CN100498410C

CN100498410C - Three-piece photographic lens group

Info

Publication number: CN100498410C
Application number: CNB2005100734171A
Authority: CN
Inventors: 野田小百合
Original assignee: Largan Precision Co Ltd
Current assignee: Largan Precision Co Ltd
Priority date: 2005-05-30
Filing date: 2005-05-30
Publication date: 2009-06-10
Anticipated expiration: 2025-05-30
Also published as: CN1873459A

Abstract

A three-piece camera lens assembly is used to correspond to a lens with high pixels, and provides a low-cost high-performance camera lens assembly by adopting the most suitable refractive power configuration and miniaturization and lightness; the three-piece photographing lens group is composed of a first lens, a second lens and a third lens, wherein the first lens is a positive refractive power meniscus lens with a convex surface facing to an object side, the second lens is arranged behind the first lens, the convex surface of the second lens faces to an image side, the third lens is arranged behind the second lens, the convex surface of the third lens faces to the object side, the composite focal length of the full series of lenses is f, and the composite focal length of the first lens and the second lens is f₁₂It is required to satisfy 1.0 < f₁₂A conditional formula of/f < 1.3; the lens set has the advantages of low cost, small size and portability, and can provide enough space for the infrared filter glass and the protective glass of the photographic element.

Description

The three piece type camera lens set

Technical field

The present invention relates to the photographic lens group that a kind of small image extraction device uses, it is relevant with the single-focus lens group of general small image extraction device, is meant three pieces of combinations that glass lens constituted of utilization especially.

Background technology

By three pieces of photographic lens groups that eyeglass constituted, following eight kinds of refracting power configuration modes are arranged; (A) just. negative. just (B) just. just. negative (C) just. just. just (D) just. negative. negative (E) is negative. just. just (F) is negative. just. negative (G) is negative. negative. just (H) is negative. negative. negative, eyeglass configuration mode headed by the wherein negative refracting power (is E, F, G and H), thereafter defocus distance is long, can't reach the demand of small portableization, do not meet and carry machine small portable demand and can't use, so in fact four kinds of refracting powers such as (A) to (D) dispose the main flow that is only design, and meet the demand of small portableization, and previous known technology, see also shown in the subordinate list two, the G that is occurred in subordinate list is represented as glass mirror, P is represented as glass lens:

At aspect A) Japanese Patent Document 1) to 10) in, it is to dispose with considering of price, adopt three pieces of glass lens mostly, yet it is looked in the distance than the ratio of optical full length (focal length with) greater than more than 1.5, therefore the photographic lens group of the small portable demand of mobile phone is also improper, in addition, because the condition of preposition its incident angle of aperture and demand are reached easily, and its defective to be second lens eccentric related that optical property reduces, and the bad configuration of its refracting power in actual production.

And at aspect A) Japanese Patent Document 11) in, it adopts the combination of three pieces of glass lens, and it is that mid-aperture can suppress the eccentric low defective of being brought of optical property, but look in the distance than be 2.5 these numerical value become very big.

At aspect A) Japanese Patent Document 12) in, adopt the combination of three pieces of glass lens and be the design of mid-aperture, it is looked in the distance than the miniaturization combination that is 1.24, open F NO be 3.5 just become dark, can't reach the bright degree that needs on actual the use, be to look in the distance again, make incident angle, become on the contrary and the bad collocation of CCD photography sub-prime greatly to 25 ° degree than little.

And aspect B) photographic lens group; in order to make it become the aspect of looking in the distance, it is more less than designing originally to look in the distance, but looks in the distance than too hour; back focus is too short apart from what become, becomes the space that infrared ray filtration eyeglass or CCD cover glass can't correctly insert its configuration.

And aspect B) Japanese Patent Document 1) to 3) or 6) to 10), it is looked in the distance than more than 1.4, does not claim small portableization, and optical full length makes it short as much as possible, the still configuration of above-mentioned embolus, it is minimal looks in the distance than will be 1.2 ~ 1.4).

Aspect B) Japanese Patent Document 4) 5) 11) three pieces of glass lens combinations, it is looked in the distance than being 1.2 ~ 1.4 o'clock, and it keeps small portableization, f ₁₂(f12 is the synthetic focal length of first eyeglass and second eyeglass in/f＜1.0, f is the synthetic focal length of complete set), with other aspect A) C) D) compare down, it is strong excessively that the refracting power of second eyeglass becomes, cause the peripheral thickness of eyeglass wayward, therefore core shift takes place when being shaped or organize the process of standing easily, also having aspect B) near in the middle of the picture band the non-difference of checking and accepting becomes big, for can the remaining receipts of revisal poor, near the core shift of the outer M picture of axle (Meridional picture) the band in the middle of picture during volume production, the problem that causes performance to reduce.

At aspect C) Japanese Patent Document in, be which its first eyeglass all is a glass material. and be the low higher-priced glass that disperses, be used in and carry on the machine, all will face the problem of high price, and the length of photographic lens group depends on looks in the distance than at 1.4 to 1.7, therefore also can't satisfy the demand of small portableization, in addition aspect C) look-ahead technique, its photographic lens group of adopting preposition aperture aspect does not exist.

At aspect D) Japanese Patent Document in, some contains A) the combination of refracting power configuration eyeglass, it is looked in the distance than 1.54 too big, exceeds the required condition of small portableization, and aspect D) look-ahead technique, the photographic lens group of adopting preposition aperture aspect does not also exist.

The combination of three pieces of eyeglasses as previously mentioned, be with aspect A) and often be used, look in the distance than T/F more than 1.4, be more improper in the optical full length cripetura, in the optical full length cripetura, aspect B) and the aspect of looking in the distance D) more favourable, and the eyeglass number of the aspect of looking in the distance less (2 or 3), be that exploitation is on the photographic lens group that the silver halide photography camera is used, because the back group has negative refracting power to want difficult difficult implementation of wide-angleization, therefore it is unaccommodated will requiring the optical system of wide-angleization the back group after, also has incident angle partly, and above-mentioned photographic lens group is not suitable for CCD solid-state image pickup sub-prime and uses.

And the contrary aspect eyeglass module of looking in the distance of (E) to (H) that negative refracting power eyeglass is the first eyeglass aspect, the VGA that these two pieces of eyeglasses constitute only uses the digital camera and the photographic lens module of carrying the last usefulness of end in 30 to 400,000 picture element grades, also have the shortening of contrary focusing aspect, optical full length also infeasible, eyeglass more than three pieces constitutes for this reason, is not used in the simple type digital camera.

Can know from above explanation, on being that eyeglass of the present invention constitutes, (C) aspect is just. just. just. three pieces of formations of eyeglass are basic structure, the corresponding three pieces of minimum eyeglasses of the shooting sub-prime of high picture element constitute for this reason, adopt optimum refracting power configuration, small portable and high performance photographic lens group can cheap price supplies.

Summary of the invention

Fundamental purpose of the present invention provides a kind of cheap photographic lens group, and it is to utilize three pieces of eyeglasses to be all the design of plastic material, so have characteristics with low cost.

Another fundamental purpose of the present invention provides a kind of photographic lens group, and the synthetic focal length of its complete series eyeglass is f, and the synthetic focal length of first eyeglass and second eyeglass is f ₁₂, and satisfy 1.0＜f ₁₂The conditional of/f＜1.3; can provide in view of the above and select optimum refracting power configuration; and have the characteristics of small portable, and eyeglass arrangement mode and configuration to have optical full length shorter, can have enough spatial configuration for the cover glass of infrared ray filter glass and photography sub-prime.

As follows for reaching the technical scheme that the foregoing invention purpose adopted: the present invention provides a kind of photographic lens group, it has first eyeglass, aperture, second eyeglass and prismatic glasses to constitute by object side to imaging side in regular turn, and wherein: first eyeglass is the positive refracting power curved month type eyeglass of convex surface to object side; It is arranged at aperture after first eyeglass; Second eyeglass is arranged on after this aperture and it is the positive refracting power curved month type eyeglass of convex surface to the imaging side; Prismatic glasses is to be arranged at after second eyeglass, and it is the positive refracting power curved month type eyeglass of convex surface to object side; It is made that first eyeglass, second eyeglass and prismatic glasses are all the plastic material of identical optical character, and the synthetic focal length of complete series eyeglass is f, and the synthetic focal length of first eyeglass and second eyeglass is f ₁₂, it need satisfy 1.0＜f ₁₂The conditional of/f＜1.3.

The synthetic focal length of described complete series eyeglass is f, and the focal length of prismatic glasses is f ₃The time, it need satisfy f/f ₃5.0 conditional.

The synthetic focal length of described complete series eyeglass is f, and the focal length of second eyeglass is f ₂The time, it need satisfy 2.0＜f ₂The conditional of/f＜11.0.

The effect of photographic lens group of the present invention, effect, eyeglass constitute and be (C) aspect of saying just now just. just. just, be arranged as in regular turn from object side specifically, first eyeglass and its convex surface are to the positive refracting power curved month type eyeglass of object side; Its convex surface of second eyeglass is to the positive refracting power curved month type eyeglass of imaging side, be convex surface at last towards the positive refracting power curved month type eyeglass of object side be that prismatic glasses constitutes the photographic lens group with this, and aperture is to be configured between first eyeglass and second eyeglass, promptly so-called mid-aperture.

Each piece eyeglass all uses with a kind of plastic material formed thereby in addition, relative can reduce fee of material and overhead cost, and glass lens can be comparatively appropriate for the distribution of refracting power configuration, also can actively import aspheric surface, can realize the combination of small portable and high performance eyeglass.

In the above-mentioned condition with 1.0＜f ₁₂The main reason of/f＜1.3 is to work as f ₁₂/ f ≧ 1.3 o'clock, it is long that optical full length becomes, and do not meet the small portable condition, works as f ₁₂/ f ≦ 1.0 o'clock; the back focus distance is too short; the infrared ray filter glass does not just have enough spatial configuration with the cover glass of shooting sub-prime; so satisfying above-mentioned conditional, to have optical full length shorter; can keep small portableization, and the cover glass of infrared ray filter glass and shooting sub-prime have enough spatial configuration.

Constitutive requirements of the present invention as mentioned above, the shooting sub-prime of high picture element are that corresponding three pieces of minimum eyeglasses constitute, only refracting power configuration mode, and miniaturization and high-performance photographic lens group can the low price supplies.

The synthetic focal length that the invention reside in complete set is f, and the focal length of prismatic glasses is f ₃The time, satisfy f ₃/ f〉5.0 (or 0＜f/f ₃＜0.2) conditional; Work as f ₃/ f ≦ 5.0 o'clock, it is too strong that the refracting power of the shared integral body of prismatic glasses becomes, the pre-group refracting power dies down, it is oversize that optical full length becomes, the ratio that promptly is the shared whole refracting power of prismatic glasses wants weak, more weak positive refracting power is important relatively, be revisal again for incident angle, the object side of prismatic glasses and imaging side both sides' refracting power aspect for example, along with the center distributes toward peripheral, slowly the aspheric surface that positive refracting power is strengthened gradually, thus towards the incident angle of the light of photography sub-prime have its necessary need littler.

Be the present invention, whole synthetic focal length is f, and the focal length of second eyeglass is f ₂The time to satisfy 2.0＜f ₂The conditional of/f＜11.0 is worked as f ₂/ f ≦ 2.0 o'clock, the refracting power of second eyeglass is strong excessively, and relative meeting moves on to the negative refracting power of prismatic glasses, has hindered incident angle, and the peripheral thickness of second eyeglass becomes the shape that can't determine simultaneously, and works as f ₂/ f ≧ 11.0 o'clock, the tortuous power of pre-group integral body dies down and optical full length is elongated.

Beneficial effect of the present invention is:

1. a kind of cheap photographic lens group provided by the invention, it is to utilize three pieces of eyeglasses to be all the design of plastic material, so have effect with low cost;

2. a kind of photographic lens group provided by the invention, the synthetic focal length of its complete series eyeglass is f, the synthetic focal length of first eyeglass and second eyeglass is f ₁₂, and satisfy 1.0＜f ₁₂The conditional of/f＜1.3; can provide in view of the above and select optimum refracting power configuration; and have the characteristics of small portable, and eyeglass arrangement mode and configuration to have optical full length shorter, can have enough spatial configuration for the cover glass of infrared ray filter glass and photography sub-prime.

Description of drawings

Figure 1A is that the eyeglass of the embodiment of the invention 1 constitutes synoptic diagram.

Figure 1B is receipts difference figure, the optical characteristics data synoptic diagram of the embodiment of the invention 1.

Fig. 2 A is that the eyeglass of the embodiment of the invention 2 constitutes synoptic diagram.

Fig. 2 B is receipts difference figure, the optical characteristics data synoptic diagram of the embodiment of the invention 2.

Fig. 3 A is that the eyeglass of the embodiment of the invention 3 constitutes synoptic diagram.

Fig. 3 B is receipts difference figure, the optical characteristics data synoptic diagram of the embodiment of the invention 3.

Fig. 4 A is that the eyeglass of the embodiment of the invention 4 constitutes synoptic diagram.

Fig. 4 B is receipts difference figure, the optical characteristics data synoptic diagram of the embodiment of the invention 4.

Fig. 5 A is that the eyeglass of the embodiment of the invention 5 constitutes synoptic diagram.

Fig. 5 B is receipts difference figure, the optical characteristics data synoptic diagram of the embodiment of the invention 5.

Fig. 6 A is that the eyeglass of the embodiment of the invention 6 constitutes synoptic diagram.

Fig. 6 B is receipts difference figure, the optical characteristics data synoptic diagram of the embodiment of the invention 6.

Fig. 7 A is that the eyeglass of the embodiment of the invention 7 constitutes synoptic diagram.

Fig. 7 B is receipts difference figure, the optical characteristics data synoptic diagram of the embodiment of the invention 7.

Subordinate list

Subordinate list one embodiment of the invention tables of data.

Subordinate list two known techniques tables of data.

The primary clustering symbol description

L1 first eyeglass

L2 second eyeglass

The L3 prismatic glasses

1 aperture

2 parallel plane glass

3 imaging surfaces

Embodiment

The present invention is by three pieces of photographic lens that eyeglass constituted, its most preferred embodiment illustrates with drawing, and Fig. 1-the 7th, the eyeglass pie graph (Figure 1A to Fig. 7 A) of embodiment one to embodiment seven represents that with optical system characteristic data (Figure 1B to Fig. 7 B) photographic lens group of the present invention is to be particularly suitable for being installed in the built-in optical system of mobile phone.

In the configuration signal that graphic Figure 1A to Fig. 7 A is each embodiment optical system, the photographic lens group is to be worked the configuration that is arranged as the first eyeglass L1, aperture 1, the second eyeglass L2, prismatic glasses L3, parallel plane glass 2, imaging surface 3 by object side along optical axis among each embodiment.

The first eyeglass L1 is the positive refracting power curved month type eyeglass of convex surface to object side, the second eyeglass L2 is the positive refracting power curved month type eyeglass of convex surface to the imaging side, prismatic glasses is the positive refracting power curved month type eyeglass of convex surface to object side, the photographic lens group that constitutes of prismatic glasses by this, each is all positive refracting power curved month type eyeglass, the first eyeglass L1 and the second eyeglass L2 form pre-group, prismatic glasses L3 forms the back group, parallel plane glass 2 has infrared ray to filter the eyeglass function, and imaging surface 3 be the configuration of the sub-prime of photographing such as CCD.

Belong to the prismatic glasses L3 among the group of back, mainly be to improve by incident angle to be disposed, and satisfy aftermentioned f ₃/ f〉5.0 conditional, prismatic glasses L3 has long focal length f ₃, tortuous power really almost being arranged, can understand thus, be used for incident angle merely and improve, prismatic glasses L3 has the formation point of inflection as the side, based on paraxial shape and ability, orders down the category of positive refracting power curved month type eyeglass.

Each eyeglass is all the plastic material formed thereby (being same plastic material) of identical optical character, compared with using on the glass mirror, can reduce material price and administered price, and the use of glass lens, the surface of its each minute surface can make the aspheric surface shape, just can reach desired optical property requirement in a small amount of eyeglass number of three pieces.

Explanation about Figure 1B to Fig. 7 B, figure is the eyeglass set of data topmost, f is a focal length, F NO (represent in the optical design numerical value of brightness big more just bright more), drawing angle 2 ω indicates, f be the synthetic focal length (mm) of photographic lens complete set under this, be divided into 1.2.3.4.5.6.7.8.9. be object side rise the order the face designation represent, (still 3 is expressions of aperture) 1.2. is the first eyeglass L1, face designation 4.5 is the second eyeglass L2, face designation 6.7 is prismatic glasses L3, face designation 8.9 is a parallel plane glass 2, its radius-of-curvature is ∞, radius-of-curvature is paraxial radius-of-curvature (mm) expression of going up, face is represented the interval numerical value between eyeglass face and the face at interval, each eyeglass is to be the formed products with material, and the flexion rate is the same numerical value with dispersion rate.

Receiving difference figure comprises and draws together sphere and receive and poor, non-check and accept difference and to distort receipts poor, no matter be which figure, all be about d line numerical data, but not check and accept difference is to represent about S image planes (SAGITTAL) data relevant with M image planes (MEERIDIONAL) two sides, receiving difference figure from these learns, no problem in the practicality, receive poor revisal.

Each eyeglass all has aspherical shape, and aspherical shape is asphericity coefficient with A.B.C.D., represents that for the benchmark of vertex of surface so Xia Mian formula can be set up from the displacement X of the optical axis of the position of the high H of optical axis:

X=(1/R) H ²/ (1+{1-(1+K) is (H/R) ²} ^1/2)+AH ⁴+ BH ⁶+ CH ⁸+ DH ¹⁰Shown in, R is paraxial radius-of-curvature, and K is the CONICAL coefficient, and the souvenir of aspheric E-03 etc. is 10 ^-3The meaning.

At f of the present invention (the synthetic focal length of complete set), f ₁₂(the synthetic focal length of the first eyeglass L1 and the second eyeglass L2), f ₂(focal length of the second eyeglass L2), f ₃(focal length of prismatic glasses L3) will satisfy following conditional:

(1)1.0<f ₁₂/f<1.3

Work as f ₁₂/ f ≧ 1.3 o'clock, it is long that optical full length becomes, and do not meet the small portable condition, also has f ₁₂/ f ≦ 1.0 o'clock, the back focus distance is too short, and the cover glass of infrared ray filter glass and shooting sub-prime does not have enough spatial configuration.

When satisfying above-mentioned conditional, optical full length shortens, and can keep light and handyization and possesses the enough spaces of back focus distance and can insert other embolus.

(2) f ₃/ f〉5.0 (or 0＜f/f ₃＜0.2)

Work as f ₃/ f ≦ 5.0 o'clock, it is too strong that the shared complete set refracting power of prismatic glasses L3 becomes, the pre-group refracting power is died down, and then make optical full length elongated, so in the full optical system, it is weak that the ratio of the refracting power of prismatic glasses is wanted, more weak positive refracting power is important relatively, revisal for incident angle, the object side of prismatic glasses L3 and imaging side both sides' refracting power for example, distribute toward peripheral with the person center, the aspheric surface that the positive refracting power that blows slowly is strengthened gradually, it is necessary wanting littler towards the incident angle of the light of shooting sub-prime.

(3) work as f ₂/ f ≦ 2.0 o'clock, the refracting power of the second eyeglass L2 can be strong excessively, and the negative refracting power of relative prismatic glasses L3 can be offset, and has hindered incident angle, and the peripheral thickness of the second eyeglass L2 becomes and can't guarantee required form simultaneously, works as f ₂/ f ≧ 11.0 o'clock, the tortuous power of pre-group dies down, and optical full length is also long.

According to photographic lens group of the present invention, look in the distance and to satisfy the relation of (4) 1.2＜T/f＜1.4 than T/f (T is the length of the face (face designation 1) of the object side of the first eyeglass L1 to imaging surface), therefore can guarantee small portableization, each embodiment (being equivalent to comparative example) of the look-ahead technique of above all genus aspect (C) shows with the ratio signal of one to embodiment seven pair of embodiments of the invention;

Learn as subordinate list 1, what any of conditional (1) (2) (3) all can satisfy photographic lens group of the present invention is the represented ratio of looking in the distance of conditional (4), so the small portable characteristic can be reached, and the back focus distance can be guaranteed, for using glass mirror on the look-ahead technique, and the present invention uses glass lens fully, and is very favourable on price, and do not need specific material for employed plastic material.

Photographic lens group of the present invention is incident angle, also be to have to satisfy the performance that is required, promptly be that incident angle is at existing small ccd, the chief ray inclination angle is in 15 °, penetrate by lens set, the necessity that incides the shooting sub-prime has, but the technical progress in the sub-prime field of making a video recording now (the shape change of micromirror) becomes tolerable in 20 ° to 23 ° scope.

Because use the made eyeglass of plastics, be shaped quite easily as the aspheric surface of its point of inflection of prismatic glasses L3.

Photographic lens group of the present invention is very suitable for the use of mobile phone camera lens, also can be used for digital camera.

See also following subordinate list again, subordinate list one is an embodiment of the invention tables of data, and second subordinate list is often to know technical data sheet, can learn effect of the present invention by each data comparison.

Subordinate list two

Claims

1. A three-piece photographic lens set, which is composed of a first lens, an aperture, a second lens and a third lens in sequence from the object side to the imaging side, and is characterized in that:

The first lens is a positive refractive meniscus lens with a convex surface facing the object side;

an aperture, which is arranged behind the first lens;

The second lens is arranged behind the aperture, and it is a positive refractive meniscus lens with a convex side facing the imaging side;

The third lens is arranged behind the second lens, and it is a positive refractive meniscus lens whose convexity faces the object side;

The first lens, the second lens and the third lens are all made of plastic material with the same optical properties, and the combined focal length of the whole series of lenses is f, and the combined focal length of the first lens and the second lens is _f12 , which requires The conditional expression of 1.0<f ₁₂ /f<1.3 is satisfied.

2. The three-piece photographic lens set according to claim 1, characterized in that: the composite focal length of the entire series of lenses is f, and when the focal length of the third lens is f ₃ , it needs to satisfy f/f ₃ Conditional expression >5.0.

3. The three-piece photographic lens set according to claim 1 or 2, characterized in that: the synthetic focal length of the entire series of lenses is f, and when the focal length of the second lens is f ₂ , it needs to satisfy 2.0< The conditional expression of f ₂ /f<11.0.