KR100616647B1 - Lens System For Camera Module - Google Patents

Abstract

The present invention is used in a camera module having at least one lens provided inside the housing, an image sensor corresponding to the imaging surface by the lens, and an optical filter for filtering the light incident on the image sensor or protecting the image sensor. The present invention relates to a lens system for a camera module, wherein the optical path is made of only a material having a refractive index higher than that of air, thereby achieving excellent optical performance and having a small number of lenses.

The lens system for the camera module is characterized in that the entire optical path from the object-side refractive surface of the first lens to which the light is incident to the optical filter is made of a material having a refractive index larger than that of air.

According to the present invention, the optical performance is excellent, such as the implementation of a high resolution, a large field of view, it is possible to implement a compact lens system that is compact compared to the same optical performance.

Media, refractive index, optical path, MTF, fluid

Description

Lens System For Camera Module             

1 is a cross-sectional view of a lens system for a camera module according to a first embodiment of the present invention.

   (a) is a cross sectional view when the object is at an infinite position,

   (b) is a sectional view of the auto-focused state when the object is 10 cm away.

2 (a) and 2 (b) are MTF curves of the lens system shown in FIG. 1 (a).

3 is an MTF curve of the lens system shown in FIG. 1 (b).

4 is a cross-sectional view of a lens system for a camera module according to a second embodiment of the present invention;

   (a) is a cross sectional view when the object is at an infinite position,

   (b) is a sectional view of the auto-focused state when the object is 10 cm away.

FIG. 5 is an MTF curve of the lens system shown in FIG. 4 (b).

6 is a cross-sectional view of a lens system for a camera module according to a third embodiment of the present invention;

   (a) is a cross sectional view when the object is at an infinite position,

   (b) is a sectional view of the auto-focused state when the object is 10 cm away.

FIG. 7 is an MTF curve of the lens system shown in FIG. 6 (a).

8 is an MTF curve of the lens system shown in FIG. 6 (b).

9 is a cross-sectional view of a lens system for a camera module according to a fourth embodiment of the present invention.

FIG. 10 is an MTF curve of the lens system shown in FIG. 9.

11 is a cross-sectional view of a lens system for a camera module according to a fifth embodiment of the present invention.

12 (a) and 12 (b) are MTF curves of the lens system shown in FIG.

13 is a cross-sectional view of a lens system for a camera module according to a sixth embodiment of the present invention.

14 (a) and 14 (b) are MTF curves of the lens system shown in FIG.

15 is a cross-sectional view of a lens system for a camera module according to a seventh embodiment of the present invention.

16 (a) and 16 (b) are MTF curves of the lens system shown in FIG.

Explanation of symbols on the main parts of the drawings

L1 ... first lens L2 ... second lens

L3 ... Third lens M1 ... First intermediate material

M2 ... Second Mediating Material M3 ... Second Mediating Material

S ... Spacer H ... Housing

OF ... optical filter IS ... image sensor

E ... Extension 110 ... Inlet

120 Groove 121 Volume change receiver

130 euros

The present invention relates to a lens system used in a camera module using a high-resolution image sensor, and more particularly, by making the entire optical path made of a material having a refractive index higher than that of air, the lens having a small number of lenses while achieving excellent optical performance It's about the system.

Recently, a camera module for a communication terminal, a digital still camera (DSC, digital still camera), a camcorder, and a PC camera (image pickup device included with a personal computer) have been studied in relation to an image pickup system. The most important component for the camera module associated with such an image pickup system to obtain an image is a lens system that forms an image.

Since the image pickup system described above requires high performance in terms of resolution, image quality, and the like, the configuration of the lens is complicated. However, when the composition / optical complexity is such, the size of the image pickup system is increased, which is contrary to miniaturization / thinning. There is this.

In particular, in the case of a small camera module, there is a limit in the number of lenses that can be provided in a limited space in the module, there is a problem that can not implement sufficient optical performance with a small number of lenses.

On the other hand, the lens system for a conventional camera module arranges lenses having a specific refractive power in order from the object side, the space between the lenses is made of air, and the image is obtained by using a plane sensor on the upper surface.

In the case of such a conventional lens system, the incident light beam passes through the lens and enters an empty space (air-filled space) between the lenses, or the light beam is refracted at a large angle when it is re-entered from the air into the lens. As a result, the aberration is greatly increased as well as the reflectance is increased, thereby lowering the optical performance of the lens system.

In addition, a lens system for a camera module using a planar image pickup device generally has a problem that an angle of view that can be taken is limited to about 60 °.

An object of the present invention is to provide a lens system for a camera module that can obtain a large angle of view and high resolution, and is compact and excellent in optical performance by reducing the difference in refractive index on an optical path.

In addition, an object of the present invention is to provide a lens system that can be applied to various camera modules by performing the auto focus or zoom function.

As one aspect for achieving the above object, the present invention, at least one lens provided in the housing, the image sensor corresponding to the image forming surface by the lens and the light incident on the image sensor or filtering the image sensor A lens system for use in a camera module having an optical filter for protecting the lens, wherein the entire optical path from the object-side refractive surface of the first lens to which the light is incident to the optical filter is made of a material having a refractive index larger than that of air. Provide a system.

Preferably, the space between the lens and the lens and the space between the lens and the optical filter are filled with a medium having a refractive index greater than that of air, and more preferably, the medium is a fluid having a refractive index larger than that of air.

Also, preferably, the entire optical path from the object-side refractive surface of the first lens to which the light is incident to the optical filter may be made of only a junction lens and an optical filter having a larger refractive index than air.

More preferably, the imaging surface and the surface of the image sensor corresponding to the imaging surface may be formed as a curved surface.

It is also preferred that an aperture stop be provided after the first lens on the light path.

In another aspect, the present invention includes at least one lens provided inside the housing, an image sensor corresponding to an image plane formed by the lens, and an optical filter for filtering light incident to the image sensor or protecting the image sensor. In the lens system used in the camera module, the entire optical path from the object-side refractive surface of the first lens to which the light is incident to the optical filter is made of a material having a refractive index larger than that of air, and for performing the auto focus or zoom function. The space in which the lens or the image sensor is transported is provided with a lens system for a camera module, characterized in that made of a medium in a fluid state having a refractive index larger than that of air.

Preferably, the housing includes an expansion and contraction portion that expands or contracts in the optical axis direction while receiving the fluid therein and elastically deforming in a direction perpendicular to the optical axis as the lens or image sensor moves. And stretching to maintain the fluid between the lens and the lens or between the lens and the optical filter.

Also preferably, a flow path for moving the fluid back and forth when a pressure is applied to the fluid by the movement of the lens or the image sensor may be formed.

In another aspect, the present invention provides a lens system for use in a camera module having at least two or more lenses spaced apart inside a housing and an image sensor corresponding to an imaging surface by the lens, the space between the lens and the lens. Provides a lens system for a camera module, which is filled with a medium in a fluid state having a refractive index greater than that of air.

Preferably, it may be provided with a volume change accommodating portion that elastically deforms according to the volume change of the fluid to absorb the volume change of the fluid according to the temperature change to maintain a stable space between the lens and the lens.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a first embodiment of the present invention, Figure 1 (a) is a cross-sectional view when the object is in an infinite position, Figure 1 (b) is an auto-focused state when the object is at a distance of 10 cm It is a cross section of. In the cross-sectional views of the following embodiments, the thickness, size, and shape of the lenses are somewhat exaggerated for the sake of explanation, and in particular, the spherical or aspherical shapes shown in the cross-sectional views are presented as an example and are not limited thereto.

In general, the camera module includes at least one lens (L1, L2, L3), a housing (H) for accommodating the lens (L1, L2, L3) is formed in a predetermined space therein, The image sensor IS corresponding to the image plane 9 by the lenses L1, L2, and L3 and the light incident to the image sensor IS may be filtered or may be protected. An optical filter OF and a circuit board (not shown) fixedly installed at the other end of the housing H and having the image sensor IS mounted on one surface thereof to process an image detected by the image sensor IS. The present invention relates to a lens system used in such a camera module.

The present invention is characterized in that in the lens system for the camera module, the entire optical path from the object-side refractive surface 1 to the optical filter OF of the first lens L1 to which light is incident is made of a material having a refractive index larger than that of air. There is this.

That is, in the related art, the space between the lens and the lens is made of air, so light is refracted at a large angle at the interface between the air and the lens having a larger refractive index than air, thereby increasing aberration and increasing reflection, thereby degrading the optical performance of the lens system. In the case of the invention, it is possible to implement a lens system having excellent optical performance by eliminating the space between such lenses or the air space between the lens and the optical filter.

Here, in order to make the entire optical path from the object-side refractive surface of the first lens into which the light is incident to the optical filter is made of a material having a refractive index larger than that of air, the space between the lenses or the space between the lens and the optical filter has a higher refractive index than air. It can be filled with large mediators, or it can be configured to consist of a combined lens and optical filter throughout the light path.

As such a mediator, water, a refractive index control oil, or a fluid to which an additive is added may be used. Examples 1 to 5, which will be described later, are cases where a mediator in a fluid state having a larger refractive index than air is used.

Meanwhile, when a solid material such as a thermosetting or photocurable polymer material, a thermoplastic polymer material, a highly transparent plastic, glass, or ceramic material is used as the medium material, the medium material part is the same as in Examples 6 and 7 to be described later. It functions in the same manner as the bonded lens bonded to the lens.

In this case, the optical path from the first lens L1 to the optical filter OF is composed only of the bonding lens and the optical filter OF having a larger refractive index than air.

On the other hand, the optical filter (OF) is composed of an infrared filter, a cover glass for protecting the image sensor (IS), a color filter, and the like, in principle does not affect the optical properties of the present invention.

The optical filter OF may be coated on the image refracting surface 7 of the third lens L3 illustrated in FIG. 1 to perform the function, and the coating surface may also belong to the optical filter OF of the present invention. I will see.

In addition, the image sensor IS is made of a Charged Coupled Device (CCD), a Complementally Metal Oxide Semiconduct (CMOS), a polymer, and the like, and receives an image formed by a lens. Corresponding to the upper surface (photosensitive surface) 9 is disposed behind the optical filter OF.

Hereinafter, a numerical embodiment of the present invention will be described in more detail. In the following embodiments, description of the same or similar parts will be omitted to avoid unnecessary duplication.

Example 1

As shown in Fig. 1, the lens system according to the first embodiment of the present invention has an aperture stop AS closest to the object side, and then the first lens L1 in order from the object side. , The first mediator M1, the second lens L2, the second mediator M2, the third lens L3, the third mediator M3, the optical filter OF, the image sensor IS Is provided, the connecting portion (M3 ') is connected to the third intermediate material portion (M3) is formed on the back of the image sensor (IS).

In the first embodiment of the present invention, the entire optical path from the object-side refractive surface 1 to the optical filter OF of the first lens L1 to which light is incident is made of a material having a refractive index larger than that of air. The space between the first lens L1 and the second lens L2, between the second lens L2 and the third lens L3, and between the third lens L3 and the optical filter OF is greater than that of air. Fill with medium with high refractive index.

As the mediator, as described above, a solid material such as a thermosetting or photocurable polymer material, a thermoplastic polymer material, a highly transparent plastic, glass, or ceramic material may be used. In this case, the intermediate material portion functions as a bonding lens, and the optical path from the first lens L1 to the optical filter OF may be regarded as only the bonding lens and the optical filter OF having a larger refractive index than air.

In addition, it is possible to use water, a refractive index oil, or a fluid added with an additive.

In the case of using such a liquid material in a fluid state, as shown in FIG. 1, spacers S are installed in the circumferential direction on the outer portion of the lens to form a closed space between the lens and the lens or between the lens and the optical filter OF. do. That is, the mediators M1, M2, and M3 become spaces partitioned by the spacer S and the lens / optical filter OF.

In addition, the injection path 110 is installed in the housing H and connected to the mediators M1, M2, and M3, and after the fluid is injected through the injection path 110, the injection path 110 is sealed. do.

Preferably, since the volume of the injected fluid changes due to temperature change, the volume change accommodating part 121 may be provided as shown in the enlarged part of FIG.

The volume change accommodating part 121 may be elastically deformed to absorb the volume change of the fluid at the same time as closing the injection passage 110 and may use a damper film.

That is, when the volume of the fluid decreases, the volume change receiving portion 121 deforms downward, and when the volume of the fluid increases, the volume change receiving portion 121 deforms upwards to change the volume of the fluid. Absorption keeps the fluid in the media material section stable.

In addition, the recess 120 may be formed to accommodate the volume change accommodating part 121 to protect the volume change accommodating part 121 from the outside.

In the case of injecting the intermediate material as described above, it is possible to reduce the cost and easily produce the lens having a shape corresponding to the space between the lens and the lens.

FIG. 1 (b) shows the automatic focusing function implemented according to the first embodiment of the present invention. When the subject is at a distance of 10 cm, the image sensor IS and the optical filter OF are controlled. ) Shows a moved state.

In order to implement the function of the automatic focusing as described above, a fluid is used as a mediator in the space portion, ie, the third mediator M3, which is transported for autofocusing, and additionally, a known operation unit is provided.

When the image sensor IS or the like is moved as shown in FIG. 1B, flow paths 130 and 130 ′ must be formed so that the fluid in the third intermediate material portion M3 can move to the connection portion M3 ′. . The flow paths 130 and 130 ′ may be installed in the housing H, or may be installed through the unused portion of the outer portion of the image sensor IS.

As such, when the image sensor IS moves toward the object side by forming the flow paths 130 and 130 ′, pressure is applied to the fluid to move the fluid from the third intermediate material portion M3 to the connection portion M3 ′. When the image sensor IS is moved in the opposite direction to the object side, the fluid moves from the connection part M3 'to the third intermediate material part M3.

On the other hand, the image sensor IS is preferably sealed so as not to contact the fluid.

In addition, the image sensor IS and the optical filter OF are preferably formed by bonding. However, since the angle of the light beam passing through the optical filter OF is small, the optical performance difference due to the difference in refractive index is different even though it passes through the air layer. The optical filter OF and the image sensor IS may be separately installed in that they are not large.

Although FIG. 1 (b) relates to the case of auto focusing, it is also applicable to a lens system which performs a zoom function.

In a conventional lens system for a camera module, the space between the lenses consists of air, in which case the incident light beam passes through the lens and enters an empty space (air-filled space) between the lenses or the light beam is again in the air. When the light is reincident to the lens, the light beam is refracted at a large angle, thereby increasing the aberration and increasing the reflectance, thereby degrading the optical performance of the lens system.

However, in the lens system according to the first embodiment and the following embodiment according to the present invention, the angle of light is large by reducing the difference in refractive index between each interface by filling this empty space with a lens or a medium having a refractive index larger than that of air. It is possible to realize excellent optical properties by preventing aberration, reducing aberration, lowering reflectance and preventing total reflection.

In addition, by varying the refractive index of each of the media (M1, M2, M3) can be implemented a lens system with further improved optical performance.

In this case, the degree of freedom to adjust the optical properties can be obtained by using the dispersion properties or the refractive index of the media material. Thus, even if a small number of lenses are used, improved optical performance can be realized. There is an advantage.

Table 1 below shows a numerical example according to the first embodiment of the present invention.

The aspherical surface used in each of the following examples is obtained from well-known Equation 1, and the 'E and subsequent numbers' used for the Conic constant (K) and the aspherical coefficients (A, B, C, D). Represents a power of 10. For example, E-05 represents the 10 ^-5.

Z: Distance from the vertex of the lens to the optical axis direction

Y: distance in the direction perpendicular to the optical axis

r: radius of curvature at the vertex of the lens

K: Conic constant

A, B, C, D: Aspheric coefficient

In the first embodiment, the F number is 2.8, the overall length TL from the object-side refracting surface of the first lens to the image surface is 7.0 mm, and the total angle 2ω of the lens is 60 °. The height of the phase is 2.6 mm.

In Table 1, * represents an aspherical surface, and the values of the koenic constant (K) and the aspherical coefficients (A, B, C, and D) according to Equation 1 are shown in Table 2 below. That is, the second surface (object side of the first lens), the third surface (image side of the first lens), the fourth surface (object side of the second lens), the fifth surface (image side of the second lens), The sixth surface (object side surface of the third lens) and the seventh surface (image side surface of the third lens) are aspherical surfaces.

As shown in FIG. 1B, when the auto focusing is performed on an object 10 cm away, the distance between the seventh and eighth surfaces is changed from 1.0401 mm to 1.0953 mm.

2 (a) and 2 (b) are the MTF curves of the lens system shown in Fig. 1 (a), which are at least 280 cycles / mm (30% MTF) at 40 ° to 60 ° at a telephone angle of up to 40 °. In full-angle, it shows excellent resolution over 220 cycles / mm (30% MTF).

FIG. 3 is the MTF curve of the lens system shown in FIG. 1 (b), showing excellent resolution of 210 cycles / mm (30% MTF) or more at a telephone angle up to 60 °.

Here, MTF (Modulation Transfer Function) depends on the spatial frequency of the cycle per millimeter, and is a value defined by the following equation (2) between the maximum intensity (Max) and the minimum intensity (Min) of light.

In the following embodiments, description of the same or similar parts will be omitted to avoid unnecessary duplication.

Example 2

Figure 4 is a second embodiment of the present invention, Figure 4 (a) is a cross-sectional view when the object is in an infinite position, Figure 4 (b) is an auto-focused state when the object is at a distance of 10 cm It is a cross section of.

The second embodiment shown in FIG. 4 is different from the first embodiment except that the housing E is provided with the elastic part E, and the part after the third lens L3 is moved for auto focusing. same.

The second embodiment is a case in which the distance between the lens and the lens is changed for auto focusing, and the thickness on the optical axis of the intermediate material portion M2 provided between the lens and the lens is changed.

The expansion and contraction portion E seals the fluid in the second intermediate material portion M2 and expands or contracts in the optical axis direction while being elastically deformed in a direction perpendicular to the optical axis as the third lens L3 moves. .

The fluid in the second intermediate material portion M2 is held between the second lens L2 and the third lens L3 by the deformation in the direction perpendicular to the optical axis of the expansion and contraction part E and the expansion and contraction in the optical axis direction. It becomes possible.

5 is an MTF curve of the lens system shown in FIG. 4 (b), and the MTF curve corresponding to FIG. 4 (a) is shown in FIGS. 2 (a) and 2 (b).

In addition, the numerical example by a 2nd Example is as Table 1 and Table 2 which showed the numerical example of the said 1st Example. However, as shown in FIG. 4 (b), when the auto focus is performed on an object 10 cm away, the distance between the fifth and sixth surfaces is changed from 1.8000 mm to 1.8912 mm due to the movement of the third lens L3. do.

Example 3

FIG. 6 is a third embodiment of the present invention, and FIG. 6 (a) is a cross sectional view when the object is at an infinite position, and FIG. 6 (b) is autofocused when the object is at a distance of 10 cm. It is a cross section of.

As shown in FIG. 6, the lens system according to the third exemplary embodiment of the present invention includes the first lens L1, the first intermediate material part M1, the aperture stop AS, and the second lens in order from the object side. L2), the second mediator M2, the third lens L3, the third mediator M3, the optical filter OF, and the image sensor IS.

In the case of the third embodiment, the optical filter is separated into a first optical filter OF1 and a second optical filter OF2 in order to implement the auto focusing function, and the first optical filter OF1 is connected to the third media material portion M3. ), And the portion after the second optical filter OF2 or before the first optical filter OF1 is moved during auto focusing.

On the other hand, the lens system according to the third embodiment shown in Figure 6 has a curved image forming surface 11, the surface of the image sensor (IS) corresponding to the image forming surface 11 is a curved surface.

When the curved image sensor IS is used as described above, the surface of the image sensor IS serves as one lens surface, so the number of lenses for realizing the same optical performance is reduced, thereby making the lens compact. The advantage is that the system can be implemented.

That is, the combination of the optical properties of the medium and the lens, the use of the curved image sensor IS, and the proper arrangement of the aperture stop AS enable the implementation of a lens system having excellent optical properties.

Table 5 below shows numerical examples according to the third embodiment of the present invention.

In the third embodiment, the F number is 2.8, the overall length TL from the object-side refracting surface of the first lens to the image surface is 7.0 mm, and the total angle 2ω of the lens is 60 °. The height of the image is 2.7 mm and the length of the image on the curved surface is 2.8 mm.

In Table 3, * represents an aspherical surface, and the values of the koenic constant (K) and the aspherical coefficients (A, B, C, and D) according to Equation 1 are shown in Table 4 below. That is, the first surface (object side of the first lens), the second surface (image side of the first lens), the sixth surface (object side of the third lens) and the seventh surface (image side of the third lens) Aspheric

FIG. 7 is an MTF curve of the lens system shown in FIG. 6 (a), and FIG. 8 is an MTF curve of the lens system shown in FIG. 30% MTF), 280 cycles / mm (30% MTF) or better.

As shown in FIG. 6 (b), when the auto focus is performed on an object at a distance of 10 cm, the distance between the ninth and tenth surfaces is changed from 0 mm to 0.26 mm due to the movement of the second optical filter OF2. .

Example 4

9 is a sectional view of a lens system according to a fourth embodiment of the present invention.

As shown in FIG. 9, the lens system according to the fourth embodiment of the present invention includes the first lens L1, the first intermediate material portion M1, the aperture stop AS, and the second lens in order from the object side. L2), the second intermediate material portion M2, the optical filter OF and the image sensor IS.

The fourth embodiment relates to a lens system capable of realizing a 90 degree telephoto angle, and through a first lens L1 protruding toward an object side and an aperture diaphragm AS provided after the first lens L1. A 90 ° telephony angle is difficult to achieve in a typical micro lens system.

Such a wide field of view is implemented through the medium material portion M1 having a larger refractive index than air, and since the first lens L1 and the first medium material portion M1 have a large refractive index, light having a wide angle of incidence may be aperture aperture AS. ) To help them pass through.

In addition, since a curved image sensor (IS) is used, a wider angle of view may be realized than when a planar image sensor is used, and a lens system having a telephone angle of 180 ° or more may be implemented through a design change.

Table 5 below shows numerical examples according to the fourth embodiment of the present invention.

In the fourth embodiment, the F number is 2.8, the overall length TL from the object-side refracting surface of the first lens to the image surface is 6.2 mm, and the full-angle angle 2ω of the lens is 90 °. The height of the phase is 2.7 mm and the length of the phase on the curved surface is 3.0 mm.

In Table 5, * represents an aspherical surface, and the values of the koenic constant (K) and the aspherical coefficients (A, B, C, and D) according to Equation 1 are shown in Table 6 below. That is, the first surface (object side surface of the first lens) and the second surface (image side surface of the first lens) are aspherical surfaces.

FIG. 10 is an MTF curve of the lens system shown in FIG. 9, showing excellent resolution of at least 135 cycles / mm (30% MTF) for a telephone angle up to 90 °.

Example 5

11 is a sectional view of a lens system according to a fifth embodiment of the present invention.

As shown in FIG. 11, the lens system according to the fifth exemplary embodiment of the present invention includes the first lens L1, the aperture stop AS, the second lens L2, and the first intermediate material part in order from the object side. M1), an optical filter OF and an image sensor IS.

In this case, the aperture stop AS is disposed between the first lens L1 and the second lens L2, and the aperture stop AS is bonded together when the first lens L1 and the second lens L2 are manufactured. You can make

In the fifth exemplary embodiment, the optical path from the refractive surface of the first lens L1 to the optical filter OF is greater than that of air because the first lens L1 and the second lens L2 are formed as a bonded lens. It is made of a material having a high refractive index.

The fifth embodiment relates to a lens system capable of realizing a very large telephone angle of 140 to 170 °, and includes an aperture diaphragm AS provided after the first lens L1 and the first lens L1 protruding toward the object side. ), It realizes a tele-angle of more than 90 ° which is difficult to realize in general micro lens system.

The first lens L1 collects light having a wide angle of incidence to pass through the aperture stop AS. Since the curved image sensor IS is used, the first lens L1 has a wider angle of view than when a flat image sensor is used. Implementation of.

Table 7 below shows numerical examples according to the fifth embodiment of the present invention.

In the fifth embodiment, the F number is 2.8, the overall length from the object-side refracting surface of the first lens to the image surface is 5.9 mm, and the image when the full-angle (2ω) of the lens is 140 °. The height is 3.8 mm and the length of the curved phase is 5.0 mm. In addition, when the full-angle (2ω) of the lens is 170 degrees, the image height is 4.2 mm, and the length of the curved image is 6.2 mm.

In Table 7, * represents an aspherical surface, and the values of the koenic constant (K) and the aspherical coefficients (A, B, C, and D) of Equation 1 are shown in Table 8 below. That is, the first surface (object side surface of the first lens) is an aspherical surface.

12 (a) and 12 (b) are the MTF curves of the lens system shown in FIG. 11, showing excellent resolution of over 120 cycles / mm (30% MTF) for a telephony angle up to 140 ° and 170 ° Although slightly different for telephony angles up to 30 cycles / mm (30% MTF), resolutions of up to 170 ° are possible.

Example 6

13 is a sectional view of a lens system according to a sixth embodiment of the present invention.

As shown in FIG. 13, the lens system according to the sixth embodiment of the present invention includes the first lens L1, the aperture stop AS, the second lens L2, and the third lens L3 in order from the object side. ), An optical filter (OF) and an image sensor (IS).

In this case, the aperture stop AS is disposed between the first lens L1 and the second lens L2, and the aperture stop AS is bonded together when the first lens L1 and the second lens L2 are manufactured. You can make

In the sixth exemplary embodiment, the first lens L1, the second lens L2, and the third lens L3 are formed as a bonded lens without using an intermediate material, whereby light of the first lens L1 is incident. A lens system in which the optical path from the refractive surface to the optical filter OF is made of a material having a refractive index larger than that of air.

The sixth embodiment shows that a very large telephone angle of 120 ° can be realized, and Table 9 shows a numerical example according to the sixth embodiment of the present invention.

In the sixth embodiment, the F number is 2.8, the overall length TL from the object-side refracting surface of the first lens to the image surface is 5.0 mm, and the telephone angle 2ω of the lens is 120 °. The height of the image is 2.8 mm and the length of the image on the curved surface is 3.4 mm.

In Table 9, * represents an aspherical surface, and the values of the koenic constant (K) and the aspherical coefficients (A, B, C, and D) of Equation 1 are shown in Table 10 below. That is, the first surface (object side surface of the first lens) is an aspherical surface.

14 (a) and 14 (b) are the MTF curves of the lens system shown in FIG. 13, showing excellent resolution of 160 cycles / mm (30% MTF) or more for a telephone angle up to 120 °.

Example 7

15 is a sectional view of a lens system according to a seventh embodiment of the present invention.

As shown in Fig. 15, the lens system according to the seventh embodiment of the present invention includes the first lens L1, the aperture stop AS, the second lens L2, and the optical filter OF in order from the object side. An image sensor IS is provided.

Like the sixth embodiment, the seventh embodiment does not use an intermediate material and is formed by bonding the first lens L1 and the second lens L2 to each other so that the light is incident from the refractive surface of the first lens L1. It is a lens system that allows the optical path to the optical filter (OF) to be made of a material having a refractive index larger than that of air.

In addition, the seventh embodiment shows that a lens system using only a spherical lens can realize a very large telephone angle of 120 to 170 degrees.

Table 11 below shows numerical examples according to the seventh embodiment of the present invention.

In the seventh embodiment, the F number is 2.8, the overall length TL from the object-side refracting surface of the first lens to the image surface is 4.9 mm, and the telephone angle 2ω of the lens is 120 °. When the height of the image is 2.7 mm, the length of the image on the curved surface is 3.3 mm.

16 (a) and 16 (b) are the MTF curves of the lens system shown in FIG. 15, and in FIG. 16 (a) excellent resolution of 150 cycles / mm (30% MTF) or more for a telephone angle of up to 80 °. can confirm.

In addition, in FIG. 16 (b), 120 cycles / mm (30% MTF) and 70 cycles / mm (30% MTF) or more for the telephone angle h2 up to 120 ° and the telephone angle h4 up to 160 °, respectively. The resolution can be confirmed, but the resolution is somewhat lower, but the resolution of 40 cycles / mm (30% MTF) even for a 170 ° telephone angle (h5), it can be seen that it is possible to implement a telephone angle up to 170 °.

As described above, according to the present invention, the entire optical path is filled with a material having a refractive index greater than that of air to reduce the difference in refractive index between the interfaces, thereby preventing light from being refracted at a large angle, thereby improving the aberration, lowering the reflectance, and total reflection. Since it can prevent, the effect which can implement | achieve the outstanding optical performance is acquired.

As another aspect, by using a curved imaging surface, high resolution can be realized, and the number of lenses can be reduced, so that a compact and compact lens system can be realized as compared to a system having the same optical performance as in the prior art.

In addition, the present invention has an effect that can be applied to a variety of lens systems in that a large angle of view can be obtained by using the intermediate material, and auto focusing or zooming can be performed.

While the invention has been shown and described with respect to particular embodiments, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention as set forth in the claims below. I want to make it clear.

Claims (11)

Lens system used in a camera module having at least one lens provided in the housing, an image sensor corresponding to the image plane by the lens and an optical filter for filtering the light incident on the image sensor or to protect the image sensor To The entire optical path from the object-side refractive surface of the first lens to which the light is incident to the optical filter is made of a material having a refractive index larger than that of air. The imaging system and the surface of the image sensor corresponding to the imaging surface is a lens system for a camera module, characterized in that the curved surface. The method of claim 1, And the space between the lens and the lens and the space between the lens and the optical filter are filled with a medium having a refractive index greater than that of air. The method of claim 2, The media material is a lens system for a camera module, characterized in that made of a fluid having a larger refractive index than air. The method of claim 1, A lens system for a camera module, wherein the entire optical path from the object-side refractive surface of the first lens to which the light is incident to the optical filter is composed of only a spherical lens and an optical filter having a larger refractive index than air. delete The method of claim 1, A lens system for a camera module, characterized in that an aperture stop is provided after the first lens on the optical path. Lens system used in a camera module having at least one lens provided in the housing, an image sensor corresponding to the image plane by the lens and an optical filter for filtering the light incident on the image sensor or to protect the image sensor To The entire optical path from the object-side refractive surface of the first lens to which the light is incident to the optical filter is made of a material having a refractive index larger than that of air, The space to which the lens or the image sensor is transferred to perform the auto focusing or zooming function is made of a fluid medium having a refractive index larger than that of air. The housing includes an expansion and contraction portion for accommodating the fluid therein and extending or contracting in the optical axis direction while being elastically deformed in a direction perpendicular to the optical axis as the lens or image sensor moves. And the fluid is retained between the lens and the lens or between the lens and the optical filter by the expansion and contraction of the expansion and contraction portion. delete The method of claim 7, wherein And a flow path for moving the fluid back and forth when pressure is applied to the fluid by the movement of the lens or the image sensor. A lens system for use in a camera module having at least two or more lenses spaced apart inside a housing and an image sensor corresponding to an imaging surface by the lens, The space between the lens and the lens is filled with a fluid medium having a refractive index larger than that of air. A lens module for a camera module, comprising: a volume change receiving portion elastically deformed according to a volume change of a fluid so as to absorb a volume change of the fluid according to a temperature change and maintain a stable space between the lens and the lens. . delete

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