Optical system for camera

Abstract

The present invention relates to an optical system for a camera. The optical system for a camera in accordance with the present invention includes: a first lens that has a positive refractive index and has a convex shape toward an object; a second lens that has a negative refractive index and has a concave shape at both surfaces; a third lens that has the positive refractive index and has the convex shape upwards; and a fourth lens that has the negative refractive index and has a concave surface on an object-side surface, and has at least one inflection point on an image surface. It is possible to implement a compact optical system for a camera which can be applied to a mobile communication terminal by improving design flexibility.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS [0002] This application claims the benefit of Korean Patent Application No. 10-2009-0089592, filed with the Korean Intellectual Property Office on September 22, 2009, the disclosure of which is incorporated herein by reference. technical field [0003] The present invention relates to an optical system for a camera, and more particularly, to an optical system for a camera in which an aperture stop is provided between lenses, and all the lenses constituting the optical system are composed of non- Spherical plastic lens composition. Background technique [0004] In recent years, with the increasing number of mobile communication devices such as mobile communication terminals, PDAs, and smartphones, services provided through communication technologies have become diverse, providing various types of additional functions in addition to basic communication functions . [0005] Among these functions, camera modules are mainly insta...

AI Technical Summary

Problems solved by technology

[0007] Thus, a plurality of lenses are used in the optical system to maintain high resolution, and it is preferable to configure the optical system by using a glass lens having a high optical transmittance and a high refractive index, however, since the optical system is designed according to the optical system characteristics, so it is difficult for an optical system installed in a mobile communication device to meet the conditions of size reduction and cost reduction

[0008] Therefore, an optical system installed in a mobile communication device uses a plastic lens that is easy to mold, and reduces the number of lenses as much as possible to reduce size and save manufacturing cost, however, the optical system uses a glass lens that has poor performance compared with a glass lens. Plastic lenses of optical performance, it is difficult to satisfy the optical performance by designing the optical system, and the design flexibility of the optical system is deteriorated due to the reduction in the number of lenses

[0009] Meanwhile, as a general design of an optical system, a design method is adopted in which an aperture stop is positioned at the forefront of each of a plurality of lenses, and the plurality of lenses are arranged in sequence, but, in this case, passing through the aperture The light at the end of the diaphragm causes many aberrations (aberration)

[0010] In addition, when the aperture stop located at the frontmost part of the optical system is far away from the first lens close to the object, the size of the first lens increases and the length of the optical system increases, thereby significantly deteriorating the optical performance

Images