Ultra-short-throw projection system

Abstract

The present invention relates to the field of projection technology, and discloses an ultra-short-focus projection system, including an optical machine with a light valve fixed thereon; a lens for projecting the light emitted by the light valve; a plurality of coaxially arranged lenses are arranged in the lens; the lenses are arranged in sequence along the propagation direction of the light: the first lens of the front group is a first spherical lens, the second lens of the front group is a second spherical lens, the third and fourth lenses of the front group are double-cemented lenses; the third lens of the front group is a first double-concave spherical lens, and the fourth lens of the front group is a second double-convex spherical lens; the first lens of the rear group is a glass spherical mirror, the second lens of the rear group is a first plastic aspherical lens, and the third lens of the rear group is a second plastic aspherical lens; the light-emitting center of the light valve and the optical axis center of the lens do not coincide. The present application realizes the overall coordination between the systems by designing the lenses in the lens system, and a wider picture can be projected at the same projection distance.

Description

Technical Field

[0001] The present invention relates to the field of projection technology, and in particular to an ultra-short-throw projection system. Background Art

[0002] A projector lens is an optical device used to project images. Based on the principle of a convex lens, it converges light from a light source to a focal point, and through the projection mechanism of the lens, the image at the focal point is magnified and projected onto a screen or other plane. The projector lens is a key component for image magnification and projection, and will directly affect the clarity and color of the projected image.

[0003] Projector lenses are usually divided into three types according to their focal lengths: short focus, medium focus, and long focus. Among them, short focus is suitable for spaces with a small installation distance, and can achieve large-screen projection within a short distance.

[0004] However, current short-throw projector lenses have the following problems:

[0005] (1) Large size: Projection for field of view applications generally uses a large number of lenses, which are relatively large in size and heavy in weight.

[0006] (2) High cost: In order to ensure the clarity of the image, more lenses are needed to ensure image quality, which increases the cost.

[0007] (3) The projection ratio is not small enough.

[0008] Therefore, based on the above situation, it is necessary to develop an ultra-short-throw projection system to solve the above problems. Summary of the invention

[0009] In order to solve the above technical problems, the present invention provides an ultra-short-throw projection system, which can ensure the quality of imaging and reduce the volume while ensuring that the projection ratio is less than 0.1.

[0010] The present invention provides an ultra-short-throw projection system, comprising:

[0011] An optical machine with a light valve fixed thereon; a lens for projecting the light emitted by the light valve; a plurality of coaxially arranged lenses are arranged in the lens; the lenses are arranged in sequence along the propagation direction of the light: the first lens of the front group is a first spherical lens, the second lens of the front group is a second spherical lens, the third and fourth lenses of the front group are double-cemented lenses; the third lens of the front group is a first biconcave spherical lens, and the fourth lens of the front group is a second biconvex spherical lens; the first lens of the rear group is a glass spherical mirror, the second lens of the rear group is a first plastic aspherical lens, and the third lens of the rear group is a second plastic aspherical lens; the light emission center of the light valve and the optical axis center of the lens do not coincide.

[0012] Furthermore, along the direction of light propagation, the refractive index ranges of each lens are 1.8-2.0, 1.5-1.6, 1.9-2.0, 1.5-1.6, 1.9-2.0, 1.5-1.6, and 1.5-1.6, respectively.

[0013] Furthermore, along the light propagation direction, the Abbe number ranges of the lenses are 40-55, 70-80, 15-25, 80-90, 20-30, 50-60, and 50-60, respectively.

[0014] Furthermore, along the direction of light propagation, the material thickness ranges of each lens are 5-7 mm, 2-3 mm, 0.5-1 mm, 6-7 mm, 3-4 mm, 2-3 mm, and 2-3 mm, respectively.

[0015] Furthermore, the air gap between the first spherical lens and the second spherical lens on the optical axis is 0.2-0.5mm, the air gap between the second spherical lens and the doublet lens on the optical axis is 1-2mm; the air gap between the doublet lens and the glass spherical mirror on the optical axis is 2-3mm; the air gap between the glass spherical mirror and the first plastic aspheric lens on the optical axis is 5-6mm; the air gap between the first plastic aspheric lens and the second plastic aspheric lens on the optical axis is 6-7mm; the air gap between the second plastic aspheric lens and the reflector on the optical axis is 30-40mm.

[0016] Furthermore, along the light propagation direction, the material curvature of the right surface of each lens is 20-30mm, 80-120mm, 130-150mm, 10-20mm, 20-30mm, 10-20mm, 10-20mm. Further, along the light propagation direction, the material curvature of the left surface of each lens is 40-50mm, 10-20mm, 10-20mm, 130-150mm, 100-130mm, 20-30mm, 10-20mm.

[0017] Furthermore, the optical power of each lens along the direction of light propagation is: positive, positive, negative, positive, positive, positive, positive, negative.

[0018] Furthermore, a reflector is provided on the side of the second plastic aspheric lens from which light emerges.

[0019] Further, the projection ratio of the projection system is less than 0.1;

[0020] The back focus distance of the projection system is BFL, the total optical length is L1, the focal length is F, and the total lens length is L2;

[0021] Then the following formula is satisfied:

[0022] .

[0023] The embodiments of the present invention have the following technical effects:

[0024] The present application achieves overall coordination between systems by designing the lenses in the lens system and setting the relevant parameters of each lens, and obtains the following beneficial effects:

[0025] (1) Small projection ratio: The projection ratio of this application is less than 0.1. At the same projection distance, a wider picture can be projected, which improves the utilization of space and is suitable for projection under more small space restrictions, such as car displays, windows, and doors;

[0026] (2) Large focusing stroke: The present application adjusts the focusing stroke by adjusting the air spacing between the rear lenses of the ultra-short-throw projection system. The adjustment range is 10 inches to 95 inches, and the quality of the projected image can be guaranteed.

[0027] (3) High cost performance: It uses a combination of glass spherical surface, plastic aspherical surface and reflector, with a small number of lenses and common materials;

[0028] (4) Small size: The total optical length of the present application is less than 90 mm, which reduces the material required for structural components and reduces weight;

[0029] (5) The present application can achieve a left or right bias of the projection image by adjusting the relative position of the optical machine and the lens while ensuring the quality of the projection image. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 It is a structural schematic diagram of the arrangement of lenses in a lens in an ultra-short-throw projection system provided by an embodiment of the present invention;

[0032] Figure 2 is a schematic diagram of a pupil projecting a picture to the left at the lower right corner provided by an embodiment of the present invention;

[0033] Figure 3 A schematic diagram of a pupil in the lower left corner projecting a picture to the right provided by an embodiment of the present invention;

[0034] Figure 4 It is a spot diagram of light spots under different field of view conditions on the imaging screen provided by an embodiment of the present invention;

[0035] Figure 5 The MTF diagram of light provided by the embodiment of the present invention, wherein the horizontal axis represents the number of line pairs and the vertical axis represents the resolution capability;

[0036] Figure 6 A relative illumination diagram provided by an embodiment of the present invention; the abscissa represents the field of view, and the ordinate represents the relative illumination;

[0037] Figure 7 The diagram provided for the embodiment of the present invention is a MTF vs. field of view diagram; the horizontal axis represents the field of view, and the vertical axis represents the MTF value;

[0038] In the figure, 1, the first spherical lens; 2, the second spherical lens; 3, the first biconcave spherical lens; 4, the second biconvex spherical lens; 5, the glass spherical mirror; 6, the first plastic aspherical lens; 7, the second plastic aspherical lens; 8, the polarizing filter; 9, the total reflection prism. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described clearly and completely below. 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 belong to the scope of protection of the present invention.

[0040] First, explain the following:

[0041] (1) Polarizing filter or polarizing filter is used to improve the resolution. The resolution of 1080P can be increased to 4k through the vibration of the galvanometer.

[0042] (2) Total reflection prisms are used to adjust, reflect or refract light to achieve specific lighting effects.

[0043] (3) Wide field of view refers to optical components such as lenses, glasses or camera lenses that can provide a wider field of view. Using lenses or devices with a wide field of view, you can see more of the environment and objects, thereby obtaining more information.

[0044] (4) The ray fan diagram mainly displays the light aberration as a function of the pupil coordinates, and can intuitively show the propagation and focusing of light after passing through the optical system.

[0045] (5) The MTF graph can quantify the resolution, contrast and other data of the lens, and is a relatively scientific method for analyzing lens imaging.

[0046] (6) Optical power is a physical quantity that describes the ability of an optical system to converge or diverge light. It is the reciprocal of the focal length. Optical power is divided into positive power and negative power. Positive power indicates that the optical system has a converging effect on light, while negative power indicates that the optical system has a diverging effect on light.

[0047] (7) Air gap refers to the space between two adjacent optical elements that is not filled with other media but is occupied only by air.

[0048] The present application provides an ultra-short-throw projection system, comprising:

[0049] A light machine with a light-emitting unit fixed thereon; the light-emitting unit is fixed at the upper left corner of the light machine;

[0050] A light engine with a light valve fixed thereto;

[0051] A lens is used to project the light emitted by the light valve; a plurality of coaxially arranged lenses are arranged in the lens.

[0052] The light valve, also called the light-emitting unit, is a light modulation element used to improve the resolution of optical projection. The light-emitting unit is fixed to the upper left of the optical machine, so that the light-emitting center of the light valve and the center of the optical axis of the lens do not coincide. By changing the relative position of the optical machine and the lens, the projection image can be 100% offset to the left or right. For example, the light-emitting unit is in the direction of emitting from the left side of the lens, so that the light is projected from the lower right. The setting of the light valve position realizes the upper, lower, left, and right offset of the image, and combined with the setting of the lens in the lens, it ensures the clarity and resolution of the projection image, and increases the application scenarios of the projection lens.

[0053] In addition, a total reflection prism 9 and a polarizer 8 are provided in the optical machine; the total reflection prism 9 causes total reflection of the light without loss of light energy, thereby increasing the brightness of the light emitted by the light valve entering the lens and saving costs; the polarizer 8 further improves the imaging resolution.

[0054] The relevant settings of the lens are as follows:

[0055] The lens has an aperture stop to ensure that the diameter of the light in the lens remains consistent as much as possible. The front group of lenses is set on the left side of the aperture stop and arranged in sequence along the direction of light propagation: the first lens of the front group is the first spherical lens 1, the second lens of the front group is the second spherical lens 2, and the third and fourth lenses of the front group are double cemented lenses; the third lens of the front group is the first biconcave spherical lens 3, and the fourth lens of the front group is the second biconvex spherical lens 4;

[0056] The rear group of lenses is arranged on the right side of the aperture stop, that is, they are arranged in sequence from the aperture stop along the light propagation direction: the first lens of the rear group is a glass spherical lens 5, the second lens of the rear group is a first plastic aspherical lens 6, and the third lens of the rear group is a second plastic aspherical lens 7.

[0057] Specifically, the following settings are performed on each lens:

[0058] The refractive index ranges of each lens along the direction of light propagation are 1.8-2.0, 1.5-1.6, 1.9-2.0, 1.5-1.6, 1.9-2.0, 1.5-1.6, and 1.5-1.6, respectively.

[0059] The Abbe number ranges of each lens along the direction of light propagation are 40-55, 70-80, 15-25, 80-90, 20-30, 50-60, and 50-60 respectively.

[0060] The material thickness ranges of each lens along the direction of light propagation are 5-7mm, 2-3mm, 0.5-1mm, 6-7mm, 3-4mm, 2-3mm, and 2-3mm respectively.

[0061] The air gap between the first spherical lens 1 and the second spherical lens 2 on the optical axis is 0.2-0.5mm, and the air gap between the second spherical lens 2 and the doublet lens on the optical axis is 1-2mm; the air gap between the doublet lens and the glass spherical mirror 5 on the optical axis is 2-3mm; the air gap between the glass spherical mirror 5 and the first plastic aspherical lens 6 on the optical axis is 5-6mm; the air gap between the first plastic aspherical lens 6 and the second plastic aspherical lens 7 on the optical axis is 6-7mm; the air gap between the second plastic aspherical lens 7 and the reflector on the optical axis is 30-40mm.

[0062] The material curvatures of the right surfaces of each lens along the direction of light propagation are 20-30mm, 80-120mm, 130-150mm, 10-20mm, 20-30mm, 10-20mm, and 10-20mm, respectively.

[0063] The material curvatures of the left surfaces of each lens along the direction of light propagation are 40-50mm, 10-20mm, 10-20mm, 130-150mm, 100-130mm, 20-30mm, and 10-20mm, respectively.

[0064] In addition, a reflector is provided on the side where the light from the second plastic aspherical lens 7 exits, corresponding to the Figure 1 The middle one is on the right side. The reflector can reflect light and change its propagation path.

[0065] In the present application, the optical power of the lens along the direction of light propagation is: positive, positive, negative, positive, positive, positive, negative, and the overall optical power is positive, ensuring that the light will be converged to a focus, which is usually located on one side of the lens or system.

[0066] Through the comprehensive setting of the above parameters and structures, the projection ratio of the projection system of the present application satisfies the condition of being less than 0.1, so that the projection device can project a picture of the same size at a shorter distance. It can not only be used in conventional scenes, such as education, medical treatment, advertising, household use, etc., but also can be added to more special occasions, such as projection of car series, car doors and windows.

[0067] In addition, assuming that the back focus of the projection system is BFL, the total optical length is L1, the focal length is F, and the total length of the lens is L2; ​​then the following formula is satisfied:

[0068] .

[0069] In this application, see Figure 1 The total optical length is the distance from the left side of the polarizer to the right side of the reflector, which is set as L1. The total length of the lens is the distance from the left side of the spherical lens to the right side of the reflector, which is set as L2. Then BFL=L1-L2.

[0070] The above formula is used to limit the size of the lens so that the total optical length is less than 90 mm to avoid excessive volume, reduce the material required for structural components, and reduce weight.

[0071] Here are the views from each lens:

[0072] The first spherical lens 1 is slightly thick, so that the optical path difference is small; the material with higher refractive index and higher Abbe number is used, which can quickly tighten the light divergence angle, which is beneficial to control the aperture of the rear group of lenses.

[0073] The combination of the second spherical lens 2 and the doublet lens can eliminate the chromatic aberration problem caused by large angle deviation.

[0074] The glass spherical mirror 5 receives the light passing through the rear group and prepares for projecting pictures of different sizes by using a material with a high refractive index for projection.

[0075] The first aspheric lens 6 is an aspheric resin lens, and utilizes its aspheric characteristics to reduce the astigmatism and field curvature of the system, thereby ensuring the subsequent projection image quality.

[0076] The second plastic aspherical lens 7 is an aspherical resin lens, which is used to achieve the purpose of enlarging the projection magnification and correct TV distortion.

[0077] By adjusting the spacing between the glass spherical mirror 5, the first aspherical lens 6 and the second plastic aspherical lens 7, the focusing stroke of the projection system can be adjusted. According to experimental verification, the adjustment range is 10 inches to 95 inches, and the projection quality of the projection picture can be guaranteed.

[0078] The reflector uses an aspherical resin lens to correct the off-axis field curvature of a large field of view and achieve a true restoration of the off-axis field of view.

[0079] In summary, in this application, by designing the lenses in the lens system and setting the parameters of each lens, through the mutual cooperation of the lens shape, material, thickness, air gap, etc., while ensuring that the projection ratio is less than 0.1, the volume of the lens is reduced.

[0080] Embodiment 2

[0081] Based on the projection system structure in Embodiment 1, this application provides a specific embodiment with the following settings to ensure imaging indicators:

[0082] The effective focal length is 1.3 mm, the left - right offset is 100% < offset < 130%, the up - down offset is 110% < offset < 145%, the resolution is 25 lp / mm, the projected image size is 10 - 95 inches, and the projection ratio is less than or equal to 0.1.

[0083] Three representative light rays with different wavelengths are set and green light is selected as the main wavelength. The three light rays have wavelengths of 0.45 um, 0.55 um, and 0.62 um respectively. These three light rays pass through the above - mentioned short - focus projection system respectively, and relevant verifications are carried out to obtain the following figures, and relevant analyses are carried out according to the content shown in the figures:

[0084] Reference Figure 2 and Figure 3 For the light fan diagrams of the light rays, when the pupils are on the right and left respectively, the images can be projected from the left and right, realizing a complete offset of the projection to the left or right. It can be clearly seen that the light ray aberration is very small and there is almost no difference.

[0085] Figure 4 Shows the schematic diagram of the point - spot imaging on the screen of the above - mentioned three - wavelength light rays under a certain field - of - view condition on the premise of different normalized field - of - view conditions, indicating that under different wavelength conditions, the convergence effect of the light spots is still good and there is no stray light around.

[0086] Figure 5 Shows the imaging quality of the three - wavelength light rays under different requirements. The higher the value of the ordinate, the stronger the resolution ability and the higher the image quality restoration degree. When the MTF is greater than 0.5, it represents that the imaging quality is very clear. It can be concluded from the figure that the resolution of the lens at different wavelengths is high and more image details can be shown.

[0087] Figure 6 Represents the uniformity of different fields of view; the higher the relative illuminance value, the better the brightness uniformity between the center and the edge. Obviously, the design scheme of this application has good uniformity.

[0088] Figure 7 It represents the MTF value under different fields of view (the horizontal axis represents the field of view, and the vertical axis represents the MTF value). When the field of view is 0-820mm, the MTF is greater than 0.6, indicating that the imaging is uniform and clear.

[0089] In summary, the present application provides a short-throw projection system that can ensure the quality of imaging while reducing the volume while ensuring that the projection ratio is less than 0.1.

[0090] It should be noted that the terms used in the present invention are only for describing specific embodiments, rather than limiting the scope of the present application. As shown in the present specification, unless the context clearly indicates an exception, the words "one", "a", "a kind of" and / or "the" do not specifically refer to the singular, but may also include the plural. The terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method or device. In the absence of more restrictions, the elements defined by the sentence "include one..." do not exclude the presence of other identical elements in the process, method or device including the elements.

[0091] It should also be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. Unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", etc. should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the technical solutions of the embodiments of the present invention.

Claims

1. An ultra-short-throw projection system, characterized in that: include: A light engine with a light valve fixed thereto; A lens for projecting the light emitted by the light valve; A plurality of coaxially arranged lenses are arranged in the lens; The lenses are arranged in sequence along the direction of light propagation: the first lens of the front group is a first spherical lens (1), the second lens of the front group is a second spherical lens (2), and the third and fourth lenses of the front group are double-cemented lenses; the third lens of the front group is a first double-concave spherical lens (3), and the fourth lens of the front group is a second double-convex spherical lens (4); the first lens of the rear group is a glass spherical lens (5), the second lens of the rear group is a first plastic aspherical lens (6), and the third lens of the rear group is a second plastic aspherical lens (7); The light emitting center of the light valve and the optical axis center of the lens do not coincide; A reflector is provided on the light-emitting side of the second plastic aspheric lens (7); The projection ratio of the projection system is less than 0.1; The back focus distance of the projection system is BFL, the total optical length is L1, the focal length is F, and the total lens length is L2; Then the following formula is satisfied: ； The material thickness ranges of each lens along the direction of light propagation are 5-7mm, 2-3mm, 0.5-1mm, 6-7mm, 3-4mm, 2-3mm, and 2-3mm; The optical power of each lens along the direction of light propagation is: positive, positive, negative, positive, positive, positive, positive, negative.

2. The ultra short throw projection system according to claim 1, characterized in that: The refractive index ranges of each lens along the direction of light propagation are 1.8-2.0, 1.5-1.6, 1.9-2.0, 1.5-1.6, 1.9-2.0, 1.5-1.6, and 1.5-1.6, respectively.

3. The ultra short throw projection system according to claim 1, characterized in that: The Abbe number ranges of each lens along the direction of light propagation are 40-55, 70-80, 15-25, 80-90, 20-30, 50-60, and 50-60 respectively.

4. The ultra short throw projection system according to claim 1, characterized in that: The air gap between the first spherical lens (1) and the second spherical lens (2) on the optical axis is 0.2-0.5 mm, and the air gap between the second spherical lens (2) and the doublet lens on the optical axis is 1-2 mm; the air gap between the doublet lens and the glass spherical mirror (5) on the optical axis is 2-3 mm; the air gap between the glass spherical mirror (5) and the first plastic aspherical lens (6) on the optical axis is 5-6 mm; the air gap between the first plastic aspherical lens (6) and the second plastic aspherical lens (7) on the optical axis is 6-7 mm; and the air gap between the second plastic aspherical lens (7) and the reflector on the optical axis is 30-40 mm.

5. The ultra short throw projection system according to claim 1, characterized in that: The material curvatures of the right surfaces of each lens along the direction of light propagation are 20-30mm, 80-120mm, 130-150mm, 10-20mm, 20-30mm, 10-20mm, and 10-20mm, respectively.

6. The ultra short throw projection system according to claim 1, characterized in that: The material curvatures of the left surfaces of each lens along the direction of light propagation are 40-50mm, 10-20mm, 10-20mm, 130-150mm, 100-130mm, 20-30mm, and 10-20mm, respectively.

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