Patent Grant
9989733
The present disclosure relates to the technical field of camera lens.
The present invention relates to a camera lens composed of one piece, with excellent optical properties, small sized, with a total angle of view (hereinafter referred to as 2ω) and a wide angle over 90°, composed of one lens with a high-luminous flux (hereinafter referred to as Fno) F less than 2.40, and applied for biological feature certification such as vein certification or eye tracking identification within the wavelength range of 750 nm˜900 nm.
The traditionally used wide angled, small sized camera lens with high-luminous flux Fno is composed of the two pieces disclosed by prior Japanese Patent Publication No. 2006-337402. The lens is composed of providing a first lens with a negative refractive power, a second lens with a positive refractive power, with a view angle of 2ω=90˜110° wide angle, and relatively small distortion aberration. It's absolutely enough to be used as identification lens, but not economic in cost with 2 lens used.
Although the camera lens disclosed by the prior Japanese Patent Publication No. 2006-079059 is of low cost by using plastic lens and being composed of one piece, as an identification camera, it's imperfect to has narrow camera range as being narrow angled with a view angle of 40°˜50
The camera lens disclosed by the prior Japanese Patent Publication No. 2011-081253 is a camera lens composed of the above-mentioned 1 lens, but it's dark at a value of F in the range of 2.8˜3.2, so it's imperfect as an identification lens.
Therefore, an improved camera lens which can overcome the disadvantages mentioned above is desired.
Many aspects of the exemplary embodiments can be better understood with reference to the following drawing. The components in the drawing are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present disclosure.
The present disclosure will hereinafter be described in detail with reference to exemplary embodiments. To make the technical problems to be solved, technical solutions and beneficial effects of the present disclosure more apparent, the present disclosure is described in further detail together with the figure and the embodiments. It should be understood the specific embodiments described hereby are only to explain the disclosure, not intended to limit the disclosure.
The first lens L1 has positive refractive power. Moreover, the surface of this one lens should be designed as the aspheric shape preferably in order to correct the aberration well. Particularly by using the aspheric shape, the spherical aberration and the coma aberration can be corrected properly.
A camera lens composed of one lens is characterized in that the camera lens meets following conditions (1)˜(4):
1.70≤(R1+R2)/(R1−R2)≤1.90 (1)
0.30≤D1/f≤0.45 (2)
0.90≤Y/f≤1.00 (3)
1.50≤(Y/f)×2ω≤1.70 (4)
where,
The shape of the first lens L1 is specified in the condition (1). When the upper limit value of the condition is exceeded, the refractive power of all lenses is increased, thus not allowing proper aberration correction of the image surface curvature, coma aberration and distortion aberration, so it's not good. Conversely, when the lower limit value of the condition is exceeded, the refractive power of all the lens is decreased, thus not allowing secured view angle and proper correction of the image surface curvature, coma aberration and distortion aberration, so it's not good.
Therefore, numerical range of condition (1) should be set within the numerical range of the following condition (1-A) preferably,
1.72≤(R1+R2)/(R1−R2)≤1.85 (1-A)
The condition (2) aims to secure the limit of back focal point while seeking miniaturization. Therefore, numerical range of condition (2) should be set within the numerical range of the following condition (2-A) preferably,
0.32≤D1/f≤0.42 (2-A)
The condition (3) is specified to secure a view angle over 90°. For example, in case of 0.90>Y/f outside the scope of the condition (3), it's difficult to develop toward miniaturization and wide angle. Besides, in case of Y/f>1.00 outside the scope of the condition (3), it's beneficial for wide angle, but it turns more difficult for correction of distortion aberration, while it turns difficult for correction of all aberrations, so it's disadvantageous.
Therefore, numerical range of condition (3) should be set within the numerical range of the following condition (3-A) preferably,
0.92≤Y/f≤0.97 (3-A)
The condition (4) is specified to secure a view angle over 90°, just as same as the condition (3). Therefore, numerical range of condition (4) should be set within the numerical range of the following condition (4-A) preferably, furthermore, by establish the condition (3) and (4) simultaneously, all aberrations can be corrected while wide angle can be ensured.
1.50≤(Y/f)×2ω≤1.60 (4-A)
A camera lens composed of one lens is characterized in that the camera lens meets following condition (5):
0.50≤f/TL≤0.60 (5)
where,
The condition (5) specifies the ratio between the focal distance f of the entire lens group and the axial distance from the image side to the camera lens of the first lens L1. In case of that outside the scope of the condition (5), it's difficult to develop toward miniaturization and wide angle.
Therefore, numerical range of condition (5) should be set within the numerical range of the following condition (5-A) preferably,
0.50≤f/TL≤0.575 (5-A)
A camera lens composed of one lens is characterized in that the first lens has positive refractive power and the camera lens meets following conditions (6), (7):
1.35≤BF/f≤1.45 (6)
1.53≤nd1≤1.60 (7)
where,
The condition (6) specifies the ratio between the back focal point BF and the focal distance f of the entire lens group. In case of that outside the condition (6), it's difficult to ensure the space provided for protective glass for protection of camera surface.
Therefore, numerical range of condition (6) shall be set within the numerical range of the following condition (6-A) preferably,
1.38≤BF/f≤1.45 (6-A)
The refractive power of the first lens L1 is specified in the condition (7). When it's below the lower limit value of the condition, the refractive power of all the lens will be decreased and the optical length is increased, so it's disadvantageous. On another side, when it's over the upper limit value of the condition, it turns to be difficult for correction of the distortion aberration, so it's disadvantageous.
As the one lens composing the camera lens LA has the aforementioned constitution and meets all the condition, so it becomes possible to manufacture a camera lens with excellent optical properties, small sized, with a wide angle of 2ω≤90° and applied for biological feature certification such as vein certification or eye tracking identification within the wavelength range of 750 nm˜900 nm.
The camera lens LA of the invention shall be explained below by using the embodiments. Moreover, the symbols used in all embodiments are shown as follows. And mm shall be taken as the unit of the distance, the radius and the center thickness.
For convenience sake, the aspheric surface shown in the formula (8) shall be taken as the aspheric surfaces of all lens' surfaces. However, the invention shall not be limited to polynomial form of the aspheric surface shown in the formula (8).
The configuration structure diagram of the camera lens LA in the Embodiment 1 is shown in the
The values in the embodiments 1, 2 and 3 the values corresponding to the parameters specified in the conditions (1)-(6) are shown in the subsequent Table 7. The designed wavelength of the embodiments 1, 2, 3 is 850 nm.
The Embodiment 1 meets the conditions (1)-(6), as shown in Table 7.
Spherical aberration of camera lens LA in embodiment 1 is shown in
The configuration structure diagram of the camera lens LA in the Embodiment 2 is shown in the
The Embodiment 2 meets the conditions (1)-(6), as shown in
Table 7.
Spherical aberration of camera lens LA in embodiment 2 is shown in
The configuration structure diagram of the camera lens LA in the Embodiment 3 is shown in the
The Embodiment 3 meets the conditions (1)-(6), as shown in Table 7.
Spherical aberration of camera lens LA in embodiment 3 is shown in
The values in all embodiments and the values corresponding to the parameters specified in the conditional formulas (1)-(6) are shown in the Table 7. Besides, the units shown in table 5 respectively are 2ω(°), f(mm), TL(mm), BF(mm), Y(mm).
It is to be understood, however, that even though numerous characteristics and advantages of the present exemplary embodiments have been set forth in the foregoing description, together with details of the structures and functions of the embodiments, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms where the appended claims are expressed.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2016-216598 | Nov 2016 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 5677798 | Hirano et al. | Oct 1997 | A |
| 6671105 | Saito | Dec 2003 | B2 |
| 20090153983 | Nakanishi et al. | Jun 2009 | A1 |
| 20090207508 | Shinohara | Aug 2009 | A1 |
| 20120224268 | Takato | Sep 2012 | A1 |
| 20140104707 | Nakamura et al. | Apr 2014 | A1 |
| Number | Date | Country | |
|---|---|---|---|
| 20180129019 A1 | May 2018 | US |
