External projection lens

Abstract

The utility model discloses a projection external lens comprising a main lens barrel, a first lens and a second lens are arranged in the main lens barrel along the light incident direction in sequence, and all the lenses are plastic aspheric surfaces. According to the utility model, the projection ratio of the projector is changed by externally connecting one lens on the basis of the original lens, the projector can be suitable for various scenes with different projection distances, and meanwhile, the high imaging quality of the original lens is ensured.

Description

Technical Field

[0001] The utility model relates to the technical field of lenses, in particular to a projection external lens. Background Art

[0002] A projector is a device that can project images or videos onto a screen, and the projection lens is its core part. However, the current projection lenses on the market can only be applied to a single scenario, and it is difficult to effectively zoom the picture when the distance cannot be changed. To fill this market gap, it is of certain significance to research and realize such lenses through forward-looking optical design. Content of the Utility Model

[0003] Aiming at the deficiencies and defects of the prior art, a projection external lens is provided. By externally connecting a lens to the original lens to change the projection ratio of the projector, it can be suitable for various scenarios with different projection distances.

[0004] To achieve the above technical purpose, the technical solution adopted by the utility model is as follows:

[0005] A projection external lens includes a main lens barrel. Inside the main lens barrel, a first lens and a second lens are sequentially arranged along the light incident direction, and the outer diameters of the lenses decrease in sequence.

[0006] A magnet is provided on the main lens barrel, and the projection external lens can be adsorbed and connected to the projector through the magnetic adsorption force of the magnet, so as to realize the quick positioning and connection of the projection external lens and the projector.

[0007] The front surface of the first lens is concave, and the radius of curvature of this front surface is -20.2 ≤ r1 ≤ -16.6 mm. The rear surface of the first lens is concave, and the radius of curvature of this rear surface is 119.3 ≤ r1 ≤ 145.7 mm; the front surface of the second lens is concave, and the radius of curvature of this front surface is -80.2 ≤ r1 ≤ -65.6 mm. The rear surface of the second lens is convex, and the radius of curvature of this rear surface is -24.6 ≤ r1 ≤ -20.2 mm;

[0008] The air gap between the first lens and the second lens is 21.4 mm.

[0009] 1. Further, the outer diameter of the first lens is 40 mm, and the outer diameter of the second lens is 34 mm.

[0010] 2. Further, the central thickness of the first lens is 3.47 mm, and the central thickness of the second lens is 8.37 mm.

[0011] 3. Further, the refractive index of the first lens is 1.491756, and the refractive index of the second lens is 1.491756.

[0012] Further, the first lens is made of PMMA, the second lens is made of PMMA, and all lenses are plastic aspherical lenses.

[0013] The beneficial effects of the present utility model are as follows: An external lens is added on the basis of the original lens to change the projection ratio of the projector, which can be suitable for various scenarios with different projection distances, and at the same time ensure the high-quality imaging quality of the original lens. Description of the Drawings

[0014] Figure 1 is the optical path structure schematic diagram of the present utility model;

[0015] Figure 2 is the overall structure cross-sectional schematic diagram of the present utility model;

[0016] Figure 3 is the MTF performance schematic diagram of the present utility model;

[0017] Figure 4 is the OTF performance schematic diagram of the present utility model;

[0018] Figure 5 is the relative illuminance performance schematic diagram of the present utility model;

[0019] Figure 6 is the distortion performance schematic diagram of the present utility model;

[0020] Figure 7 is the point spread function schematic diagram of the present utility model;

[0021] Figure 8 is the CRA curve schematic diagram of the present utility model.

[0022] In the figure: 1. First lens; 2. Second lens; 3. Main lens barrel; 4. Magnet; 5. Light inlet path; 6. Photosensitive element. Detailed Embodiments

[0023] In the description of the present utility model, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present utility model 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 should not be construed as a limitation of the present utility model.

[0024] In the present utility model, unless otherwise clearly specified and defined, terms such as "installation", "connection", "linkage", "fixation", "socket connection", etc. shall be understood in a broad sense. For example, it can be a 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 an indirect connection through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0025] The following further describes the present utility model with reference to the accompanying drawings.

[0026] A projection external lens includes a main lens barrel 3. Inside the main lens barrel 3, a first lens 1 and a second lens 2 are sequentially arranged along the light incident direction, and the outer diameters of the lenses decrease in sequence.

[0027] The main lens barrel 3 is provided with a magnet, and the projection external lens can be adsorbed and connected to the projector through the magnetic adsorption force of the magnet, so that the quick positioning and connection of the projection external lens and the projector can be realized.

[0028] The front surface of the first lens 1 is a concave surface, and the radius of curvature of this front surface is -20.2 ≤ r1 ≤ -16.6 mm. The rear surface of the first lens 1 is a concave surface, and the radius of curvature of this rear surface is 119.3 ≤ r1 ≤ 145.7 mm; the front surface of the second lens 2 is a concave surface, and the radius of curvature of this front surface is -80.2 ≤ r1 ≤ -65.6 mm. The rear surface of the second lens 2 is a convex surface, and the radius of curvature of this rear surface is -24.6 ≤ r1 ≤ -20.2 mm;

[0029] The air gap between the first lens 1 and the second lens 2 is 21.4 mm.

[0030] In this specific embodiment, the outer diameter of the first lens 1 is 40 mm, and the outer diameter of the second lens 2 is 34 mm.

[0031] In this specific embodiment, the central thickness of the first lens 1 is 3.47 mm, and the central thickness of the second lens 2 is 8.37 mm.

[0032] 4. In this specific embodiment, the refractive index of the first lens 1 is 1.491756, and the refractive index of the second lens 2 is 1.491756.

[0033] In this specific embodiment, the material of the first lens 1 is PMMA, and the material of the second lens 2 is PMMA. All lenses are plastic aspherical lenses.

[0034] In this specific embodiment, the specific parameters of the optical lens

[0035]

[0036] In this embodiment, the focal length f of the optical lens is 41 mm, and it can work at a working distance of more than 2 m; the aperture F / N0 is 2.9, the optical back focal length is 90 mm, and the distance from the outer surface of the first lens 1 to the central axis of the imaging surface is 125 mm.

[0037] The performance test curve of this specific embodiment is as Figures 4-6 , and it can be clearly seen from the data of multiple tests of this lens that the principal ray angle of the lens changes linearly, reaching a maximum of 54 degrees, the relative illumination is greater than 45%, the TV distortion is less than 40%, and it can be seen from the MTF performance analysis that the image acquisition resolution of the lens can reach 1080P, providing high-definition resolution images. The working wavelength of the present utility model is 420 - 680 nm.

[0038] The beneficial effect of the present utility model is that an additional lens is externally connected to the original lens to change the projection ratio of the projector, which can be suitable for various scenarios with different projection distances, while ensuring the high-quality imaging quality of the original lens.

[0039] The above embodiments are only used to illustrate the present utility model, rather than to limit the present utility model. Those of ordinary skill in the relevant technical field can also make various changes and modifications without departing from the spirit and scope of the present utility model. Therefore, all equivalent technical solutions also belong to the scope of the present utility model, and the patent protection scope of the present utility model shall be defined by the claims.

Claims

1. A projection external lens, characterized in that It includes a main lens barrel, and a first lens and a second lens are sequentially arranged in the main lens barrel along the light incident direction, and the outer diameters of the lenses decrease in sequence; The front surface of the first lens is concave, and the radius of curvature of this front surface is -20.2 ≤ r1 ≤ -16.6 mm. The rear surface of the first lens is concave, and the radius of curvature of this rear surface is 119.3 ≤ r1 ≤ 145.7 mm. The front surface of the second lens is concave, and the radius of curvature of this front surface is -80.2 ≤ r1 ≤ -65.6 mm. The rear surface of the second lens is convex, and the radius of curvature of this rear surface is -24.6 ≤ r1 ≤ -20.2 mm; The air gap between the first lens and the second lens is 21.4 mm; The main light angle of the lens changes linearly, with a maximum of 54 degrees, the relative illumination is greater than 45%, the TV distortion is less than 40%, the lens image acquisition resolution can reach 1080P, and the working wavelength is 420 - 680 nm.

2. The projection external lens according to claim 1, characterized in that, A magnet is provided on the main lens barrel, and the projection external lens can be adsorbed and connected to the projector through the magnetic adsorption force of the magnet, so as to realize the rapid positioning and connection of the projection external lens and the projector.

3. A projection external lens according to claim 2, characterized in that, The outer diameter of the first lens is 40 mm, and the outer diameter of the second lens is 34 mm.

4. A projection external lens according to claim 2, characterized in that The central thickness of the first lens is 3.47 mm, and the central thickness of the second lens is 8.37 mm.

5. A projection external lens according to claim 2, characterized in that, The refractive index of the first lens is 1.491756, and the refractive index of the second lens is 1.491756.

6. A projection external lens according to any one of claims 1-5, characterized in that The material of the first lens is PMMA, the material of the second lens is PMMA, and all lenses are plastic aspherical lenses.

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