-15 -6.8742650E-15 3.2804323E-14 A17 -1.7815303E-16 -7.9402795E-17 -3.8248555E-16 -1.5070497E-15 A18 4.9532053E-18 4.3964873E-18 1.9315186E-17 -8.5253187E-17 A19 1.6957184E-19 5.6667683E-20 3.6799041E-19 2.3111904E-18 A20 -6.3112819E-21 -3.4337244E-21 -1.9941538E-20 9.4633625E-20

[0230] Regarding the projection optical systems of Examples 1 to 6 in Table 25, the corresponding values ​​of conditional expressions (1) to (8), the β used in calculating the corresponding value of conditional expression (6), and the value of Ymax at each β value are shown.

[0231] [Table 25]

[0232]

[0233] In the projection optical systems of Examples 1 to 6, the full viewing angle at the wide-angle end is 120 degrees or more, and has a wide viewing angle. In the projection optical systems of Examples 1 to 6, the F value is 2.1 or less, and has a small F value. In addition, in the projection optical systems of Examples 1 to 6, although the configuration is small, various aberrations are well corrected, and high optical performance is achieved.

[0234] Next, a projection display device according to an embodiment of the present invention will be described. Fig.18 It is a schematic structural diagram of a projection display device according to one embodiment of the present invention. Fig.18 The projection display device 100 shown has: a projection optical system 10 according to an embodiment of the present invention; a light source 15; and transmissive display elements 11a to 11c as light valves, which correspond to the light of each color and output an optical image. In addition, the projection display device 100 has dichroic mirrors 12 and 13 for color separation, a cross dichroic prism 14 for color synthesis, condensing lenses 16a to 16c, and total reflection mirrors 18a to 18c for deflecting the light path. In addition, Fig.18 1 and 2 schematically show the projection optical system 10. In addition, an integrator is arranged between the light source 15 and the dichroic mirror 12. Fig.18 The illustration is omitted.

[0235] The white light from the light source 15 is separated into three color light beams (green light, blue light, and red light) by the dichroic mirrors 12 and 13, and then passes through the condenser lenses 16a to 16c and is incident on the transmission type display elements 11a to 11c corresponding to the light beams of the respective colors to be modulated, and after being color-synthesized by the cross dichroic prism 14, it is incident on the projection optical system 10. The projection optical system 10 projects an optical image based on the modulated light modulated by the transmission type display elements 11a to 11c onto the screen 105.

[0236] Fig.19 It is a schematic structural diagram of a projection display device according to another embodiment of the present invention. Fig.19The projection display device 200 shown has: a projection optical system 210 according to an embodiment of the present invention; a light source 215; and DMD (Digital Micromirror Device: registered trademark) elements 21a to 21c as light valves, which correspond to light of each color and output optical images. In addition, the projection display device 200 has TIR (Total Internal Reflection) prisms 24a to 24c for color separation and color synthesis and a polarized light separation prism 25 for separating illumination light and projection light. In addition, Fig.19 210 is schematically shown in FIG. 21. In addition, an integrator is arranged between the light source 215 and the polarization separation prism 25. Fig.19 The illustration is omitted.

[0237] The white light from the light source 215 is reflected by the reflection surface inside the polarized light separation prism 25, and then is separated into three color light beams (green light, blue light, and red light) by the TIR prisms 24a to 24c. The separated color light beams are respectively incident on the corresponding DMD elements 21a to 21c to be modulated, and then travel in the opposite directions in the TIR prisms 24a to 24c again and undergo color synthesis, and then pass through the polarized light separation prism 25 and are incident on the projection optical system 210. The projection optical system 210 projects an optical image based on the modulated light modulated by the DMD elements 21a to 21c onto the screen 205.

[0238] Fig. 20 It is a schematic structural diagram of a projection display device according to still another embodiment of the present invention. Fig. 20 The projection display device 600 shown in the figure has: a projection optical system 66 according to an embodiment of the present invention; a light source 61; and a DMD element 64 as a light valve, which outputs an optical image corresponding to each color of light. In addition, the projection display device 600 has a color wheel 62, a light guide optical system 63, and a TIR prism 65. Fig. 20 The projection optical system 66 is schematically shown in FIG.

[0239] The color wheel 62 is provided with color filters of three colors, namely green, blue and red, on the circumference. When the color wheel 62 rotates, the color filters of each color are sequentially embedded in the optical path. The white light from the light source 61 is incident on the rotating color wheel 62 and time-decomposed into three color light beams (green light, blue light, and red light). After the time-decomposed color light beams pass through the light guide optical system 63 and the TIR prism 65, they are incident on the DMD element 64 to be modulated, and then pass through the TIR prism 65 again to be incident on the projection optical system 66. The projection optical system 66 projects the optical image based on the modulated light modulated by the DMD element 64 onto the screen 67.

[0240] The above examples and embodiments are used to illustrate the technology of the present invention, but the technology of the present invention is not limited to the above examples and embodiments, and various modifications are possible. For example, the radius of curvature, surface spacing, refractive index, dispersion coefficient, and aspheric coefficient of each lens are not limited to the values ​​shown in the above examples, and other values ​​may be used.

[0241] Furthermore, the projection display device involved in the technology of the present invention is not limited to the above-mentioned structure. For example, the optical components and light valves used for light beam separation or light beam synthesis can be changed in various ways. The light valve is not limited to a method of spatially modulating the light from the light source through the image display element to output as an optical image based on the image data, but can also be a method of outputting the light itself output from the self-luminous image display element as an optical image based on the image data. As a self-luminous image display element, for example, an image display element formed by a two-dimensional arrangement of light-emitting elements such as LED (Light Emitting Diode) or OLD (Organic Light Emitting Diode) can be cited. The light valve is not limited to a three-plate method, but can be a single-plate method. By configuring the light valve to correspond to the single-plate method, the miniaturization of the optical engine can be achieved.

[0242] Regarding the above-mentioned implementation modes and examples, the following additional notes are further disclosed.

[0243] [Supplementary Item 1]

[0244] A projection optical system is a projection optical system that projects an image displayed on a display surface of a display element on a reduction side onto a projection surface on an enlargement side, wherein:

[0245] Excluding reflective surfaces with optical power,

[0246] The optical path of the projection optical system includes at least one optical path deflection surface that bends the optical path by 90 degrees.

[0247] The sum of the thicknesses on the optical axis of all the optical elements included in the range from the lens surface of the projection optical system closest to the magnification side to the lens surface of the projection optical system closest to the reduction side is ΣTHe,

[0248] The height of the optical axis of the maximum effective light from the display surface is set to Imax,

[0249] The focal length of the projection optical system is f,

[0250] When the projection optical system is a variable magnification optical system, f is set to a value at the wide-angle end.

[0251] When mm is used as the unit of length,

[0252] Satisfying the following conditional expressions (1) and (2),

[0253] ∑THe<70mm (1)

[0254] 1.7<Imax / |f| (2).

[0255] [Supplementary Item 2]

[0256] The projection optical system according to Supplementary Item 1, wherein:

[0257] The optical path of the projection optical system includes only two optical path deflection surfaces.

[0258] The distance on the optical axis from the optical path deflecting surface on the magnification side to the optical path deflecting surface on the reduction side is d1,

[0259] When the distance on the optical axis from the optical path deflection surface on the reduction side to the lens surface of the projection optical system closest to the reduction side is set as d2, and when the projection optical system is a variable magnification optical system, d1 and d2 are set as values ​​at the wide-angle end,

[0260] Satisfying the following conditional expressions (3) and (4),

[0261] d1<70mm (3)

[0262] d2<100mm (4).

[0263] [Supplementary item 3]

[0264] The projection optical system according to Supplementary Item 1 or 2, wherein:

[0265] When the longest diameter of the largest area in the display element capable of displaying the image is DL,

[0266] Satisfying the conditional expression (5) expressed as follows,

[0267] Imax / DL<0.78 (5).

[0268] [Supplementary Item 4]

[0269] The projection optical system according to any one of Supplementary Items 1 to 3, wherein:

[0270] The height of the optical axis of the maximum effective light from the projection surface is set to Ymax,

[0271] When the magnification side is defined as the object side and the reduction side is defined as the image side, the paraxial image magnification of the projection optical system is defined as β,

[0272] When the projection optical system is a variable magnification optical system, and β is set to a value at the wide-angle end,

[0273] Satisfying the conditional expression (6) expressed as follows,

[0274] -0.05<(Imax-β×Ymax) / (β×Ymax)<0.05 (6).

[0275] [Supplementary Note 5]

[0276] The projection optical system according to any one of Supplementary Items 1 to 4, wherein:

[0277] The sum of the thicknesses on the optical axis of all optical elements having optical power from the lens surface closest to the magnification side of the projection optical system to the lens surface closest to the reduction side of the projection optical system is ∑THpw,

[0278] When the sum of the thicknesses on the optical axis of all optical elements having optical power from the lens surface closest to the magnification side of the projection optical system to the lens surface closest to the reduction side of the projection optical system and having a refractive index of 1.8 or more with respect to the d-line is ∑TH18,

[0279] Satisfying the conditional expression (7) expressed as follows,

[0280] 0.27<∑TH18 / ∑THpw<0.5 (7).

[0281] [Supplementary Item 6]

[0282] The projection optical system according to any one of Supplementary Items 1 to 5, wherein:

[0283] An intermediate image is formed inside the projection optical system.

[0284] [Supplementary Item 7]

[0285] The projection optical system according to Supplementary Item 6, wherein:

[0286] The optical path of the projection optical system includes only two optical path deflection surfaces.

[0287] The intermediate image is formed on the optical path between the optical path deflecting surface on the magnification side and a surface adjacent to the reduction side of the optical path deflecting surface on the reduction side.

[0288] [Supplementary Item 8]

[0289] The projection optical system according to Supplementary item 6 or 7, wherein:

[0290] includes an aperture stop on the reduction side of the intermediate image,

[0291] The real image of the aperture diaphragm exists inside the projection optical system on the magnification side relative to the intermediate image.

[0292] The position where the light rays emitted from the outermost periphery of the effective image circle on the reduction side and passing through the center of the aperture stop toward the magnification side intersect the optical axis on the magnification side of the intermediate image is defined as Enp(Imax).

[0293] The position of the paraxial image of the aperture diaphragm is set to Enp(0),

[0294] Let DifE be the air-converted distance on the optical axis from Enp(0) to Enp(Imax).

[0295] The sign of DifE is based on Enp(0), with the distance on the reduction side being positive and the distance on the enlargement side being negative.

[0296] When the projection optical system is a variable magnification optical system, when DifE is set to a value at the wide-angle end,

[0297] Satisfying the conditional expression (8) expressed as follows,

[0298] -3<DifE / Imax<-0.2 (8).

[0299] [Supplementary Item 9]

[0300] The projection optical system according to any one of Supplementary Items 1 to 8, wherein:

[0301] The lens closest to the magnification side has a rotationally symmetrical shape with a portion missing.

[0302] [Supplementary Item 10]

[0303] The projection optical system according to Supplementary item 2 or 7, wherein:

[0304] At least one of the light path deflecting surfaces is a surface of a reflecting mirror.

[0305] [Supplementary Item 11]

[0306] The projection optical system according to Supplementary item 2 or 7, wherein:

[0307] At least one of the light path deflecting surfaces is a prism surface.

[0308] [Supplementary Item 12]

[0309] The projection optical system according to any one of the appendix items 1 to 11, which satisfies the conditional formula (1-1) represented by the following:

[0310] 30mm<∑THe<70mm (1-1).

[0311] [Supplementary Item 13]

[0312] The projection optical system according to any one of the appendix items 1 to 12, which satisfies the conditional expression (2-1) represented by the following:

[0313] 2<Imax / |f|<3.5 (2-1).

[0314] [Supplementary Item 14]

[0315] The projection optical system according to Supplementary Item 2 satisfies the conditional expression (3-1) represented by the following:

[0316] 10mm<d1<50mm (3-1).

[0317] [Supplementary Item 15]

[0318] The projection optical system according to Supplementary Item 2 satisfies the conditional expression (4-1) represented by the following:

[0319] 20mm<d2<75mm (4-1).

[0320] [Supplementary Item 16]

[0321] The projection optical system according to Supplementary Item 3 satisfies the conditional expression (5-1) represented by the following:

[0322] 0.65<Imax / DL<0.72 (5-1).

[0323] [Supplementary Item 17]

[0324] The projection optical system according to Supplementary Item 4 satisfies the conditional expression (6-1) represented by the following:

[0325] -0.03<(Imax-β×Ymax) / (β×Ymax)<0.03 (6-1).

[0326] [Supplementary Item 18]

[0327] The projection optical system according to Supplementary Item 5 satisfies the conditional expression (7-1) represented by the following:

[0328] 0.3<∑TH18 / ∑THpw<0.4 (7-1).

[0329] [Supplementary Item 19]

[0330] The projection optical system according to Supplementary Item 8 satisfies the conditional expression (8-1) represented by the following:

[0331] -2.5<DifE / Imax<-0.5 (8-1).

[0332] [Supplementary item 20]

[0333] A projection display device comprises the projection optical system according to any one of Supplementary Items 1 to 19.

Claims

1. A projection optical system, characterized in that: The projection optical system is a projection optical system for projecting an image displayed on a display surface of a display element on a reduction side onto a projection surface on an enlargement side, wherein: Excluding reflective surfaces with optical power, The optical path of the projection optical system includes at least one optical path deflection surface that bends the optical path by 90 degrees. The sum of the thicknesses on the optical axis of all the optical elements included in the range from the lens surface of the projection optical system closest to the magnification side to the lens surface of the projection optical system closest to the reduction side is ΣTHe, The height of the optical axis of the maximum effective light from the display surface is set to Imax, The focal length of the projection optical system is f, When the projection optical system is a variable magnification optical system, f is set to a value at the wide-angle end. When mm is used as the unit of length, Satisfying the following conditional expressions (1) and (2), ΣTHe<70mm (1) 1.7<Imax / |f| (2) 2. The projection optical system according to claim 1, wherein: The optical path of the projection optical system includes only two optical path deflection surfaces. The distance on the optical axis from the optical path deflecting surface on the magnification side to the optical path deflecting surface on the reduction side is d1, When the distance on the optical axis from the optical path deflection surface on the reduction side to the lens surface of the projection optical system closest to the reduction side is set as d2, and when the projection optical system is a variable magnification optical system, d1 and d2 are set as values ​​at the wide-angle end, Satisfying the following conditional expressions (3) and (4), d1<70mm (3) d2<100mm(4) 3. The projection optical system according to claim 1 or 2, wherein: When the longest diameter of the largest area in the display element capable of displaying the image is DL, Satisfies the conditional expression (5) expressed as follows, Imax / DL<0.78(5).

4. The projection optical system according to claim 1 or 2, wherein: The height of the optical axis of the maximum effective light on the projection surface is set to Ymax, The paraxial image magnification of the projection optical system when the magnification side is the object side and the reduction side is the image side is β, When the projection optical system is a variable magnification optical system, when β is set to a value at the wide-angle end, Satisfies the conditional expression (6) expressed as follows, -0.05<(Imax-β×Ymax) / (β×Ymax)<0.05 (6).

5. The projection optical system according to claim 1 or 2, wherein: The sum of the thicknesses on the optical axis of all optical elements having optical power from the lens surface closest to the magnification side of the projection optical system to the lens surface closest to the reduction side of the projection optical system is ΣTHpw, When the sum of the thicknesses on the optical axis of all optical elements having optical power from the lens surface closest to the magnification side of the projection optical system to the lens surface closest to the reduction side of the projection optical system and having a refractive index of 1.8 or more with respect to the d-line is ΣTH18, Satisfies the conditional expression (7) expressed as follows, 0.27<ΣTH18 / ΣTHpw<0.5 (7).

6. The projection optical system according to claim 1 or 2, wherein: An intermediate image is formed inside the projection optical system.

7. The projection optical system according to claim 6, wherein: The intermediate image is formed on the optical path between the optical path deflecting surface on the magnification side and a surface adjacent to the reduction side of the optical path deflecting surface on the reduction side.

8. The projection optical system according to claim 6, wherein: includes an aperture stop on the reduction side of the intermediate image, The real image of the aperture diaphragm exists inside the projection optical system on the magnification side relative to the intermediate image. The position where the light rays emitted from the outermost periphery of the effective image circle on the reduction side and passing through the center of the aperture stop toward the magnification side intersect the optical axis on the magnification side of the intermediate image is defined as Enp (Imax). The position of the paraxial image of the aperture diaphragm is set to Enp(0), Let DifE be the air-converted distance on the optical axis from Enp(0) to Enp(Imax). The sign of DifE is based on Enp (0), with the distance on the reduction side being positive and the distance on the enlargement side being negative. When the projection optical system is a variable magnification optical system, when DifE is set to a value at the wide-angle end, Satisfies the conditional expression (8) expressed as follows, -3<DifE / Imax<-0.2 (8).

9. The projection optical system according to claim 1 or 2, wherein: The lens closest to the magnification side has a rotationally symmetrical shape with a portion missing.

10. The projection optical system according to claim 2, wherein: At least one of the light path deflecting surfaces is a surface of a reflecting mirror.

11. The projection optical system according to claim 2, wherein: At least one of the light path deflecting surfaces is a prism surface.

12. The projection optical system according to claim 1 or 2, which satisfies the conditional expression (1-1) represented by the following: 30mm<ΣTHe<70mm (1-1).

13. The projection optical system according to claim 1 or 2, which satisfies the conditional expression (2-1) represented by the following: 2<Imax / |f|<3.5 (2-1).

14. The projection optical system according to claim 2, which satisfies the conditional expression (3-1) represented by the following: 10mm<d1<50mm (3-1).

15. The projection optical system according to claim 2, which satisfies the conditional expression (4-1) represented by the following: 20mm<d2<75mm (4-1).

16. The projection optical system according to claim 3, which satisfies the conditional expression (5-1) represented by the following: 0.65<Imax / DL<0.72 (5-1).

17. The projection optical system according to claim 4, which satisfies the conditional expression (6-1) represented by the following: -0.03<(Imax-β×Ymax) / (β×Ymax)<0.03 (6-1).

18. The projection optical system according to claim 5, which satisfies the conditional expression (7-1) represented by the following: 0.3<ΣTH18 / ΣTHpw<0.4 (7-1).

19. The projection optical system according to claim 8, which satisfies the conditional expression (8-1) represented by the following: -2.5<DifE / Imax<-0.5 (8-1).

20. A projection display device, characterized in that: A projection optical system comprising the projection optical system according to any one of claims 1 to 19.

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