Camera lens

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority benefit of Japanese Patent Application Ser. No. 2018-137211 filed on Jul. 20, 2018, the entire content of which is incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to the field of camera lenses, and more particularly, to a camera lens, which is constituted by eight lenses, is applicable to a mobile phone camera assembly, a WEB camera lens or the like using camera elements such as a high-pixel CCD and a CMOS, and meanwhile has an excellent optical characteristic, an ultra-thin appearance with total track length (TTL)/image height (IH)≤1.65, a wide angle with a field of view (hereinafter briefly referred to as 2ω) of 70° or more, and an F-number (hereinafter briefly referred to as Fno) of 1.45 or less.

BACKGROUND

In recent years, various types of camera devices using camera elements such as a CCD and a CMOS have been widely applied. With miniaturization and high performance-oriented development of these camera elements, the society has a stronger demand for a camera lens with excellent optical characteristics, an ultra-thin appearance, a wide-angle and a bright Fno.

A camera lens which is constituted by eight lenses and has a bright Fno is disclosed in the related art. Refractive powers of respective lenses from a 1st lens to an 8th lens are (positive, negative, positive, negative, positive, negative, negative, negative), (positive, negative, positive, negative, positive, positive, negative, negative), (positive, positive, negative, positive, negative, positive, negative, negative), or (positive, positive, negative, positive, positive, positive, negative, negative), so Fno=1.20˜1.60 which is bright, but TTL/IH>1.90 which is not ultra-thin enough.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing a configuration of a camera lens LA according to an embodiment of the present disclosure.

FIG. 2 is a diagram showing a configuration of a specific Embodiment 1 of the camera lens LA.

FIG. 3 is an axial aberration diagram of the camera lens LA according to Embodiment 1.

FIG. 4 is a magnification chromatism diagram of the camera lens LA according to the Embodiment 1.

FIG. 5 is a field curvature and distortion diagram of the camera lens LA according to Embodiment 1.

FIG. 6 is a diagram showing a configuration of a specific Embodiment 2 of the camera lens LA.

FIG. 7 is an axial aberration diagram of the camera lens LA according to Embodiment 2.

FIG. 8 is a magnification chromatism diagram of the camera lens LA according to Embodiment 2.

FIG. 9 is a field curvature and distortion diagram of the camera lens LA according to Embodiment 2.

FIG. 10 is a diagram showing a configuration of a specific Embodiment 3 of the above-described camera lens LA.

FIG. 11 is an axial aberration diagram of the camera lens LA according to Embodiment 3.

FIG. 12 is a magnification chromatism diagram of the camera lens LA according to Embodiment 3.

FIG. 13 is a field curvature and distortion diagram of the camera lens LA according to Embodiment 3.

FIG. 14 is a diagram showing a configuration of a specific Embodiment 4 of the camera lens LA.

FIG. 15 is an axial aberration diagram of the camera lens LA according to Embodiment 4.

FIG. 16 is a magnification chromatism diagram of the camera lens LA according to Embodiment 4.

FIG. 17 is a field curvature and distortion diagram of the camera lens LA according to Embodiment 4.

FIG. 18 is a diagram showing a configuration of a specific embodiment 5 of the above-described camera lens LA.

FIG. 19 is an axial aberration diagram of the camera lens LA according to Embodiment 5.

FIG. 20 is a magnification chromatism diagram of the camera lens LA according to Embodiment 5.

FIG. 21 is a field curvature and distortion diagram of the camera lens LA according to Embodiment 5.

FIG. 22 is a diagram showing a configuration of a specific embodiment 6 of the above-described camera lens LA.

FIG. 23 is an axial aberration diagram of the camera lens LA according to Embodiment 6.

FIG. 24 is a magnification chromatism diagram of the camera lens LA according to Embodiment 6.

FIG. 25 is a field curvature and distortion diagram of the camera lens LA according to Embodiment 6.

DETAILED DESCRIPTION

An embodiment of a camera lens related to the present disclosure will be described with reference to the accompanying drawings. FIG. 1 is a diagram showing a configuration of a camera lens according to an embodiment of the present disclosure. The camera lens LA is constituted by a lens group with eight lens, and a 1st lens L1, a 2nd lens L2, a 3rd lens L3, a 4th lens L4, a 5th lens L5, a 6th lens L6, a 7th lens L7 and an 8th lens L8 are configured successively from an object side to an image side. A glass flatplate GF is provided between the 8th lens L8 and an image surface. The glass flatplate GF may be a glass cover sheet or an optical filter having an IR cut-off function. Or, the glass flatplate GF may not be provided between the 8th lens L8 and the image surface.

The 1st lens L1 has a positive refractive power, the 2nd lens L2 has a negative refractive power, the 3rd lens L3 has a negative refractive power, the 4th lens L4 has a positive refractive power, the 5th lens L5 has a negative refractive power, the 6th lens L6 has a positive refractive power, the 7th lens L7 has a positive refractive power, and the 8th lens L8 has a negative refractive power. In order to better correct an aberration problem, it is most preferable to design surfaces of the eight lenses as aspherical.

The camera lens LA is a camera lens that satisfies conditional formulas (1)-(4) below:

1.00≤f1/f≤1.50 (1);
−8.00≤f2/f≤−5.00 (2);
−8.00≤f3/f≤−5.00 (3);
1.00≤R5/R6≤1.40 (4);

Where,

f: a focal length of the overall camera lens;

f1: a focal length of the 1st lens;

f2: a focal length of the 2nd lens;

f3: a focal length of the 3rd lens;

R5: a curvature radius of an object side surface of the 3rd lens;

R6: a curvature radius of an image side surface of the 3rd lens.

The conditional formula (1) specifies a positive refractive power of the 1st lens L1. Outside a range of the conditional formula (1), it is difficult to develop toward ultra-thinness and wide-angle with Fno≤1.45.

Here, it is most preferable to set a numerical range of the conditional formula (1) within a numerical range of a conditional formula (1-A) below:

1.05≤f1/f≤1.20 (1-A).

The conditional formula (2) specifies a negative refractive power of the 2nd lens L2. Outside a range of the conditional formula (2), it is difficult to correct on-axis and off-axis color, and aberration, with Fno≤1.45.

Here, it is most preferable to set a numerical range of the conditional formula (2) within a numerical range of a conditional formula (2-A) below:

−7.00≤f2/f≤−6.00 (2-A).

The conditional formula (3) specifies a negative refractive power of the 3rd lens L3. Outside a range of the conditional formula (3), it is difficult to correct on-axis and off-axis color, and aberration, with Fno≤1.45.

Here, it is most preferable to set a numerical range of the conditional formula (3) within a numerical range of a conditional formula (3-A) below:

−7.00≤f3/f≤−6.00 (3-A).

The conditional formula (4) specifies a ratio of the curvature radius of the object side surface to the curvature radius of the image side surface of the 3rd lens L3. Outside a range of the conditional formula (4), it is difficult to develop toward ultra-thinness and wide-angle with Fno≤1.45.

Here, it is most preferable to set a numerical range of the conditional formula (4) within a numerical range of a conditional formula (4-A) below:

1.20≤R5/R6≤1.35 (4-A).

The 4th lens L4 has a positive refractive power and satisfies a conditional formula (5) below:

5.00≤f4/f≤15.00 (5).

Where,