CN101131461A - Optical lens - Google Patents

Abstract

The invention discloses a optical lens including the first lens, the fixing diaphragm, the second lens, the third lens and light filter which are all in the same axis and arrayed from object direction to image direction. The front and back surface of the first lens are all sphere, the front and back surface of the second and third lens are all aspheric surface. The front surface of first lens projects to the object and the back surface concaves to the object; the up and down ends of front surface of second lens are plane and the center concaves to image direction, the back surface project to the image direction; the front surface center of third lens concaves to image direction; the up and down ends of back surface undulate and the center concaves to object direction. By using the aspheric surface lens, it can eliminate the edge light image errors including the ball error, coma, astigmation, field curvature and aberrance; by using the plastic lens, it avoids the glass lens processing difficulty and decreases the weight, also it can satisfy the big production and decrease the cost but improve the production efficient.

Description

Optical lens

Technical field

The present invention relates to field of optical lens, especially about a kind of optical lens that is used for the mobile phone cam module.

Background technology

Along with the rising of the continuous progress of science and technology and people's purchasing power, mobile phone is universal day by day, and function is also all the more powerful.Present mobile phone is more like a kind of fashion, and the mobile phone of the capable of taking pictures and recorded video of band camera is in the tip of this fashion especially, is subjected to pursuing of consumers in general.

Mobile phone cam mostly is embedded, and the compact trend of mobile phone requires the thickness of its all parts all constantly to shorten, and mobile phone cam is no exception.In fact the thickness of control mobile phone cam be exactly the length overall of controlling its optical lens.For optical lens, under the prerequisite that does not reduce image quality, shorten its length overall, but also will make great efforts to reduce its cost, so that the design of optical lens just seems is very important.The design of optical lens mainly is that the material selection of the face shape design of its lens and eyeglass is particularly important.

Summary of the invention

Technical matters to be solved by this invention is, overcomes the deficiencies in the prior art, provides good imaging quality and cost low optical lens.

The technical solution adopted for the present invention to solve the technical problems is: this optical lens comprises first lens, fixed aperture, second lens, the 3rd lens and the optical filter of arranging in turn to picture side from object space, this first, second and third lens common optical axis, the forward and backward surface of these second, third lens is aspheric surface, and its face shape formula is:

$Z=\frac{y^2}{R+\sqrt{R^2-(1+k)y^2}}+a{y}^4+b{y}^6+c{y}^8+d{y}^{10}+e{y}^{12}$

Wherein, Z represents the Building Z scale value of lens surface each point, y represents the y coordinate figure of lens surface each point, R is the radius-of-curvature of lens surface each point, k is the circular cone coefficient, a, b, c, d, e are the high-order asphericity coefficient, and each parameter on the forward and backward surface of first, second lens is respectively as shown in Table 1 and Table 2:

Table 1

	Front surface (near object space)	Rear surface (near picture side)
			R	-1.668476	-0.590762

k	-1.942507	-3.085375
			a	-0.271662	-0.377297
b	-0.119644	0.230310
			c	-0.1132607	-0.082048
d	-0.251989	-0.114107
			e	0.543009	0.087085

Table 2

	Front surface (near object space)	Rear surface (near picture side)
			R	-18.944288	0.789318
k	120.274104	-7.864124
			a	-0.115914	-0.097753
b	0.049512	-0.025262
			c	0.012253	-0.004781
d	-0.011003	0.000803
			e	0.001605	0.000117

, the front surface of these first lens is a sphere, and its radius-of-curvature is 1.592340, and the rear surface of these first lens is a sphere, and its radius-of-curvature is 7.245661mm.

The front surface of described first lens protrudes to object space, its rear surface is recessed to object space, the two ends up and down of the front surface of second lens are that plane and middle position are recessed to picture side, protrude to picture side its rear surface, the middle position of the front surface of the 3rd lens is recessed to picture side, and the upper and lower side of its rear surface rises and falls and middle position is recessed to object space.

The material of the material of described first lens and second lens is refractive index 1.49 to 1.53 and abbe number greater than 54 optical plastic, and the material of the 3rd lens is an optical grade PC resin.

The invention has the beneficial effects as follows,, can effectively eliminate the aberration of marginal ray, comprise spherical aberration, coma, astigmatism, the curvature of field and distortion etc. by adopting aspherical lens; By adopting the eyeglass of plastic material, avoided the processing difficulties of glass lens, alleviated the weight of camera lens, satisfied mass-produced requirement simultaneously, reduced manufacturing cost, improved production efficiency; By the setting of special parameter eyeglass, can effectively reduce aberration, improve optical transfer function, the optics length overall is very short, and field angle is greater than 60 °, and the edge chief ray angle is less than 23 °, the image quality height.

Description of drawings

Fig. 1 is the structural representation of optical lens of the present invention;

Fig. 2 is the MTF figure of optical lens of the present invention.

Fig. 3 is the relative exposure figure of optical lens of the present invention.

Fig. 4 is the curvature of field figure of optical lens of the present invention.

Fig. 5 is the distortion figure of optical lens of the present invention.

Fig. 6 is the chromaticity difference diagram of optical lens of the present invention.

Embodiment

See also Fig. 1, optical lens of the present invention is a mobile lens, and it comprises first lens 1, fixed aperture 2, second lens 3, the 3rd lens 4 and the optical filter of arranging in turn 5, this first, second, third lens common optical axis, these first lens are near object space, and this optical filter is near picture side.

These first lens 1 are positive lens, its material is refractive index 1.49 to 1.53 and abbe number greater than 54 optical plastic, the thickness of these first lens is 0.5mm, its front surface (near object space) and rear surface (near picture side) are sphere, this front surface is that crescent is protruded, its radius-of-curvature is 1.592340mm, and this rear surface is that crescent is recessed, and its radius-of-curvature is 7.245661mm.The material of second lens is refractive index 1.49 to 1.53 and abbe number greater than 54 optical plastic.The forward and backward surface of these second lens is aspheric surface, and the two ends up and down of this front surface are the plane and middle position is recessed to picture side, and this rear surface is protruding in picture side.The 3rd lens adopt optical grade PC resin material (polycarbonate), and its refractive index is 1.58, and abbe number is 28.The front surface and the rear surface of the 3rd lens are aspheric surface, and the middle position of this front surface is recessed to picture side, and the upper and lower side of its rear surface rises and falls and middle position is recessed to object space.This fixed aperture 2 is between first, second lens 1,3.This optical filter 6 adopts glass material, after it is positioned at the 3rd lens 4.This optical lens is imaged on imaging surface 6 (being the focal plane).

What second and third lens adopted is 12 rank even aspherical lens, and this guarantees to reduce high-order aspheric surface number of times when using aspheric surface to reach required image quality as far as possible, thereby has reduced the difficulty that Mould Machining is made.The face shape formula of these second, third lens is:

$Z=\frac{y^2}{R+\sqrt{R^2-(1+k)y^2}}+a{y}^4+b{y}^6+c{y}^8+d{y}^{10}+e{y}^{12}$

Wherein Z represents the Z coordinate figure of lens surface each point, and y represents the y axial coordinate value of each point on the lens surface, and R is the radius-of-curvature of lens surface each point, and k is the circular cone coefficient of curve, and a, b, c, d, e are the high-order asphericity coefficient.

The face shape parameter value such as the table 1 of second lens:

The face shape parameter of table 1 second lens

	Front surface (near object space)	Rear surface (near picture side)
			R	-1.668476	-0.590762
K	-1.942507	-3.085375
			a	-0.271662	-0.377297
b	-0.119644	0.230310
			c	-0.1132607	-0.082048
d	-0.251989	-0.114107
			e	0.543009	0.087085

The face shape parameter value such as the table 2 of the 3rd lens:

The face shape parameter of table 2 the 3rd lens

	Front surface (near object space)	Rear surface (near picture side)
			R	-18.944288	0.789318
K	120.274104	-7.864124
			a	-0.115914	-0.097753
b	0.049512	-0.025262
			c	0.012253	-0.004781
d	-0.011003	0.000803
			e	0.001605	0.000117

The effective focal length of optical lens of the present invention is 3.30mm, back focal length is 0.61500, and the optics length overall is 4.40mm, and relative aperture can reach F2.8, use the camera module height of this camera lens can be, for the exploitation of more small-sized shooting mobile phone provides solution less than 6mm.

See also Fig. 2, among the optical transfer function of this camera lens (MTF) figure, the resolution of the visual field, center during MTF=0.3 has reached 200lp/mm; During MTF=0.2, the resolution of visual field, edge also reaches 125lp/mm, can satisfy the resolution requirement of the following CMOS/CCD image sensor of hundred everything elements.

See also Fig. 3 to Fig. 5, the curvature of field that can find out camera lens is less than 0.1mm, and lateral chromatic aberration is less than 5um, within Airy disk (diffraction spot) range of size.The optical distortion of this camera lens is less than 2%, and the optical distortion of general digital camera lens requires to get final product (being difficult for discovering at this distortion human eye below value) less than 2%.Adopt disc of confusion spot size and how much spot sizes of each visual field of optical system of this structure all to be within the small range simultaneously, show the primary aberration correction better.

See also Fig. 6, the relative exposure of this optical lens shows that greater than 45% the illumination of this visual field, camera lens edge and visual field, center is even, bright and clear.Simultaneously, the maximum field of view angle of whole optical system is 68 °, and the edge chief ray angle can cooperate the requirement of the CMOS/CCD image sensor reception of main flow on the market less than 23 °.

Lens construction of the present invention is not only applicable to the mobile phone cam module, can be applicable in other portable type camera shot equipments simultaneously, as computer camera, small-sized watch-dog etc. yet.

Above content be in conjunction with concrete preferred implementation to further describing that the present invention did, can not assert that concrete enforcement of the present invention is confined to these explanations.For the general technical staff of the technical field of the invention, without departing from the inventive concept of the premise, can also make some simple deduction or replace, all should be considered as belonging to the scope of patent protection that the present invention is determined by claims of being submitted to.

Claims (3)

1. optical lens, it is characterized in that: comprise first lens, fixed aperture, second lens, the 3rd lens and the optical filter arranged in turn to picture side from object space, this first, second and third lens common optical axis, the forward and backward surface of these second, third lens is aspheric surface, and its face shape formula is:

$Z=\frac{y^2}{R+\sqrt{R^2-(1+k)y^2}}+{\mathrm{ay}}^4+{\mathrm{by}}^6+{\mathrm{cy}}^8+{\mathrm{dy}}^{10}+{\mathrm{ey}}^{12}$

Wherein, Z represents the Building Z scale value of lens surface each point, y represents the y coordinate figure of lens surface each point, R is the radius-of-curvature of lens surface each point, k is the circular cone coefficient, a, b, c, d, e are the high-order asphericity coefficient, and each parameter on the forward and backward surface of first, second lens is respectively as shown in Table 1 and Table 2:

Table 1

Front surface (near object space) Rear surface (near picture side) R -1.668476 -0.590762 k -1.942507 -3.085375 a -0.271662 -0.377297 b -0.119644 0.230310 c -0.1132607 -0.082048 d -0.251989 -0.114107 e 0.543009 0.087085

Table 2

Front surface (near object space) Rear surface (near picture side) R -18.944288 0.789318 k 120.274104 -7.864124 a -0.115914 -0.097753 b 0.049512 -0.025262 c 0.012253 -0.004781 d -0.011003 0.000803

e 0.001605 0.000117 , the front surface of these first lens is a sphere, and its radius-of-curvature is 1.592340, and the rear surface of these first lens is a sphere, and its radius-of-curvature is 7.245661mm.

2. according to the described optical lens of claim 1, it is characterized in that: the front surface of described first lens protrudes to object space, its rear surface is recessed to object space, the two ends up and down of the front surface of second lens are that plane and middle position are recessed to picture side, protrude to picture side its rear surface, the middle position of the front surface of the 3rd lens is recessed to picture side, and the upper and lower side of its rear surface rises and falls and middle position is recessed to object space.

3. according to the described optical lens of claim 2, it is characterized in that: the material of the material of described first lens and second lens is refractive index 1.49 to 1.53 and abbe number greater than 54 optical plastic, and the material of the 3rd lens is an optical grade PC resin.

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