News Column

"Imaging Lens and Imaging Apparatus Including the Imaging Lens" in Patent Application Approval Process

July 4, 2014



By a News Reporter-Staff News Editor at Health & Medicine Week -- A patent application by the inventors NISHIHATA, Sumihiro (Saitama-ken, JP); ISHII, Yoshiaki (Saitama-ken, JP), filed on December 11, 2013, was made available online on June 19, 2014, according to news reporting originating from Washington, D.C., by NewsRx correspondents (see also FUJIFILM Corporation).

This patent application is assigned to FUJIFILM Corporation.

The following quote was obtained by the news editors from the background information supplied by the inventors: "This invention relates to a fixed-focus imaging lens that forms an optical image of a subject on an imaging device, such as a CCD (Charge Coupled Device) and a CMOS (Complementary Metal Oxide Semiconductor), and to an imaging apparatus, such as a digital still camera, a cellular phone with a camera, an information mobile terminal (PDA: Personal Digital Assistance), a smartphone, a mobile game machine, and a tablet terminal, on which the imaging lens is mounted to perform photography.

"As personal computers became owned by many families and the like in recent years, digital still cameras, which can input image data of a landscape, a portrait and the like obtained by photography into the personal computers, have rapidly spread. Further, camera modules for inputting images became often mounted on cellular phones, smartphones and tablet terminals. Such equipment having an imaging function uses an imaging device, such as a CCD and a CMOS. As the size of the imaging device became small in recent years, the total size of imaging equipment and the size of an imaging lens to be mounted on the imaging equipment also need to be reduced. Further, since the resolution of the imaging device has become higher at the same time, the imaging lens needs to have high resolution and high performance. For example, the imaging lens needs to have performance corresponding to high resolution of 5 megapixels or higher, and desirably performance corresponding to 8 megapixels or higher.

"To satisfy such need, Japanese Unexamined Patent Publication No. 2012-155223 (Patent Document 1) discloses a lens system consisting of seven lenses, which are a relatively large number of lenses, to reduce the total length of the lens system and to increase resolution."

In addition to the background information obtained for this patent application, NewsRx journalists also obtained the inventors' summary information for this patent application: "However, the lens disclosed in Patent Document 1, which consists of seven lenses, further needs to correct various aberrations in an excellent manner to satisfy the aforementioned need for higher performance.

"In view of the foregoing circumstances, it is an object of the present invention to provide an imaging lens that can correct aberrations in an excellent manner and achieve high image formation performance from a center of an angle of view through a peripheral portion of the angle of view, and an imaging apparatus on which the imaging lens is mounted, and which can obtain a high resolution imaging image.

"The imaging lens of the present invention is an imaging lens substantially consisting of seven lenses of:

"a first lens that has positive refractive power in the vicinity of an optical axis and a convex surface facing an object side in the vicinity of the optical axis;

"a second lens;

"a third lens;

"a fourth lens;

"a fifth lens;

"a sixth lens; and

"a seventh lens having a concave surface facing an image side in the vicinity of the optical axis, and at least one of the surfaces of which includes an inflection point, and both of the surfaces of which are aspherical, which are in this order from the object side,

"wherein each of the first lens through the seventh lens is a single lens.

"In the imaging lens of the present invention, the expression 'substantially consisting of seven lenses' means that the imaging lens of the present invention may include a lens substantially without power, an optical element, such as a stop and a cover glass, which is not a lens, a mechanism part, such as a lens flange, a lens barrel, an imaging device and a hand shake blur correction mechanism, and the like besides the seven lenses. When the lens includes an aspherical surface, the sign of the surface shape and refractive power of the lens is considered in a paraxial region.

"Further, the term 'single lens' refers to a lens consisting of one lens, and which is not a cemented lens.

"It is possible to improve the optical performance of the imaging lens of the present invention by further adopting and satisfying the following desirable structure or structures.

"It is desirable that the imaging lens of the present invention further includes an aperture stop arranged on the object side of an object-side surface of the third lens.

"In the imaging lens of the present invention, it is desirable that the fifth lens has positive refractive power in the vicinity of the optical axis.

"In the imaging lens of the present invention, it is desirable that the first lens has a meniscus shape in the vicinity of the optical axis.

"In the imaging lens of the present invention, it is desirable that the second lens has a convex surface facing the object side in the vicinity of the optical axis.

"In the imaging lens of the present invention, it is desirable that the third lens has a concave surface facing the object side in the vicinity of the optical axis.

"In the imaging lens of the present invention, it is desirable that the fourth lens has a convex surface facing the object side in the vicinity of the optical axis.

"In the imaging lens of the present invention, it is desirable that the sixth lens has a convex surface facing the image side in the vicinity of the optical axis.

"It is desirable that the imaging lens of the present invention satisfies at least one of the following conditional formulas (1) through (8). As a desirable mode, the imaging lens may satisfy one of the following conditional formulas (1) through (8). Alternatively, the imaging lens may satisfy an arbitrary combination of conditional formulas (1) through (8):

"f/f67

"-2
"0
"0.2
"minvd

"0.2<.SIGMA.Dt/.SIGMA.D

"0.2<.SIGMA.Dt/TCL

"0
"0.2<.SIGMA.Dt/.SIGMA.Da

"and

"0
"f67: a combined focal length of the sixth lens and the seventh lens,

"f: a focal length of an entire system,

"f123: a combined focal length of the first lens, the second lens and the third lens,

"minvd: the smallest one of Abbe numbers for d-line of lenses with negative refractive power included in the imaging lens,

".SIGMA.Dt: a sum of center thicknesses of the first lens through the seventh lens,

".SIGMA.D: a length on the optical axis from an object-side surface of the first lens to an image-side surface of the seventh lens,

"TCL: a length on an optical axis from an object-side surface of the first lens to an image formation surface,

"f1: a focal length of the first lens,

".SIGMA.Da: a sum of the lengths of air spaces on an optical axis from an image-side surface of the first lens through an object-side surface of the seventh lens, and

"f6: a focal length of the sixth lens.

"With respect to the length on the optical axis from the object-side surface of the first lens to the image formation surface (total lens length), distance in air is used for a back focus portion. For example, when a member, such as a filter and a cover glass, which does not have any refractive power is inserted between the most-image-side lens and the image formation surface, distance in air is used for the thickness of this member.

"The imaging apparatus of the present invention includes the imaging lens of the present invention.

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

"Effects of the Invention

"According to the imaging lens of the present invention, the structure of each lens element is optimized in a lens structure consisting of seven lenses in total. Especially, all of lenses, which are the first lens through the seventh lens, are single lenses. Therefore, it is possible to excellently correct various aberrations, and to achieve a lens system having high image formation performance from a center of an angle of view through a peripheral portion of the angle of view.

"Further, according to the imaging apparatus of the present invention, imaging signals based on an optical image formed by the imaging lens of the present invention, which has high image formation performance, are output. Therefore, it is possible to obtain high resolution photography images.

BRIEF DESCRIPTION OF THE DRAWINGS

"FIG. 1 is a diagram illustrating a first structural example of an imaging lens according to an embodiment of the present invention, and which is a lens cross section corresponding to Example 1;

"FIG. 2 is a diagram illustrating a second structural example of an imaging lens according to an embodiment of the present invention, and which is a lens cross section corresponding to Example 2;

"FIG. 3 is a diagram illustrating a third structural example of an imaging lens according to an embodiment of the present invention, and which is a lens cross section corresponding to Example 3;

"FIG. 4 is a diagram illustrating a fourth structural example of an imaging lens according to an embodiment of the present invention, and which is a lens cross section corresponding to Example 4;

"FIG. 5 is a diagram illustrating a fifth structural example of an imaging lens according to an embodiment of the present invention, and which is a lens cross section corresponding to Example 5;

"FIG. 6 is a diagram illustrating a sixth structural example of an imaging lens according to an embodiment of the present invention, and which is a lens cross section corresponding to Example 6;

"FIG. 7 is a diagram illustrating a seventh structural example of an imaging lens according to an embodiment of the present invention, and which is a lens cross section corresponding to Example 7;

"FIG. 8 is a cross section illustrating optical paths of the imaging lens illustrated in FIG. 3;

"FIG. 9 is an aberration diagram illustrating various aberrations of an imaging lens in Example 1 of the present invention, and Section A shows a spherical aberration, and Section B shows astigmatism (curvature of field), and Section C shows distortion, and Section D shows a lateral chromatic aberration;

"FIG. 10 is an aberration diagram illustrating various aberrations of an imaging lens in Example 2 of the present invention, and Section A shows a spherical aberration, and Section B shows astigmatism (curvature of field), and Section C shows distortion, and Section D shows a lateral chromatic aberration;

"FIG. 11 is an aberration diagram illustrating various aberrations of an imaging lens in Example 3 of the present invention, and Section A shows a spherical aberration, and Section B shows astigmatism (curvature of field), and Section C shows distortion, and Section D shows a lateral chromatic aberration;

"FIG. 12 is an aberration diagram illustrating various aberrations of an imaging lens in Example 4 of the present invention, and Section A shows a spherical aberration, and Section B shows astigmatism (curvature of field), and Section C shows distortion, and Section D shows a lateral chromatic aberration;

"FIG. 13 is an aberration diagram illustrating various aberrations of an imaging lens in Example 5 of the present invention, and Section A shows a spherical aberration, and Section B shows astigmatism (curvature of field), and Section C shows distortion, and Section D shows a lateral chromatic aberration;

"FIG. 14 is an aberration diagram illustrating various aberrations of an imaging lens in Example 6 of the present invention, and Section A shows a spherical aberration, and Section B shows astigmatism (curvature of field), and Section C shows distortion, and Section D shows a lateral chromatic aberration;

"FIG. 15 is an aberration diagram illustrating various aberrations of an imaging lens in Example 7 of the present invention, and Section A shows a spherical aberration, and Section B shows astigmatism (curvature of field), and Section C shows distortion, and Section D shows a lateral chromatic aberration;

"FIG. 16 is a diagram illustrating an imaging apparatus that is a cellular phone terminal including an imaging lens of the present invention; and

"FIG. 17 is a diagram illustrating an imaging apparatus that is a smartphone including an imaging lens of the present invention."

URL and more information on this patent application, see: NISHIHATA, Sumihiro; ISHII, Yoshiaki. Imaging Lens and Imaging Apparatus Including the Imaging Lens. Filed December 11, 2013 and posted June 19, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=4670&p=94&f=G&l=50&d=PG01&S1=20140612.PD.&OS=PD/20140612&RS=PD/20140612

Keywords for this news article include: Astigmatism, Eye Diseases, Refractive Errors, FUJIFILM Corporation.

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


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Source: Health & Medicine Week


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