News Column

Patent Issued for Optical Image Capturing Lens System

February 26, 2014



By a News Reporter-Staff News Editor at Electronics Newsweekly -- Largan Precision Co., Ltd. (Taichung, TW) has been issued patent number 8649113, according to news reporting originating out of Alexandria, Virginia, by VerticalNews editors.

The patent's inventors are Tsai, Tsung-Han (Taichung, TW); Chen, Wei-Yu (Taichung, TW).

This patent was filed on September 12, 2012 and was published online on February 11, 2014.

From the background information supplied by the inventors, news correspondents obtained the following quote: "The present invention relates to an optical image capturing lens system, and more particularly, to a compact optical image capturing lens system used in electronic products.

"The demand for compact imaging lens assembly has grown in recent years as the popularity of portable electronic products with the photographing function has increased. The sensor of a general photographing camera is none other than CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor Sensor). Furthermore, as advanced semiconductor manufacturing technology has allowed the pixel size of sensors to be reduced, and the current electronic products are leaning toward a trend of being more compact, there is an increasing demand for compact imaging lens assembly featuring better image quality.

"Imaging lenses used in vehicle cameras, security surveillance cameras or electronic game devices typically require a larger field of view to capture an image of a larger area at one time. Generally, a conventional imaging lens assembly with a large angle of view, such as the four-element lens assembly disclosed in U.S. Pat. No. 7,446,955, is arranged in such manner that the front lens group has negative refractive power and the rear lens group has positive refractive power, thereby forming an inverse telephoto structure to achieve a wide field of view. While such arrangement facilitates the enlargement of the field of view, the aberration correction of the optical system is ineffective due to the inclusion of only one lens element in the rear lens group. Moreover, vehicles equipped with rear-view cameras have become more and more common, and there is a trend toward high-resolution, wide-angle lenses for rear-view cameras. Therefore, a need exists in the art for a wide-angle imaging lens assembly, which has a wide field of view, high image quality and a moderate total track length."

Supplementing the background information on this patent, VerticalNews reporters also obtained the inventors' summary information for this patent: "Through the arrangement depicted below, the optical image capturing lens system of the present invention allows the angle of view to increase effectively to a proper range and to suppress the distortion produced by the wide-angle lens system with a large angle of view. In addition, when comparing to other image lens systems with a large angle of view, the present invention has a tighter arrangement of the lens elements and a smaller back focal length, and therefore is more appropriate for the compact device.

"The present invention provides an optical image capturing lens system comprising, in order from an object side to an image side: a first lens element with negative refractive power having a convex object-side surface at paraxial region and a concave image-side surface at the paraxial region; a second lens element with positive refractive power; a third lens element with negative refractive power; a fourth lens element with positive refractive power having a convex image-side surface at the paraxial region; a fifth lens element with negative refractive power having a convex object-side surface at the paraxial region as well as a concave at the paraxial region and convex at a peripheral region image-side surface, at least one of an object-side surface and the image-side surface thereof being aspheric, and the fifth lens element is made of plastic; and the lens elements of the optical image capturing lens system with refractive power are the first lens element, the second lens element, the third lens element, the fourth lens element and the fifth lens element; wherein a focal length of the optical image capturing lens system is f, a focal length of the first lens element is f1, an axial distance between the object-side surface of the first lens element and the image-side surface of the fifth lens element of the optical image capturing lens system is Td, a sum of central thicknesses of all lens elements with refractive power of the optical image capturing lens system is .SIGMA.CT, the central thickness of the fourth lens element is CT4, and they satisfy the following relations: -0.33
"On the other hand, the present invention provides an optical image capturing lens system comprising, in order from an object side to an image side: a first lens element with negative refractive power; a second lens element with positive refractive power; a third lens element with negative refractive power; a fourth lens element with positive refractive power having a convex image-side surface at the paraxial region; a fifth lens element with negative refractive power having a concave image-side surface at the paraxial region and convex shape at the peripheral region, at least one of an object-side surface and the image-side surface thereof being aspheric, and the fifth lens element is made of plastic; and the lens elements of the optical image capturing lens system with refractive power are the first lens element, the second lens element, the third lens element, the fourth lens element and the fifth lens element; wherein a focal length of the optical image capturing lens system is f, a focal length of the first lens element is f1, an axial distance between the object-side surface of the first lens element and the image-side surface of the fifth lens element of the optical image capturing lens system is Td, a sum of central thicknesses of all lens elements with refractive power of the optical image capturing lens system is .SIGMA.CT, a curvature radius of the object-side surface of the fifth lens element is R9, a curvature radius of the image-side surface of the fifth lens element is R10, and they satisfy the following relations: -0.33
"Furthermore, the present invention provides an optical image capturing lens system comprising, in order from an object side to an image side: a first lens element with negative refractive power having a convex object-side surface at paraxial region and a concave image-side surface at the paraxial region; a second lens element with positive refractive power having a convex object-side surface at paraxial region; a third lens element with negative refractive power having a concave or plane object-side surface at the paraxial region, both of the object-side and the image-side surfaces thereof being aspheric, and the third lens element is made of plastic; a fourth lens element with positive refractive power having a concave object-side surface at the paraxial region and a convex image-side surface at the paraxial region, both of the object-side and the image-side surfaces thereof being aspheric, and the fourth lens element is made of plastic; a fifth lens element with negative refractive power having a convex object-side surface at the paraxial region as well as a concave at the paraxial region and convex at a peripheral region image-side surface, both of the object-side and the image-side surfaces thereof being aspheric, and the fifth lens element is made of plastic; the lens elements of the optical image capturing lens system with refractive power are the first lens element, the second lens element, the third lens element, the fourth lens element and the fifth lens element; and the optical image capturing lens system further comprises a stop disposed between an object and the second lens element; wherein a focal length of the optical image capturing lens system is f, a focal length of the first lens element is f1, an axial distance between the object-side surface of the first lens element and the image-side surface of the fifth lens element of the optical image capturing lens system is Td, a sum of central thicknesses of all lens elements with refractive power of the optical image capturing lens system is .SIGMA.CT, the central thickness of the fourth lens element is CT4, and they satisfy the following relations: -0.45
"In the aforementioned optical image capturing lens system, the first lens element has negative refractive power, and thereby it is favorable for enlarging the field of view of the system. When the second lens element has positive refractive power, and thereby can provide significant refractive power needed for the system and is favorable for reducing the total track length thereof. When the third lens element has negative refractive power, the aberrations produced by the second lens element can be effectively corrected. When the fourth lens element has positive refractive power, the positive refractive power of the second lens element can be effectively distributed for reducing the sensitivity of the system. Moreover, when the fourth lens element has positive refractive power and the fifth lens element has negative refractive power, a positive-negative telephoto structure is formed so that the back focal length of the system is favorably reduced for shortening the total track length of the system.

"In the aforementioned optical image capturing lens system, when the first lens element has a convex object-side surface at the paraxial region and a concave image-side surface at the paraxial region, the field of view of the lens system can be favorably enlarged, and the refraction of the incident light is more moderate for preventing the aberrations from being excessively large; therefore, it is favorable for obtaining a better balance between wide field of view and aberration corrections. When the second lens element has a convex object-side surface at the paraxial region, it favorably corrects astigmatic aberrations produced by the first lens element having a concave image-side surface with a stronger curvature. When the third lens element has a concave object-side surface at the paraxial region and a concave image-side surface at the paraxial region, it effectively reinforces the negative refractive power of the third lens element for favorably correcting the aberrations of the lens system. Additionally, when the third lens element has a concave image-side surface at the paraxial region and convex shape at the peripheral region, it favorably corrects the astigmatic aberrations of the optical image capturing lens system thereby. When the fourth lens element has a concave object-side surface at the paraxial region and a convex image-side surface at the paraxial region, it favorably corrects the astigmatism of the lens system. When the fifth lens element has a concave image-side surface at the paraxial region, the principal point of the system can be positioned away from the image plane so that the back focal length of the system is favorably reduced for shortening the total track length in order to keep the system compact. Besides, when the fifth lens element has a concave image-side surface at the paraxial region and convex shape at the peripheral region, the angle at which light projects onto the image sensor from the off-axis field can be effectively reduced so that the sensing efficiency of the image sensor can be improved and the off-axis aberrations can be further corrected."

For the URL and additional information on this patent, see: Tsai, Tsung-Han; Chen, Wei-Yu. Optical Image Capturing Lens System. U.S. Patent Number 8649113, filed September 12, 2012, and published online on February 11, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=40&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=1981&f=G&l=50&co1=AND&d=PTXT&s1=20140211.PD.&OS=ISD/20140211&RS=ISD/20140211

Keywords for this news article include: Electronics, Semiconductor, Largan Precision Co. Ltd..

Our reports deliver fact-based news of research and discoveries from around the world. Copyright 2014, NewsRx LLC


For more stories covering the world of technology, please see HispanicBusiness' Tech Channel



Source: Electronics Newsweekly


Story Tools