CN101140352A - Minisize imagery - Google Patents

Abstract

A miniature view-finding wide-angle lens is suitable for image capture products and comprises a first lens of negative diopter, a free curved prism of positive diopter, a second lens of positive diopter and a third lens of negative diopter. Wherein, the free curved prism is arranged in parallel with the first lens. The second lens and the third lens are positioned below the free curved prism and adjacent to an image space. The free curved prism is equivalent to that an aspheric lens coefficients are evaluated on a right-angled prism surface. A lens structure using the present invention can not only reduce total lens length, save cost and decrease common difference but also obtain better optical quality.

Description

Minisize imagery

Technical field

The present invention relates to a kind of minisize image acquisition lens, particularly about a kind of minisize imagery that is applicable to image capture unit with free form surface.

Background technology

The integration of image capture products and photoelectric technology has become one of trend of current development in science and technology, in order to satisfy portable requirement, light, thin, short, the little primary demand that has become image capture unit.Eyeglass form and material at sampling image lens are selected, because the selection of the material of traditional sphere abrading glass eyeglass is more, comparatively favourable for correcting chromatic aberration, widely industry is used.Yet when sphere abrading glass eyeglass was used in less and visual angle (Wide-angle) the bigger situation of numerical aperture (FNumber), the correction of aberrations such as spherical aberration and astigmatism is difficulty still.The appearance of aspheric mirror has solved the problems referred to above, be applied in the optical system of camera lens, can significantly improve image quality, reduce the barrel distortion of wide-angle lens, and the alternative several spherical lens aberration for compensation of a slice non-spherical lens, can simplify the optical design of camera lens quite significantly, reduce its volume and weight.Yet, the traditional glass camera lens still must use a plurality of eyeglasses could correct with great visual angle off-axis aberration and the problem of aberration, the camera lens overall dimensions is long, volume is big, cost is higher thereby cause, and the processing of aspheric surface glass mirror is difficult for, and therefore has been subjected to considerable restraint when being used in the light and thin type digital product.Comparatively speaking, the aspheric surface glass lens is more easily processed, cost is lower, and therefore, industry adopts the optical element of aspheric surface glass lens as the small image extraction camera lens more, to shorten whole optical system.

With regard to the design of wide-angle lens, the design factor that needs to consider comprises off-axis aberration and the aberration that must correct with great visual angle, and severe distortion etc., therefore design is more difficult, problems such as finally easily cause the shape of eyeglass to be difficult to process or main beam incident angle (Chief Ray Angle) is too big.Though many designs of wide-angle lens have been exposed in U.S. Patent number 4493537,5251073,4525038 etc., can under very short length overall, overcome various optical aberrations and take into account problems such as actual processing extremely rare.Therefore, also there is prior art to propose to utilize the pattern of periscopic or free form surface (Free-Form Surface) prism to reach the purpose of compression stroke, as U.S. Patent number 6323892 etc.Yet periscopic design only can realize purpose with the light path turnover, the function of not correcting aberration by a catoptron.

The employing free curved surface prism has the following advantages: light path is repeatedly reflection in prism, can make total system shorten because of folding (Folding) effect; Reflecting surface can not produce aberration (Chromatic A berration), so total system can be because of a large amount of aberration that traditional refractor produced, and needs other eyeglass to do compensation (Compensation), thereby the element number of total system is few; Therefore optical surface is easier to stablize when system assembles because prism concerns that its relative position is fixed.But the free curved surface prism structure that existing sampling image lens adopts is comparatively complicated mostly, and therefore design, processing, fixing all difficulties comparatively still have necessity of further improvement.

Summary of the invention

Fundamental purpose of the present invention is to provide a kind of minisize imagery, and this wide-angle lens adopts a free curved surface prism, by the incident beam reflection can be reached the purpose that shortens the optics length overall.

Another object of the present invention is to provide a kind of minisize imagery, it is simple in structure, handling ease, tolerance tolerance big, cost is lower, has with great visual angle and have good image quality.

For achieving the above object, the invention provides a kind of minisize imagery, can be applicable on the image capture products, this camera lens comprises the prism of negative dioptric first lens, positive diopter from the object side to the image side successively, second lens of positive diopter and negative dioptric the 3rd lens, wherein first lens and prism are arranged side by side, and second lens and the 3rd lens are positioned at the below and the contiguous picture side of prism.First lens are a biconcave lens, comprise that one is depression first of configuration and also is second of depression configuration with respect to imaging surface with respect to subject.This prism is a free curved surface prism, and it is equivalent to the attached asphericity coefficient that gives on a right-angle prism face.This prism comprises second with first lens is relative and establish the plane of incidence, the reflecting surface that is provided with of inclined light shaft, and the exit facet of establishing towards imaging surface relatively, and wherein the plane of incidence, exit facet are convex surface, and reflecting surface is a plane.These second lens and the 3rd lens glue together mutually and are one, are arranged between free curved surface prism and the imaging surface.Further be provided with an aperture diaphragm between these second lens and the free curved surface prism.Further be provided with a glass plate between the 3rd lens and the imaging surface.

Have at least one side to be aspheric surface in first, second face of first lens.The plane of incidence and the exit facet of prism are aspheric surface.

Preferably, first lens and prism are made of plastics, and second lens and the 3rd lens are then made by glass.

Minisize imagery of the present invention meets the following conditions:

1.0＜|f1/f|＜1.9；

1.6＜f2/f＜3.2；

2.5＜(f34)/f＜4.5; And

0.8＜(R34)/f＜1.8

Wherein, f is the whole effective focal length (Effective focal length) of system, and f1 is the effective focal length of first lens, and f2 is the effective focal length of prism, f34 is the synthetic focal length of second lens and the 3rd lens, and R34 is the radius-of-curvature of the cemented surface of second lens and the 3rd lens.

Compared with prior art, minisize imagery of the present invention only is made up of three lens and a prism, has that framework is succinct, easy to assembly, the visual angle is big, volume is little, lightweight advantage; By adopting a free curved surface prism, optical axis can be folded to 90 degree, make light path produce turnover, thereby shorten the front and back length and the reduced volume of camera lens, rectifiable various aberrations obtain the good picture of separating simultaneously; Adopt the glass lens of ejection formation and add aspheric surface,, can significantly reduce cost, and be easy to aberration correction, shorten the optics length overall of camera lens and improve yield to replace traditional glass mirror.In addition, free curved surface prism of the present invention is equivalent to the attached asphericity coefficient that gives on a right-angle prism face, compares with the free curved surface prism that existing design is complicated, process stable, simple and easy, the tolerance tolerance is big.Second, third lens are composed one mutually, also can avoid unnecessary tolerance to produce, make the easier processing of native system.

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

Description of drawings

Fig. 1 is the optical structure chart of minisize imagery of the present invention.

Fig. 2 is the optical structure chart of minisize imagery of the present invention according to numerical value embodiment one.

Fig. 2 A～2E is respectively the performance figure of longitudinal spherical aberration, the curvature of field, distortion, lateral chromatic aberration and the light meet curve of numerical value embodiment one of the present invention.

Fig. 3 is the optical structure chart of minisize imagery of the present invention according to numerical value embodiment two.

Fig. 3 A～3E is respectively the performance figure of longitudinal spherical aberration, the curvature of field, distortion, lateral chromatic aberration and the light meet curve of numerical value embodiment two of the present invention.

Fig. 4 is the optical structure chart of minisize imagery of the present invention according to numerical value embodiment three.

Fig. 4 A～4E is respectively the performance figure of longitudinal spherical aberration, the curvature of field, distortion, lateral chromatic aberration and the light meet curve of numerical value embodiment three of the present invention.

Embodiment

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

Minisize imagery of the present invention can be applicable to image capture unit, is used for object is imaged in an Image Sensor, as charge coupled cell (CCD) or complementary metal oxide semiconductor (CMOS).

Please refer to the composition framework of minisize imagery of the present invention shown in Figure 1, it comprises the prism 2 of negative dioptric first lens 1, positive diopter, second lens 3 and negative dioptric the 3rd lens 7 of positive diopter from the object side to the image side successively.Wherein, the prism 2 and first lens 1 are arranged side by side.Second lens 3 and the 3rd lens 7 are incorporated into a balsaming lens 8, and this balsaming lens 8 is positioned at the below and the contiguous picture side of prism 2.After seeing through first lens 1, prism 2 and balsaming lens 8 from the light of subject, focus on a CCD or the CMOS image sensor 4 (imaging surface), and obtain blur-free imaging.

Wherein, first lens 1 are biconcave lenss, and its optical function is mainly collection light.These first lens 1 comprise that one is cave in first S1 of configuration and second S2 that also is the configuration that caves in respect to prism 2 with respect to subject, and have at least one side to be aspheric surface among first, second face S1, the S2, in order to correct distortion (Distortion) and lateral chromatic aberration (Lateral Color).

Prism 2 is a free curved surface prism (Free-Form Surface Prism), is equivalent to the attached asphericity coefficient that gives on a right-angle prism (Right Angle Prism) face.Though also can use the prism of on-right angle, yet consider processing stability and tolerance (Tolerance) tolerance, the right angle is an optimized angle.Prism 2 can be realized multinomial optical function simultaneously, except that optical axis being turned to 90 degree, also provides three faces to be used for correcting aberration.This prism 2 comprises second S2 with first lens 1 is relative and establish plane of incidence S3, the reflecting surface S4 that is provided with of inclined light shaft relatively, and the exit facet S5 that establishes towards imaging surface 4, wherein plane of incidence S3, exit facet S5 are convex surface and are aspheric surface, and reflecting surface S4 is a plane.

Balsaming lens 8 is arranged between free curved surface prism 2 and the imaging surface 4, main optical function is for revising upward aberration (Axial Color) of spherical aberration (Spherical Aberration) and axle, light in the visible wavelength range (0.436 μ m to 0.656 μ m) can be concentrated in the 0.02mm, and move the paraxial beam quality to the approximate optics diffraction limit (Diffraction Limit), this is unapproachable in general wide-angle lens.

Further be provided with an aperture diaphragm (Aperture Stop) 5 between second lens 3 and the free curved surface prism 2, in order to control light amount of incident.For obtaining imaging effect preferably, between the 3rd lens 7 and imaging surface 4, further be provided with a glass plate (Glass Cover) 6, can plate and have certain effect the film of (for example: antireflection or infrared ray filter) on it.

As mentioned above, in the present invention, first lens 1 all can adopt the aspheric surface design with free curved surface prism 2, but except compensate for chromatic aberration and rectification off-axis aberration, also help to shorten the length overall of lens optical system, make the eyeglass minimum number and the weight reduction significantly of camera lens.In addition, second lens 3 and the 3rd lens 7 compose one mutually, can avoid unnecessary tolerance to produce, and make processing become easy.Preferably, first lens 1 are made of plastics with prism 2, and second lens 3 and the 3rd lens 7 are made by glass.

In the minisize imagery of the present invention, after seeing through first lens 1 from the light beam of subject, plane of incidence S3 by prism 2 is incident in the prism 2 and the face S4 of being reflected reflexes to exit facet S5, sees through exit facet S5 at last and penetrates to balsaming lens 8 by aperture diaphragm 5.The reflecting surface S4 of prism 2 can make the optical axis folding of the optical system of sampling image lens of the present invention turn 90 degrees to the internal reflection of light beam,, can make light path folding that is, therefore compares with dioptric system, and optical system itself is reduced.In addition, free curved surface prism 2 comprises plane of incidence S3 and the exit facet S5 as plane of refraction that is equivalent to 3 eyeglasses, and reflecting surface S4, compares with the catoptron that has only reflecting surface, and the degree of freedom of aberration correction is big.And,, therefore design specific energy prolongation optical path length mutually, thereby make optical system slimming, miniaturization with being configured in airborne lens or catoptron etc. owing to be full of the transparent body higher than the refractive index of air in prism 2 inside.

For reaching preferable optical property, imagery of the present invention meets the following conditions:

1.0＜|f1/f|＜1.9(1)

Wherein, f is the whole effective focal length of system, and f1 is the effective focal length of first lens 1.When | f1/f| prescribes a time limit astigmatism (Astigmatism) undercorrection greater than last; As less than lower limit, then longitudinal chromatic aberration (Axial color) becomes big.

1.6＜f2/f＜3.2(2)

Wherein, f is the whole effective focal length of system, and f2 is the effective focal length of prism 2.When f2/f greater than last in limited time, it is big that lateral chromatic aberration becomes; As less than lower limit, then spherical aberration (SphericalAberration) and coma (Coma) are difficult to correct.

2.5＜(f34)/f＜4.5(3)

Wherein, f is the whole effective focal length of system, and f34 is the synthetic focal length of second lens 3 and the 3rd lens 7.When (f34)/f greater than last in limited time, promptly the synthetic focal length of second lens 3 and the 3rd lens 7 is oversize, can cause total system elongated gradually; As less than lower limit, then coma and astigmatism are difficult to correct.

0.8＜(R34)/f＜1.8(4)

Wherein, f is the whole effective focal length of system, and R34 is the radius-of-curvature of the cemented surface S8 of second lens 3 and the 3rd lens 7.In limited time promptly the radius-of-curvature of the cemented surface of second lens 3 and the 3rd lens 7 is too big greater than last as (R34)/f, and the axle colouring missionary society rectification of system is bad, has a strong impact on whole optical quality, can't be near the diffraction limit; As less than lower limit, promptly the radius-of-curvature of the cemented surface of second lens 3 and the 3rd lens 7 is too little, can cause the thick deficiency in second lens, 3 limits, or is difficult to problems such as processing.

Concrete numerical value embodiment below with reference to caption minisize imagery of the present invention.

Numerical value embodiment one

As shown in Figure 2, the embodiment one of minisize imagery of the present invention comprises free curved surface prism 21, an aperture diaphragm 51 of negative dioptric first lens 11, a positive diopter, second lens, 31, one negative dioptric the 3rd lens 71, a glass plate 61 and an imaging surface 41 of a positive diopter, and wherein second lens 31 and the 3rd lens 71 are incorporated into a balsaming lens 81.The concrete numerical value such as the following table of each element are listed:

The surface sequence number	Radius-of-curvature (mm) (Radius of Curvature)	Distance/thickness (mm) (Distance/Thickness)	Refractive index (Nd)	Abbe number (Vd)
					S0		∞
S11	-6.773	1.2	1.5136	57.4
					S21	1.823	1.70
S31	4.486	2.2	1.5136	57.4
					S41	∞	-2.2	1.5136	57.4
S51	2.931	-0.6
					S61	∞	-0.1
S71	-3.331	-2.0	1.6204	60.3
					S81	2.5	-0.6	1.8466	23.8
S91	38.925	-1.844
					S101	∞	0.8	1.51633	64.1
S111	∞

Illustrate: in last table,, therefore negative spacing is arranged because of rotated 90 degree in the reflecting surface S41 place of prism 21 coordinate system.

In numerical value embodiment one, first lens 11 and prism 21 are aspheric mirror, and it satisfies following aspheric surface formula:

$z=\frac{{\mathrm{<figure-callout\; id="2"\; label="ch"\; filenames="A20061012918600241.png"\; state="\{\{state\}\}">ch</figure-callout>}}^2}{1+{[1-(k+1)c^2{h}^2]}^{\frac{1}{2}}}+{\mathrm{<figure-callout\; id="4"\; label="Ah"\; filenames="A20061012918600241.png,A20061012918600301.png"\; state="\{\{state\}\}">Ah</figure-callout>}}^4+{\mathrm{<figure-callout\; id="6"\; label="Bh"\; filenames="A20061012918600241.png"\; state="\{\{state\}\}">Bh</figure-callout>}}^6+{\mathrm{<figure-callout\; id="8"\; label="Ch"\; filenames="A20061012918600241.png"\; state="\{\{state\}\}">Ch</figure-callout>}}^8+{\mathrm{Dh}}^{10}$

Wherein, z be along optical axis direction highly for the position of h with the surface vertices shift value apart from optical axis for referencial use, k is the tapering constant, c represents the inverse of radius-of-curvature, h represents the eyeglass height, A, B, C, D is asphericity coefficient, A represents quadravalence asphericity coefficient (4thOrder Aspherical Coefficient), B represents six rank asphericity coefficients (6th OrderAspherical Coefficient), C represents eight rank asphericity coefficients (8th OrderAspherical Coefficient), and D represents ten rank asphericity coefficients (10th OrderAspherical Coefficient).

Particularly, two surperficial S11, the S21 of first lens 11, and the plane of incidence S31 of prism 21 and exit facet S51 be aspheric surface, its aspheric correlation values is listed in the table below successively:

The correlated performance index such as the following table of the minisize imagery of implementing according to numerical value embodiment one:

Effective Focal length(f)	2.0mm
		Field of View(F.O.V)	120degree
Total Length of Lens System	13.24mm
		F-number	2.86
|f1/f|	1.335
		f2/f	2.16
f34/f	3.775
		R34/f	1.25

As seen from the above table, the focal length ratio that is limited to (4) by expression formula (1) | f1/f| is 1.335, and f2/f is 2.16, and f34/f is 3.775, and R34/f is 1.25, all is positioned at desired bound scope.

Fig. 2 A～2E has shown longitudinal spherical aberration (Longitudinal Spherical Aberration), the curvature of field (Field Sags), distortion, lateral chromatic aberration and 2D light meet (the 2D Ray Intercept) curve map of the camera lens of numerical value embodiment one of the present invention respectively, shows that the camera lens of numerical value embodiment one of the present invention has preferable optical appearance.

Numerical value embodiment two

As shown in Figure 3, the embodiment two of minisize imagery of the present invention comprises free curved surface prism 22, an aperture diaphragm 52 of negative dioptric first lens 12, a positive diopter, second lens, 32, one negative dioptric the 3rd lens 72, a glass plate 62 and an imaging surface 42 of a positive diopter, and wherein second lens 32 and the 3rd lens 72 are incorporated into a balsaming lens 82.The concrete numerical value such as the following table of each element are listed:

The surface sequence number	Radius-of-curvature (mm) (Radius of Curvature)	Distance/thickness (mm) (Distance/Thickness)	Refractive index (Nd)	Abbe number (Vd)
					S0		∞
S12	-4.652	1.0	1.5136	57.4
					S22	2.199	2.2
S32	4.289	2.5	1.5136	57.4
					S42	∞	-2.5	1.5136	57.4
S52	3.559	-0.6
					S62	∞	-0.563
S72	-3.439	-2.3	1.6204	60.3
					S82	2.222	-0.6	1.8466	23.8
S92	17.473	-1.735
					S102	∞	-0.8	1.51633	64.1
S112	∞

Illustrate: in last table,, therefore negative spacing is arranged because of rotated 90 degree in the reflecting surface S42 place of prism 22 coordinate system.

Among the numerical value embodiment two, first lens 12 and prism 22 are aspheric mirror, and it satisfies following aspheric surface formula:

$z=\frac{{\mathrm{<figure-callout\; id="2"\; label="ch"\; filenames="A20061012918600241.png"\; state="\{\{state\}\}">ch</figure-callout>}}^2}{1+{[1-(k+1)c^2{h}^2]}^{\frac{1}{2}}}+{\mathrm{<figure-callout\; id="4"\; label="Ah"\; filenames="A20061012918600241.png,A20061012918600301.png"\; state="\{\{state\}\}">Ah</figure-callout>}}^4+{\mathrm{<figure-callout\; id="6"\; label="Bh"\; filenames="A20061012918600241.png"\; state="\{\{state\}\}">Bh</figure-callout>}}^6+{\mathrm{<figure-callout\; id="8"\; label="Ch"\; filenames="A20061012918600241.png"\; state="\{\{state\}\}">Ch</figure-callout>}}^8+{\mathrm{Dh}}^{10}$

Wherein, z be along optical axis direction highly for the position of h with the surface vertices shift value apart from optical axis for referencial use, k is the tapering constant, c represents the inverse of radius-of-curvature, and h represents the eyeglass height, and A, B, C, D are asphericity coefficient, A represents the quadravalence asphericity coefficient, B represents six rank asphericity coefficients, and C represents eight rank asphericity coefficients, and D represents ten rank asphericity coefficients.

Particularly, two surperficial S12, the S22 of first lens 12, and the plane of incidence S32 of prism 22 and exit facet S52 be aspheric surface, its aspheric correlation values is listed in the table below successively:

The correlated performance index such as the following table of the minisize imagery of implementing according to numerical value embodiment two:

Effective Focallength(f)	2.0mm
		Field of View(F.O.V)	120degree
Total Length of Lens System	12.96mm
		F-number	2.86
|f1/f|	1.445
		f2/f	2.635
f34/f	3.315
		R34/f	1.11

As seen from the above table, the focal length ratio that is limited to (4) by expression formula (1) | f1/f| is 1.445, and f2/f is 2.635, and f34/f is 3.315, and R34/f is 1.11, all is positioned at desired bound scope.

Fig. 3 A～3E has shown longitudinal spherical aberration, the curvature of field, distortion, lateral chromatic aberration and the 2D light meet curve map of the camera lens of numerical value embodiment two of the present invention respectively, shows that the camera lens of numerical value embodiment two of the present invention has preferable optical appearance.

Numerical value embodiment three

As shown in Figure 4, the embodiment three of minisize imagery of the present invention comprises free curved surface prism 23, an aperture diaphragm 53 of negative dioptric first lens 13, a positive diopter, second lens, 33, one negative dioptric the 3rd lens 73, a glass plate 63 and an imaging surface 43 of a positive diopter, and wherein second lens 33 and the 3rd lens 73 are incorporated into a balsaming lens 83.The concrete numerical value such as the following table of each element are listed:

The surface sequence number	Radius-of-curvature (mm) (Radius of Curvature)	Distance/thickness (mm) (Distance/Thickness)	Refractive index (Nd)	Abbe number (Vd)
					S0		∞
S13	-3.897	1.4	1.5136	57.4
					S23	2.076	1.8
S33	3.243	2.39	1.5136	57.4
					S43	∞	-2.2	1.5136	57.4
S53	3.16	-0.6
					S63	∞	-0.1
S73	-3.92	-2.0	1.6204	60.3
					S83	-2.2	-0.6	1.8466	23.8
S93	14.387	-1.874
					S103	∞	-0.8	1.51633	64.1
S113	∞

Illustrate: in last table,, therefore negative spacing is arranged because of rotated 90 degree in the reflecting surface S43 place of prism 23 coordinate system.

Among the numerical value embodiment 3, first lens 13 and prism 23 are aspheric mirror, and it satisfies following aspheric surface formula:

$z=\frac{{\mathrm{<figure-callout\; id="2"\; label="ch"\; filenames="A20061012918600241.png"\; state="\{\{state\}\}">ch</figure-callout>}}^2}{1+{[1-(k+1)c^2{h}^2]}^{\frac{1}{2}}}+{\mathrm{<figure-callout\; id="4"\; label="Ah"\; filenames="A20061012918600241.png,A20061012918600301.png"\; state="\{\{state\}\}">Ah</figure-callout>}}^4+{\mathrm{<figure-callout\; id="6"\; label="Bh"\; filenames="A20061012918600241.png"\; state="\{\{state\}\}">Bh</figure-callout>}}^6+{\mathrm{<figure-callout\; id="8"\; label="Ch"\; filenames="A20061012918600241.png"\; state="\{\{state\}\}">Ch</figure-callout>}}^8+{\mathrm{Dh}}^{10}$

Wherein, z be along optical axis direction highly for the position of h with the surface vertices shift value apart from optical axis for referencial use, k is the tapering constant, c represents the inverse of radius-of-curvature, and h represents the eyeglass height, and A, B, C, D are asphericity coefficient, A represents the quadravalence asphericity coefficient, B represents six rank asphericity coefficients, and C represents eight rank asphericity coefficients, and D represents ten rank asphericity coefficients.

Particularly, two surperficial S13, the S23 of first lens 13, and the plane of incidence S33 of prism 23 and exit facet S53 be aspheric surface, its aspheric correlation values is listed in the table below successively:

The correlated performance index such as the following table of the minisize imagery of implementing according to numerical value embodiment three:

Effective Focal length(f)	2.0mm
		Field of View(F.O.V)	120degree
Total Length of Lens System	14.625mm
		F-number	2.86
|f1/f|	1.355
		f2/f	2.41
f34/f	3.31
		R34/f	1.1

As seen from the above table, the focal length ratio that is limited to (4) by expression formula (1) | f1/f| is 1.355, and f2/f is 2.41, and f34/f is 3.31, and R34/f is 1.1, all is positioned at desired bound scope.

Fig. 4 A～4E has shown longitudinal spherical aberration, the curvature of field, distortion, lateral chromatic aberration and the 2D light meet curve map of the camera lens of numerical value embodiment three of the present invention respectively, shows that the camera lens of numerical value embodiment three of the present invention has preferable optical appearance.

In sum, compared with prior art, minisize imagery of the present invention only is made up of three lens and a prism, has that framework is succinct, easy to assembly, the visual angle is big, volume is little, lightweight advantage; By adopting a free curved surface prism, optical axis can be folded to 90 degree, make light path produce turnover, thereby shorten the front and back length and the reduced volume of camera lens, rectifiable various aberrations obtain the good picture of separating simultaneously; Adopt the glass lens of ejection formation and add aspheric surface,, can significantly reduce cost, and be easy to aberration correction, shorten the optics length overall of camera lens and improve yield to replace traditional glass mirror.In addition, free curved surface prism of the present invention is equivalent to the attached asphericity coefficient that gives on a right-angle prism face; Compare with the free curved surface prism that existing design is complicated, process stable, simple and easy, the tolerance tolerance is big.Second, third lens are composed one mutually, also can avoid unnecessary tolerance to produce, make the easier processing of native system.

It should be noted that the present invention is a kind of minisize imagery, the visual angle can reach 120 degree, therefore is suitable as very much on-vehicle lens, surveillance or network video camera lens.Certainly, optical system of the present invention also be operable in less than on the visual angles of 120 degree as general wide-angle sampling image lens.Optical system length overall of the present invention has only about 8.0mm, more helps being installed on automobile, burglary-resisting system or the computing machine perimeter systems, even on the mobile phone.Utilize framework of the present invention not only can shorten length overall, save cost, reduce the generation of tolerance, and still can obtain preferable optical quality.

Claims (14)

1. minisize imagery, it is characterized in that: this wide-angle lens comprises the free curved surface prism of negative dioptric first lens, a positive diopter, second lens and negative dioptric the 3rd lens of a positive diopter from the object side to the image side successively, wherein this free curved surface prism and first lens are arranged side by side, and these second lens and the 3rd lens are positioned at the below and the contiguous picture side of free curved surface prism.

2. minisize imagery as claimed in claim 1, it is characterized in that these second lens and the 3rd lens compose one mutually, satisfy 0.8＜(R34)/f＜1.8, wherein, f is the whole effective focal length of system, and R34 is the radius-of-curvature of the cemented surface of second lens and the 3rd lens.

3. minisize imagery as claimed in claim 2, the effective focal length that it is characterized in that these first lens is f1, satisfy 1.0＜| f1/f|＜1.9.

4. minisize imagery as claimed in claim 3, the effective focal length that it is characterized in that this free curved surface prism is f2, satisfies 1.6＜f2/f＜3.2.

5. minisize imagery as claimed in claim 4, the synthetic focal length that it is characterized in that these second lens and the 3rd lens is f34, satisfies 2.5＜(f34)/f＜4.5.

6. minisize imagery as claimed in claim 1 is characterized in that further being provided with an aperture diaphragm between this free curved surface prism and this second lens.

7. minisize imagery as claimed in claim 1 is characterized in that further being provided with between the 3rd lens and the picture side glass plate.

8. minisize imagery as claimed in claim 1 is characterized in that these first lens have at least one side to be aspheric surface.

9. minisize imagery as claimed in claim 8 is characterized in that this free curved surface prism is equivalent to the attached asphericity coefficient that gives on a right-angle prism face.

10. minisize imagery as claimed in claim 9 is characterized in that this free curved surface prism comprises and the plane of incidence established relative with first lens, the reflecting surface that is provided with of inclined light shaft relatively, and towards the exit facet of picture Fang Ershe.

11. minisize imagery as claimed in claim 10 is characterized in that the plane of incidence of this free curved surface prism and exit facet are aspheric surface.

12. minisize imagery as claimed in claim 10 it is characterized in that the plane of incidence of this free curved surface prism, exit facet are convex surface, and reflecting surface is a plane.

13. minisize imagery as claimed in claim 1 is characterized in that these first lens and this free curved surface prism are made of plastics.

14. minisize imagery as claimed in claim 13 is characterized in that these second lens and the 3rd lens are made by glass.

Images