CN101135767A - Sampling image lens - Google Patents

Abstract

From objet side to the imaging side, the lens group comprises a first lens having positive refraction force, a second lens having negative force and a third lens having negative diopter. The first lens is a new moon shape lens with a convex surface facing to the object side; the second lens is a new moon shape lens with a convex surface facing to the imaging side. At least one of the first, second and third lenses have an aspheric surface; an aperture is located between the second les and the object. The lens group thereof must satisfies the following conditions: V1 is the abbe number of the first lens to the d light; V2 is the abbe number of the second lens to d light; V3 is the abbe number of third lens to d light; the wavelength of the d light is 587.5618nm.

Description

Sampling image lens

Technical field

The present invention relates to a kind of sampling image lens, particularly about a kind of camera head and lightweight sampling image lens of being applied to.

Background technology

In recent years, mobile phone, portable digital-assistant (PDA) and notebook computer have been equipped with the camera lens module that can make a video recording mostly.This camera lens module wants cube little, in light weight mostly, and because image sensing unit in the past, as CCD or CM0S, resolution quite low, therefore existing camera lens module has only one piece of eyeglass to two piece eyeglass mostly.

Nowadays, along with the manufacture of semiconductor development of technology, make the image sensing unit of using for mobile phone, portable digital-assistant and notebook computer be promoted to mega pixel gradually; But the eyeglass number of camera lens then can't provide preferable image quality as very little.Therefore, how to use minimum eyeglass quantity that high-resolution imaging is provided, just become a technical barrier.The present invention is intended to overcome this difficult problem.

Summary of the invention

The object of the present invention is to provide a kind of sampling image lens of legerity type, this sampling image lens only uses three pieces of lens to reduce its length and weight; Simultaneously, can revise optical aberration to obtain splendid image.

For achieving the above object, the invention provides a kind of sampling image lens, comprise first lens of positive refractive index, second lens of positive refractive index and the 3rd lens of negative refractive index from the thing end to the imaging end successively.First lens are that meniscus lens and its convex surface are towards the thing end; Second lens are that meniscus lens and its convex surface are held towards picture.Above-mentioned first, second and the 3rd lens all have an aspheric surface at least; And aperture is between second lens and thing end.

As mentioned above, sampling image lens of the present invention need meet the following conditions: $0.85\&le;\frac{v1}{\mathrm{<figure-callout\; id="2"\; label="v"\; filenames="A20061012916000151.png"\; state="\{\{state\}\}">v</figure-callout>}2}\&le;1.15$ $0.85\&le;\frac{v2}{v3}\&le;1.25$

Wherein, v1 is the Abbe numbers (abbe number) of first lens to d light, and v2 is the Abbe numbers of second lens to d light, and v3 is the Abbe numbers of the 3rd lens to d light, and the wavelength of d light is 587.5618nm.

As mentioned above, the refractive index at the paraxial place of the 3rd lens of sampling image lens of the present invention for the refractive index of negative and edge for just, and the concave surface of close imaging surface is recessed to the thing end.

Preferably, aperture is between first lens and second lens.

Compared with prior art, the invention has the advantages that: only use three pieces of lens, make sampling image lens of the present invention have advantage in light weight and that length is short.Preferably, first, second and the 3rd lens all make made of plastic.

The present invention is further illustrated below in conjunction with accompanying drawing and embodiment.

Description of drawings

Fig. 1 summary has shown the sampling image lens of first embodiment of the invention.

Fig. 2 A shows the sampling image lens of first embodiment of the invention, at the modulus (Modulus) of the optical transfer function (OTF) of unit space frequency change.

Fig. 2 B shows the sampling image lens of first embodiment of the invention, the TOLERANCE ANALYSIS result of the mtf value of its full visual field when 901p/mm.

Fig. 3 summary has shown the sampling image lens of second embodiment of the invention.

Fig. 4 A shows the sampling image lens of second embodiment of the invention, at the modulus (Modulus) of the optical transfer function (OTF) of unit space frequency change.

Fig. 4 B shows the sampling image lens of second embodiment of the invention, the TOLERANCE ANALYSIS result of the mtf value of its full visual field when 901p/mm.

Embodiment

Relevant detailed description of the present invention and technology contents, existing as follows with regard to accompanying drawings:

Sampling image lens of the present invention can be applied to image capture unit, is used for object is imaged in Image Sensor, as charge coupled cell (Charge Coupled Device is called for short CCD) or complementary metal oxide semiconductor (CMOS).This sampling image lens comprises first lens with positive refractive index, the 3rd lens that have second lens of positive refractive index and have negative refractive index successively from the thing end to the imaging end.First lens are the meniscus lens, and its convex surface is towards the thing end; Second lens also are the meniscus lens, and its convex surface is towards the picture end.

Sampling image lens of the present invention comprises first positive lens, second positive lens and the 3rd negative lens successively from the thing end to the imaging end; The 3rd negative lens for negative refractive index, is positive refractive index in edge at paraxial place.Preferably, the concave surface of the contiguous picture end of the 3rd negative lens is recessed to the thing end.

In the sampling image lens of the present invention, aperture diaphragm is between second lens and thing end.Preferably, aperture diaphragm is between first lens and second lens.

Sampling image lens of the present invention must meet the following conditions: $0.85\&le;\frac{v1}{\mathrm{<figure-callout\; id="2"\; label="v"\; filenames="A20061012916000151.png"\; state="\{\{state\}\}">v</figure-callout>}2}\&le;1.15......\left(1\right)$ $0.85\&le;\frac{v2}{\mathrm{<figure-callout\; id="3"\; label="v"\; filenames="A20061012916000151.png"\; state="\{\{state\}\}">v</figure-callout>}3}\&le;1.25......\left(2\right)$

Wherein, v1 is the Abbe numbers (abbe number) of first lens to d light, and v2 is the Abbe numbers of second lens to d light, and v3 is the Abbe numbers of the 3rd lens to d light, and the wavelength of d light is 587.5618nm.Preferably, first, second and the 3rd lens are all made with plastics.

In the sampling image lens of the present invention, first, second and the 3rd lens all have at least one non-spherical surface.Preferably, the surface of the contiguous picture end of the 3rd lens is an aspheric surface structure.

Sampling image lens of the present invention only has first, second, third lens, has the short advantage of in light weight, low cost and lens length.

Fig. 1 is first embodiment of sampling image lens of the present invention.This sampling image lens comprises the first lens G1 of positive refractive index, the second lens G2 of positive refractive index and the 3rd lens G3 of negative refractive index successively from thing end OBJ to imaging end IMA.System's focal length of this sampling image lens is f=2.8mm, and Fno.=4.43.

The first lens G1 is meniscus lens, and the Surface L 1 of adjacent near the object end OBJ is protruded towards thing end OBJ; And its thing end surfaces L1 and be aspheric surface as end surfaces L2.The first lens G1 is 56 to Abbe numerical value (abbe number) v1 of d light, and wherein the wavelength of d light is 587.5618nm.

The second lens G2 is meniscus lens, and the Surface L 4 of contiguous picture end IMA is protruded towards picture end IMA; And its thing end surfaces L3 and be aspheric surface as end surfaces L4.The second lens G2 is 56 to the Abbe numerical value v2 of d light, and wherein the wavelength of d light is 587.5618nm.

The 3rd lens G3 is a negative lens, and contiguous optical axis place has negative refractive index and the neighboring edge place has positive refractive index.The Surface L 6 of the contiguous picture end of the 3rd lens G3 IMA is protruded towards thing end OBJ; And its thing end surfaces L5 and be aspheric surface as end surfaces L6.The 3rd lens G3 is 56 to the Abbe numerical value v3 of d light, and wherein the wavelength of d light is 587.5618nm.

In the first embodiment of the present invention, the parameters of first, second of sampling image lens and the 3rd lens is listed in the table 1 successively:

Table 1
					The focal length f=2.8mm of system; Fno.=4.43
The surface sequence number	Radius-of-curvature (mm)	Thickness (mm)	Refractive index (Nd)	Abbe coefficient (vd)
					L1	1.593	1.00	1.525	56
L2	3.145	0.19	1.000
					STO.	Infinity	0.84	1.000
L3	-1.144	1.07	1.525	56
					L4	-1.126	0.05	1.000
L5	3.959	0.79	1.525	56
					L6	2.979	0.80	1.000
P7	Infinity	0.80	1.5168	64.17
					P8	Infinity	0.71	1.000

In addition, in the embodiments of the invention, lens surface sequence number L5, the L6 of lens surface sequence number L1, the L2 of the first lens G1, lens surface sequence number L3, the L4 of the second lens G2 and the 3rd lens G3 are aspheric surface, and its aspheric correlation values is listed in table 2 successively:

Table 2
					The surface sequence number	K	E4	E6	E8
L1	-0.316606	0.0211578	0.0115944	-0.00519998
					L2	4.314233	-0.00454571	0.250795	-0.93661
L3	-0.32273	-0.0779431	-0.479243	0.457364
					L4	-0.708159	0.001049	-0.0930141	0.136729
L5	-0.287817	-0.08365	0.0239588	-0.00121568
					L6	-1.747252	-0.100458	0.0278774	-0.0058658

Table 2
					The surface sequence number	E10	E12	E14	E16
L1	0.0303318	-0.0470834	0.0369086	-0.01012
					L2	1.60071	-0.621181	-0.695896	0.0257509
L3	0.457364	0.58652	-0.908866	0.28028
					L4	-0.101186	0.0132277	0.0198597	-0.00642623
L5	-0.000623994	0.000109251	-3.10646E-06	-5.07824E-07
					L6	0.000738036	-2.60573E-06	-9.18641E-06	4.762E-07

According to table 1,, can obtain v1/v2=1, v2/v3=1, eligible really (1) and condition (2) with the Abbe numerical value of the Abbe numerical value v2 of Abbe numerical value v1, the 2nd lens G2 of the 1st lens G1 and the 3rd lens G3 substitution v1/v2 and v2/v3 respectively.

Fig. 2 A shows the sampling image lens of first embodiment of the invention, at the modulus (Modulus) of the optical transfer function (OTF) of unit space frequency change.Fig. 2 B shows the sampling image lens of first embodiment of the invention, and the mtf value of its full visual field is when 901p/mm, and the probability greater than 0.2 after TOLERANCE ANALYSIS surpasses 60%.

Fig. 3 is second embodiment of sampling image lens of the present invention.This sampling image lens comprises the first lens G1 ' of positive refractive index, the second lens G2 ' of positive refractive index and the 3rd lens G3 ' of negative refractive index successively from thing end OBJ to imaging end IMA.System's focal length of this sampling image lens is f=2.8 mm, and Fno.=4.43.

The first lens G1 ' is meniscus lens, and the Surface L 1 of adjacent near the object end OBJ is protruded towards thing end OBJ; And its thing end surfaces L1 and be aspheric surface as end surfaces L2.The first lens G1 ' is 70 to Abbe numerical value (abbe number) v1 of d light, and wherein the wavelength of d light is 587.5618nm.

The second lens G2 ' is meniscus lens, and the Surface L 4 of contiguous picture end IMA is protruded towards picture end IMA; And its thing end surfaces L3 and be aspheric surface as end surfaces L4.The second lens G2 ' is 70 to the Abbe numerical value v2 of d light, and wherein the wavelength of d light is 587.5618nm.

The 3rd lens G3 ' is a negative lens, and contiguous optical axis place has negative refractive index and the neighboring edge place has positive refractive index.The Surface L 6 of the contiguous picture end of the 3rd lens G3 ' IMA is protruded towards thing end OBJ; And its thing end surfaces L5 and be aspheric surface as end surfaces L6.The 3rd lens G3 ' is 56 to the Abbe numerical value v3 of d light, and wherein the wavelength of d light is 587.5618nm.

In the second embodiment of the present invention, the parameters of first, second of sampling image lens and the 3rd lens is listed in the table 3 successively:

Table 3
					The focal length f=2.8mm of system; Fno.=4.43
The surface sequence number	Radius-of-curvature (mm)	Thickness (mm)	Refractive index (Nd)	Abbe coefficient (Vd)
					L1	1.864	1.39	1.54	70
L2	3.452	0.11	1.000
					STO.	Infinity	0.84	1.000
L3	-1.656	1.33	1.5015	70
					L4	-0.837	0.05	1.000
L5	3.7241	0.5	1.525	56
					L6	1.095	0.80	1.000
P7	Infinitv	0.80	1.5168	64.17
					P8	Infinitv	0.60	1.000

In addition, in the embodiments of the invention, lens surface sequence number L5, the L6 of lens surface sequence number L1, the L2 of the first lens G1 ', lens surface sequence number L3, the L4 of the second lens G2 ' and the 3rd lens G3 ' are aspheric surface, and its aspheric correlation values is listed in table 4 successively:

Table 4
					The surface sequence number	K	E4	E6	E8
L1	-0.580231	0.0228818	-0.00839148	0.000819163
					L2	5.742227	0.00103754	0.230143	-1.52144
L3	-3.265107	-0.187364	-0.0444653	-0.499144
					L4	-2.302380	-0.0413259	-0.141386	0.157312
L5	-2.225?99	-0.0884449	0.0369153	-0.00487975
					L6	-6.753998	-0.0686475	0.0265519	-0.00638302

Table 4
					The surface sequence number	E10	E12	E14	E16
L1	0.0383694	-0.051821	0.027889	-0.00542557
					L2	4.20072	-3.85756	-0.790565	0.214415
L3	0.717434	0.397411	-1.68285	0.898962
					L4	-0.0851881	0.00225215	0.0180014	-0.00581729
L5	-0.000313012	-9.38789E-05	9.06596E-05	-1.31912E-05
					L6	0.000801524	-1.81967E-05	-8.78242E-06	3.95783E-07

According to table 3, with the Abbe numerical value of the Abbe numerical value v2 of Abbe numerical value v1, the 2nd lens G2 ' of the 1st lens G1 ' and the 3rd lens G3 ' substitution v1/v2 and v2/v3 respectively, can obtain v1/v2=1, v2/v3=1.25, eligible really (1) and condition (2).

Fig. 4 A shows the sampling image lens of second embodiment of the invention, at the modulus (Modulus) of the optical transfer function (OTF) of unit space frequency change.Fig. 4 B shows the sampling image lens of second embodiment of the invention, and the mtf value of its full visual field is when 901p/mm, and the probability greater than 0.2 after TOLERANCE ANALYSIS is lower than 40%.

As known from the above, the sampling image lens of the embodiment of the invention has splendid image quality; Though first lens, second lens and the 3rd lens all use the lens of plastics ejection formation, be not subjected to temperature variation and image quality is worsened.

With reference to figure 1, Fig. 3 and table 1, table 3, the aperture diaphragm STO of sampling image lens of the present invention is between the first lens G1 and the second lens G2.

Compared with prior art, the present invention has only used three pieces of lens when guaranteeing splendid image quality, so that sampling image lens of the present invention has advantage lightweight and that length is short. Preferably, first, second and the 3rd lens all make made of plastic.

Claims (7)

1. sampling image lens comprises on optical axis from the thing end to the imaging end it is characterized in that first lens, second lens and the 3rd lens successively:

These first lens are positive refractive index and have the meniscus shape that its thing end surfaces protrudes towards the thing end;

These second lens are positive refractive index and have the meniscus shape that it protrudes towards the imaging end as end surfaces; And

The 3rd lens are an aspheric surface for negative refractive index and as end surfaces;

Wherein, this sampling image lens meets the following conditions:

$0.85\&le;\frac{v1}{v2}\&le;1.15$

$0.85\&le;\frac{v2}{v3}\&le;1.25$

Wherein, ν 1 is the Abbe numerical value (abbe number) of first lens to d light, and ν 2 is the Abbe numerical value of second lens to d light, and ν 3 is the Abbe numerical value of the 3rd lens to d light, and the wavelength of d light is 587.5618nm.

2. sampling image lens as claimed in claim 1, the refractive index that it is characterized in that the contiguous optical axis of the 3rd lens be for negative, and the refractive index of the 3rd rims of the lens is for just.

3. sampling image lens as claimed in claim 1 is characterized in that this sampling image lens further comprises an aperture diaphragm, between the thing end and second lens.

4. sampling image lens as claimed in claim 1 is characterized in that it is aspheric surface that these first lens, second lens have at least one surface respectively.

5. sampling image lens comprises on optical axis from the thing end to the imaging end it is characterized in that first lens, second lens, aperture diaphragm and the 3rd lens successively:

These first lens are positive refractive index and have the meniscus shape that its thing end surfaces protrudes towards the thing end;

These second lens are positive refractive index and have the meniscus shape that it protrudes towards the imaging end as end surfaces;

This aperture diaphragm is between first lens and second lens; And

The 3rd lens are an aspheric surface for negative refractive index and its as end surfaces;

Wherein, this sampling image lens meets the following conditions:

$0.85\&le;\frac{v1}{v2}\&le;1.15$

$0.85\&le;\frac{v2}{v3}\&le;1.25$

Wherein, ν 1 is the Abbe numerical value (abbenumber) of first lens to d light, and ν 2 is the Abbe numerical value of second lens to d light, and ν 3 is the Abbe numerical value of the 3rd lens to d light, and the wavelength of d light is 587.5618nm.

6. sampling image lens as claimed in claim 5, the refractive index that it is characterized in that the contiguous optical axis of the 3rd lens be for negative, and the refractive index of the 3rd rims of the lens is for just.

7. sampling image lens as claimed in claim 5 is characterized in that it is aspheric surface that these first, second lens have at least one surface respectively.

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