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Patent Issued for Imaging Lens and Imaging Apparatus Provided with the Imaging Lens

June 25, 2014



By a News Reporter-Staff News Editor at Journal of Engineering -- From Alexandria, Virginia, VerticalNews journalists report that a patent by the inventor Shinohara, Yoshikazu (Saitama-ken, JP), filed on November 6, 2013, was published online on June 10, 2014.

The patent's assignee for patent number 8749896 is Fujifilm Corporation (Tokyo, JP).

News editors obtained the following quote from the background information supplied by the inventors: "The present invention relates to a fixed focus imaging lens for forming an optical image of a subject on an image sensor, such as a CCD (Charge Coupled Device), CMOS (Complementary Metal Oxide Semiconductor), or the like, and an imaging apparatus provided with the imaging lens to perform imaging, such as a digital still camera, camera-equipped cell phone, personal digital assistance (PDA), smartphone, portable video game player, or the like.

"Recently, along with the spread of personal computers to homes and the like, digital still cameras capable of inputting image information obtained by imaging a landscape, a person, or the like to a personal computer have been spreading rapidly. In addition, more and more cell phones and smartphoes have built-in camera modules for inputting images. Such devices with imaging capabilities employ image sensors such as CCDs, CMOSs, and the like. Recently, these types of image sensors have been downsized greatly and, consequently, imaging devices as a whole and imaging lenses mounted on such devices have also been demanded to have more compact sizes. At the same time, the pixel count of image sensors has been increasing, thereby causing a growing demand for improvement of imaging lenses in resolution and performance. For example, performance corresponding to high pixel counts, such as more than 5 Mega Pixels, and more preferably more than 8 Mega Pixels is demanded.

"For responding to such demands, it is conceivable to employ a relatively large number of lenses, such as a five- or six-lens configuration, in order to achieve, for example, reduction in overall length and improvement in resolution (refer to Korean Unexamined Patent Publication No. 2010-0040357 and Chinese Utility Model Publication No. 202067015 (U.S. Pat. No. 8,385,006))."

As a supplement to the background information on this patent, VerticalNews correspondents also obtained the inventor's summary information for this patent: "In imaging lenses required of reduction in overall length, such as those having a relatively large number of lenses as described above and used, in particular, for personal digital assistance devices, realization of an imaging lens having a large image size and applicable to an image sensor having a large size comparable to that of conventional image sensors is demanded.

"In order to respond to these demands, the imaging lens formed of six lenses described in Patent Document 1 requires further reduction in overall length. The imaging lens described in Patent Document 2 has a large ratio of overall length relative to the size of image sensor, and when applied to an image sensor having a relatively large size by extending proportionally, the overall length becomes long, so that the overall length needs to be further reduced after all.

"The present invention has been developed in view of the circumstances described above and it is an object of the present invention to provide an imaging lens having a large image size and capable of realizing high image quality from the central angle of view to peripheral angle of view with reduced overall length. It is a further object of the present invention to provide an imaging apparatus provided with the imaging lens and capable of obtaining a high resolution image.

"An imaging lens of the present invention substantially consists of six lenses, composed of:

"a first lens having a positive refractive power and a convex surface on the object side;

"a second lens having a negative refractive power and a concave surface on the image side;

"a third lens having a positive refractive power and a convex surface on the object side;

"a fourth lens having a positive refractive power;

"a fifth lens having a negative refractive power and a concave surface on the image side; and

"a sixth lens having a negative refractive power with the image side surface having an aspherical shape which is concave on the image side near the optical axis and convex in a peripheral region, arranged in this order from the object side.

"According to the imaging lens of the present invention, the structure of each lens element is optimized and, in particular, the first to third, fifth, and sixth lenses are formed in appropriate shapes in a lens configuration of six lenses in total. This allows realization of a lens system having high resolution performance, while the overall length is reduced.

"The term 'substantially consists of six lenses' as used herein refers to that the imaging lens of the present invention includes a lens substantially without any refractive power, an optical element other than a lens, such as an aperture stop, cover glass, or the like, a lens flange, a lens barrel, an image sensor, and a mechanism, such as a camera-shake correction mechanism or the like, other than the six lenses.

"In the imaging lens of the present invention, further adoption and satisfaction of the following preferable configurations may further improve the optical performance.

"In the imaging lens of the present invention, the third lens is preferably a bi-convex lens.

"In the imaging lens of the present invention, an aperture stop is preferably disposed on the object side of the object side surface of the second lens and more preferably on the object side of the object side surface of the first lens.

"Further, in the imaging lens of the present invention, the image side surface of the fifth lens has an aspherical shape which is concave on the image side near the optical axis and convex in a peripheral region.

"Preferably, the imaging lens of the present invention satisfies any one or any combination of the conditional expressions (1) to (4-2) given below: vd5

"f1 is a focal length of the first lens;

"f2 is a focal length of the second lens;

"f3 is a focal length of the third lens;

"f6 is a focal length of the sixth lens;

"vd2 is an Abbe number of the second lens with respect to the d-line; and

"vd5 is an Abbe number of the fifth lens with respect to the d-line.

"The imaging apparatus of the present invention is provided with the imaging lens of the present invention.

"The imaging apparatus of the present invention may obtain a high resolution image signal based on a high resolution optical image obtained by the imaging lens of the present invention.

"According to the imaging lens of the present invention, the structure of each lens element is optimized, in particular, the first and sixth lens are formed in appropriate shapes in a lens configuration of six lenses in total. This allows realization of a lens system having a large image size and high image quality from the central angle of view to peripheral angle of view, while the overall length is reduced.

"According to the imaging apparatus of the present invention, an image signal is outputted according to an optical image formed by the imaging lens of the present invention having high image quality described above, so that a high resolution image may be obtained based on the image signal."

For additional information on this patent, see: Shinohara, Yoshikazu. Imaging Lens and Imaging Apparatus Provided with the Imaging Lens. U.S. Patent Number 8749896, filed November 6, 2013, and published online on June 10, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=8749896.PN.&OS=PN/8749896RS=PN/8749896

Keywords for this news article include: Fujifilm Corporation.

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Source: Journal of Engineering


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