IMAGE LENS AND CAMERA MODULE WITH IT

Description

[Technical Field]

[0001] The invention relates to an imaging lens and a camera module.[Background Art]

[0002] US 2005 / 0018313 A1 discloses a imaging lens according to the preamble of claim 1. Conventional film cameras have been replaced by a camera module for mobile phones using a small-sized solid-state imaging element, such as a CCD or a CMOS, a digital still camera (DSC), a camcorder, a PC camera (an imaging device attached to a personal computer), etc., and these imaging devices are being developed with the goal of miniaturization and slimming.

[0003] In order to satisfy this trend, miniaturization of light receiving elements, such as a charge coupled device (CCD), mounted in small-sized solid-state imaging devices is underway, and the part of an imaging device which occupies the largest volume is an imaging lens part.

[0004] Therefore, the element of the imaging device, which is the key issue in terms of miniaturization and slimming, is an imaging lens which forms an image of an object.

[0005] Here, the imaging lens requires not only a small size but also high performance in response to the high performance of the light receiving elements. However, a zoom lens, in which distances between lenses are variable, is widely used as the miniaturized imaging lens in order to implement high performance.

[0006] The conventional imaging lens, particularly the zoom lens, may be excessively thick and thus not have a small size, and may be less sensitive at a high resolution and thus not implement high performance. US 2010 / 0226018 A1 discloses a zoom optical system, which comprises a prism component which comprises in order from an object side, an entrance surface having negative refracting power, and a reflecting surface, and movable groups which are movable when either of zooming or focusing is carried out. US 2004 / 0130647 A1 relates to a zoom optical system whose optical axis is bent, and in particular, to a path bending zoom optical system in which a path-bending prism is placed in order to achieve a slim design. JP 2007 072291 A relates to a zoom lens, and particularly to a zoom lens suitable as a photographing lens for a compact digital still camera.[Disclosure][Technical Problem]

[0007] Embodiments provide an imaging lens including a subminiature zoom lens having a small thickness.

[0008] Embodiments provides an image lens, the sensitivity of which is not deteriorated even at a high resolution, so as to implement high performance.[Technical Solution]

[0009] The invention is as defined in claim 1.

[0010] At least one second lens of the second lens group may have an object surface configured to be convex towards the object side and an image surface configured to be convex towards the image side.

[0011] The second lens group may include two lenses, and the third lens group may include four lenses.

[0012] The EFLs of the image lens may be within a range of 8.6 mm to 16.5 mm.

[0013] In another embodiment, a camera module includes the above-described imaging lens; a filter configured to selectively transmit light having passed through the imaging lens depending on a wavelength of the light; a light receiving element configured to receive light having passed through the filter.

[0014] A maximum aperture of lenses forming the first to third lens groups may be 0.2 to 0.3 times the TTL.

[0015] The maximum aperture of the lenses may be 5 mm or less.[Advantageous Effects]

[0016] An imaging lens having a zoom function according to one embodiment may be implemented as a subminiature zoom lens having a small thickness.

[0017] Further, the sensitivity of the imaging lens is not deteriorated even at a high resolution, and thus the imaging lens may implement high performance.[Description of Drawings]

[0018] FIGs. 1a and 1b are views illustrating an imaging lens according to an embodiment of the invention, FIG. 2a illustrates graphs showing aberrations of the imaging lens according to the embodiment in a wide mode, FIG. 2b illustrates graphs showing aberrations of the imaging lens according to the embodiment in a middle mode, and FIG. 2c illustrates graphs showing aberrations of the imaging lens according to the embodiment in a tele mode, FIGs. 3a and 3b are views illustrating an imaging lens according to a first illustrative example that is not part of the claimed invention, FIG. 4a illustrates graphs showing aberrations of the imaging lens according to the first illustrative example that is not part of the claimed invention, in a wide mode, FIG. 4b illustrates graphs showing aberrations of the imaging lens according to the first illustrative example in a middle mode, and FIG. 4c illustrates graphs showing aberrations of the imaging lens according to the first illustrative example in a tele mode, FIGs. 5a and 5b are views illustrating an imaging lens according to a second illustrative example that is not part of the claimed invention,, and FIG. 6a illustrates graphs showing aberrations of the imaging lens according to the second illustrative example in a wide mode, and FIG. 6b illustrates graphs showing aberrations of the imaging lens according to the second illustrative example in a tele mode. [Best Mode]

[0019] Hereinafter, an embodiment of the invention and two illustrative examples that are not part of the claimed invention will be described with reference to the annexed drawings and description.

[0020] In the following description, it will be understood that an 'object surface' means the surface of a lens facing an object side based on an optical axis, and an 'image surface' means the surface of the lens facing an image side based on the optical axis.

[0021] Further, it will be understood that "+ power" of a lens indicates a convergent lens which converges parallel light, and "- power" of a lens indicates a divergent lens which diverges parallel light.

[0022] An imaging lens according to the embodiment includes first to third lens groups arranged sequentially from an object side to an image side and having refractive power, and the first to third lens groups may be formed of plastic. The total magnification of the imaging lens is no more than 2.5 times, and particularly, a ratio of tele EFL / wide EFL may be no more than 2.5, and tele EFL and wide EFL are equivalent focal lengths (EFLs) of the imaging lens in a tele mode and a wide mode. Further, in the imaging lens, 2<F Number <5 and 15 mm<TTL≤40 mm is satisfied. That is, the distances to the second lens group and the third lens group from the first lens group are variable such that a tele mode having a narrow angle of view and a wide mode having a wide angle of view can be implemented, and the EFL in the tele mode is no more than 2.5 times the EFL in the wide mode.

[0023] Among the first to third lens groups, the first lens group is formed of a prism, has a thickness of 3 mm or more, and is stationary. Since the thickness of the first lens group is 3 mm or more, light is focused and thus secures resolution. Further, second and third lens groups can move in the direction of an optical axis.

[0024] Further, in order to reduce the total volume of the imaging lens, the maximum aperture of the first to third lens groups is defined as T, and T may be 5 mm or less. In addition, a ratio of T to TTL (T / TTL) may be 0.2 to 0.3, for example, 0.25. Here, when T is excessively small, a quantity of light is decreased and the resolution of the imaging lens may be lowered, and when TTL is excessively lengthened, a quantity of necessary light is increased and the resolution of the imaging lens may be lowered.

[0025] EFLs of imaging lenses according to the embodiment and the first illustrative example, which will be described below, may be 9.94 to 16.5, that is, tele EFLs may be 16.5 and wide EFLs may be 9.94.

[0026] Further, EFLs of an imaging lens according to a second illustrative example that is not part of the claimed invention and which will be described below, may be 8.6 to 12.8, that is, a tele EFL may be 12.9 and a wide EFL may be 8.6.

[0027] FIGs. 1a and 1b are views illustrating the imaging lens according to the embodiment.

[0028] The imaging lens according to this embodiment includes first to third lens groups G1-G3, a filter 180 and a light receiving element 190, which are arranged sequentially from an object side to an image side so as to form the imaging lens in a camera module.

[0029] The first lens group G1 includes a first lens 110, the second lens group G2 includes a second lens 120 and a third lens 130, and the third lens group G3 includes fourth to seventh lenses 140-170. At least one of object surfaces and image surfaces of the above-described first lens 110 to seventh lens 170 may be an aspherical surface, and when an aspherical surface is formed as at least one surface of the lenses, correction of various aberrations, such as spherical aberration, coma aberration and distortion, may be excellent.

[0030] Table 1 shows EFLs, etc. of the imaging lens according to the embodiment in a wide mode, a middle mode and a tele mode. [Table 1]WideMiddleTeleEFL9. 941116.5BFL0.65211.566.1179FFL-14.1764-15.6106-24.5528F Number 2.51932.78144.125

[0031] A stop is arranged between the first lens group G1 and the second lens group G2, and the position of the stop is stationary, for example, the stop may be provided on the rear surface of the first lens group G1. The filter 180 may be a plate-shaped optical member, such as an infrared ray filter or the like, the cover glass 190 may be a cover glass for protecting an optical member, for example, an imaging surface, and the light receiving element may be an image sensor stacked on a printed circuit board (not shown). The light emitting element may be the image sensor, and horizontal and / or vertical lengths of a unit pixel of the image sensor may be 2 µm (micrometer) or less. The above-described embodiment and illustrative examples, which will be described below, may provide imaging lenses which may be applied to a camera module having high pixels and / or a large number of pixels, the above camera module may have an image sensor or light receiving element having high pixels and / or a large number of pixels, and in this case, horizontal and / or vertical lengths of a unit pixel thereof may be 2 µm or less.

[0032] 'S11' is an object surface of the first lens 110, 'S12' is an image surface of the first lens 110, 'S21' is an object surface of the second lens 120, 'S22' is an image surface of the second lens 120, 'S31' is an object surface of the second lens 120, 'S32' is an image surface of the third lens 130, 'S41' is an object surface of the fourth lens 140, 'S42' is an image surface of the fourth lens 140, 'S51' is an object surface of the fifth lens 150, 'S52' is an image surface of the fifth lens 150, 'S61' is an object surface of the sixth lens 160, 'S62' is an image surface of the sixth lens 160, 'S71' is an object surface of the seventh lens 170, and 'S72' is an image surface of the seventh lens 170.

[0033] Table 2 shows radiuses of curvature, etc. of the image surfaces and the object surfaces of the first lens 110 to the seventh lens 170 of the imaging lens according to the embodiment. Here, a radius of curvature of infinity indicates a flat surface, a - sign indicates a surface which is convex towards the image side, no sign, i.e., a + value, indicates a surface which is convex towards the object side, and these are the same in illustrative examples which will be described below. [Table 2]Radius of curvature (mm)Thickness (mm)Refractive indexAbbe's numberS11-83.507464.751.5544256S12InfinityAS2115.224161.5985911.5544256S22-5.338880.100157S31-8.054920.657511.66120.4S32-11.577970.100277+BS416.920151.9998111.5544256S4251.680150.192691S51-7.2295821.66120.4S52-60.274910.829393S61-3.853560.31.5544256S624.760380.101489S712.668950.6399611.66120.4S725.072070.15318S81Infinity0.21S82InfinityC-DS91Infinity

[0034] Here, A to D are variable, and may have values given in Table 3 below. [Table 3]ABCDWide2.4933331093.0330148030.6521345530.037865415Middle2.3036045722.3114302551.5600145010.031298517Tele0.1081888440.16.117872231-0.099701394

[0035] Table 3 shows changes in the values of A to D of the image lens according to the embodiment in the wide mode, the middle mode and the tele mode. That is, the value of A may be changed as the distance between the first lens group G1 and the second lens group G2 is changed, and the value of B may be changed as the distance between the second lens group G2 and the third lens group G3 is changed. FIG. 2a illustrates graphs showing aberrations of the imaging lens according to the embodiment in the wide mode, FIG. 2b illustrates graphs showing aberrations of the imaging lens according to the embodiment in the middle mode, and FIG. 2c illustrates graphs showing aberrations of the imaging lens according to the embodiment in the tele mode. In the respective figures, graphs showing longitudinal spherical aberration, astigmatic field curves, and distortion are illustrated sequentially from the left, the Y-axis means the sizes of images, the X-axis means focal distances (in mm) and degrees of distortion (in %), and as curves approach the Y-axis, an aberration correcting function may be improved.

[0036] FIGs. 3a and 3b are views illustrating an imaging lens according to a first illustrative example that is not part of the claimed invention. A detailed description of some parts in this embodiment, which are substantially the same as those in the above-described embodiment, is omitted because it is considered to be unnecessary.

[0037] The imaging lens according to this embodiment includes first to third lens groups G1-G3, a filter 180 and a light receiving element 190, which are arranged sequentially from an object side to an image side so as to form the imaging lens in a camera module.

[0038] The first lens group G1 may include a first lens 110, the second lens group G2 may include a second lens 120, and the third lens group G3 may include third to fifth lenses 130-150.

[0039] Table 4 shows EFLs, etc. of the imaging lens according to the first illustrative example in a wide mode, a middle mode and a tele mode. [Table 4]WideMiddleTeleEFL9. 941116.5BFL0.591.25954.9831FFL-21.0035-22.7093-31.9802F Number 2.4852.754.125

[0040] A stop may be arranged on the front surface, for example, an object surface, of the first lens group G1. Table 5 shows radiuses of curvature, etc. of the image surfaces and the object surfaces of the first lens 110 to the fifth lens 150 of the imaging lens according to the first illustrative example. [Table 5]Radius of curvature (mm)Thickness (mm)Refractive indexAbbe's numberS1129.490374.751.565333.93S12InfinityAS2120.218181.6627281.49151S22-7.510160.1+BS313.914121.2531451.49151S32-110.268450.170351S41-5.405551.9996671.66120.4S42-336.870251.280838S51-2.311640.31.4993947.92S52135.934220.1S81Infinity0.21S82InfinityC-DS91Infinity

[0041] Here, A to D are variable, and may have values given in Table 6 below. [Table 6]ABCDWide1. 6286175192.75447470.5899939630.1Middle1.5945866162.11972231.2594742360.089300774Tele0.10.14.983063739-0.1

[0042] Table 6 shows changes in the values of A to D of the image lens according to the first illustrative example in the wide mode, the middle mode and the tele mode. That is, the value of A may be changed as the distance between the first lens group G1 and the second lens group G2 is changed, and the value of B may be changed as the distance between the second lens group G2 and the third lens group G3 is changed. FIG. 4a illustrates graphs showing aberrations of the imaging lens according to the first illustrative example in the wide mode, FIG. 4b illustrates graphs showing aberrations of the imaging lens according to the first illustrative example in the middle mode, and FIG. 4c illustrates graphs showing aberrations of the imaging lens according to the first illustrative example in the tele mode.

[0043] FIGs. 5a and 5b are views illustrating an imaging lens according to a second illustrative example. A detailed description of some parts in this illustrative example, which are substantially the same as those in the above-described first and second embodiments, is omitted because it is considered to be unnecessary.

[0044] The imaging lens according to this illustrative example includes first to third lens groups G1-G3, a filter 180 and a light receiving element 190, which are arranged sequentially from an object side to an image side so as to form the imaging lens in a camera module.

[0045] The first lens group G1 includes a first lens 110, the second lens group G2 includes a second lens 120, and the third lens group G3 includes third to fifth lenses 130-150. Further, the first lenses 110 in the embodiment and the first illustrative example that is not part of the claimed invention, is a prism.

[0046] Table 7 shows EFLs, etc. of the imaging lens according to the second illustrative example that is not part of the claimed invention in a wide mode and a tele mode. [Table 7]WideTeleEFL8.612.8BFL0.59583.3328FFL-11.0385-20.9963F Number 2.153.2

[0047] A stop may be arranged between the first lens group G1 and the second lens group G2. Table 8 shows radiuses of curvature, etc. of the image surfaces and the object surfaces of the first lens 110 to the fifth lens 150 of the imaging lens according to the second illustrative example. [Table 8]Radius of curvature (mm)Thickness (mm)Refractive indexAbbe's numberS115.7520131.66120.4S12InfinityAS213.54611.4980931.5544256S22-4.885BS31-7.8135831.66120.4S3239.505510.137165S41-11.894540.5678181.66120.4S42-3.910530.063993S51-2.556160.7734651.5544256S52134.424180.1S81Infinity0.21S82InfinityC-DS91Infinity

[0048] Here, A to D are variable, and may have values given in Table 9 below. [Table 9]ABCDWide2.0728670670.8123898880.595820535-0.005852723Tele0.10.1000195253.332786668-0.047616293

[0049] Table 9 shows changes in the values of A to D of the image lens according to the second illustrative example in the wide mode and the tele mode. That is, the value of A may be changed as the distance between the first lens group G1 and the second lens group G2 is changed, and the value of B may be changed as the distance between the second lens group G2 and the third lens group G3 is changed. FIG. 6a illustrates graphs showing aberrations of the imaging lens according to the second illustrative example in the wide mode, and FIG. 6b illustrates graphs showing aberrations of the imaging lens according to the second illustrative example in the tele mode.

[0050] The camera module including the above-described imaging lens may be installed in various digital devices, such as a digital camera, a smart phone, a notebook, a tablet PC, etc., and particularly, be installed in a mobile device so as to implement a high-performance and ultra-thin zoom lens.

[0051] Various variations and modifications are possible in the component parts and / or arrangements of the subject combination arrangement within the scope of the claims.[Mode for Invention]

[0052] Modes for carrying out the disclosure have been described in the best mode for carrying out the disclosure.[Industrial Applicability]

[0053] An imaging lens according to embodiments is usable in a camera module and a digital device.

Claims

1. An imaging lens comprising first to third lens groups (G1-G3) arranged sequentially from an object side to an image side and having refractive power, wherein: a first lens (110) is the only lens of the first lens group (G1) and has an object side configured to be concave towards the object and has a negative refractive power, wherein the first lens group (G1) is formed of a prism and is stationary, and has a thickness of 3 mm or more, distances to the second lens group (G2) and the third lens group (G3) from the first lens group (G1) are variable such that the imaging lens has a tele mode having a narrow angle of view and a wide mode having a wide angle of view; and an equivalent focal length EFL of the imaging lens in a tele mode is no more than 2.5 times an EFL in a wide mode, 2<Fnumber<5, a maximum distance between the first lens group (G1) and an image of the imaging lens on an optical axis, as defined as a TTL, is more than 15 mm and is no more than 40 mm, characterized in that a stop is disposed between the first lens group (G1) and the second lens group (G2), and a position of the stop is stationary.

2. The imaging lens according to claim 1, wherein a second lens of the second lens group (G2) has an object surface configured to be convex towards the object side and an image surface configured to be convex towards the image side.

3. The imaging lens according to claim 1, wherein the second lens group (G2) comprises two lenses (120, 130), and the third lens group (G3) comprises four lenses (140, 150, 160, 170).

4. The imaging lens according to claim 1, wherein the second lens group (G2) comprises one lens (120), and the third lens group (G3) comprises three lenses (130, 140, 150).

5. The imaging lens according to claim 1, wherein the EFLs of the imaging lens are within a range of 8.6 mm to 16.5 mm.

6. The imaging lens according to claim 1, wherein a total magnification of the imaging lens is no more than 2.5 times.

7. The imaging lens according to claim 1, wherein an image side of the first lens (110) of the first lens group (G1) is flat.

8. The imaging lens according to claim 1, wherein a third lens (130) of the second lens group (G2) has an object side configured to be convex towards the image and an image side configured to be convex towards the image.

9. A camera module comprising: the imaging lens according to any one of claims 1 to 8; a filter (180) configured to selectively transmit light having passed through the imaging lens depending on a wavelength of the light; and a light receiving element (190) configured to receive light having passed through the filter (180).

10. The camera module according to claim 9, wherein a maximum aperture of lenses forming the first to third lens groups (G1-G3) is 0.2 to 0.3 times the TTL.

11. The camera module according to claim 10, wherein the maximum aperture of the lenses is 5 mm or less.