Fixed-focus projection optical system

Abstract

The invention discloses a fixed-focus projection optical system, and relates to the technical field of optics, and the fixed-focus projection optical system is provided with an object side and an image side which are oppositely arranged along the direction of an optical axis. The fixed-focus projection optical system comprises a micro-mirror array, an equivalent prism, a galvanometer, a first lens group, a second lens group, a plane mirror and a curved surface mirror which are sequentially arranged from the object side to the image side; wherein the plane mirror and the curved surface mirror are respectively arranged at two sides of the optical axis, the plane mirror and the optical axis are arranged in an included angle, and one end of the plane mirror is intersected with the optical axis; the focal power of the first lens group is positive, the focal power of the second lens group is positive, and the second lens group can move along the optical axis, so that the fixed-focus projection optical system is zoomed, and the length in the projection direction is greatly reduced and the size of the system is reduced by adopting two times of reflection of the plane reflecting mirror and the curved surface reflecting mirror.

Description

Technical Field

[0001] The invention relates to the field of optical technology, and in particular to a fixed-focus projection optical system. Background Art

[0002] In recent years, with the development of projection technology, ultra-short-throw projectors have been widely used in home use. Because they can project large images at a short distance, they tend to gradually replace traditional televisions.

[0003] The ultra-short-throw projection lens designs currently on the market mainly adopt a structure of a refractive lens group plus a single reflector group, and the length is often relatively large. Summary of the invention

[0004] The main purpose of the present invention is to provide a fixed-focus projection optical system, aiming to provide a small-volume fixed-focus projection optical system.

[0005] To achieve the above-mentioned object, the present invention proposes a fixed-focus projection optical system, wherein the fixed-focus projection optical system has an object side and an image side which are arranged opposite to each other along the optical axis direction, and the fixed-focus projection optical system comprises a micromirror array, an equivalent prism, a galvanometer, a first lens group, a second lens group, a plane reflector, and a curved reflector which are sequentially arranged from the object side to the image side;

[0006] Wherein, the plane reflector and the curved reflector are respectively arranged on both sides of the optical axis, the plane reflector is arranged at an angle with the optical axis, and one end of the plane reflector intersects with the optical axis;

[0007] The first lens group has a positive optical power, the second lens group has a negative optical power, and the second lens group can move along the optical axis to focus the fixed-focus projection optical system when the projection distance changes.

[0008] In one embodiment, the first lens group includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an aperture, and an eighth lens arranged in sequence from the object side to the image side, and the first lens has a positive optical power, the second lens has a positive optical power, the third lens has a positive optical power, the fourth lens has a negative optical power, the fifth lens has a positive optical power, the sixth lens has a negative optical power, the seventh lens has a positive optical power, and the eighth lens has a positive optical power; and / or,

[0009] The second lens group includes a ninth lens, a tenth lens, an eleventh lens, a twelfth lens and a thirteenth lens arranged in sequence from the object side to the image side, and the ninth lens has a positive optical power, the tenth lens has a positive optical power, the eleventh lens has a negative optical power, the twelfth lens has a negative optical power, and the thirteenth lens has a negative optical power.

[0010] In one embodiment, the optical power of the first lens group is φ 100 , the focal power of the second lens group is φ 200 , the focal length of the curved reflector is φ 400 , the optical power satisfies:

[0011] 0.04≤|φ 100 |≤0.06,0.003≤|φ 200 |≤0.01,0.04≤|φ 400 |≤0.08.

[0012] In one embodiment, the optical power of the first lens group is φ 100 , the focal power of the second lens group is φ 200 , the ratio of the focal power of the first lens group to the focal power of the second lens group satisfies:

[0013] 7≤|φ 100 / φ 200 |≤11.

[0014] In one embodiment, the focal power of the first lens is φ1, the focal power of the second lens is φ2, and the sum of the focal powers of the third lens, the fourth lens, and the fifth lens is φ 345 The sum of the focal lengths of the sixth lens and the seventh lens is φ 67 The focal power of the eighth lens is φ8; the focal power of the ninth lens is φ9; the sum of the focal powers of the tenth lens and the eleventh lens is φ 1011 ; The focal power of the twelfth lens is φ 12 The focal power of the thirteenth lens is φ 13 , the focal power of each lens satisfies:

[0015] 0.01≤|φ1|≤0.03, 0.04≤|φ2|≤0.07, 0.002≤|φ 345 |≤0.05, 0.01≤|φ 67 |≤0.04, 0.02≤|φ8|≤0.05, 0.01≤|φ9|≤0.04, 0.01≤|φ 1011 |≤0.04, 0.01≤|φ 12 |≤0.04, 0.02≤|φ 13 |≤0.06.

[0016] In one embodiment, the first lens group includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, a stop, and an eighth lens arranged in sequence from the object side to the image side, and the second lens group includes a ninth lens, a tenth lens, an eleventh lens, a twelfth lens, and a thirteenth lens arranged in sequence from the object side to the image side;

[0017] The distance between the center of the thirteenth lens and the center of the plane reflector is T1, the distance between the center of the plane reflector and the center of the curved reflector is T2, and the center distance T13 between the center of the first lens and the center of the thirteenth lens 13 satisfies:

[0018] 0.5≤T13 / (T1+T2)≤0.9.

[0019] In one embodiment, the first lens group includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an aperture, and an eighth lens arranged in sequence from the object side to the image side;

[0020] The distance from the first lens to the intersection of the plane reflector and the optical axis along the optical axis direction is T00, the distance from the micromirror array to the first lens is T11, and the ratio of T00 to T11 satisfies:

[0021] T00 / T11≤4.5.

[0022] In one embodiment, the first lens group includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, a stop, and an eighth lens arranged in sequence from the object side to the image side; the second lens group includes a ninth lens, a tenth lens, an eleventh lens, a twelfth lens, and a thirteenth lens arranged in sequence from the object side to the image side;

[0023] The second lens, the eighth lens and the ninth lens are glass aspherical lenses, and the twelfth lens, the thirteenth lens and the curved reflector are plastic aspherical lenses.

[0024] In one embodiment, the first lens group includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, a stop, and an eighth lens arranged in sequence from the object side to the image side, and the second lens group includes a ninth lens, a tenth lens, an eleventh lens, a twelfth lens, and a thirteenth lens arranged in sequence from the object side to the image side;

[0025] The third lens, the fourth lens and the fifth lens are cemented together, the sixth lens and the seventh lens are cemented together, and the tenth lens and the eleventh lens are cemented together.

[0026] In one embodiment, the angle between the optical axes of the plane reflector and the refractor assembly is 45°.

[0027] In the technical solution of the present invention, an image light beam is emitted from a micromirror array, passes through a protective glass, an equivalent prism, a galvanometer, a first lens group and a second lens group in sequence, and when the light beam reaches the plane reflector, the plane reflector reflects the light beam to the curved reflector, and then reflects the light beam to the projection screen through the curved reflector, thereby changing the direction of the light path and shortening the length in the projection direction, wherein a first imaging is performed between the plane reflector and the curved reflector, and the plane reflector and the curved reflector reflect the first imaging to the projection screen to form a second imaging; when it is necessary to change the size of the projection screen / projection ratio, the second lens group moves along the optical axis to focus the fixed-focus projection optical system; through the reasonable arrangement of the structures and positions of the first lens group with positive optical focal length, the second lens group with negative positive optical focal length, the plane reflector and the curved reflector, the plane reflector and the curved reflector reflect the light beam twice, which greatly reduces the length in the projection direction, so that the fixed-focus projection optical system has a small volume. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0029] Figure 1 A schematic structural diagram of an embodiment of a fixed-focus projection optical system provided by the present invention;

[0030] Figure 2 for Figure 1 Light path diagram of the medium fixed focus projection optical system;

[0031] Figure 3 for Figure 1 MTF performance graph of a medium fixed focus projection optical system with a projection size of 68 feet;

[0032] Figure 4 for Figure 1 Schematic diagram of the distortion of the medium fixed focus projection optical system when the projection size is 68 feet;

[0033] Figure 5 for Figure 1 MTF diagram of the medium fixed focus projection optical system when the projection size is 150 feet;

[0034] Figure 6 for Figure 2 MTF diagram of a medium fixed focus projection optical system at a projection size of 40 feet.

[0035] Description of Figure Numbers:

[0036] 1000, fixed-focus projection optical system; 100, first lens group; 200, second lens group; 300, plane reflector; 400, curved reflector; 1, first lens; 2, second lens; 3, third lens; 4, fourth lens; 5, fifth lens; 6, sixth lens; 7, seventh lens; 8, eighth lens; 9, ninth lens; 10, tenth lens; 11, eleventh lens; 12, twelfth lens; 13, thirteenth lens; a, micromirror array; b, protective glass; c, equivalent prism; d, galvanometer; e, aperture.

[0037] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0040] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features limited to "first" and "second" may explicitly or implicitly include at least one of the features. In addition, if "and / or" or "and / or" appears in the full text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or solutions that satisfy both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0041] In order to solve the above problems, the present invention proposes a fixed-focus projection optical system 1000 .

[0042] First of all, it can be understood that the focal length is equal to the difference between the convergence of the image-side light beam and the convergence of the object-side light beam, and it characterizes the ability of the optical system to deflect light. The larger the absolute value of the focal length, the stronger the ability to bend light, and the smaller the absolute value of the focal length, the weaker the ability to bend light. When the focal length is a positive number, the refraction of light is convergent; when the focal length is a negative number, the refraction of light is divergent. The focal length can be used to characterize a certain refractive surface of a lens (i.e., a surface of a lens), can be used to characterize a certain lens, and can also be used to characterize a system formed by multiple lenses (i.e., a lens group).

[0043] See also Figure 1 In one embodiment of the present invention, the fixed-focus projection optical system 1000 has an object side and an image side which are arranged opposite to each other along the optical axis direction. The fixed-focus projection optical system 1000 comprises a micromirror array a, an equivalent prism c, a galvanometer d, a first lens group 100, a second lens group 200, a plane reflector 300, and a curved reflector 400 which are arranged in sequence from the object side to the image side; wherein the plane reflector 300 and the curved reflector 400 are respectively arranged on both sides of the optical axis, the plane reflector 300 is arranged at an angle with the optical axis, and one end thereof intersects with the optical axis; the first lens group 100 has a positive optical focal length, the second lens group 200 has a positive optical focal length, and the second lens group 200 can move along the optical axis, so as to focus the fixed-focus projection optical system when the projection distance changes.

[0044] It should be noted that the micromirror array a is an optical element composed of a large number of micromirrors. By controlling the tilt angle of each micromirror, precise control of incident light can be achieved, thereby realizing image display.

[0045] In addition, in one embodiment of the present invention, the fixed-focus optical system also includes a protective glass b, which is arranged between the equivalent prism c and the micromirror array a, and is arranged close to the micromirror array a, thereby providing effective protection for the micromirror array a.

[0046] In the technical solution of the present invention, an image beam is emitted from a micromirror array a, passes through a protective glass b, an equivalent prism c, a galvanometer d, a first lens group 100, and a second lens group 200 in sequence. When the light beam reaches the plane reflector 300, the plane reflector 300 reflects the light beam to the curved reflector 400, and then reflects the light beam to the projection screen through the curved reflector 400, thereby changing the direction of the light path and shortening the length of the projection direction. The first imaging is performed between the plane reflector 300 and the curved reflector 400, and the plane reflector 300 and the curved reflector 400 reflect the first imaging to the projection screen. The screen forms a second image; when the projection screen size / projection ratio needs to be changed, the second lens group 200 moves along the optical axis toward the image side to focus the fixed-focus projection optical system 100; through the reasonable arrangement of the structures and positions of the first lens group 100 with positive optical focal length, the second lens group 200 with negative positive optical focal length, the plane reflector 300 and the curved reflector 400, the plane reflector 300 and the curved reflector 400 reflect the light beam twice, which greatly reduces the length in the projection direction, so that the fixed-focus projection optical system 1000 has a small volume.

[0047] Specifically, in an embodiment of the present invention, the first lens group 100 includes a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, a fifth lens 5, a sixth lens 6, a seventh lens 7, an aperture e, and an eighth lens 8, which are arranged in sequence from the object side to the image side, and the first lens 1 has a positive focal power, the second lens 2 has a positive focal power, the third lens 3 has a positive focal power, the fourth lens 4 has a negative focal power, the fifth lens 5 has a positive focal power, the sixth lens 6 has a negative focal power, the seventh lens 7 has a positive focal power, and the eighth lens 8 has a positive focal power; by setting the positive focal power and the object side to be The first lens 1 with a convex side surface is conducive to increasing the main light angle of the edge field of view, which can effectively increase the field of view range; and an aperture e is provided between the seventh lens 7 and the eighth lens 8, so that the aperture e is located in the middle position of the system, which is used to adjust the light flux according to actual conditions, reduce distortion, and improve imaging quality; by comprehensively setting the focal length of each lens, the fixed-focus projection optical system 1000 can well control the trend of light, while introducing more light, making the structure more compact, and realizing miniaturization; by combining different lenses with each other and reasonably allocating the focal length, it has a large viewing angle, a short focal length and low distortion, and a better imaging effect.

[0048] In addition, in an embodiment of the present invention, the second lens group 200 includes a ninth lens 9, a tenth lens 10, an eleventh lens 11, a twelfth lens 12 and a thirteenth lens 13 arranged in sequence from the object side to the image side, and the ninth lens 9 has a positive optical focal power, the tenth lens 10 has a positive optical focal power, the eleventh lens 11 has a negative optical focal power, the twelfth lens 12 has a negative optical focal power, and the thirteenth lens 13 has a negative optical focal power. By comprehensively setting the optical focal power of each lens, the fixed-focus projection optical system 1000 can well control the light trend, make the structure more compact while introducing more light, and achieve miniaturization; by combining different lenses with each other and reasonably allocating the optical focal power, it has a large viewing angle, a short focal length and low distortion, and a better imaging effect.

[0049] In one embodiment of the present invention, the focal length of the first lens group 100 is φ100, the focal length of the second lens group 200 is φ200, and the focal length of the curved reflector is φ400. The focal lengths satisfy: 0.04≤|φ100|≤0.06, 0.003≤|φ200|≤0.01, 0.04≤|φ400|≤0.08. According to the above focal length distribution, a projection ratio of less than 0.25 can be achieved. It can be understood that the projection ratio refers to the ratio between the projection distance of the projector and the width of the projection screen. The smaller the projection ratio, the larger the width of the projection screen at the same projection distance. On the contrary, the larger the ratio, the smaller the width of the projection screen. Because the projection ratio data is smaller when projecting the same size of the screen, the closer the projection distance is, so the lens with a smaller numerical projection ratio is easier to meet the space requirements of different scenes.

[0050] In order to improve the clarity at different projection distances, in one embodiment of the present invention, the optical focal length of the first lens group 100 is φ100, the optical focal length of the second lens group 200 is φ200, and the optical focal length ratio of the first lens group 100 and the second lens group 200 satisfies: 7≤|φ100 / φ200|≤11; in this way, when the projection distance is changed, the second lens group 200 moves back and forth to achieve zooming, which can improve the clarity at different projection distances and reduce distortion.

[0051] In one embodiment of the present invention, the first lens 1 has a focal power of φ1, the second lens 2 has a focal power of φ2, the sum of the focal powers of the third lens 3, the fourth lens 4, and the fifth lens 5 is φ345; the sum of the focal powers of the sixth lens 6 and the seventh lens 7 is φ67; the focal power of the eighth lens 8 is φ8; the focal power of the ninth lens 9 is φ9; the sum of the focal powers of the tenth lens 10 and the eleventh lens 11 is φ1011; the focal power of the twelfth lens 12 is φ12; the focal power of the thirteenth lens 13 is φ13, The optical focal length of each lens satisfies: 0.01≤|φ1|≤0.03, 0.04≤|φ2|≤0.07, 0.002≤|φ345|≤0.05, 0.01≤|φ67|≤0.04, 0.02≤|φ8|≤0.05, 0.01≤|φ9|≤0.04, 0.01≤|φ1011|≤0.04, 0.01≤|φ12|≤0.04, 0.02≤|φ13|≤0.06. By limiting the optical focal length of each lens, the clarity of the fixed-focus projection optical system 1000 is improved.

[0052] In an embodiment of the present invention, the first lens group 100 includes a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, a fifth lens 5, a sixth lens 6, a seventh lens 7, an aperture e, and an eighth lens 8, which are arranged in sequence from the object side to the image side; the second lens group 200 includes a ninth lens 9, a tenth lens 10, an eleventh lens 11, a twelfth lens 12, and a thirteenth lens 13, which are arranged in sequence from the object side to the image side; the distance between the center of the thirteenth lens 13 and the center of the plane reflector 300 is T1, the distance between the center of the plane reflector 300 and the center of the curved reflector is T2, and the distance T13 between the center of the first lens 1 and the center of the thirteenth lens 1313 satisfies: 0.5≤T13 / (T1+T2)≤0.9. In this way, while ensuring that the reflected light can be incident on the curved reflector, the light path emitted by the curved reflector does not interfere with the first lens group 100 and the second lens group 200, thereby increasing the projection effect.

[0053] In an embodiment of the present invention, the first lens group 100 includes a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, a fifth lens 5, a sixth lens 6, a seventh lens 7, an aperture e, and an eighth lens 8, which are arranged in sequence from the object side to the image side; the distance from the first lens 1 to the intersection of the plane reflector 300 and the optical axis along the optical axis direction is T00, the distance from the micromirror array a to the first lens 1 is T11, and the ratio of T00 to T11 satisfies: T00 / T11≤4.5; in this way, the volume is further reduced.

[0054] In an embodiment of the present invention, the first lens group 100 includes a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, a fifth lens 5, a sixth lens 6, a seventh lens 7, an aperture e, and an eighth lens 8, which are arranged in sequence from the object side to the image side; the second lens group 200 includes a ninth lens 9, a tenth lens 10, an eleventh lens 11, a twelfth lens 12, and a thirteenth lens 13, which are arranged in sequence from the object side to the image side;

[0055] The second lens 2 , the eighth lens 8 and the ninth lens 9 are glass aspherical lenses, and the twelfth lens 12 , the thirteenth lens 13 and the curved reflector 400 are plastic aspherical lenses.

[0056] It can be understood that the characteristics of aspherical lenses are: the curvature changes continuously from the center of the lens to the periphery of the lens. Unlike spherical lenses with constant curvature from the center of the lens to the periphery of the lens, aspherical lenses have better curvature radius characteristics and have the advantages of improving distortion aberration and improving astigmatism aberration. After using aspherical lenses, the aberrations that occur during imaging can be eliminated as much as possible, thereby improving the imaging quality of the lens.

[0057] Among them, the second lens 2 is a glass aspheric surface, which can correct the coma and distortion caused by a large field of view. The eighth lens 8 is an aspheric surface, and the ninth lens 9 is an aspheric surface. At the same time, the twelfth lens 12, the thirteenth lens 13 and the curved reflector 400 are plastic aspheric surfaces. The aspheric surface further reduces the field curvature and distortion at different projection distances, thereby achieving a projection range of 40-150 feet.

[0058] In addition, the present invention achieves no out-of-focus when the brightness output is below 2000 lm and a higher manufacturing yield through the reasonable combination of plastic lenses with positive and negative optical powers.

[0059] Specifically, in one embodiment of the present invention, the surface shape of the aspheric lens in the fixed-focus projection optical system 1000 should satisfy the following equation:

[0060]

[0061] Among them, c is the curvature corresponding to the radius; y is the radial coordinate (its unit is the same as the lens length unit); k is the conic quadratic curve coefficient, and A, B, C, D, E, F, G... represent the fourth-order, sixth-order, eighth-order, tenth-order, twelfth-order, fourteenth-order, sixteenth-order... aspheric coefficients respectively.

[0062] More specifically, in one embodiment of the present invention, the even-order coefficients of each aspherical surface are shown in Table 1 below.

[0063] Table 1

[0064]

[0065]

[0066] Furthermore, in an embodiment of the present invention, the third lens 3, the fourth lens 4 and the fifth lens 5 are glued together, the sixth lens 6 and the seventh lens 7 are glued together, and the tenth lens 10 and the eleventh lens 11 are glued together; by gluing the third lens 3, the fourth lens 4 and the fifth lens 5, the chromatic aberration of a large field of view is corrected, and the sixth lens 6 and the seventh lens 7 are double-glued lenses to further correct the magnification chromatic aberration of the correction system, so that the system obtains a smaller chromatic aberration while increasing the light height of the off-axis field of view, so that the system has a larger target surface.

[0067] In addition, in one embodiment of the present invention, the first lens 1, the third lens 3, the fourth lens 4, the fifth lens 5, the sixth lens 6, the seventh lens 7, the tenth lens 10, and the eleventh lens 11 are glass spherical lenses. In order to improve the imaging quality of the lens at various magnifications, the present invention combines high-refractive-index glass with ultra-low-dispersion glass materials to reduce various optical aberrations while effectively suppressing the chromatic aberration of the system. At the same time, because the glass lens is not easily affected by thermal expansion and contraction and has a focus shift phenomenon, the glass lens can well resist the problem of thermal deformation of the lens and maintain the high precision of the lens for a long time. In addition, the aberration that occurs during imaging can be eliminated as much as possible, thereby improving the imaging quality of the lens and reducing the influence of temperature on the optical performance of the lens.

[0068] Specifically, in one embodiment of the present invention, when the projection ratio is 0.25, the micromirror array a is 0.47 inches, the chip pixel size is 5.4 microns, and T00 / T11≤4.5, the parameters of the zoom lens are shown in Table 2 below.

[0069] Table 2

[0070]

[0071]

[0072] In addition, under different projection sizes, the moving distance of the second lens group is as follows:

[0073]

[0074] Figure 3 The MTF performance diagram is shown in this embodiment when the projection size is 68 feet. Figure 4 The figure shows the distortion diagram when the projection size is 68 feet in this embodiment. Figure 5The figure shows the MTF diagram when the projection size is 150 feet in this embodiment. Figure 6 The figure shows the MTF diagram when the projection size is 40 feet in this embodiment. Figure 2-6 It can be seen that the fixed-focus optical system provided in this embodiment has good imaging capability within a projection range of 40-150 feet.

[0075] In addition, in order to better change the direction of the light path, in one embodiment of the present invention, the angle between the optical axes of the plane reflector 300 and the refracting mirror group is 45°, which changes the direction of the light path and greatly shortens the length of the system along the projection direction, further improving the miniaturization of the fixed-focus projection optical system 1000.

[0076] The above description is only an exemplary embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A fixed-focus projection optical system, characterized in that: The fixed-focus projection optical system has an object side and an image side that are arranged opposite to each other along the optical axis direction, and the fixed-focus projection optical system includes a micromirror array, an equivalent prism, a galvanometer, a first lens group, a second lens group, a plane reflector, and a curved reflector that are sequentially arranged from the object side to the image side; Wherein, the plane reflector and the curved reflector are respectively arranged on both sides of the optical axis, the plane reflector is arranged at an angle with the optical axis, and one end of the plane reflector intersects with the optical axis; The first lens group has a positive optical power, the second lens group has a negative optical power, and the second lens group can move along the optical axis to focus the fixed-focus projection optical system when the projection distance changes.

2. The fixed-focus projection optical system according to claim 1, characterized in that: The first lens group includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an aperture, and an eighth lens, which are arranged in sequence from the object side to the image side, and the first lens has a positive optical power, the second lens has a positive optical power, the third lens has a positive optical power, the fourth lens has a negative optical power, the fifth lens has a positive optical power, the sixth lens has a negative optical power, the seventh lens has a positive optical power, and the eighth lens has a positive optical power; and / or, The second lens group includes a ninth lens, a tenth lens, an eleventh lens, a twelfth lens and a thirteenth lens arranged in sequence from the object side to the image side, and the ninth lens has a positive optical power, the tenth lens has a positive optical power, the eleventh lens has a negative optical power, the twelfth lens has a negative optical power, and the thirteenth lens has a negative optical power.

3. The fixed-focus projection optical system according to claim 1, wherein: The focal power of the first lens group is φ 100 , the focal power of the second lens group is φ 200 , the focal length of the curved reflector is φ 400 , the optical power satisfies: 0.04≤|φ 100 |≤0.06,0.003≤|φ 200 |≤0.01,0.04≤|φ 400 |≤0.08。 4. The fixed-focus projection optical system according to claim 4, characterized in that: The focal power of the first lens group is φ 100 , the focal power of the second lens group is φ 200 , the ratio of the focal power of the first lens group to the focal power of the second lens group satisfies: 7≤|φ 100 / f 200 |≤11。 5. The fixed-focus projection optical system according to claim 1, wherein: The focal power of the first lens is φ1, the focal power of the second lens is φ2, and the sum of the focal powers of the third lens, the fourth lens, and the fifth lens is φ 345 The sum of the focal lengths of the sixth lens and the seventh lens is φ 67 The focal power of the eighth lens is φ8; the focal power of the ninth lens is φ9; the sum of the focal powers of the tenth lens and the eleventh lens is φ 1011 ; The focal power of the twelfth lens is φ 12 The focal power of the thirteenth lens is φ 13 , the focal power of each lens satisfies: 0.01≤|φ1|≤0.03,0.04≤|φ2|≤0.07,0.002≤|φ 345 |≤0.05,0.01≤|φ 67 |≤0.04,0.02≤|φ8|≤0.05,0.01≤|φ9|≤0.04,0.01≤|φ 1011 |≤0.04,0.01≤|φ 12 |≤0.04,0.02≤|φ 13 |≤0.06。 6. The fixed-focus projection optical system according to claim 1, wherein: The first lens group includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, a stop, and an eighth lens arranged in sequence from the object side to the image side, and the second lens group includes a ninth lens, a tenth lens, an eleventh lens, a twelfth lens, and a thirteenth lens arranged in sequence from the object side to the image side; The distance between the center of the thirteenth lens and the center of the plane reflector is T1, the distance between the center of the plane reflector and the center of the curved reflector is T2, and the center distance T13 between the center of the first lens and the center of the thirteenth lens 13 satisfies: 0.5≤T13 / (T1+T2)≤0.

9.

7. The fixed-focus projection optical system according to claim 1, wherein: The first lens group includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, a stop, and an eighth lens, which are arranged in sequence from the object side to the image side; The distance from the first lens to the intersection of the plane reflector and the optical axis along the optical axis direction is T00, the distance from the micromirror array to the first lens is T11, and the ratio of T00 to T11 satisfies: T00 / T11≤4.

5.

8. The fixed-focus projection optical system according to claim 1, wherein: The first lens group includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, a stop, and an eighth lens arranged in sequence from the object side to the image side; the second lens group includes a ninth lens, a tenth lens, an eleventh lens, a twelfth lens, and a thirteenth lens arranged in sequence from the object side to the image side; The second lens, the eighth lens and the ninth lens are glass aspherical lenses, and the twelfth lens, the thirteenth lens and the curved reflector are plastic aspherical lenses.

9. The fixed-focus projection optical system according to claim 1, wherein: The first lens group includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, a stop, and an eighth lens arranged in sequence from the object side to the image side, and the second lens group includes a ninth lens, a tenth lens, an eleventh lens, a twelfth lens, and a thirteenth lens arranged in sequence from the object side to the image side; The third lens, the fourth lens and the fifth lens are cemented together, the sixth lens and the seventh lens are cemented together, and the tenth lens and the eleventh lens are cemented together.

10. The fixed-focus projection optical system according to claim 1, wherein: The included angle between the optical axes of the plane reflector and the refractor group is 45°.

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