A day / night switching low-light imaging lens and electronic device

Abstract

This invention discloses a day / night switching low-light imaging lens and electronic device. The lens, from object side to image side, comprises, in sequence, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an aperture stop, an eighth lens, a ninth lens, a filter, and a protective film. The first lens has positive refractive power and a convex object-side surface; the second lens has positive refractive power and both the object-side and image-side surfaces are convex; the third lens has negative refractive power and both the object-side and image-side surfaces are concave; the fourth lens has negative refractive power and both the object-side and image-side surfaces are concave; the fifth lens has positive refractive power and both the object-side and image-side surfaces are convex; the sixth lens has positive refractive power and both the object-side and image-side surfaces are convex; the seventh lens has negative refractive power and both the object-side and image-side surfaces are concave, etc. This lens can solve at least one of the technical shortcomings mentioned in the background art.

Description

Technical Field

[0001] This invention relates to the field of day / night switching lens technology, and more particularly to a day / night switching low-light imaging lens and electronic device. Background Technology

[0002] Normally, only the visible light band of 400-700nm can be perceived by the human eye in nature. In dimly lit environments such as at night, the human eye faces various limitations in observing targets. Therefore, low-light night vision devices are needed to greatly extend the spectral detection range, allowing the observation of near-infrared radiation information in addition to visible light. However, current conventional low-light night vision lenses have at least one of the following drawbacks:

[0003] 1) Existing low-light night vision lenses typically do not have filters, and their wavelengths are limited to 300-400nm with violet fringing.

[0004] Light with wavelengths between 650nm and 1000nm can easily enter the system, causing color casts in images and resulting in violet and red light interference. Using a dual-peak filter can easily produce red light during the day.

[0005] 2) Existing low-light night vision lenses have short back focal lengths, which do not allow for more space to be placed for ICR filters;

[0006] 3) Existing low-light night vision lenses cannot meet the requirements for filters and protective sheets of a specific thickness. Filters and protective sheets that are too thick are prone to field curvature and deterioration of image quality.

[0007] 4) Existing low-light night vision lenses have high production costs and are expensive. Summary of the Invention

[0008] In view of this, the object of the present invention is to provide a day / night switching low-light imaging lens and electronic device. This lens can at least solve one of the technical shortcomings mentioned in the background art.

[0009] According to one aspect of the present invention, a day / night switching low-light imaging lens is provided, comprising, from the object side to the image side, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an aperture stop, an eighth lens, a ninth lens, a filter, and a protective sheet.

[0010] The first lens has positive refractive power and its object-side surface is convex.

[0011] The second lens has positive refractive power, and the object side is convex, as is the image side;

[0012] The third lens has negative refractive power, and both the object-side and image-side surfaces are concave.

[0013] The fourth lens has negative refractive power, and both the object-side and image-side surfaces are concave.

[0014] The fifth lens has positive refractive power, and the object side is convex, as is the image side;

[0015] The sixth lens has positive refractive power, and the object side is convex, as is the image side;

[0016] The seventh lens has negative refractive power, and both the object-side and image-side surfaces are concave.

[0017] The eighth lens has positive refractive power, and the object side and the image side are both convex.

[0018] The ninth lens has negative refractive power, and the object side is concave, as is the image side;

[0019] The image side of the second lens and the object side of the third lens are glued together to form a first cemented lens;

[0020] The image side of the fourth lens and the object side of the fifth lens are glued together to form a second cemented lens;

[0021] The image side of the sixth lens and the object side of the seventh lens are glued together to form a third cemented lens;

[0022] The filter uses an ICR dual filter switcher, which is equipped with a visible light filter and an infrared light filter of equal thickness.

[0023] The lens satisfies the following condition:

[0024] 0.1 <BFL / y<1.2

[0025] In the formula, BFL is the optical back focal length of the lens, and y is the half-image height of the imaging plane of the lens on the image plane.

[0026] In the above technical solution, an equal-thickness ICR filter switching scheme is adopted, using two equal-thickness filters. Coatings are applied for different operating wavelengths. During the day, visible light is used, employing an IR glass coating process to cut off light wavelengths of 700–1050 nm. At night, visible and infrared light are used, employing an AR glass coating process to enhance the transmission of light wavelengths of 420–1100 nm. This effectively improves and enhances the performance, preventing the influence of infrared light during daytime use and avoiding a reddish-purple tint. At night, visible light and weak near-infrared light can pass through, making full use of the weak nighttime light. Simultaneously, by controlling the backstop of the optical system, a longer backstop space can be well adapted to the ICR filter switching between day and night. Furthermore, the last lens element is stepped, increasing the distance from the lens frame to the image plane, meeting the space requirements of the ICR filter and the camera, and preventing interference between components at the rear of the lens. The conventional design uses a concave surface of the lens as a flat surface, with the entire lens surface resting directly on the lens frame. To create more space at the back, steps were cut into the lenses, allowing the frame's backing surface to move to the left and increasing the space at the back.

[0027] In some embodiments, the eighth lens is an aspherical lens and is made of low-melting-point glass.

[0028] In the above technical solution, by using non-curved lenses, the overall length and external dimensions of the optical system are reduced, achieving miniaturization requirements. This reduces the sensitivity of the optical system, improves the yield rate, and lowers the cost of optical manufacturing.

[0029] In some embodiments, the lens satisfies the following condition:

[0030] 6 <TTL / y<10;2.8<f / y<7.6

[0031] In the formula, TTL is the total optical length of the lens, and f is the focal length of the lens.

[0032] In the above technical solution, the above conditional formula enables the lens to have optical performance of short total length and large image area.

[0033] In some embodiments, the lens satisfies the following condition:

[0034] 25 <R 01 <60;|R 02 |>100; 5mm <T1<14mm

[0035] -50 <R 15 <-15; 10 <R 16 <60; 0.4mm <T 15 <6mm

[0036] In the formula, R 01 R is the radius of curvature of the side surface of the first lens. 02 R is the radius of curvature of the image-side surface of the first lens, T1 is the center thickness of the first lens, and R 15 R is the radius of curvature of the side surface of the ninth lens. 16 T is the radius of curvature of the image side surface of the ninth lens. 15 The center thickness of the ninth lens is given.

[0037] In the above technical solution, by controlling the curve radius and core thickness of the lens, the residual spherical aberration of the optical system is minimized, the blur value of the optical system is small and the light spot is circular, thereby improving the resolution of the optical system.

[0038] In some embodiments, the lens satisfies the following condition:

[0039] 1.0 < |f2 / f3| < 2.6; 7 <T3+T4<14

[0040] In the formula, f2 is the focal length of the second lens, f3 is the focal length of the third lens, T3 is the center thickness of the second lens, and T4 is the center thickness of the third lens.

[0041] In the above technical solution, the spherical aberration of the optical system is corrected by optical power distribution.

[0042] In some embodiments, the lens satisfies the following condition:

[0043] 6 <d7+d8<14

[0044] In the formula, d7 is the distance from the aperture stop to the center of the image side of the seventh lens, and d8 is the distance from the aperture stop to the center of the object side of the eighth lens.

[0045] In the above technical solution, the installation of the aperture component is facilitated by controlling the position of the aperture stop and the front and rear lenses.

[0046] In some embodiments, the lens satisfies the following condition:

[0047] |Vd4-Vd5|<5

[0048] In the formula, Vd4 is the Abbe number of the fourth lens, and Vd5 is the Abbe number of the fifth lens.

[0049] In the above technical solution, the above conditional expression can effectively correct the residual spherical aberration of the system.

[0050] In some embodiments, the lens satisfies the following condition:

[0051] 0.15mm < T G1<0.8mm; 0.2mm <T G2 <2.3mm

[0052] In the formula, T G1 T is the thickness of the filter. G2 The thickness of the protective sheet is given.

[0053] In the above technical solution, the thickness of the filter and the thickness of the protective film are added to optimize the field curvature of the optical system and achieve high image quality output.

[0054] According to another aspect of the present invention, an electronic device is provided, comprising the above-described day / night switching low-light imaging lens; and

[0055] An image sensor is configured to receive images formed by the day-night switching low-light imaging lens.

[0056] In the above technical solution, the advantage of this electronic device relies on a low-light imaging lens that switches between day and night, which will not be elaborated here. Attached Figure Description

[0057] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0058] Figure 1 This is a schematic diagram of the structure of an example 1 of a day-night switching low-light imaging lens of the present invention;

[0059] Figure 2 This is an optical path diagram of an example 1 of a day / night switching low-light imaging lens of the present invention;

[0060] Figure 3 This is an example 1 of the day-night switching low-light imaging lens of the present invention, showing the MTF curve under daily use;

[0061] Figure 4 This is a field distortion diagram under daytime use for an example 1 of a day / night switching low-light imaging lens of the present invention;

[0062] Figure 5 This is a relative illumination diagram under daytime use for an example 1 of a day / night switching low-light imaging lens of the present invention;

[0063] Figure 6 This is an energy concentration diagram of a daytime use example 1 of a day / night switching low-light imaging lens of the present invention;

[0064] Figure 7This is an example 1 of the day-night switching low-light imaging lens of the present invention, showing the MTF curve under nighttime use;

[0065] Figure 8 This is a field curvature distortion diagram of a day / night switching low-light imaging lens example 1 under nighttime use;

[0066] Figure 9 This is a relative illumination diagram of a day / night switching low-light imaging lens example 1 under nighttime use;

[0067] Figure 10 This is an example 1 of the day-night switching low-light imaging lens of the present invention, showing the energy concentration diagram under nighttime use;

[0068] Figure 11 This is a real-world simulation of Example 1 of a day-night switching low-light imaging lens of the present invention;

[0069] Figure 12 This is a schematic diagram of the structure of an electronic device example 2 of the present invention. Detailed Implementation

[0070] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be particularly noted that the following embodiments are for illustrative purposes only and do not limit the scope of the invention. Similarly, the following embodiments are only some, not all, embodiments of the present invention, and all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0071] The purpose of this invention is to provide a day / night switching low-light imaging lens and electronic device with high optical performance. Embodiments according to the invention will now be described in detail with reference to the accompanying drawings.

[0072] Figure 1 , Figure 2 These are cross-sectional views and optical path diagrams of the day / night switching low-light imaging lens (optical system) according to Example 1. The day / night switching low-light imaging lens according to the example is used in imaging equipment including digital video cameras, digital still cameras, broadcast cameras, surveillance cameras, etc., and in electronic devices with interchangeable lenses. In the cross-sectional view and optical path diagram, the left side is the object-side OBJ and the right side is the image-side IMA. The optical axis is OA, Li represents the i-th lens, Ci represents the i-th cemented lens, ST represents the aperture stop (fixed aperture stop or visible aperture stop), G1 represents the filter, and G2 represents the protective lens. IMA represents the image plane, and when the day / night switching low-light imaging lens 1 according to the example is used in the imaging optical system of a digital video camera or digital still camera, a solid-state imaging element (photoelectric conversion element), such as a CMOS image sensor or a CCD image sensor, is arranged on the image plane IMA.

[0073] According to Example 1, the day / night switching low-light imaging lens consists of the following elements in order from the object side to the image side: first lens L1, second lens L2, third lens L3, fourth lens L4, fifth lens L5, sixth lens L6, seventh lens L7, aperture ST, eighth lens L8, ninth lens L9, filter G1, and protective sheet G2.

[0074] The first lens L1 has positive refractive power and its object-side surface is convex.

[0075] The second lens L2 has positive refractive power, and the object-side surface is convex, as is the image-side surface;

[0076] The third lens L3 has negative refractive power, and the object side is concave, as is the image side;

[0077] The fourth lens L4 has negative refractive power, and the object side is concave, as is the image side;

[0078] The fifth lens L5 has positive refractive power, and the object side is convex, as is the image side.

[0079] The sixth lens L6 has positive refractive power, and the object-side surface is convex, as is the image-side surface;

[0080] The seventh lens L7 has negative refractive power, and both the object-side and image-side surfaces are concave.

[0081] The eighth lens L8 has positive refractive power, with a convex object side and a convex image side; the eighth lens L8 is an aspherical lens and is made of low melting point glass.

[0082] The ninth lens L9 has negative refractive power, and the object side is concave, as is the image side;

[0083] The image-side of the second lens L2 and the object-side of the third lens L3 are cemented together to form a first cemented lens C1; the image-side of the fourth lens L4 and the object-side of the fifth lens L5 are cemented together to form a second cemented lens C2; the image-side of the sixth lens L6 and the object-side of the seventh lens L7 are cemented together to form a third cemented lens C3; the filter G1 uses an ICR dual filter switcher, which is equipped with a visible light filter and an infrared light filter of equal thickness, and adopts a push-pull switching structure. This optical system consists of 9 elements in 6 groups, with the aperture ST located between the seventh lens L7 and the eighth lens L8. The light passes through the lens interior, gradually narrowing the aperture, and finally forming an image on the photosensitive surface IMA of the sensor. The center of gravity of the lens is shifted to the left. The three groups of cemented lenses effectively improve the chromatic aberration of the optical system.

[0084] The example day / night switching low-light imaging lens can satisfy at least one of the following settings 1) to 6):

[0085] 1) 0.1 <BFL / y<1.2;

[0086] 2)6 <TTL / y<10;2.8<f / y<7.6;

[0087] 3)25 <R 01 <60;|R 02 |>100; 5mm <T1<14mm;-50<R 15 <-15; 10 <R 16 <60; 0.4mm<

[0088] T 15 <6mm;

[0089] 4) 1.0 < |f2 / f3| < 2.6; 7 <T3+T4<14;

[0090] 5)6 <d7+d8<14;

[0091] 6) |Vd4-Vd5|<5;

[0092] 7) 0.15mm < T G1 <0.8mm; 0.2mm <T G2 <2.3mm;

[0093] In the above conditions, BFL is the optical back focal length of the lens, y is the half-image height of the lens's imaging plane on the image plane, TTL is the total optical length of the lens, f is the focal length of the lens, and R... 01 R is the radius of curvature of the side surface of the first lens. 02 R is the radius of curvature of the image-side surface of the first lens, T1 is the center thickness of the first lens, and R 15 R is the radius of curvature of the side surface of the ninth lens. 16 T is the radius of curvature of the image side surface of the ninth lens. 15 f2 is the center thickness of the ninth lens, f3 is the focal length of the second lens, f4 is the center thickness of the third lens, d7 is the distance from the aperture stop to the center of the image side of the seventh lens, d8 is the distance from the aperture stop to the center of the object side of the eighth lens, Vd4 is the Abbe number of the fourth lens, Vd5 is the Abbe number of the fifth lens, and T is the center thickness of the center of the image side of the seventh lens. G1 T is the thickness of the filter. G2 The thickness of the protective sheet is given.

[0094] Condition 1) defines the ratio of optical back focal length to half-image height. By appropriately setting the condition, the back focal length of the optical system can be controlled. A long back focal length can well accommodate ICR filters that switch between day and night, meeting the space requirements of the ICR filter and the camera, and preventing interference between components. If it exceeds the upper limit, the optical back focal length will be too long, resulting in a large system size, or the imaging target surface will be too small, leading to poor image lighting performance. However, if it is below the lower limit, the optical back focal length will be too short, causing interference with the rear camera, or the imaging target surface will be too large, resulting in a bulky system size. Furthermore, to reliably obtain the effect of condition 1), it is preferable to set the value of condition 1) to 0.7.

[0095] Condition 2) defines the ratio of total optical length to half-image height and the ratio of lens focal length to half-image height, respectively. By appropriately setting the conditions, the lens can achieve optical performance with a short total length and a large image area. If the value is higher than the upper limit, the total length of the optical system will be too long, resulting in a large system volume. However, if the value is lower than the lower limit, the optical target area will be too large, increasing the overall system size. Furthermore, to reliably obtain the effect of condition 2), it is more preferable to set the value of condition 2) to 8.4.

[0096] Condition 3) defines the center thickness of the first lens and the ninth lens, as well as the radii of curvature of the object-side and image-side surfaces. By appropriately setting these conditions, the spherical aberration of the optical system is optimized. If the center thickness is higher than the upper limit, the spherical aberration of the optical system increases; however, if the center thickness is lower than the lower limit, the spherical aberration also increases. If the radii of curvature of the object-side surfaces of the first and ninth lenses are higher than the upper limit, the coma of the optical system decreases; however, if they are lower than the lower limit, the coma increases. If the radii of curvature of the image-side surface of the first lens are lower than the lower limit, the spherical aberration of the optical system increases. If the radii of curvature of the image-side surface of the ninth lens are higher than the upper limit, the spherical aberration of the optical system decreases; however, if they are lower than the lower limit, the spherical aberration increases. Furthermore, to reliably obtain the effect of condition 4), it is more preferable to set the value of condition 4) to 3).

[0097] R01, |R02|, R15, and R16 are shown in Table 1; T1 = 9.13 mm; T15 = 1.42 mm.

[0098] Condition 4) defines the focal length ratio and center thickness of the second and third lenses, respectively. By appropriately setting the conditions, the spherical aberration of the optical system is corrected. If both parameters are higher than the upper limit, the residual spherical aberration of the optical system is too large, and the spot diameter increases. However, if they are lower than the lower limit, the residual spherical aberration of the optical system is also too large, and the spot diameter increases. Furthermore, in order to reliably obtain the effect of condition 4), it is more preferable to set the values ​​of condition 4) as follows: f2 = 48.6 mm; f3 = -34 mm; T3 = 9.05 mm; T4 = 1.8 mm; |f2 / f3| = 1.43; T3 + T4 = 10.9;

[0099] Condition 5) defines the distance from the aperture stop to the center of the image side of the seventh lens, and the distance from the aperture stop to the object side of the eighth lens. The distance from the center of the aperture allows for easier installation of the aperture assembly by controlling the positions of the aperture stop and the front and rear lenses. If it exceeds the upper limit, If the aperture position space is too large, the system size will be large. However, if it is below the lower limit, the aperture position space will be too small to accommodate it. Aperture component. Furthermore, to reliably obtain the effect of condition 5), it is more preferable to set the value of condition 5) to d7 = 5). 4.85mm; d8=3.33mm;

[0100] d7+d8=8.18mm.

[0101] Condition 6) defines the absolute value of the difference between the Abbe numbers of the fourth and fifth lenses. By setting the conditions appropriately, the residual spherical aberration of the system can be effectively corrected. If the value is higher than the upper limit, the residual chromatic aberration of the optical system will be too large. Furthermore, in order to reliably obtain the effect of condition 6), it is more preferable to set the value of condition 6) to |Vd4-Vd5|=1.

[0102] Condition 7) defines the thicknesses of the filter and the protective film, respectively. By appropriately setting the conditions, the field curvature of the optical system is optimized by incorporating the thicknesses of the filter and the protective film, achieving high image quality output. If the value exceeds the upper limit, the planar aberration of the optical system has an excessive impact, which is inconsistent with reality. However, if the value is below the lower limit, the planar aberration of the optical system has an insufficient impact, which is also inconsistent with reality. Furthermore, to reliably obtain the effect of condition 7), it is more preferable to set the value of condition 7) to T. G1 =0.3mm; T G2 =1.1mm.

[0103] A detailed description of day-night switching low-light imaging lenses based on various examples is now provided.

[0104] Please refer to the optical structure of Example 1. Figure 1 The specific parameters for Example 1 are shown in Table 1 below. In Example 1, the working wavelength of the day / night switching low-light imaging lens is 400–1000 nm, the F-number is 1.0, and the lens focal length is f = 47 mm. The conditional expressions are as follows:

[0105] 1) BFL=6.4mm; y=9.1mm; BFL / y=0.7;

[0106] 2)TTL=76.8mm; TTL / y=8.4; f / y=5.2;

[0107] 3)R 01 、|R 02 |、R 15 R 16 See Table 1; T1 = 9.13 mm; T 15 =1.42mm;

[0108] 4) f2=48.6mm; f3=-34mm; T3=9.05mm; T4=1.8mm; |f2 / f3|=1.43; T3+T4=10.9;

[0109] 5)d7=4.85mm; d8=3.33mm; d7+d8=8.18mm;

[0110] 6) |Vd4-Vd5|=1;

[0111] 7)T G1 =0.3mm; T G2 =1.1mm;

[0112] Table 1 Example 1 Parameter Table

[0113] Face number type radius of curvature thickness Material Refractive index Dispersion coefficient 1 First lens 47.8 9.13 Glass 1.7 41 2 Infinity 0.19 3 Second lens 35.8 9.05 Glass 1.6 69 4 Third lens -128.2 1.80 Glass 1.7 29 5 29.1 6.53 6 Fourth lens -66.4 1.80 Glass 1.8 44 7 Fifth lens 21.9 7.96 Glass 1.7 45 8 -445.2 0.15 9 Sixth lens 21.2 9.01 Glass 1.6 69 10 Seventh Lens -77.5 6.88 Glass 1.5 64 11 36.0 4.85 12 ST Infinity 3.33 13 Eighth lens 21.0 7.71 Low melting point glass 1.8 41 14 -78.1 0.55 15 Ninth Lens -31.8 1.42 Glass 1.7 30 16 28.0 3.68 17 Filter Infinity 0.30 Glass 1.5 64 18 Infinity 1.05 19 Protective glass Infinity 1.10 Glass 1.5 64 20 Infinity 0.28 21 IMA Infinity

[0114] Table 2 Example 1 Aspheric Coefficients Table

[0115] Face number K A4 A6 A8 A10 13 2.46 -5.324E-05 -7.814E-07 6.108E-09 -9.072E-11 14 18.98 -9.691E-06 -2.537E-07 -7.079E-09 2.768E-11

[0116] Please see Figure 3 Example 1 shows the MTF curve under normal use; the horizontal axis represents frequency, in line pairs. The vertical axis represents MTF value, with no unit. As shown in the graph, the wavelength is in the 435-650nm visible light band, and infrared interference is filtered out. The MTF value is greater than 0.4 at 40 Lp / mm. The imaging quality is good and meets the requirements of the paired sensor.

[0117] Please see Figure 4 Example 1 shows the field curvature distortion diagram under normal use. The left diagram is the field curvature diagram, with the horizontal axis representing the field curvature value in millimeters and the vertical axis representing the normalized field of view in infinitesimal. From the diagram, it can be clearly seen that the field curvature of this lens is within 0.2mm. The right diagram is the relative optical distortion diagram, with the horizontal axis representing the percentage of relative optical distortion in % and the vertical axis representing the normalized field of view in infinitesimal. From the diagram, it can be clearly seen that the relative optical distortion of the lens is approximately 1.3%, which is sufficient for direct human observation.

[0118] Please see Figure 5 Example 1: Relative illuminance diagram under daily use; As can be seen from the diagram, the relative illuminance of the optical system across the entire field of view is 56%, the resulting image has uniform brightness, and there is no obvious dark corner phenomenon at the edges.

[0119] Please see Figure 6 Example 1 shows the energy concentration diagram under daily use; as can be seen from the diagram, 80% of the energy in the central field of view is concentrated within 10µm, and 80% of the energy in the entire field of view is concentrated around 25µm. This optical system has high energy concentration and a relatively small system dispersion spot.

[0120] Please see Figure 7Example 1: MTF curve under nighttime use; the horizontal axis represents frequency, in line pairs. The vertical axis represents MTF value, unitless. As shown in the graph, the wavelength is the full 435-1000nm band. At night, the focus is on infrared light while also considering visible light. The MTF value is greater than 0.4 at 40 Lp / mm. The image quality is good and meets the requirements of the paired sensor.

[0121] Please see Figure 8 Example 1 shows the field curvature distortion diagram under nighttime use. The left diagram is the field curvature diagram, with the horizontal axis representing the field curvature value in millimeters and the vertical axis representing the normalized field of view in infinitesimal. From the diagram, it can be clearly seen that the field curvature of this lens is within 0.2mm. The right diagram is the relative optical distortion diagram, with the horizontal axis representing the percentage of relative optical distortion in % and the vertical axis representing the normalized field of view in infinitesimal. From the diagram, it can be clearly seen that the relative optical distortion of the lens is approximately 1.4%, which is sufficient for direct human observation.

[0122] Please see Figure 9 Example 1: Relative illumination diagram under nighttime use; As can be seen from the diagram, the relative illumination of the optical system across the entire field of view is 57%, the resulting image has uniform brightness, and there is no obvious dark corner phenomenon at the edges.

[0123] Please see Figure 10 Example 1 shows the energy concentration diagram under nighttime use; as can be seen from the diagram, 80% of the energy in the central field of view is concentrated within 10 μm, and 80% of the energy in the entire field of view is concentrated around 23 μm. This optical system has high energy concentration and a relatively small system dispersion spot.

[0124] Please see Figure 11 Example 1 shows a real-world simulation image; as can be seen from the image, the optical system performs a real-world simulation with good image quality, uniform illumination, and no obvious vignetting.

[0125] Based on Example 1, this case has the following advantages:

[0126] 1. By adopting an equal-thickness ICR filter switching scheme, visible light is used during the day and visible and infrared light are used at night, which can effectively improve the performance. During the day, the influence of infrared light can be avoided, and a dual-peak filter is used at night.

[0127] 2. By adding operands to control the back cutoff of the optical system and by cutting a step in the last lens to increase the distance from the frame to the image plane, the space requirements of the ICR filter and the camera are met, and interference between the various components is prevented.

[0128] 3. Increasing the thickness of the filter and the protective layer optimizes the field curvature of the optical system, achieving high image quality output.

[0129] 4. By sharing non-curved lenses, the sensitivity of the optical system is reduced, the yield of the optical system is improved, and the cost of optical manufacturing and processing is reduced.

[0130] Example 2

[0131] For reference Figure 12 A description of an electronic device A according to Example 2 of the present invention will be given. Figure 12 This is a schematic diagram of an electronic device (industrial line scan camera) used in a camera optical system, based on any of the day-night switching low-light imaging lenses in Example 1.

[0132] exist Figure 12 In the figures, reference numeral A2 indicates the main body of the electronic device, and reference numeral A1 indicates any of the camera optical systems (interchangeable lenses) including the day-night switching low-light imaging lens according to Example 1. Reference numeral A3 indicates an image sensor (photoelectric conversion element), such as a CMOS image sensor or a CCD image sensor, which is built into the camera body A2 and receives light (the optical image formed by the camera optical system A1) from the camera optical system A1 and performs photoelectric conversion. Reference numeral A4 indicates an ICR dual filter switcher, which is equipped with a visible light filter and an infrared light filter of equal thickness and adopts a push-pull switching structure.

[0133] By using the day-night switching low-light imaging lens according to Example 1 in an electronic device such as a digital still camera, an electronic device with a day-night switching low-light imaging lens having high optical performance can be obtained.

[0134] Although the invention has been described with reference to exemplary embodiments, it should be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims will be given the broadest interpretation to cover all such modifications and equivalent structures and functions.

Claims

1. A day / night switching low-light imaging lens, characterized in that, The lens consists of nine lenses, which are arranged in the following order from the object side to the image side: first lens, second lens, third lens, fourth lens, fifth lens, sixth lens, seventh lens, aperture, eighth lens, ninth lens, filter and protective sheet. The first lens has positive refractive power and its object-side surface is convex. The second lens has positive refractive power, and the object side is convex, as is the image side; The third lens has negative refractive power, and both the object-side and image-side surfaces are concave. The fourth lens has negative refractive power, and both the object-side and image-side surfaces are concave. The fifth lens has positive refractive power, and the object side is convex, as is the image side; The sixth lens has positive refractive power, and the object side is convex, as is the image side; The seventh lens has negative refractive power, and both the object-side and image-side surfaces are concave. The eighth lens has positive refractive power, and the object side and the image side are both convex. The ninth lens has negative refractive power, and the object side is concave, as is the image side; The image side of the second lens and the object side of the third lens are glued together to form a first cemented lens; The image side of the fourth lens and the object side of the fifth lens are glued together to form a second cemented lens; The image side of the sixth lens and the object side of the seventh lens are glued together to form a third cemented lens; The filter uses an ICR dual filter switcher, which is equipped with a visible light filter and an infrared light filter of equal thickness. The lens satisfies the following condition: 0.1 <BFL / y<1.2 In the formula, BFL is the optical back focal length of the lens, and y is the half-image height of the imaging plane of the lens on the image plane.

2. The day / night switching low-light imaging lens as described in claim 1, characterized in that, The eighth lens is an aspherical lens and is made of low-melting-point glass.

3. The day / night switching low-light imaging lens as described in claim 1, characterized in that, The lens satisfies the following condition: 6 <TTL / y<10;2.8<f / y<7.6 In the formula, TTL is the total optical length of the lens, and f is the focal length of the lens.

4. A day / night switching low-light imaging lens as described in claim 1, characterized in that, The lens satisfies the following condition: 25<R 01 <60;|R 02 |>100;5mm<T1<14mm -50<R 15 <-15;10<R 16 <60;0.4mm< T 15 <6mm In the formula, R 01 R is the radius of curvature of the side surface of the first lens. 02 R is the radius of curvature of the image-side surface of the first lens, T1 is the center thickness of the first lens, and R 15 R is the radius of curvature of the side surface of the ninth lens. 16 T is the radius of curvature of the image side surface of the ninth lens. 15 The center thickness of the ninth lens is given.

5. A day / night switching low-light imaging lens as described in claim 1, characterized in that, The lens satisfies the following condition: 1.0 < |f2 / f3| < 2.6; 7 <T3+T4<14 In the formula, f2 is the focal length of the second lens, f3 is the focal length of the third lens, T3 is the center thickness of the second lens, and T4 is the center thickness of the third lens.

6. A day / night switching low-light imaging lens as described in claim 1, characterized in that, The lens satisfies the following condition: 6mm <d7+d8<14mm In the formula, d7 is the distance from the aperture stop to the center of the image side of the seventh lens, and d8 is the distance from the aperture stop to the center of the object side of the eighth lens.

7. A day / night switching low-light imaging lens as described in claim 1, characterized in that, The lens satisfies the following condition: |Vd4-Vd5| <5 In the formula, Vd4 is the Abbe number of the fourth lens, and Vd5 is the Abbe number of the fifth lens.

8. A day / night switching low-light imaging lens as described in claim 1, characterized in that, The lens satisfies the following condition: 0.15mm<T G1 <0.8mm;0.2mm<T G2 <2.3mm In the formula, T G1 T is the thickness of the filter. G2 The thickness of the protective sheet is given.

9. An electronic device, characterized in that, A day / night switching low-light imaging lens according to any one of claims 1-8; and, An image sensor is configured to receive images formed by the day-night switching low-light imaging lens.

Images