1. Field of the Invention
The present invention relates to an imaging lens and an electronic apparatus, more particularly to an imaging lens having four lens elements and an electronic apparatus having the same.
2. Description of the Related Art
In recent years, as use of portable electronic devices (e.g., mobile phones and digital cameras) becomes ubiquitous, much effort has been put into reducing dimensions of portable electronic devices. Moreover, as dimensions of charged coupled device (CCD) and complementary metal-oxide semiconductor (CMOS) based optical sensors are reduced, dimensions of imaging lenses for use with the optical sensors must be correspondingly reduced without significantly compromising optical performance.
In view of the above, each of U.S. Pat. No. 7,355,801 and US Patent Application Publication No. 20120013998 discloses a conventional imaging lens with four lens elements, of which the image-side surface of a second lens element is a concave surface.
Japanese Patent Application Publication No. 2011-064989, U.S. Pat. Nos. 7,920,340 and 7,777,972, and U.S. Patent Application Publication No. 20110058089 also disclose conventional imaging lenses with four lens elements, each of which is spaced apart from an adjacent one of the lens elements by a relatively wide gap. In the fifth embodiment of U.S. Pat. No. 7,920,340, the lens has a length of 7 mm, which goes against the trend toward reducing thickness of portable electronic products, such as mobile phones and digital cameras.
Thus, it is apparent that the current trend in development of imaging systems for portable electronic devices focuses on reducing overall lengths of the imaging systems. However, optical performances and imaging qualities of the imaging systems may be compromised as the overall lengths are reduced.