Monitoring lens

Abstract

The invention relates to a monitoring lens which is successively provided with a first meniscus-shaped lens element, a second lens element, a third lens element and a lens component, starting from the side facing an object, wherein the first meniscus-shaped lens element has negative focal power and protrudes to the object side; the second lens element comprises a spherical or non-spherical lens with negative focal power, and a diaphragm is arranged behind the second lens element; the third lens element comprises a spherical or non-spherical lens with positive focus power, and is used for correcting the third lens element in the field curvature; and the lens component has positive focus power and is formed by connecting a fourth lens element and a fifth lens element, and wherein the following conditions need to be satisfied: BFL (back focal length) / EFL (effective focal length) is less than or equal to 2.8 and greater than or equal to 2.3, wherein the BFL is the distance from an outermost point of an image side of the fifth lens element of a wide angle security monitoring lens to the image face; and the EFL is the focusing value of a wide angle high definition security monitoring lens. By utilizing the monitoring lens, shortcomings in the prior art can be overcome, and the invention provides a wide angle security monitoring lens with moderate cost, light weight, small size, high resolution, long operating distance and wide operating temperature range.

Description

【Technical field】 [0001] The invention relates to a monitoring lens system, and is especially suitable for security monitoring cameras and driving recorder image systems that have higher requirements on the working distance of the lens and wider operating temperature conditions. 【Background technique】 [0002] With the rapid rise of the security monitoring market this year and the optimization and improvement of digital processing and network transmission speeds, the quality requirements for security monitoring lenses have been greatly improved, from ordinary monitoring requirements to high-definition identification. [0003] At present, the security monitoring lens is generally composed of 4 to 8 lenses. For example, the wide-angle security monitoring lens with the Chinese Patent No. 200910099703 is composed of 4 glass and 2 plastic lenses. However, this wide-angle security monitoring lens has a large size and high Limited in low-temperature and high-humidity environments, ...

AI Technical Summary

Problems solved by technology

[0003] At present, the security monitoring lens is generally composed of 4 to 8 lenses. For example, the wide-angle security monitoring lens with the Chinese Patent No. 200910099703 is composed of 4 glass and 2 plastic lenses. However, this wide-angle security monitoring lens has a large size and high Restricted in low-temperature and high-humidity environments, it cannot meet customer requirements for small size and high performance

[0004] To this end, the wide-angle security monitoring lens developed by the company adopts plastic aspheric technology to reduce weight, cost and deformation, but its light transmission performance is weak, the working distance BFL is also short, and the temperature compensation characteristics are not good, so it cannot Satisfied to maintain perfect imaging clarity in the temperature range of -60℃~+85℃

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