Short-focus projection optical system and projection device

Abstract

The application discloses a short-focus projection optical system and a projection device, which comprise, in sequence from the direction of a projection surface to a light source, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a diaphragm, a seventh lens, an eighth lens, a ninth lens, a tenth lens, an eleventh lens, a twelfth lens, a thirteenth lens, a fourteenth lens, a fifteenth lens, an equivalent prism and a light-emitting chip; the projection ratio of the short-focus projection optical system is less than or equal to 0.43; the first lens and the second lens are negative and are made of plastic aspherical surfaces, and can correct large-angle distortion; the cost is greatly reduced because the first lens and the second lens are made of plastic lenses; the image surface of the combined optical system is large, and can match a 0.64-inch chip; the aperture is large, and can support an F1.7 optical-mechanical system; the brightness output is more than 10000 lm; and the cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of optical system technology, and particularly to short-throw projection optical systems and projection devices. Background Technology

[0002] Short-throw lenses are widely used in office and commercial settings because they can project large images from a short distance, and are especially favored in the field of engineering projectors.

[0003] Short-throw lenses on the market are mostly used in engineering projectors. Because engineering projectors are used in environments with bright ambient light, the brightness of the projector is often above 7000lm to achieve a good visual effect. Therefore, they generally use large-area light-emitting chips and large-aperture lenses. At the same time, the requirements for the heat resistance and temperature drift of the lens are high. In order to avoid the influence of temperature drift caused by high brightness, most engineering projectors use a plastic lens combined with a large-diameter spherical lens, which results in high cost. Summary of the Invention

[0004] The main objective of this invention is to propose a short-throw projection optical system and projection device. The system has a large image plane and a large aperture, which can support an F1.7 optical engine system and achieve a brightness output of more than 10,000 lm, while reducing manufacturing costs.

[0005] To achieve the above objectives, this invention proposes a short-throw projection optical system, comprising a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, an aperture stop, a seventh lens, an eighth lens, a ninth lens, a tenth lens, an eleventh lens, a twelfth lens, a thirteenth lens, a fourteenth lens, a fifteenth lens, an equivalent prism, and a light-emitting chip, arranged sequentially along the projection surface to the light source direction. The projection ratio of the short-throw projection optical system is less than or equal to 0.43, wherein:

[0006] The first lens is a plastic aspherical lens with negative optical power;

[0007] The second lens is a plastic aspherical lens with negative optical power;

[0008] The third lens is a spherical lens with negative optical power;

[0009] The fourth lens is a spherical lens with negative optical power;

[0010] The fifth lens is a spherical lens with positive optical power;

[0011] The sixth lens is a spherical lens with positive optical power;

[0012] The seventh lens is a spherical lens with a negative optical power;

[0013] The eighth lens is a spherical lens with positive optical power;

[0014] The ninth lens is an aspherical lens with positive optical power;

[0015] The tenth lens is a spherical lens with a negative optical power;

[0016] The eleventh lens is a spherical lens with positive optical power;

[0017] The twelfth lens is a spherical lens with positive optical power;

[0018] The thirteenth lens is a spherical lens with a negative optical power;

[0019] The fourteenth lens is a spherical lens with positive optical power;

[0020] The fifteenth lens is a spherical lens with positive optical power.

[0021] Optionally, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, the ninth lens, the tenth lens, the eleventh lens, the twelfth lens, the thirteenth lens, the fourteenth lens, and the fifteenth lens are made of glass.

[0022] Optionally, the seventh lens and the eighth lens are bonded together with adhesive.

[0023] The tenth lens and the eleventh lens are bonded together with adhesive.

[0024] The twelfth lens, the thirteenth lens, and the fourteenth lens are bonded together with adhesive.

[0025] Optionally, the opposite sides of the first lens, the second lens, and the sixth lens are all curved towards the projection surface; the third lens and the seventh lens are concave lenses with their concave surfaces facing the projection surface; the fourth lens and the tenth lens are biconcave lenses; the fifth lens, the twelfth lens, and the fifteenth lens are convex lenses facing the light source; the eighth lens is a convex lens facing the projection surface; the ninth lens, the eleventh lens, and the fourteenth lens are biconvex lenses; and the thirteenth lens is a concave lens with its concave surface facing the light source.

[0026] Optionally, the optical power of the first lens to the fourth lens is The optical power of the fifth lens to the sixth lens is The optical power of the seventh lens to the fifteenth lens is satisfy:

[0027]

[0028] Optionally, the optical power of the first lens is The coefficient of thermal expansion is T1, and the optical power of the second lens is... The coefficient of thermal expansion T2, and the optical power of the twelfth lens are Coefficient of thermal expansion T 12 The optical power of the fourteenth lens is Coefficient of thermal expansion T 14 ,in:

[0029]

[0030] 50<|T1-T 12 |<56,40<|T2-T 14 |<55.

[0031] Optionally, the refractive index temperature coefficient dn / dt of the twelfth lens is negative, and the refractive index temperature coefficient dn / dt of the fourteenth lens is also negative.

[0032] The present invention also proposes a projection device, including the aforementioned short-throw projection optical system.

[0033] In the technical solution of this invention, the first and second lenses have negative optical power and are made of plastic aspherical surfaces, which can correct large-angle distortions and achieve a projection ratio of less than or equal to 0.43. At the same time, the use of plastic lenses greatly reduces costs. The third and fourth lenses have negative optical power, which further reduces the height of light entering the rear group and reduces off-axis aberrations. The fifth and sixth lenses have positive optical power, which increases the entrance pupil of the rear group, enabling the system to achieve a larger aperture. The seventh and eighth lenses correct axial chromatic aberration. The ninth lens is a glass aspherical surface, which corrects pupil aberration caused by a large aperture. The tenth and eleventh lenses correct residual spherical aberration of the system. The twelfth, thirteenth, and fourteenth lenses are triple-corrected for magnification chromatic aberration and can also increase the height of light in the off-axis field of view, giving the system a larger target surface. The fifteenth lens further corrects system distortion and converges the remaining aberrations of the system, so that the system finally obtains a large target surface and has high-resolution image quality. The combined optical system has a large image plane, which can be matched with a 0.64-inch chip, and a large aperture, which can support an F1.7 optical engine system, achieving a brightness output of over 10,000 lm, while reducing costs. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0035] Figure 1 This is a schematic diagram of an embodiment of the short-throw projection optical system provided by the present invention;

[0036] Figure 2 for Figure 1 A schematic diagram of a medium-short focal length projection optical system;

[0037] Figure 3 for Figure 1 Distortion curves of a medium-short focal length projection optical system;

[0038] Figure 4 for Figure 1 A point diagram of a medium-short focal length projection optical system;

[0039] Figure 5 for Figure 1 MTF curve of a medium-short throw projection optical system at room temperature;

[0040] Figure 6 for Figure 1 High-temperature MTF curve of medium-short focal length projection optical system.

[0041] Explanation of icon numbers:

[0042] 100 Short-throw projection optical system 10 Ninth Lens 1 First lens 11 Tenth Lens 2 Second lens 12 Eleventh Lens 3 Third lens 13 The Twelfth Lens 4 Fourth lens 14 The Thirteenth Lens 5 Fifth lens 15 Fourteenth Lens 6 Sixth lens 16 The Fifteenth Lens 7 aperture 17 Equivalent prism 8 Seventh Lens 18 LED chip 9 Eighth lens

[0043] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0044] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0045] It should be noted that if the embodiments of the present invention involve directional indication, the directional indication is only used to explain the relative positional relationship and movement of the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0046] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0047] Short-throw lenses are widely used in office and commercial settings due to their ability to project large images from short distances, especially in the field of engineering projectors. Most short-throw lenses on the market are used in engineering projectors. Because engineering projectors operate in bright environments, their brightness often needs to be above 7000lm to achieve a good visual effect. Therefore, they generally use large-area light-emitting chips and large-aperture lenses. At the same time, they require high performance in terms of heat resistance and temperature drift. To avoid the effects of temperature drift caused by high brightness, most engineering projectors use a single plastic lens combined with a large-diameter spherical lens, resulting in high costs.

[0048] In view of this, the present invention provides a short-throw projection optical system with a large image plane and a large aperture, which can support an F1.7 optical engine system and achieve a brightness output of more than 10,000 lm, while reducing manufacturing costs. Figures 1 to 5 An embodiment of the short-throw projection optical system provided by the present invention.

[0049] Please refer to Figures 1 to 2The short-throw projection optical system 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, an aperture 7, a seventh lens 8, an eighth lens 9, a ninth lens 10, a tenth lens 11, an eleventh lens 12, a twelfth lens 13, a thirteenth lens 14, a fourteenth lens 15, a fifteenth lens 16, an equivalent prism 17, and a light-emitting chip 18, arranged sequentially along the projection surface to the light source direction. The projection ratio of the short-throw projection optical system 100 is less than or equal to 0.43. Specifically, the first lens 1 is a plastic aspherical lens with negative optical power; the second lens 2 is a plastic aspherical lens with negative optical power; the third lens 3 is a spherical lens with negative optical power; the fourth lens 16... Lens 4 is a spherical lens with negative optical power; the fifth lens 5 is a spherical lens with positive optical power; the sixth lens 6 is a spherical lens with positive optical power; the seventh lens 8 is a spherical lens with negative optical power; the eighth lens 9 is a spherical lens with positive optical power; the ninth lens 10 is an aspherical lens with positive optical power; the tenth lens 11 is a spherical lens with negative optical power; the eleventh lens 12 is a spherical lens with positive optical power; the twelfth lens 13 is a spherical lens with positive optical power; the thirteenth lens 14 is a spherical lens with negative optical power; the fourteenth lens 15 is a spherical lens with positive optical power; and the fifteenth lens 16 is a spherical lens with positive optical power.

[0050] In the technical solution of this invention, the first lens 1 and the second lens 2 have negative optical power and are made of plastic aspherical surfaces, which can correct large-angle distortions and achieve a projection ratio of less than or equal to 0.43. At the same time, the use of plastic lenses greatly reduces costs. The third lens 3 and the fourth lens 4 have negative optical power, which further reduces the height of light entering the rear group and reduces off-axis aberrations. The fifth lens 5 and the sixth lens 6 have positive optical power, which increases the entrance pupil of the rear group, enabling the system to achieve a larger aperture. The seventh lens 8 and the eighth lens 9 correct axial chromatic aberration. The ninth lens 10 is a glass aspherical surface, which corrects pupil aberration caused by a large aperture. The tenth lens 11 and the eleventh lens 12 correct the residual spherical aberration of the system. The twelfth lens 13, the thirteenth lens, and the fourteenth lens are triple-corrected magnification chromatic aberration, and can also increase the height of light in the off-axis field of view, giving the system a larger target surface. The fifteenth lens 16 further corrects system distortion and converges the residual aberrations of the system, so that the system finally obtains a large target surface and has high-resolution image quality. The combined optical system has a large image plane, which can be matched with a 0.64-inch chip, and a large aperture, which can support an F1.7 optical engine system, achieving a brightness output of over 10,000 lm, while reducing costs.

[0051] Furthermore, the third lens 3, the fourth lens 4, the fifth lens 5, the sixth lens 6, the seventh lens 8, the eighth lens 9, the ninth lens 10, the tenth lens 11, the eleventh lens 12, the twelfth lens 13, the thirteenth lens 14, the fourteenth lens 15, and the fifteenth lens 16 are made of glass.

[0052] Furthermore, the seventh lens 8 and the eighth lens 9 are glued together to form a bonded lens, which together corrects axial chromatic aberration. The tenth lens 11 and the eleventh lens 12 are glued together to form a cemented lens, which together corrects residual spherical aberration of the system. The twelfth lens 13, the thirteenth lens, and the fourteenth lens are glued together to form a triple-bonded lens, which together corrects magnification chromatic aberration and increases the light height of the off-axis field of view, giving the system a larger target surface.

[0053] Based on the above embodiments, in order to achieve the corresponding technical effects of the optical system, the lens types of each lens should be reasonably selected. In one embodiment, the opposite sides of the first lens 1, the second lens 2, and the sixth lens 6 are all bent towards the projection surface; the third lens 3 and the seventh lens 8 are concave lenses with their concave surfaces facing the projection surface; the fourth lens 4 and the tenth lens 11 are biconcave lenses; the fifth lens 5, the twelfth lens 13, and the fifteenth lens 16 are convex lenses facing the light source; the eighth lens 9 is a convex lens facing the projection surface; the ninth lens 10, the eleventh lens 12, and the fourteenth lens 15 are biconvex lenses; and the thirteenth lens 14 is a concave lens with its concave surface facing the light source.

[0054] Furthermore, the optical power of the first lens 1 to the fourth lens 4 is The optical power of the fifth lens 5 to the sixth lens 6 is The optical power of the seventh lens 8 to the fifteenth lens 16 is satisfy This optical power allocation can be used to create a reverse telephoto structure, achieving a smaller overall length while obtaining a larger back focal length, i.e., a larger back working distance. The total system length is the distance L between the side of the first lens 1 facing the projection surface and the side of the fifteenth lens 16 facing the light source. 1-15 The system's back focal length, i.e., the distance BFL between the side of the fifteenth lens 16 facing the light source and the light-emitting chip 18, and their L... 1-15 / BFL≤5.

[0055] Furthermore, the optical power of the first lens 1 is The coefficient of thermal expansion is T1, and the optical power of the second lens 2 is... The coefficient of thermal expansion T2, and the optical power of the twelfth lens 13 are Coefficient of thermal expansion T 12 The optical power of the fourteenth lens 15 is Coefficient of thermal expansion T 14 ,in

[0056] 50 < |T1-T12| < 56, 40 < |T2-T14| < 55. It should be understood that optical power characterizes the ability of an optical system to deflect light, while the coefficient of thermal expansion is an indicator of the stability of a material in high-temperature environments. By limiting these two values, design requirements can be met while simultaneously achieving the desired optical effects.

[0057] Furthermore, in this embodiment, the refractive index temperature coefficient dn / dt of the twelfth lens 13 and the refractive index temperature coefficient dn / dt of the fourteenth lens 15 are both negative. Based on the above limitations on optical power and thermal expansion coefficient, it is possible to achieve focus stability when the projector outputs 10,000 lm of brightness using multiple plastic lenses, while also significantly reducing costs.

[0058] In the technical solution of this embodiment, the surface shapes of the aspherical surfaces of the first lens 1, the second lens 2, and the ninth lens 10 satisfy the following equation:

[0059]

[0060] In the formula, parameter c is the curvature corresponding to the radius, y is the radial coordinate with the same unit as the lens length, k is the conic quadratic coefficient, and a1 to a8 represent the coefficients corresponding to each radial coordinate.

[0061] Specifically, when the coefficient k is less than -1, the surface shape curve of the lens is a hyperbola; when the coefficient k is equal to -1, the surface shape curve of the lens is a parabola; when the coefficient k is between -1 and 0, the surface shape curve of the lens is an ellipse; when the coefficient k is equal to 0, the surface shape curve of the lens is a circle; and when the coefficient k is greater than 0, the surface shape curve of the lens is an oval.

[0062] The following table shows the actual design parameters of a projection lens with an F1.7 aperture, a throw ratio of 0.43, and a matching 0.64-inch LED, achieving a lens output brightness of 1000 lm and a system length-to-BFL ratio of less than 5:

[0063]

[0064]

[0065] The coefficient of the first surface S1 of the first lens 1 is: k: 0.1556105

[0066] a1:0

[0067] a2: 1.2901982e-005

[0068] a3: -1.0210583e-008

[0069] a4: 6.255823e-012

[0070] a5: -2.6139304e-015

[0071] a6: 7.0602553e-019

[0072] a7: -1.0985806e-022

[0073] a8: 7.5147663e-027

[0074] The coefficient of the second surface S2 of the first lens 1 is: k: -7.07424

[0075] a1:0

[0076] a2: 3.4587606e-006

[0077] a3: 1.7761648e-008

[0078] a4: -3.7425198e-011

[0079] a5: 2.8873245e-014

[0080] a6: -9.8205835e-018

[0081] a7: 9.1100734e-022

[0082] a8: 1.5985755e-025

[0083] The coefficient of the first surface S3 of the second lens 2 is: k: 0.0106

[0084] a1:0

[0085] a2: -1.8225137e-005

[0086] a3: 5.8046449e-008

[0087] a4: -9.5750599e-011

[0088] a5: 7.9835899e-014

[0089] a6: -3.683649e-017

[0090] a7: 9.1983737e-021

[0091] a8: -1.035388e-024

[0092] The coefficient of the second surface S4 of the second lens 2 is: k: 0.3582

[0093] a1:0

[0094] a2: 1.4927246e-005

[0095] a3: -2.6068981e-008

[0096] a4: 1.7471845e-010

[0097] a5: -5.3678995e-013

[0098] a6: 8.8115644e-016

[0099] a7: -7.7289462e-019

[0100] a8: 2.7909944e-022

[0101] The coefficient of the first surface S17 of the ninth lens 10 is: k: -0.068

[0102] a1:0

[0103] a2: -5.2427669e-007

[0104] a3: 9.8463701e-008

[0105] a4: -4.6199416e-009

[0106] a5: 1.2465686e-010

[0107] a6: -2.429068e-012

[0108] a7: 2.4067368e-014

[0109] a8: -1.0400253e-016

[0110] The coefficient of the second surface S18 of the ninth lens 10 is: k: -4.621322

[0111] a1:0

[0112] a2: -1.3292832e-005

[0113] a3: 8.5105968e-008

[0114] a4: -5.6727461e-009

[0115] a5: 6.9490891e-011

[0116] a6: -6.2728462e-013

[0117] a7: 2.3313132e-015

[0118] a8: -9.8272003e-018

[0119] Compared with the prior art, the technical solution of the present invention has the following technical effects:

[0120] 1. The use of two plastic lenses greatly reduces costs;

[0121] 2. The system of this invention has a large image area and can be matched with a 0.64-inch chip;

[0122] 3. This invention has a large aperture, which can support an F1.7 optical engine system and achieve a brightness output of over 10,000 lm;

[0123] 4. This invention is applicable to optical-mechanical systems with a brightness of 10,000 lm, and there is no thermal defocusing phenomenon;

[0124] 5. The system of this invention has a shorter length and a larger working distance.

[0125] 6. This invention achieves a projection ratio of less than or equal to 0.43.

[0126] The present invention also provides a projection device, including the short-throw projection optical system 100 described above. The projection device includes all the technical features of the short-throw projection optical system 100 described above, and therefore also has the technical effects brought about by all the above technical features, which will not be described in detail here.

[0127] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made under the concept of the present invention using the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A short-throw projection optical system, characterized in that, The short-throw projection optical system comprises, sequentially arranged along the projection surface towards the light source, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, an aperture stop, a seventh lens, an eighth lens, a ninth lens, a tenth lens, an eleventh lens, a twelfth lens, a thirteenth lens, a fourteenth lens, a fifteenth lens, an equivalent prism, and a light-emitting chip. The projection ratio of the short-throw projection optical system is less than or equal to 0.

43. The first lens is a plastic aspherical lens with negative optical power. The side of the first lens facing the projection surface is concave, and the side facing the light source is also concave. The second lens is a plastic aspherical lens with positive optical power; the side of the second lens facing the projection surface is convex, and the side facing the light source is concave. The third lens is a spherical lens with negative optical power; the side facing the projection surface is convex, and the side facing the light source is concave. The fourth lens is a spherical lens with negative optical power; the side of the fourth lens facing the projection surface is concave, and the side facing the light source is also concave. The fifth lens is a spherical lens with positive optical power; the side facing the projection surface is convex, and the side facing the light source is also convex. The sixth lens is a spherical lens with positive optical power; the side of the sixth lens facing the projection surface is convex, and the side facing the light source is concave. The seventh lens is a spherical lens with negative optical power; the side facing the projection surface is concave, and the side facing the light source is also concave. The eighth lens is a spherical lens with positive optical power; the side facing the projection surface is convex, and the side facing the light source is concave. The ninth lens is an aspherical lens with positive optical power; the side of the ninth lens facing the projection surface is convex, and the side facing the light source is also convex. The tenth lens is a spherical lens with negative optical power; the side of the tenth lens facing the projection surface is concave, and the side facing the light source is also concave. The eleventh lens is a spherical lens with positive optical power; the side facing the projection surface is convex, and the side facing the light source is also convex. The twelfth lens is a spherical lens with positive optical power; the side facing the projection surface is convex, and the side facing the light source is also convex. The thirteenth lens is a spherical lens with negative optical power; the side facing the projection surface is concave. The fourteenth lens is a spherical lens with positive optical power; the side facing the projection surface is convex, and the side facing the light source is also convex. The fifteenth lens is a spherical lens with positive optical power. The side facing the projection surface is convex, and the side facing the light source is also convex.

2. The short-throw projection optical system as described in claim 1, characterized in that, The third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth, thirteenth, fourteenth, and fifteenth lenses are made of glass.

3. The short-throw projection optical system as described in any one of claims 1 to 2, characterized in that, The seventh and eighth lenses are bonded together with adhesive. The tenth lens and the eleventh lens are bonded together with adhesive. The twelfth lens, the thirteenth lens, and the fourteenth lens are bonded together with adhesive.

4. The short-throw projection optical system as described in claim 1, characterized in that, The optical power of the first lens to the fourth lens is φ 1-4 The optical power of the fifth lens to the sixth lens is φ 5-6 The optical power of the seventh lens to the fifteenth lens is φ 7-15 ,satisfy: -0.15<φ 1-4 <-0.1,0.02<φ 5-6 <0.04,0.03<φ 7-15 <0.05。 5. The short-throw projection optical system as described in claim 1, characterized in that, The first lens has an optical power of φ1 and a coefficient of thermal expansion of T1; the second lens has an optical power of φ2 and a coefficient of thermal expansion of T2; and the twelfth lens has an optical power of φ... 12 thermal expansion coefficient T 12 The optical power of the fourteenth lens is φ 14 thermal expansion coefficient T 14 ,in: -0.04<φ1+φ2<-0.02,0.01<φ 12 +φ 14 <0.03, 0.08<|(φ1+φ2) / (φ 12 +φ 14 )|<4,50<|T1-T 12 |<56,40<|T2-T 14 |<55。 6. The short-throw projection optical system as described in claim 5, characterized in that, The refractive index temperature coefficient dn / dt of the twelfth lens is negative, and the refractive index temperature coefficient dn / dt of the fourteenth lens is also negative.

7. A projection device, characterized in that, Includes the short-throw projection optical system as described in any one of claims 1 to 6.

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