TWI803955B - Projection lens and projection apparatus - Google Patents

Abstract

A projection lens including a first lens group, an aperture stop, a second lens group, and a reflective optical element sequentially arranged from a minified side to a magnified side along an optical axis is provided. The first lens group has positive refractive power. The second lens group has negative refractive power. The reflective optical element has positive refractive power. The projection lens satisfies 1.2 ＜ | F ₂/F ₁| ＜ 3.5, wherein F ₂is an effective focal length of the reflective optical element, and F ₁is an effective focal length of the first lens group and the second lens group. A projection apparatus is also provided.

Description

Projection lens and projection device

The present invention relates to an optical lens and an optical device, and in particular to a projection lens and a projection device.

Existing ultra-short-throw projection lenses generally include a first optical system, a second optical system, a first stop, a second stop and a reflective optical system (which may be a concave mirror). The light valve is located at the reduction side, and the first optical system includes a plurality of lenses for forming a first intermediate image from the light valve incident image from the reduction side. The second optical system includes a plurality of lenses for receiving the first intermediate image from the first optical system and forming a second intermediate image. The reflective optical system has positive diopter and is closer to the magnification side than the second intermediate image. The first diaphragm is arranged between the light exit surface of the light valve and the first intermediate image. The second diaphragm is disposed between the first intermediate image and the second intermediate image. The second intermediate image from the second optical system is enlarged and projected on the imaging screen through the reflective surface of the reflective optical system.

However, the existing ultra-short-throw projection lens has too many lenses, resulting in higher production costs. Moreover, based on the aforementioned optical system, the mechanism design is relatively complicated, and the overall length of the lens becomes longer. Therefore, the existing ultra-short-focus projection lens has the problem that it is not suitable for small-sized projectors.

The "Prior Art" paragraph is only used to help understand the content of the present invention, so the content disclosed in the "Prior Art" paragraph may contain some conventional technologies that do not constitute the knowledge of those with ordinary skill in the art. The content disclosed in the "Prior Art" paragraph does not mean that the content or the problems to be solved by one or more embodiments of the present invention have been known or recognized by those with ordinary knowledge in the technical field before the application of the present invention.

The invention provides a projection lens, which can reduce the number of lenses in the system.

The present invention provides a projection device using the above-mentioned projection lens, the length of the system is small, and the cost is reduced.

An embodiment of the present invention provides a projection lens, which includes a first lens group, a diaphragm, a second lens group and a reflective optical element sequentially arranged along an optical axis from a reduction side to an enlargement side. The first lens group has positive diopter. The second lens group has negative diopter. Reflective optics have positive diopters. The projection lens satisfies 1.2 < | F ₂ /F ₁ | < 3.5, wherein F ₂ is the effective focal length of the reflective optical element, and F ₁ is the effective focal length of the first lens group and the second lens group.

In an embodiment of the present invention, the above-mentioned first lens group includes seven lenses. The diopters of the seven lenses are positive, positive, negative, positive, negative, negative, and positive from the reduction side to the enlargement side. Abbe numbers of at least two of the seven lenses are greater than or equal to 70.

In an embodiment of the present invention, the above-mentioned second lens group includes four lenses. The diopters of the four lenses are positive, negative, negative, and negative in order from the reduction side to the enlargement side.

In an embodiment of the present invention, the above-mentioned first lens group includes six lenses. The diopters of the six lenses are positive, positive, negative, positive, negative, and positive from the reduction side to the enlargement side. Abbe numbers of at least two of the six lenses are greater than or equal to 70.

In an embodiment of the present invention, the above-mentioned first lens group includes at least one set of cemented lenses.

In an embodiment of the present invention, the above-mentioned first lens group includes at least one aspherical lens. The second lens group includes at least one aspherical lens.

In an embodiment of the present invention, the aperture of the projection lens is in the range of 1.7 to 2.0.

In an embodiment of the present invention, the above-mentioned first lens group is a compensation group, and the second lens group is a focusing group. When the projection lens is in focus, the first lens group and the second lens group are suitable for The optical axis moves.

An embodiment of the invention provides a projection device, which includes an illumination system, a light valve, and a projection lens. The lighting system is adapted to provide a lighting beam. The light valve is arranged on the transmission path of the illuminating light beam and is suitable for converting the illuminating light beam into an image light beam. The projection lens is arranged on the transmission path of the image beam, and is suitable for receiving the image beam from the light valve and projecting the projection beam. The projection lens includes a first lens group, a diaphragm, a second lens group and reflective optical elements arranged sequentially along the optical axis from the reduction side to the enlargement side. The first lens group has positive diopter. The second lens group has negative diopter. Reflective optics have positive diopters. The projection lens satisfies 1.2 < | F ₂ /F ₁ | < 3.5, wherein F ₂ is the effective focal length of the reflective optical element, and F ₁ is the effective focal length of the first lens group and the second lens group.

In an embodiment of the present invention, the above-mentioned first lens group includes seven lenses. The diopters of the seven lenses are positive, positive, negative, positive, negative, negative, and positive from the reduction side to the enlargement side. Abbe numbers of at least two of the seven lenses are greater than or equal to 70.

In an embodiment of the present invention, the above-mentioned second lens group includes four lenses. The diopters of the four lenses are positive, negative, negative, and negative in order from the reduction side to the enlargement side.

In an embodiment of the present invention, the above-mentioned first lens group includes six lenses. The diopters of the six lenses are positive, positive, negative, positive, negative, and positive from the reduction side to the enlargement side. Abbe numbers of at least two of the six lenses are greater than or equal to 70.

In an embodiment of the present invention, the above-mentioned first lens group includes at least one set of cemented lenses.

In an embodiment of the present invention, the above-mentioned first lens group includes at least one aspherical lens. The second lens group includes at least one aspherical lens.

In an embodiment of the present invention, the aperture of the projection lens is in the range of 1.7 to 2.0.

In an embodiment of the present invention, the above-mentioned first lens group is a compensation group, and the second lens group is a focusing group. When the projection lens is in focus, the first lens group and the second lens group are suitable for The optical axis moves.

In an embodiment of the present invention, the above projection light beam is projected from the projection device to form an image on the imaging plane.

In an embodiment of the present invention, the central image light beam emitted by the center of the above-mentioned light valve is projected by the projection lens to correspond to the center of the image on the imaging plane. There are two intersections between the central image beam and the optical axis.

Based on the above, in one embodiment of the present invention, since the projection lens or projection device is designed to comply with 1.2 < | F ₂ /F ₁ | < 3.5, the optical structure of the projection lens or projection device is relatively simple, making the mechanism design Also easier.

In order to make the above-mentioned features and advantages of the present invention more comprehensible, the following specific embodiments are described in detail together with the accompanying drawings.

The aforementioned and other technical contents, features and effects of the present invention will be clearly presented in the following detailed description of a preferred embodiment with reference to the drawings. The directional terms mentioned in the following embodiments, such as: up, down, left, right, front or back, etc., are only directions referring to the attached drawings. Accordingly, the directional terms used are for the purpose of illustration and not for the purpose of limiting the invention.

FIG. 1 is a block diagram of a projection apparatus according to a first embodiment of the present invention. Please refer to FIG. 1 , an embodiment of the present invention provides a projection device 10 , which includes an illumination system 50 , a light valve 60 and a projection lens 100 . The illumination system 50 is adapted to provide an illumination beam I. The light valve 60 is disposed on the transmission path of the illumination beam I, and is suitable for converting the illumination beam I into the image beam IB. The projection lens 100 is disposed on the transmission path of the image beam IB, and is suitable for receiving the image beam IB from the light valve 60 and projecting a projection beam PB. Wherein, the projection beam PB is projected from the projection device 10 to form an image on the imaging surface IP.

In detail, the lighting system 50 of this embodiment includes, for example, a plurality of light emitting elements, wavelength conversion elements, light homogenizing elements, light filtering elements and a plurality of light splitting and combining elements to provide light of different wavelengths as a source of image light . The plurality of light-emitting elements are, for example, metal halide bulbs (Lamps), high-pressure mercury bulbs, or solid-state illumination sources, such as light emitting diodes (light emitting diodes), laser diodes (laser diodes) diode) etc. However, the present invention does not limit the type or form of the lighting system 50 in the projection device 10 , and its detailed structure and implementation can be obtained from sufficient teachings, suggestions and implementation descriptions based on common knowledge in the technical field, so details are not repeated here.

In this embodiment, the light valve 60 is, for example, a reflective light modulator such as a Liquid Crystal On Silicon panel (LCoS panel) or a digital micro-mirror device (Digital Micro-mirror Device, DMD). In some embodiments, the light valve 60 can also be a transparent liquid crystal panel (Transparent Liquid Crystal Panel), an electro-optical modulator (Electro-Optical Modulator), a magneto-optic modulator (Magneto-Optic modulator), an acousto-optic modulator Acousto-Optic Modulator (AOM) and other transmissive optical modulators. The present invention does not limit the type and type of the light valve 60 . The detailed steps and implementation of the method for the light valve 60 to convert the illumination beam I into the image beam IB can be obtained from the general knowledge in the technical field for sufficient teaching, suggestion and implementation description, so no further description is given. In this embodiment, the number of light valves 60 is one, such as the projection device 10 using a single digital micromirror device (DMD), but there may be multiple light valves in other embodiments, and the present invention is not limited thereto.

FIG. 2 is a schematic diagram of a projection lens in the projection device of FIG. 1 . Please refer to FIG. 2. In this embodiment, the projection lens 100 includes a first lens group G1, a stop ST, a second lens group G2 and reflective optical elements arranged in sequence along the optical axis OA from the reduction side A1 to the enlargement side A2. 110. In this embodiment, the light valve 60 is arranged on the reduction side A1, and the image beam IB from the light valve 60 passes through the first lens group G1, the diaphragm ST and the second lens group G2 in order from the reduction side A1, and then passes to the The reflective optical element 110 , the image beam IB is reflected by the reflective optical element 110 to form a projection beam PB toward the magnifying side A2 .

In this embodiment, the central image beam CP emitted by the center of the light valve 60 is projected by the projection lens 100 to correspond to the center of the image on the imaging plane IP. There are two intersections P1, P2 between the central image beam CP and the optical axis OA.

In this embodiment, the first lens group G1 includes seven lenses L1 , L2 , L3 , L4 , L5 , L6 , L7 sequentially arranged along the optical axis OA from the reducing side A1 to the magnifying side A2 . The first lens group G1 has positive diopter. Furthermore, the diopters of the seven lenses L1, L2, L3, L4, L5, L6, and L7 are positive, positive, negative, positive, negative, negative, and positive in order from the reduction side A1 to the enlargement side A2. The Abbe numbers of at least two of the seven lenses L1, L2, L3, L4, L5, L6, and L7 in the first lens group G1 are greater than or equal to 70, such as lens L2 and lens L4, which for example use Abbe numbers greater than or equal to 70 nitrate material. The second lens group G2 includes four lenses L8 , L9 , L10 , and L11 sequentially arranged along the optical axis OA from the reduction side A1 to the enlargement side A2 . The second lens group G2 has negative diopter. Furthermore, the diopters of the four lenses L8, L9, L10, and L11 are positive, negative, negative, and negative in order from the reduction side A1 to the enlargement side A2. Therefore, compared with the conventional lens, the total number of lenses used in the projection lens 100 of the present invention is reduced to 11, so that the length of the lens is reduced, and the material volume of the system can also be reduced, further reducing the cost. Since the length of the projection lens 100 is reduced, the projection lens 100 is suitable for projection devices of various sizes. Moreover, using the characteristics of cemented lenses, together with lenses whose Abbe number is designed to be greater than or equal to 70, can help reduce optical chromatic aberration.

In this embodiment, the first lens group G1 includes at least one set of cemented lenses. For example lenses L2, L3, L4 are a set of cemented lenses, and lenses L5, L6, L7 are another set of cemented lenses.

In this embodiment, the first lens group G1 includes at least one aspherical lens. The second lens group G2 includes at least one aspheric lens. For example, the lens L1 in the first lens group G1 or the lens L9 and the lens L11 in the second lens group G2 are aspherical lenses.

In this embodiment, the reflective optical element 110 has a positive diopter, and the reflective optical element 110 includes a reflective surface S25. The reflective surface S25 has positive diopter and is aspheric.

The data of a preferred embodiment of the projection lens 100 are listed in Table 1 to Table 2 below. However, the data listed below are not intended to limit the invention. Any person skilled in the art may make appropriate changes to the parameters or settings after referring to the present invention, but they still fall within the scope of the present invention.

In this embodiment, the actual design of the aforementioned elements can be seen in Table 1 below.

Table 1 element surface type Curvature (1/mm) Distance (mm) Refractive index (Nd) Abbe number (Vd) 110 S25 Aspherical -0.032 -71.36 L11 S24 Aspherical 0.038 -2.20 1.53 56.28 S23 Aspherical -0.068 -2.23 L10 S22 sphere -0.060 -1.20 1.78 45.70 S21 sphere -0.089 -1.78 L9 S20 Aspherical -0.070 -3.68 1.53 56.28 S19 Aspherical -0.076 -3.71 L8 S18 sphere -0.045 -3.50 1.65 28.59 S17 sphere -0.003 -14.07 ST flat 0.000 -2.43 L7 S16 sphere -0.036 -4.30 1.59 35.23 L6 S15 sphere 0.162 -1.00 1.57 52.28 L5 S14 sphere 0.121 -1.00 1.80 37.39 S13 sphere 0.058 -0.74 L4 S12 sphere -0.008 -3.45 1.50 81.59 L3 S11 sphere 0.092 -0.80 1.81 24.99 L2 S10 sphere -0.003 -4.28 1.50 81.59 S9 sphere 0.081 -0.20 L1 S8 Aspherical -0.037 -3.10 1.60 59.52 S7 Aspherical 0.019 -1.70

In Table 1, the lens L1 has a surface S7 and a surface S8 from the reduction side A1 to the enlargement side A2, that is, the surface S7 faces the light valve 60, the surface S8 faces the reflective optical element 110, and the lens L2 is sequentially from the reduction side A1 to the enlargement side A2 It has a surface S9 and a surface S10 , that is, the surface S9 faces the light valve 60 , and the surface S10 faces the reflective optical element 110 . Among them, lenses L2, L3, and L4 are a set of cemented lenses, so the surface of lens L2 toward the enlargement side A2 and the surface of lens L3 toward the reduction side A1 are the same surface S10, and the surface of lens L3 toward the enlargement side A2 is the same surface S10 as lens L4 toward the enlargement side. The surface of the reduction side A1 is the same surface S11. By analogy, the surface corresponding to each element will not be described again. In addition, in Table 1, "distance" refers to the distance between two adjacent surfaces on the optical axis OA. In the projection lens 100 , the image beam exits from the surface S0 of the light valve 60 on the reduction side A1 , enters the projection lens 100 and exits from the enlargement side A2 . For example, the distance corresponding to the surface S25 refers to the distance on the optical axis OA between the surface S25 and the surface S24, and the distance corresponding to the surface S24 is the straight-line distance between the surface S24 and the surface S23 on the optical axis OA, and so on.

In this embodiment, the surface S7 and the surface S8 of the lens L1, the surface S19 and the surface S20 of the lens L9, the surface S23 and the surface S24 of the lens L11, and the reflective surface S25 of the reflective optical element 110 are all aspheric surfaces, while the other lenses The surfaces are all spherical. The formula for an aspheric surface is as follows:

In the above formula, x is the offset (sag) in the direction of the optical axis. c' is the reciprocal of the radius of the Osculating Sphere, that is, the reciprocal of the radius of curvature near the optical axis, K is the coefficient of the quadric surface, and y is the height of the aspheric surface, which is the height from the center of the lens to the edge of the lens. A-G respectively represent aspheric coefficients of each order of the aspheric polynomial. Table 2 lists the parameter values of surface S7 and surface S8 of lens L1, surface S19 and surface S20 of lens L9, surface S23 and surface S24 of lens L11, and reflective surface S25 of reflective optical element 110, wherein the second-order aspheric coefficient A is is 0.

Table 2 S7 S8 S19 S20 K 0 0 0 0 B 1.53E-04 1.73E-04 -1.09E-03 -1.23E-03 C -7.98E-08 5.02E-07 2.09E-05 2.63E-05 D. 5.16E-08 4.65E-08 -6.35E-07 -4.47E-07 E. -3.57E-10 -8.82E-11 2.23E-08 7.44E-09 f -3.77E-10 -6.76E-11 G 3.04E-12 2.79E-13 h -1.01E-14 -2.69E-16 S23 S24 S25 K 1.094 0 -1.100 B -4.06E-04 -2.86E-04 1.26E-06 C 4.75E-06 2.40E-06 -2.32E-09 D. 2.50E-07 -2.45E-08 1.83E-12 E. -7.83E-09 1.81E-10 -1.13E-15 f 1.05E-10 -1.02E-12 4.08E-19 G -7.19E-13 3.72E-15 -7.07E-23 h 2.09E-15 -6.49E-18

In this embodiment, the projection lens 100 satisfies 1.2 < | F ₂ /F ₁ | < 3.5, wherein F ₂ is the effective focal length of the reflective optical element 110, and F ₁ is the distance between the first lens group G1 and the second lens group G2 effective focal length.

In this embodiment, the aperture of the projection lens 100 falls within the range of 1.7 to 2.0.

In this embodiment, the first lens group G1 of the projection lens 100 is a compensation group, and the second lens group G2 is a focusing group. When the projection lens 100 is in focus, the first lens group G1 is adapted to move along the optical axis OA to compensate for the sharpness of the near-axis image, and the second lens group G2 is adapted to move along the optical axis OA to adjust the off-axis viewing angle. The resolution of the field image. Since the focal length of the projection lens 100 can be adjusted, a clear projection image can be maintained.

In addition, in this embodiment, the projection lens 100 further includes glass pieces 130, 150 and a lens 140 disposed between the light valve 60 and the first lens group G1, the glass piece 130 is, for example, a protective cover of the light valve 60, wherein The glass part 130 , the glass part 140 and the glass part 150 are arranged sequentially along the optical axis OA from the reducing side A1 to the magnifying side A2 .

Figures 3 to 7 are the Transverse ray fan plots of the projection lens in Figure 2 at different object heights, where the maximum and minimum scales of the ex, ey, Px, and Py axes are respectively + 20 microns (μm) and -20 microns. Please refer to FIG. 3 to FIG. 7 , the graphs shown in FIG. 3 to FIG. 7 are all within the standard range, so it can be verified that the projection lens 100 of this embodiment can achieve good optical imaging quality.

Figures 8 to 12 are spot diagrams of light of different wavelengths at different image heights and object heights after passing through the projection lens in Figure 2, where the maximum range of the x-axis and y-axis is 20 microns. Please refer to FIG. 8 to FIG. 12 , the light spots of each wavelength after passing through the projection lens 100 are not too large, so the image projected by the projection lens 100 of this embodiment has higher imaging quality.

FIG. 13 is a diagram of the modulation transfer function of the projection lens in FIG. 2 . 13 is a diagram of the modulation transfer function (modulation transfer function, MTF) of the projection lens 100 at different image heights, where the horizontal axis is the focus shift, and the vertical axis is the modulus of the optical transfer function (modulus of the optical transfer function), T represents the curve in the meridian direction, S represents the curve in the sagittal direction, and the value marked next to "TS" represents the image height. Therefore, it can be verified that the optical transfer function curve displayed by the projection lens 100 of this embodiment is within the standard range, so it has good optical imaging quality, as shown in FIG. 13 .

Based on the above, in one embodiment of the present invention, the projection lens 100 or the projection device 10 is provided with a reflective optical element 100, and by designing the projection lens to comply with 1.2 < | F ₂ /F ₁ | < 3.5, the projection lens 100 or the optical structure of the projection device 10 is relatively simple, which makes the mechanism design easier.

FIG. 14 is a schematic diagram of a projection lens according to a second embodiment of the present invention. Please refer to FIG. 14, the projection lens 100' of the second embodiment of the present invention is roughly similar to the projection lens 100 of the first embodiment, and the differences between the two are as follows: each optical data and lenses L1, L2, L3, L4, The parameters between L5, L6, L7, L8, L9 and L10 are more or less different.

In this embodiment, the first lens group G1 includes six lenses L1 , L2 , L3 , L4 , L5 , and L6 sequentially arranged along the optical axis OA from the reducing side A1 to the magnifying side A2 . The diopters of the six lenses L1, L2, L3, L4, L5, and L6 are positive, positive, negative, positive, negative, and positive from the reduction side A1 to the enlargement side A2 in sequence. The Abbe numbers of at least two of the six lenses L1, L2, L3, L4, L5, and L6 in the first lens group G1 are greater than or equal to 70, such as lens L2 and lens L4, which for example use Abbe numbers greater than or equal to 70 Made of nitrate. The first lens group G1 includes at least one set of cemented lenses. For example lenses L2, L3, L4 are a set of cemented lenses, and lenses L5, L6 are another set of cemented lenses. The first lens group G1 includes at least one aspherical lens. For example, lens L1 is an aspherical lens.

In addition, the second lens group G2 includes four lenses L7 , L8 , L9 , and L10 sequentially arranged along the optical axis OA from the reducing side A1 to the magnifying side A2 , wherein the lenses L8 and L10 are aspherical lenses.

The data of a preferred embodiment of the projection lens 100' are listed in Table 3 to Table 4 below. However, the data listed below are not intended to limit the invention. Any person skilled in the art may make appropriate changes to the parameters or settings after referring to the present invention, but they still fall within the scope of the present invention.

In this embodiment, the actual design of the aforementioned components can be seen in Table 3 below.

table 3 element surface type Curvature (1/mm) Distance (mm) Refractive index (Nd) Abbe number (Vd) 110 S24 Aspherical -0.033 -71.36 L10 S23 Aspherical 0.043 -2.20 1.53 56.28 S22 Aspherical -0.067 -2.24 L9 S21 sphere -0.056 -1.20 1.77 49.60 S20 sphere -0.090 -1.81 L8 S19 Aspherical -0.053 -3.67 1.53 56.28 S18 Aspherical -0.056 -2.72 L7 S17 sphere -0.059 -3.50 1.87 19.99 S16 sphere -0.016 -14.17 ST flat 0.000 -2.46 L6 S15 sphere -0.019 -2.70 1.51 56.50 L5 S14 sphere 0.113 -0.60 1.75 50.71 S13 sphere 0.068 -1.00 L4 S12 sphere -0.032 -3.45 1.50 81.59 L3 S11 sphere 0.092 -0.80 1.86 23.05 L2 S10 sphere -0.017 -4.28 1.50 81.59 S9 sphere 0.078 -0.20 L1 S8 Aspherical -0.003 -3.10 1.92 18.9 S7 Aspherical 0.043 -1.70

Table 4 lists the parameter values of surface S7 and surface S8 of lens L1, surface S18 and surface S19 of lens L8, surface S22 and surface S23 of lens L10, and reflective surface S24 of reflective optical element 110, wherein the second-order aspheric coefficient A is is 0.

Table 4 S7 S8 S18 S19 K 0 0 0 0 B 2.02E-04 2.37E-04 -1.12E-03 -1.34E-03 C 8.59E-07 2.12E-06 1.84E-05 2.66E-05 D. 5.96E-09 -5.11E-09 -6.57E-07 -4.52E-07 E. 2.24E-10 7.96E-10 2.28E-08 7.42E-09 f -3.77E-10 -6.76E-11 G 3.04E-12 2.79E-13 h -1.01E-14 -2.69E-16 S22 S23 S24 K 1.152 0 -1.104 B -3.97E-04 -2.97E-04 1.28E-06 C 5.19E-06 2.40E-06 -2.31E-09 D. 2.49E-07 -2.39E-08 1.81E-12 E. -7.85E-09 1.76E-10 -1.13E-15 f 1.05E-10 -1.02E-12 4.11E-19 G -7.19E-13 3.72E-15 -7.30E-23 h 2.09E-15 -6.49E-18

Figures 15 to 19 are the lateral beam fan diagrams of the projection lens 100' in Figure 14 at different object heights, where the maximum scale and minimum scale of the ex, ey, Px and Py axes are respectively +20 microns (μm) and -20 Microns. Please refer to FIG. 15 to FIG. 19 , the graphs shown in FIG. 15 to FIG. 19 are all within the standard range, thus it can be verified that the projection lens 100' of this embodiment can achieve good optical imaging quality.

20 to 24 are spot diagrams of light of different wavelengths at different image heights and object heights after passing through the projection lens of FIG. 14 , where the maximum range of the x-axis and y-axis is 20 microns. Please refer to FIG. 20 to FIG. 24 , the light spots of each wavelength after passing through the projection lens 100' are not too large, so the image projected by the projection lens 100' of this embodiment has higher imaging quality.

FIG. 25 is a diagram of the modulation transfer function of the projection lens in FIG. 14 . Therefore, it can be verified that the optical transfer function curve displayed by the projection lens 100' of this embodiment is within the standard range, so it has good optical imaging quality.

Based on the above, compared with the conventional lenses, since the total number of lenses used in the projection lens 100' of the second embodiment of the present invention is reduced to 10, the length of the lens is reduced, and the material volume of the system can also be reduced, further reducing the cost .

To sum up, in one embodiment of the present invention, the projection lens or projection device is equipped with reflective optical elements, and by designing the projection lens to meet 1.2 < | F ₂ /F ₁ | < 3.5, the projection lens or The optical structure of the projection device is relatively simple, so that the mechanism design is also relatively easy.

But the above-mentioned ones are only preferred embodiments of the present invention, and the scope of implementation of the present invention cannot be limited with this, that is, all simple equivalent changes and modifications made according to the patent scope of the present invention and the contents of the description of the invention, All still belong to the scope covered by the patent of the present invention. In addition, any embodiment or scope of claims of the present invention does not need to achieve all the objectives or advantages or features disclosed in the present invention. In addition, the abstract and the title are only used to assist the search of patent documents, and are not used to limit the scope of rights of the present invention. In addition, terms such as "first" and "second" mentioned in this specification or the scope of the patent application are only used to name elements (elements) or to distinguish different embodiments or ranges, and are not used to limit the number of elements. upper or lower limit.

60: light valve 100, 100': projection lens 110: reflective optics 130, 150: glass parts 140: 稜鏡 A1: Reduction side A2: Magnification side CP: Central Image Beam G1: The first lens group G2: Second lens group IP: imaging surface L1, L2, L3, L4, L5, L6, L7, L8, L9, L10, L11: Lens OA: optical axis P1, P2: Intersection S0, S1, S2, S3, S4, S6, S5, S7, S8, S9, S10, S11, S12, S13, S14, S15, S16, S17, S18, S19, S20, S21, S22, S23, S24: surface S25: reflective surface ST: light bar

FIG. 1 is a block diagram of a projection apparatus according to a first embodiment of the present invention. FIG. 2 is a schematic diagram of a projection lens in the projection device of FIG. 1 . 3 to 7 are the transverse beam fan diagrams of the projection lens in FIG. 2 at different object heights, respectively. FIGS. 8 to 12 are spot diagrams of light of different wavelengths at different image heights and object heights after passing through the projection lens in FIG. 2 . FIG. 13 is a diagram of the modulation transfer function of the projection lens in FIG. 2 . FIG. 14 is a schematic diagram of a projection lens according to a second embodiment of the present invention. 15 to 19 are the transverse beam fan diagrams of the projection lens in FIG. 14 at different object heights, respectively. FIGS. 20 to 24 are respectively light spot diagrams at different image heights and object heights after light of different wavelengths passes through the projection lens of FIG. 14 . FIG. 25 is a diagram of the modulation transfer function of the projection lens in FIG. 14 .

60: light valve 100: projection lens 110: reflective optics 130, 150: glass parts 140: 稜鏡 A1: Reduction side A2: Magnification side CP: Central Image Beam G1: The first lens group G2: Second lens group L1, L2, L3, L4, L5, L6, L7, L8, L9, L10, L11: Lens OA: optical axis P1, P2: Intersection S0, S1, S2, S3, S4, S6, S5, S7, S8, S9, S10, S11, S12, S13, S14, S15, S16, S17, S18, S19, S20, S21, S22, S23, S24: surface S25: reflective surface ST: light bar

Claims (18)

A projection lens, comprising a first lens group, a diaphragm, a second lens group and a reflective optical element sequentially arranged along an optical axis from a reduction side to an enlargement side; wherein the first lens group has positive diopter; said second lens group has negative diopter; and said reflective optical element has positive diopter; wherein said projection lens complies with 1.2 < | F ₂ /F ₁ | < 3.5, wherein F ₂ is said reflective optical element The effective focal length of F ₁ is the effective focal length of the first lens group and the second lens group. The projection lens according to claim 1, wherein the first lens group includes seven lenses, and the diopters of the seven lenses are positive, positive, negative, positive, Negative, negative, positive, the Abbe number of at least two of the seven lenses is greater than or equal to 70. The projection lens according to claim 1, wherein the second lens group includes four lenses, and the diopters of the four lenses are positive, negative, negative, and negative in order from the reduction side to the enlargement side. The projection lens according to claim 1, wherein the first lens group includes six lenses, and the diopters of the six lenses are positive, positive, negative, positive, Negative and positive, the Abbe number of at least two of the six lenses is greater than or equal to 70. The projection lens according to claim 1, wherein the first lens group comprises at least one set of cemented lenses. The projection lens according to claim 1, wherein the first lens group includes at least one aspheric lens, and the second lens group includes at least one aspheric lens. The projection lens as claimed in claim 1, wherein the aperture of the projection lens falls within the range of 1.7 to 2.0. The projection lens according to claim 1, wherein the first lens group is a compensation group, and the second lens group is a focusing group. When the projection lens is in focus, the first lens group and The second lens group is adapted to move along the optical axis. A projection device comprising: an illumination system adapted to provide an illumination beam; a light valve disposed on a transmission path of the illumination beam and adapted to convert the illumination beam into an image beam; and a projection lens, arranged on the transmission path of the image beam, suitable for receiving the image beam from the light valve and projecting a projection beam, and the projection lens includes sequentially along an optical axis from a reduction side to an enlargement side A first lens group, a diaphragm, a second lens group and a reflective optical element are arranged; wherein the first lens group has positive diopter; the second lens group has negative diopter; and the reflective optical element Positive diopter; wherein the projection lens complies with 1.2 < | F ₂ /F ₁ | < 3.5, wherein F ₂ is the effective focal length of the reflective optical element, and F ₁ is the first lens group and the second The effective focal length of the lens group. The projection device according to claim 9, wherein the first lens group includes seven lenses, and the diopters of the seven lenses are positive, positive, negative, positive, Negative, negative, positive, the Abbe number of at least two of the seven lenses is greater than or equal to 70. The projection device according to claim 9, wherein the second lens group includes four lenses, and the diopters of the four lenses are positive, negative, negative, and negative in order from the reduction side to the enlargement side. The projection device according to claim 9, wherein the first lens group includes six lenses, and the diopters of the six lenses are positive, positive, negative, positive, Negative and positive, the Abbe number of at least two of the six lenses is greater than or equal to 70. The projection device as claimed in claim 9, wherein the first lens group comprises at least one set of cemented lenses. The projection device according to claim 9, wherein the first lens group includes at least one aspheric lens, and the second lens group includes at least one aspheric lens. The projection device as claimed in claim 9, wherein the aperture of the projection lens falls within the range of 1.7 to 2.0. The projection device according to claim 9, wherein the first lens group is a compensation group, and the second lens group is a focusing group. When the projection lens is in focus, the first lens group and The second lens group is adapted to move along the optical axis. The projection device as claimed in claim 9, wherein the projection light beam is projected from the projection device to form an image on an imaging plane. The projection device as claimed in claim 17, wherein a central image beam emitted from the center of the light valve is projected by the projection lens to correspond to the center of the image on the imaging plane, the central image There are two intersections between the light beam and the optical axis.

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