KR200426481Y1 - Optical system for broadband security camera with special lens arragement - Google Patents

Abstract

The present invention relates to an optical system for a wideband surveillance camera using a special lens array, comprising: a first lens which is a negative ((-) Power) magnification lens having a convex surface on an object side and a concave surface on an image side; A second lens having a positive [(+) Power] magnification lens having a convex surface on an object side and a concave or convex surface on an image side, and formed of an ultra-high refractive special lens; A third lens having a positive ((+) Power] magnification lens having a convex or concave surface on the object side and a convex surface on the image side; A fourth lens which is a positive [(+) Power] magnification lens having convex surfaces on both the object side and the image side; A fifth lens having a negative [(-) Power] magnification lens having a concave surface on the object side and a concave or convex surface on the object side, and formed of an ultra-high refractive special lens; An aperture for selectively converging light incident from the second lens; Technical features of the present invention include an infrared filter for a mega class color sensor arranged in front of the image side of the fifth lens.

According to the present invention, by using and arranging a special spherical lens properly, the resolution of the optical system is greatly increased, and at the same time, it satisfies the optical system that can be used for a wide range of wavelengths regardless of the wavelength. It can be used without any change in image quality, and its spherical configuration enables high resolution performance of mega class as well as shortening optical field, making it easy to install in narrow spaces.

Description

Optical system for broadband surveillance camera {OPTICAL SYSTEM FOR BROADBAND SECURITY CAMERA WITH SPECIAL LENS ARRAGEMENT}

1 is a view showing an optical system characterized by an angle of view of 60 degrees of the arrangement of the optical system for a wideband surveillance camera according to the present invention.

2 is a view showing an optical system characterized by an angle of view of 90 degrees of the arrangement of the optical system for a wideband surveillance camera according to the present invention.

Figure 3 is a view showing an optical system characterized by an angle of view of 110 degrees of the arrangement of the optical system for a wideband surveillance camera according to the present invention.

4A to 4F are diagrams showing aberration characteristics of the optical system forming the 60 degree angle of view of FIG.

5A to 5F are diagrams showing aberration characteristics of the optical system forming the 90-degree field of view of FIG.

6A to 6F illustrate aberration characteristics of the optical system forming the 110-degree field of view of FIG.

Explanation of symbols on the main parts of the drawings

10: first lens 20: second lens

30: third lens 40: fourth lens

50: fifth lens 60: aperture

70: infrared filter 80: window glass

90: imaging device

The present invention relates to an ultra-small spherical optical system for a high-pixel surveillance camera that can be easily mounted in a narrow space and can be used both day and night. More specifically, the spherical special lens can be used appropriately and arranged to cover a wide range of wavelengths. In addition, the present invention relates to an optical system for wideband surveillance cameras using a special lens array that enables high resolution mega-pixel performance without changing the picture quality even when the environment changes day and night.

Existing low-cost surveillance cameras have been mainly used in closed spaces such as parking lots and elevators of apartments or in places where people such as factories are not suitable for direct monitoring, but it was difficult to secure accurate data in case of an accident due to poor image quality. .

In particular, there was a problem that a significant change in image quality occurs by showing a difference in resolution in the environmental changes between day and night.

In addition, the existing spherical lenses used for surveillance cameras have a problem of deteriorating optical performance because the image curvature or distortion is large and the amount of ambient light is significantly reduced to less than 30% to less than 60%. More than 70% of these lenses should be used, which makes it difficult to apply the existing optical system and development of a lens suitable for a CMOS camera has not been made until now.

Furthermore, as the market grows, application fields are diversified and the market demands the development of smaller lenses as well as the improvement of image sensor technology and the superior optical performance.

The present invention has been devised in view of the above problems, and its purpose is to use a spherical special lens in an optical system and arrange it properly so that a change in light in the visible region or light in the infrared region or the rear focal length occurs. It is designed to be used for broadband wavelengths, to be used without changing the image quality even when changing the surrounding environment (day / night), and to create a special lens array that can exhibit mega-resolution high resolution performance even with a spherical configuration. The present invention provides an optical system for a wideband surveillance camera.

In addition, another object of the present invention is a broadband surveillance camera using a special lens array that is designed to form an ambient light ratio of 90% or more, and to resolve the difference in brightness between the center and the surroundings of the lens so that it can be used throughout CCD and CMOS cameras. It is to provide an optical system for.

The present invention for achieving the above object, in the optical system for surveillance cameras composed of a plurality of spherical lenses are arranged and assembled, negative [(-) Power] having a convex surface on the object side and a concave surface on the image side A first lens which is a magnification lens of; A second lens having a positive [(+) Power] magnification lens having a convex surface on an object side and a concave surface or a convex surface on an image side, and formed of an ultra-high refractive special lens; A third lens having a positive ((+) Power] magnification lens having a convex surface or a concave surface on an object side and a convex surface on an image side; A fourth lens which is a positive [(+) Power] magnification lens having convex surfaces on both the object side and the image side; A fifth lens having a negative [(-) Power] magnification lens having a concave surface on the object side and a concave or convex surface on the object side, and formed of an ultra-high refractive special lens; An aperture for selectively converging light incident from the second lens; And an infrared filter for mega color sensors arranged in front of the image side of the fifth lens.

Here, the second lens and the fifth lens are made of any one selected from Hoya's FDS1 lens, Schott's SF58 lens or SF59 lens, Ohara's PBH21 lens, PBH71 lens, and PBH72 lens. .

When the focal length, which is the distance from the first lens to the image, is f, and the rear focal length, which is the distance from the image side surface of the fifth lens to the image, is B, the condition that 1.23 ≦ B / f ≦ 2.09 is satisfied do.

The optical field, which is the distance from the first lens to the fifth lens, is T and the focal length of the entire lens system is f, where T / f ≦ 4.3 is satisfied.

Each of the second lens and the fifth lens is configured to satisfy a condition that a refractive index n is 1.90 ≦ n ≦ 1.95 and a dispersion ratio v is 20 ≦ v ≦ 22.

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

The optical system for surveillance camera using the special lens array of the present invention is composed of three spherical lenses with positive and negative magnification and ultra-high refractive spherical lenses with two special properties with positive and negative magnification. When the change of the resolution is a problem that occurs, and the conventional surveillance cameras by the spherical lens to solve the problem that does not come out of the mega-class resolution.

1 to 3 is a view showing the arrangement according to the field of view characteristics of the optical system for a wideband surveillance camera using a special lens array according to the present invention, Figure 1 is an arrangement state having an angle of view of 60 degrees, Figure 2 3 is an arrangement state having an angle of view characteristic, and FIG. 3 is a view showing an arrangement state having an angle of view characteristic of 110 degrees.

1 to 3, the optical system for a wideband surveillance camera using a special lens array according to the present invention is a lens system formed of five spherical lenses 10, 20, 30, 40, 50, The diaphragm 60 includes an aperture 60, an infrared filter 70, a window glass 80, and an imaging device 90.

The lens system comprises: a first lens (10) which is a negative ((-) Power) magnification lens having a convex surface (R1) on an object side and a concave surface (R2) on an image side; A second lens 20 having a convex surface R3 on the object side and a concave surface or convex surface R4 on the image side, the second lens 20 formed of an ultra-high refractive special lens; A third lens 30 which is a positive [(+) Power] magnification lens having a convex surface or a concave surface R5 on the object side and a convex surface R6 on the image side; A fourth lens 40 which is a positive [(+) Power] magnification lens having convex surfaces R7 and R8 on both the object side and the image side; A fifth (50) magnification lens having a concave surface (R9) on the object side and a concave surface or convex surface (R10) on the image side, and a fifth lens 50 formed of an ultra-high refractive index special lens is sequentially Consisting of arranged arrangements.

In this case, the second lens 20 and the third lens 30 are arranged to be spaced apart at regular intervals with the aperture 60 interposed therebetween, and the fourth lens 40 and the fifth lens 50 are in surface contact with each other. The joint arrangement is made so as to abut, so that the chromatic aberration of the junction can be corrected.

The image side surface R4 of the second lens 20 has a concave surface when forming an angle of view of 60 degrees and 110 degrees as in FIGS. 1 and 3, and a convex surface when forming an angle of view of 90 degrees as in FIG. 2. It is preferable to configure to have.

The object side surface R5 of the third lens 30 has a concave surface when forming an angle of view of 60 degrees as shown in FIGS. 1 and 2, and a convex surface when forming an angle of view of 110 degrees as in FIG. 3. It is preferable to.

The image side surface R10 of the fifth lens 50 has a convex surface when forming an angle of view of 60 degrees and 90 degrees as in FIGS. 1 and 2, and a concave surface when forming an angle of view of 110 degrees as in FIG. 3. It is preferable to configure to have.

The first lens 10 to the fifth lens 50 are all composed of spherical lenses, and in particular, the second lens 20 and the fifth lens 50 are composed of special spherical lenses having ultra high refractive property. By removing the chromatic aberration of the broadband and to minimize the chromatic aberration of the broadband wavelengths, it is configured to have a very high resolution regardless of the wavelength used.

Here, as the first lens 10, a spherical lens having a hardness so as to be very resistant to external environmental changes is used to ensure safety with little scratch or lens damage.

As the third lens 30 and the fourth lens 40, a general high refractive spherical lens was used, and was configured to satisfy the optimization of the overall power and dispersion of the lens system.

As the second lens 20 and the fifth lens 50, special spherical lenses having ultra-high refractive properties were used. These were Hoya's FDS1 lens, Schott's SF58 lens, SF59 lens, It would be desirable to have one selected from Ohara's PBH21 lens, PBH71 lens and PBH72 lens.

In this case, the second lens 20 and the fifth lens 50 have the characteristics of the most compact and thin lens with the correction function of chromatic aberration, which enables the overall miniaturization and weight reduction of the optical system, and the refractive index and dispersion ratio By having the lens shape in consideration, it is possible to eliminate the phenomenon of darkening of the image and to increase the brightness.

The aperture 60 performs a function of selectively converging the light incident from the second lens 20.

The infrared filter 70 is configured as an IR cut-off filter to selectively remove the light of the infrared (IR) area that is unnecessary in color photographing, and is particularly preferably configured for the mega class color sensor.

The window glass 80 is installed between the infrared filter 70 and the imaging device 90 to prevent protection of the imaging device 90 and the inflow of foreign matters.

The imaging device 90 includes a CCD sensor or a CMOS sensor, and converts light into an electrical signal to perform image input.

The present invention as described above is a configuration of a fixed-focus optical system that does not change the light in the visible region, the light in the infrared region, or the back focal length, and includes three general spherical lenses 10 and 30 ( 40) and two ultra-high refractive index spherical lenses 20 and 50 are arranged in combination and distributed at an appropriate magnification to improve aberration correction while at the same time minimizing chromatic aberration of broadband wavelengths. It is designed to have excellent resolution regardless of wavelength.

In addition, in the present invention, the optical length of the optical system is 21mm, the aperture ratio is F / 2.0, and the angle of view (clock angle) is configured to form 60 degrees, 90 degrees, and 110 degrees, and the first lens 10 to the fifth. The lens 40 was designed to satisfy the following conditions 1,2,3.

[Condition 1]

1.23 ≤ B / f ≤ 2.09

The focal length f, which is the distance from the first lens 10 to the image, is f, and the back focal length B, which is the distance from the image side surface of the fifth lens 50 to the image, is B.

[Condition 2]

T / f ≤ 4.3

Here, the distance from the first first lens 10 to the last fifth lens 50 of the optical system is T, and the focal length of the entire lens system is f.

[Condition 3]

1.90≤n≤1.95, 20≤v≤22 [second lens]

1.90 ≦ n ≦ 1.95, 20 ≦ v ≦ 22 [Fifth Lens]

Where n is the refractive index of the lens and v is the dispersion of the lens.

Furthermore, Tables 1 to 3 below show the results of analyzing the radius of curvature, the center interval, the refractive index, the dispersion coefficient (dispersion ratio), and the like of the optical system of the present invention configured by the above-described configuration and conditions. Each optical system data according to the angle of view is shown.

[Table 1] Optical system data with 60-degree field of view

Lens surface Radius of curvature (r) Interval (d) Refractive index (n) Dispersion rate (v) Remarks First side (R1) 1.5751 0.1655 1.7234 37.99 2nd side (R2) 0.5148 0.1825 Page 3 (R3) 1.3392 0.4966 1.9229 20.88 Fourth side (R4) 2.3533 0.1806 iris 0.1020 Page 5 (R5) -1.5751 0.4966 1.6968 55.46 Page 6 (R6) -0.8045 0.0083 Page 7 (R7) 1.7017 0.4304 1.6968 55.46 8th page (R8) -1.0181 0 Joint surface Page 9 (R9) -1.0181 0.0828 1.9229 20.88 Joint surface Page 10 (R10) -3.4597 0.0662 Infrared filter 0.2649 1.5168 64.20 Window glass 0.1242 1.5168 64.20 Image pickup device 0.1986

Here, each of the data is a value normalized to 1.0 mm of effective focal length (EFL).

[Table 2] Optical system data having a 90 degree angle of view

Lens surface Radius of curvature (r) Interval (d) Refractive index (n) Dispersion rate (v) Remarks First side (R1) 12.813 0.2330 1.7234 37.99 2nd side (R2) 0.7855 0.3101 Page 3 (R3) 3.0946 0.6614 1.9229 20.88 Fourth side (R4) -44.356 0.7046 iris 0.0225 Page 5 (R5) -10.046 0.5946 1.6968 55.46 Page 6 (R6) -1.3644 0.0116 Page 7 (R7) 1.8879 0.7521 1.6968 55.46 8th page (R8) -1.1709 0 Joint surface Page 9 (R9) -1.1709 0.1996 1.9229 20.88 Joint surface Page 10 (R10) -8.8917 0.0932 Infrared filter 0.3727 1.5168 64.20 Window glass 0.1747 1.5168 64.20 Image pickup device 0.2796

Here, each of the data is a value normalized to 1.0 mm of effective focal length (EFL).

[Table 3] Optical system data with 110 degree field of view

Lens surface Radius of curvature (r) Interval (d) Refractive index (n) Dispersion rate (v) Remarks First side (R1) 14.733 0.2679 1.7234 37.99 2nd side (R2) 0.9196 0.3712 Page 3 (R3) 3.2369 0.8036 1.9229 20.88 Fourth side (R4) 11.723 1.0437 iris 0.0268 Page 5 (R5) 9.1478 0.6833 1.6968 55.46 Page 6 (R6) -1.7899 0.0134 Page 7 (R7) 1.8975 0.9115 1.6968 55.46 8th page (R8) -1.3065 0 Joint surface Page 9 (R9) -1.3065 0.1339 1.9229 20.88 Joint surface Page 10 (R10) -61.193 0.1071 Infrared filter 0.4286 1.5168 64.20 Window glass 0.2009 1.5168 64.20 Image pickup device 0.3214

Here, each of the data is a value normalized to 1.0 mm of effective focal length (EFL).

The present invention has a focal length measurement of the entire lens system with a resolution measurement, an effective mirror, and a spherometer measured by a PROFILE PROJECTOR, f the rear focal length B, and the first first lens 10 of the optical system. When the distance from the last fifth lens 50 to T, the angle of view measured value θ by the projector, and the center (CR) and the periphery (PR) of the resolution measured value are the ratio (f / dl = F / 2.0) It can be seen that the lens shape and the lens arrangement of the optical system according to the present invention satisfy all of the conditions 1, 2, and 3 described above.

That is, [condition 1]

1.23 ≤ B / f ≤ 2.09,

[Condition 2]

With T / f ≤ 4.3,

[Condition 3]

1.90≤n≤1.95, 20≤v≤22 [second lens]

1.90? N? 1.95 and 20? V? 22 [Fifth Lens] are satisfied.

Therefore, the optical system for a wideband surveillance camera using a special lens array according to the present invention exhibits optical performance having an optical field length of 21 mm, an aperture ratio F / 2.0 and an angle of view (view angle) of 60 degrees / 90 degrees / 110 degrees.

On the other hand, Figures 4a to 6f is an analysis graph showing the aberration characteristics of the optical system for a wideband surveillance camera using a special lens array having an angle of view of 60 degrees, 90 degrees and 110 degrees in the present invention.

4A, 5A, and 6A show meridian aberrations and spherical aberrations at regions 0, 0.7, and 1.0 on the optical axis, respectively. : Astigmatism of Tangential Field Curvature) and Sagittal Field Curvature (S), FIG. 4C, FIG. 5C, and FIG. 6C show Distortion, and FIG. 4D, FIG. 5D, and FIG. FIG. 6D shows Lateral Color Aberration, FIGS. 4E and 5E and 6E show Longitudinal Spherical Average, and FIGS. 4F and 5F and 6F show Chromatic Focal Shift. The relationship is shown.

As shown in the analysis graphs of FIGS. 4A to 6F, the optical system for a wideband surveillance camera using a special lens array according to the present invention shows the values of images in almost all fields adjacent to the axis, such as spherical aberration or meridian aberration, It shows that the correction of the percentage distortion and chromatic aberration is good, and that the design is very effective with improved brightness.

In particular, it shows that there is almost no change in focal length at broadband wavelengths, which means that it can be used regardless of the wavelength, and that a high-pixel fixed-focus optical system is designed, and it is an auto focus system day or night. Mega-quality image quality can be achieved even at fixed focus without additional devices.

In addition, in view of the fact that the distortion aberration in the optical system is minimized when the image distance and the object distance are similar, the conventional optical system corrects the distortion aberration by adjusting the shape of the lens, the arrangement of the refractive power, and the position of the aperture. In the present invention, by properly arranging two special spherical lenses having the properties of ultra-high refractive properties, it is possible to improve the correction state of spherical aberration and meridian aberration and improve brightness.

As described above, according to the optical system for a wideband surveillance camera using a special lens array according to the present invention, by using and arranging a special spherical lens, the resolution of the optical system is greatly increased, As it satisfies the optical system that can be used, it can be used without changing the image quality even when changing the surrounding environment (day / night), and the spherical configuration not only shows mega-resolution high resolution performance but also the optical field is shortened and the space is narrow. Ease of installation is also possible, which provides usefulness for a wide range of applications.

In addition, the present invention minimizes chromatic aberration even at a wide-band wavelength, enabling perfect mega-class image quality even at fixed focus without additional device of auto focus system, and the ambient light ratio forms more than 90%. The difference in brightness around them can be eliminated, making it useful for CCD and CMOS cameras.

Claims (5)

An optical system for surveillance cameras comprising a plurality of spherical lenses arranged in an array; A first lens which is a negative ((-) Power) magnification lens having a convex surface on an object side and a concave surface on an image side; A second lens having a positive [(+) Power] magnification lens having a convex surface on an object side and a concave surface or a convex surface on an image side, and formed of an ultra-high refractive special lens; A third lens having a positive ((+) Power] magnification lens having a convex surface or a concave surface on an object side and a convex surface on an image side; A fourth lens which is a positive [(+) Power] magnification lens having convex surfaces on both the object side and the image side; A fifth lens having a negative [(-) Power] magnification lens having a concave surface on the object side and a concave or convex surface on the object side, and formed of an ultra-high refractive special lens; An aperture for selectively converging light incident from the second lens; And an infrared filter for mega-class color sensors arranged in front of the image side of the fifth lens. The method of claim 1, The second lens and the fifth lens are any one selected from Hoya's FDS1 lens, Schott's SF58 lens or SF59 lens, Ohara's PBH21 lens, PBH71 lens and PBH72 lens; And said second and fifth lenses each satisfy a condition that a refractive index n is 1.90 ≦ n ≦ 1.95 and a dispersion ratio v is 20 ≦ v ≦ 22. The method of claim 1, When a focal length that is the distance from the first lens to the image is f and a rear focal length that is the distance from the image side surface to the image of the fifth lens is B, An optical system for a wideband surveillance camera, characterized by satisfying a condition of 1.23? B / f? 2.09. The method of claim 1, When the optical length that is the distance from the first lens to the fifth lens is T and the focal length of the entire lens system is f, An optical system for a wideband surveillance camera, characterized by satisfying a condition of T / f ≦ 4.3. delete

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