KR20240048496A - Lens system for infrared rays - Google Patents

Abstract

The present invention relates to an infrared lens system, which includes an aspherical first surface (S1) that primarily refracts light incident from a subject, and an aspherical convex surface that secondarily refracts light passing through the first surface (S1). It includes a lens having two surfaces (S2), wherein the curvature radii of the first surface and the second surface are -9.24858 mm and -3.014753 mm, respectively, the thickness of the lens is 2.750 mm, and the refractive index of the lens is 2.61. The Abbe number of the lens is 108.53, and it features an infrared lens system that can be operated inside the vehicle even in extreme vehicle environments and can recognize objects in blind spots.

Description

Infrared lens system {LENS SYSTEM FOR INFRARED RAYS}

The present invention relates to an infrared lens system, and more specifically, to an infrared lens system that can ensure high resolution inside a vehicle even in extreme field environments such as extreme heat.

Recently, heat waves, heavy snow, and cold waves due to abnormal climate have become more frequent, and vehicles are driven while exposed to these extreme environments.

In particular, there was an accident in which a child was found dead after being left in a daycare van during a recent heat wave. Children cannot easily get out of the vehicle when left alone, and the temperature inside a vehicle parked under strong sunlight rises to over 70 degrees during the hot summer months.

Accidents like this can be prevented just by adults taking a look inside the vehicle. For this purpose, a device has been developed that installs a button at the rear of the vehicle and requires pressing the button to turn off the engine and lock the doors. In other words, after the driver has finished driving, he must go to the back of the vehicle to press this button, so he can check to see if there are any children who are asleep or playing hide and seek.

Another method is to use smartphone functions such as near-field communication (NFC). When the vehicle is turned off, an alarm sounds on the driver's cell phone, and the driver must tap the smartphone to the NFC tags attached to various parts of the vehicle to stop it. A device has been developed.

Both of the above two methods are devices that help teachers and bus drivers check the inside of the vehicle. Since a person must physically move and check the inside of the vehicle with the naked eye, there is a problem of not being able to recognize the child inside the vehicle if visual identification is not possible. there was.

In addition, there are cases where images inside the vehicle are checked using CCTV inside the vehicle, but existing CCTVs use visible light to capture images, so if a child is in a blind spot that is obscured by a seat inside the vehicle, There was a problem that made it difficult to recognize a child through video.

Korean Patent No. 10-2380994 (2022.03.28) “Infrared Camera Lens Module” Japanese Patent Publication No. 2022-185161 (2022.12.14) “Infrared lens and imaging device”

The object of the present invention is to solve the conventional problems as described above, and the purpose is to provide an infrared lens system that can be operated inside a vehicle even in extreme vehicle environments and can recognize objects in blind spots.

The above problem is, in accordance with the present invention, in an infrared lens system, an aspherical first surface (S1) that primarily refracts light incident from a subject, and secondarily refracts the light passing through the first surface (S1). It includes a lens having a second refractive aspherical convex surface (S2), wherein the curvature radii of the first surface and the second surface are -9.24858 mm and -3.014753 mm, respectively, and the thickness of the lens is 2.750 mm. This can be achieved by an infrared lens system where the refractive index of the lens is 2.61 and the Abbe number of the lens is 108.53.

Here, the material of the lens may be chalcogenide.

Additionally, the focal length of the infrared lens system may be 2.2mm.

Additionally, the angle of view of the infrared lens system may be 80°.

Additionally, the first surface of the lens is concave, the second surface of the lens is convex, and each surface can be derived by the following <Equation 1>.

<Equation 1>

[Table 1]

According to the present invention, the object is to provide an infrared lens system that can be operated inside a vehicle even in extreme vehicle environments and can recognize objects in blind spots.

1 is a schematic diagram of an infrared lens system according to a first embodiment of the present invention;
2 to 6 are MTF curve graphs of the infrared lens system of FIG. 1.

Prior to description, in various embodiments, components having the same configuration will be described using the same symbols.

Hereinafter, a lens system for image capture according to a first embodiment of the present invention will be described in detail with reference to the attached drawings.

1 is a schematic diagram of an infrared lens system according to a first embodiment of the present invention. Referring to FIG. 1, the infrared lens system according to the first embodiment of the present invention is configured to include an aperture (ST), a lens 10, an optical filter 20, and an image sensor 30 from the subject.

The aperture (ST) is a means for controlling the amount of light incident on the lens.

In the description of the shape of the lens, saying that one side is convex means that the paraxial region of the surface is convex, and that one side is concave means that the paraxial region of the surface is concave. Therefore, even if one surface of the lens is described as having a convex shape, the edge portion of the lens may be concave. Likewise, even if one side of the lens is described as having a concave shape, the edge of the lens may be convex. The paraxial region refers to a very narrow area near the optical axis.

The lens 10 has an aspherical first surface (S1) that primarily refracts the light incident from the subject and an aspherical second surface (S2) that secondarily refracts the light passing through the first surface (S1). have

Here, the first surface S1 is concave in the paraxial region, and the second surface S2 is convex in the paraxial region.

At this time, the first surface (S1) and the second surface (S2) are aspherical as described above, and through this, the resolution difference in each image area can be minimized.

Meanwhile, the first surface (S1) and the second surface (S2) are specified by Equation 1 and Tables 1 and 2 below, and the infrared lens system according to the first embodiment of the present invention is characterized by an angle of view of 80 degrees. Do it as

<Equation 1>

At this time, K is the conic coefficient, A, B, C, D are the aspherical coefficients, Y is the height of the light ray incident on the lens, and c is the lens curvature.

noodle Radius of curvature (1/c) Lens thickness (d) Material information Refractive index (n) Abesu (v) S1 -9.24858 2.750 2.61 108.53 S2 -3.014753

Meanwhile, the focal length of the lens of the present invention is 2.20 mm, and the focal length is calculated by the following <Equation 2>.

<Equation 2>

Here, f' means the focal length of the lens, and y means the diagonal length of the sensor used. At this time, y is a value calculated by <Equation 3> below, and the θ value is 40°.

<Equation 3>

Meanwhile, the Abbe number (v) is calculated by <Equation 4> below.

<Equation 4>

At this time, Nr refers to the refractive index of the lens at a wavelength of 10 μm, NL refers to the refractive index of the lens at a wavelength of 8 μm, and N1 refers to the refractive index of the lens at a wavelength of 12 μm.

Meanwhile, in the infrared lens system according to the first embodiment of the present invention, the lens material is made of chalcogenide, and the chalcogenide is a material that transmits infrared rays in the 8-12㎛ band.

The optical filter 20 may be a cover glass, and such an optical filter is not expected to affect optical performance. Additionally, the image sensor has an imaging surface on which light through a lens is formed.

Meanwhile, the infrared lens system according to the first embodiment of the present invention has specifications as shown in Table 3 below.

division specification Effective focal length (EFL) 2.2 mm Back focal length (BFL) 2.9 mm (Incl. 0.5T CG) Sensor 200 x 150 Pixel 12um Nq Frequency 41.6 lp/mm Sensor Size D/H/V 3mm/2.4mm/1.8mm FOV D/H/V 82°/ 64°/ 47° F/# 1.05 MTF (0.0F) 30% at 42lp/mm TTL (Optical) 5.9mm Construction 1 GM Lens Material Chalcogenide Weight (Optics Only) < 1g

Meanwhile, referring to Figures 2 to 6, it can be seen that the infrared lens system according to the first embodiment of the present invention displays images normally in the range of -20°C to 85°C.

The scope of the present invention is not limited to the above-described embodiments, but may be implemented in various forms of embodiments within the scope of the appended claims. It is considered to be within the scope of the claims of the present invention to the extent that anyone skilled in the art can make modifications without departing from the gist of the invention as claimed in the claims.

※Explanation of symbols for main parts of the drawing※
10: Lens 20: Optical filter
30: image sensor

Claims (5)

In the infrared lens system,
It includes a lens having an aspherical first surface (S1) that primarily refracts the light incident from the subject and an aspherical convex second surface (S2) that secondarily refracts the light passing through the first surface (S1). And
The curvature radii of the first surface and the second surface are -9.24858 mm and -3.014753 mm, respectively,
The thickness of the lens is 2.750 mm,
The refractive index of the lens is 2.61,
An infrared lens system whose Abbe number is 108.53. According to paragraph 1,
An infrared lens system in which the material of the lens is chalcogenide. According to paragraph 1,
The infrared lens system has a focal length of 2.2mm. According to paragraph 1,
The infrared lens system has an angle of view of 80°. According to paragraph 1,
A first side of the lens is concave, a second side of the lens is convex,
A lens system where each surface is derived and specified by <Equation 1> .
<Equation 1>

[Table 1]