External overlooking optical viewfinder

Abstract

The utility model provides an external overlooking optical viewfinder, which comprises 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 fifth lens 7 and a sixth lens 8 from an object side to a human eye side along an optical axis. The reflecting mirror 2 has the capability of reflecting light; the second lens element 3 has positive refractive power. And the second lens 3 adopts a Fresnel lens, and the lens design of large, medium and small sizes and short focal length can be realized by using a relatively thin thickness, so that the overall structure of the optical assembly is more compact, the miniaturization and reasonable matching of refractive power and surface types can be conveniently realized, and the wide-angle view finding requirement can be realized.

Description

Technical Field

[0001] The utility model application relates to the technical field of viewfinders, and in particular to an external top-down optical viewfinder. Background Art

[0002] Most existing viewfinders are electronic viewfinders, which have problems such as power consumption, color cast, and unclear display under sunlight during use. Optical viewfinders can overcome the shortcomings of electronic viewfinders.

[0003] Optical viewfinders are primarily eye-level and top-down, and are available in either built-in, integrated-with-the-camera configuration or external, independent optical structures. One type of external top-down optical viewfinder consists of a front vertical convex lens, a rear horizontal convex lens, and a 45-degree reflector placed at the midline intersection between the lenses.

[0004] However, due to the structural characteristics of the convex lens, the larger the diameter and the shorter the focal length, the thicker the convex lens. Therefore, the existing external top-down optical viewfinders are mostly used to adapt to lenses with a focal length of 50mm and above. It is difficult to reduce the size of the viewfinder, and there are few viewfinders suitable for wide-angle lenses. Summary of the Invention

[0005] The purpose of the present utility model application is to provide an external top-down optical viewfinder that can solve the above-mentioned problems.

[0006] In order to achieve the purpose of this utility model application, this application provides the following technical solutions.

[0007] In the first aspect, the utility model application provides an external top-down optical viewfinder, which comprises, along the optical axis direction from the object side to the human eye side, a first lens with positive refractive power; a reflector with the ability to reflect light; and a second lens with positive refractive power.

[0008] In the second aspect, the utility model application provides an external top-down optical viewfinder, which comprises, along the optical axis direction from the object side to the human eye side, a first lens, which is placed vertically; a reflector, which is placed at a forty-five-degree angle facing the first lens and the second lens; and a second lens, which is placed horizontally.

[0009] In the third aspect, the utility model application provides an external top-down optical viewfinder, which comprises, along the optical axis direction from the object side to the human eye side, a first lens, which is a plano-convex lens or a biconvex lens, and the object side surface of the first lens is a convex surface; a reflector, the center point of the mirror surface intersects with the intersection point of the extension line of the center line of the first lens and the second lens; the second lens is a Fresnel lens, also known as a threaded lens, and the human eye side surface of the second lens is a serrated surface, the second lens is a thin lens with uniform thickness, one side of the surface of the second lens is a smooth surface, and the other side is a serrated surface, and concentric circles from small to large are evenly distributed outward from the center of the second lens.

[0010] The optical component structure of the utility model application adopts a Fresnel lens as the second lens, which can realize the design of lenses of large, medium and small sizes and short focal lengths with a relatively thin thickness, making the overall structure of the optical component more compact and facilitating miniaturization. The reasonable combination of refractive power and surface shape can meet the needs of wide-angle framing. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a schematic diagram of the structure of the external top-down optical viewfinder applied for by the utility model DETAILED DESCRIPTION

[0012] The technical solutions in the present utility model application will be described below in conjunction with the drawings in the present utility model application. It should be noted that the technical solutions described are only part of the implementation methods of the present application, rather than all of the implementation methods. Based on the implementation methods in the present application, any structural modifications, changes in proportional relationships, or adjustments in size, without affecting the effects that can be produced by the present application and the purposes that can be achieved, all fall within the scope of protection of the present application. Those of ordinary skill in the art, without substantially changing the technical content, should also be considered as the scope of implementation of the present application.

[0013] The embodiment of the present application provides an external top-down optical viewfinder, which includes, in order from the object side to the human eye side along the optical axis, a first lens 1, a reflector 2, and a second lens 3.

[0014] In the embodiment of this application, the second lens element 3 utilizes a Fresnel lens, which allows for thinner designs for large, medium, and small sizes, as well as short focal lengths. In one embodiment, the refractive power of the second lens element 3 can be flexibly designed to meet the wide-angle viewing requirements. By using different refractive powers for the second lens element 3, the lens thickness can be maintained constant, and the overall height of the optical assembly can also be maintained.

[0015] The structure of the optical components of the implementation scheme of the present application is compact as a whole, which is convenient for miniaturization. At the same time, the reasonable combination of refractive power and surface shape can meet the needs of wide-angle framing.

[0016] The above is a detailed introduction to this implementation plan. Specific cases are used in this article to illustrate this application. The description of the above implementation plan is only used to help understand the technical solution of this application. At the same time, for general technical personnel in this field, there will be changes in the specific implementation plan and application scope based on the technical solution of this application. In summary, the content of this specification should not be understood as a limitation on this application.

Claims

1. An external top-down optical viewfinder, characterized in that: The optical system comprises, in order from the object side to the eye side, a first lens, a reflector, and a second lens; the first lens has positive refractive power and is placed vertically; the first lens is a plano-convex lens or a biconvex lens, and the object-side surface of the first lens is a convex surface; the reflector has the ability to reflect light and is placed at a 45-degree angle facing the first lens and the second lens, with the center point of the reflector surface intersecting with the intersection point of the extended center lines of the first lens and the second lens; The second lens has positive refractive power and is placed horizontally. The second lens is a Fresnel lens, also known as a spiral lens. The side of the second lens on the human eye is a serrated surface. The second lens is a thin lens with uniform thickness. One side of the second lens is a smooth surface and the other side is a serrated surface. Concentric circles from small to large are evenly distributed outward from the center of the second lens.

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