Day and night switching weak light imaging lens and electronic equipment

Abstract

The invention discloses a day and night switching weak light imaging lens and electronic equipment. The lens sequentially comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, a diaphragm, an eighth lens, a ninth lens, an optical filter and a protection sheet from an object side to an image side. The first lens has positive diopter, and the object side surface is a convex surface; the second lens has positive diopter, the object side surface is a convex surface, and the image side surface is a convex surface; the third lens has negative diopter, the object side surface is a concave surface, and the image side surface is a concave surface; the fourth lens has negative diopter, the object side surface is a concave surface, and the image side surface is a concave surface; the fifth lens has positive diopter, the object side surface is a convex surface, and the image side surface is a convex surface; the sixth lens has positive diopter, the object side surface is a convex surface, and the image side surface is a convex surface; and the seventh lens has negative diopter, the object side surface is a concave surface, the image side surface is a concave surface and the like. The lens can solve at least one technical defect mentioned in the background technology.

Description

Technical Field

[0001] The present invention relates to the technical field of day-night switching lenses, and in particular to a day-night switching weak-light imaging lens and electronic equipment. Background Art

[0002] Usually, only the visible light band of 400-700nm in nature can be recognized by the human eye. In dim environments such as at night, the human eye has various limitations in observing targets, so a low-light night vision device is needed to greatly extend the spectrum detection range. In addition to visible light, near-infrared radiation information can be observed. However, conventional low-light night vision lenses currently have at least one of the following disadvantages:

[0003] 1) Existing low-light-level night vision lenses usually do not have filters, 300-400nm purple-edge wavelength and

[0004] Light with a wavelength of 650nm-1000nm can easily enter the system, causing image color cast and interference between purple and red light. Using a dual-peak filter can easily produce red light during the day;

[0005] 2) The existing low-light-level night vision lens has a short back intercept and cannot spare more space for placing the ICR filter;

[0006] 3) Existing low-light-level night vision lenses cannot meet the requirements for the use of filters and protective films of a certain thickness. Filters and protective films that are too thick are prone to field curvature and poor imaging quality.

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

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

[0009] According to one aspect of the present invention, a day-night switching low-light imaging lens is provided, which comprises, 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, an eighth lens, a ninth lens, a filter, and a protective sheet;

[0010] The first lens has positive refractive power and a convex object side surface;

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

[0012] The third lens has negative refractive power, and its object side surface is concave and its image side surface is concave;

[0013] The fourth lens element has negative refractive power, and its object side surface is concave and its image side surface is concave;

[0014] The fifth lens element has positive refractive power, and its object side surface is convex, and its image side surface is convex;

[0015] The sixth lens has positive refractive power, and its object-side surface is convex, and its image-side surface is convex;

[0016] The seventh lens element has negative refractive power, and its object side surface is concave and its image side surface is concave;

[0017] The eighth lens has positive refractive power, and its object-side surface is convex, and its image-side surface is convex;

[0018] The ninth lens element has negative refractive power, and its object side surface is concave and its image side surface is concave;

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

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

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

[0022] The filter adopts an ICR double filter switcher, which is equipped with a visible light filter and an infrared light filter of equal thickness;

[0023] The lens satisfies the following conditional formula:

[0024] 0.1 <BFL / y<1.2

[0025] Wherein, BFL is the optical back focus of the lens, and y is the half image height of the imaging surface of the lens on the image plane.

[0026] In the above technical solution, two equal-thickness filters are used by adopting the equal-thickness ICR filter switching solution. Coating is performed for different working wavelengths. During the day, visible light is used, and the IR glass coating process is used to cut off the light with a wavelength of 700 to 1050nm. At night, visible and infrared light are used, and the AR glass coating process is used to enhance the transmittance of the light with a wavelength of 420 to 1100nm. It can effectively improve and enhance the use effect, so that the influence of infrared light can be avoided during daytime use, and the reddish purple color can be prevented during daytime use. When used at night, visible light and weak near-infrared light can be transmitted, making full use of the weak light at night. At the same time, by controlling the back intercept of the optical system, the longer back intercept space can be well adapted to the ICR filter that switches day and night, and the last lens is stepped to increase the distance from the frame to the image plane, meet the space requirements of the ICR filter and the camera, and prevent the various components at the rear end of the lens from interfering with each other. In the conventional design, the concave surface of the lens is made into a flat surface, and the flat surface of the lens is directly placed on the frame. In order to make more room at the back, a step is dug into the lens so that the support surface of the frame can be moved to the left, 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 total length and size of the optical system are reduced to achieve miniaturization requirements, reduce the sensitivity of the optical system, improve the yield of the optical system, and reduce the cost of optical manufacturing and processing.

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

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

[0031] Wherein, 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 expression enables the lens to have the optical performance of short total length and large image surface.

[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 is the radius of curvature of the first lens object side, R 02 is the radius of curvature of the image side of the first lens, T1 is the center thickness of the first lens, R 15 is the radius of curvature of the object side of the ninth lens, R 16 is the curvature radius of the image side of the ninth lens, T 15 is the center thickness of the ninth lens.

[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 diffuse spot value of the optical system is small and the 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] Wherein, 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] Wherein, d7 is the distance from the aperture to the center of the image side of the seventh lens, and d8 is the distance from the aperture to the center of the object side of the eighth lens.

[0045] In the above technical solution, the aperture component can be easily installed by controlling the positions of the aperture and the front and rear lenses.

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

[0047] |Vd4-Vd5|<5

[0048] Wherein, 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] Where, T G1 is the thickness of the filter, T G2 is the thickness of the protective sheet.

[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, which uses the above-mentioned day-night switching weak light imaging lens; and

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

[0056] In the above technical solution, the advantage of the electronic device depends on switching the low-light imaging lens between day and night, which will not be elaborated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0058] Figure 1 This is a structural schematic diagram of Example 1 of a day-night switching weak light imaging lens according to the present invention;

[0059] Figure 2 This is a light path diagram of Example 1 of a day-night switching weak light imaging lens of the present invention;

[0060] Figure 3 This is an MTF curve diagram of Example 1 of a day-night switching weak light imaging lens under daily use of the present invention;

[0061] Figure 4 This is a field curvature distortion diagram of Example 1 of a day-night switching weak light imaging lens of the present invention under daily use;

[0062] Figure 5 This is a relative illumination diagram of Example 1 of a day-night switching weak light imaging lens of the present invention under daily use;

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

[0064] Figure 7This is an MTF curve diagram of Example 1 of a day-night switching low-light imaging lens for night use according to the present invention;

[0065] Figure 8 This is a field curvature distortion diagram of Example 1 of a day-night switching weak light imaging lens of the present invention under night use;

[0066] Fig. 9 This is a relative illumination diagram of Example 1 of a day-night switching weak light imaging lens of the present invention under night use;

[0067] Fig.10 This is an energy concentration diagram of a day-night switching weak light imaging lens example 1 under night use of the present invention;

[0068] Fig.11 This is a real-scene simulation diagram of Example 1 of a day-night switching weak light imaging lens of the present invention;

[0069] Fig.12 It is a structural diagram of an electronic device example 2 of the present invention. DETAILED DESCRIPTION

[0070] The present invention will be further described in detail below in conjunction with the accompanying drawings and examples. It is particularly noted that the following examples are only used to illustrate the present invention, but are not intended to limit the scope of the present invention. Similarly, the following examples are only partial embodiments of the present invention rather than all embodiments, and all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present invention.

[0071] The purpose of the present invention is to provide a day-night switching weak light imaging lens and electronic equipment with high optical performance. Now, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0072] Figure 1 , Figure 2 They are respectively a cross-sectional view and an optical path diagram of a day-night switching weak light imaging lens (optical system) according to Example 1. The day-night switching weak light imaging lens according to the example is used for electronic devices including imaging devices such as digital cameras, digital still cameras, broadcast cameras, surveillance cameras, and interchangeable lenses. In the cross-sectional view and the optical path diagram, the left side is the object side OBJ and the right side is the image side IMA, the optical axis OA, Li represents the i-th lens, Ci represents the i-th cemented lens, ST represents the aperture (fixed aperture or visible aperture), G1 represents the filter, and G2 represents the protective lens. IMA represents the image plane, and when the day-night switching weak light imaging lens 1 according to the example is used in the imaging optical system of a digital camera or a 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 imaging plane IMA.

[0073] The day / night switching low-light imaging lens according to Example 1 comprises, from the object side to the image side, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, an aperture ST, an eighth lens L8, a ninth lens L9, a filter G1, and a protective sheet G2;

[0074] The first lens L1 has positive refractive power, and the object side surface is convex;

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

[0076] The third lens L3 has a negative refractive power, a concave object-side surface, and a concave image-side surface;

[0077] The fourth lens L4 has a negative refractive power, a concave object-side surface, and a concave image-side surface;

[0078] The fifth lens L5 has positive refractive power, and its object-side surface is convex and its image-side surface is convex;

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

[0080] The seventh lens L7 has negative refractive power, and its object-side surface is concave and its image-side surface is concave.

[0081] The eighth lens L8 has positive refractive power, a convex object-side surface, and a convex image-side surface. 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, a concave object-side surface, and a concave image-side surface;

[0083] The image side surface of the second lens L2 and the object side surface of the third lens L3 are glued to each other to form a first glued lens C1; the image side surface of the fourth lens L4 and the object side surface of the fifth lens L5 are glued to each other to form a second glued lens C2; the image side surface of the sixth lens L6 and the object side surface of the seventh lens L7 are glued to each other to form a third glued lens C3; the filter G1 adopts an ICR double 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. The optical system consists of 9 pieces and 6 groups, and the aperture ST is located between the seventh lens L7 and the eighth lens L8. The optical system passes through the inside of the lens, gradually shrinks the aperture of the light, and finally forms an image on the photosensitive surface IMA of the sensor. The center of gravity of the lens is offset to the left. The three groups of glued lenses can effectively improve the chromatic aberration of the optical system.

[0084] The day-night switching low-light imaging lens according to the example may satisfy at least one of the following setting conditions 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 <6 mm;

[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 conditional formula, BFL is the optical back focus of the lens, y is the half image height of the imaging surface of the lens on the image plane, TTL is the total optical length of the lens, f is the focal length of the lens, R 01 is the radius of curvature of the first lens object side, R 02 is the radius of curvature of the image side of the first lens, T1 is the center thickness of the first lens, R 15 is the radius of curvature of the object side of the ninth lens, R 16 is the curvature radius of the image side of the ninth lens, T 15 is the center thickness of the ninth lens, 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, T4 is the center thickness of the third lens, d7 is the distance from the aperture to the center position of the image side surface of the seventh lens, d8 is the distance from the aperture to the center position of the object side surface of the eighth lens, Vd4 is the Abbe number of the fourth lens, Vd5 is the Abbe number of the fifth lens, T G1 is the thickness of the filter, T G2 is the thickness of the protective sheet.

[0094] Conditional formula 1) defines the ratio of the optical back focus to the half image height. By setting the conditions appropriately, the back intercept of the optical system is controlled. The long back intercept space can be well adapted to the ICR filter that switches day and night, meet the space requirements of the ICR filter and the camera, and prevent the various components from interfering with each other. If it is higher than the upper limit, the optical back intercept is too long and the system volume is large, or the imaging target surface is too small and the image light and shadow performance is poor. However, if it is lower than the lower limit, the optical back intercept is too short and interferes with the rear camera, or the imaging target surface is too large and the system volume is bulky. In addition, in order to reliably obtain the effect of the conditional formula 1), it is more preferred to set the value of the conditional formula 1) to 0.7.

[0095] Conditional formula 2) defines the ratio of the total optical length to the half image height and the ratio of the focal length of the lens to the half image height, respectively. By setting the conditions appropriately, the lens has the optical performance of a short total length and a large image plane. If it is higher than the upper limit, the total length of the optical system is too long and the system volume is large. However, if it is lower than the lower limit, the optical target surface is too large and the system size increases. In addition, in order to reliably obtain the effect of conditional formula 2), it is more preferred to set the value of conditional formula 2) to 8.4.

[0096] Conditional equation 3) defines the center thickness of the first lens and the ninth lens, as well as the radius of curvature of the object side and the image side, respectively. By setting the conditions appropriately, the spherical aberration of the optical system is optimized to the best. If the center thickness is higher than the upper limit, the spherical aberration of the optical system becomes larger, but if the center thickness is lower than the lower limit, the spherical aberration of the optical system will also become larger. If the radius of curvature of the object side of the first lens and the ninth lens is higher than the upper limit, the coma of the optical system decreases, but if it is lower than the lower limit, the coma of the optical system increases. If the radius of curvature of the image side of the first lens is lower than the lower limit, the spherical aberration of the optical system increases. If the radius of curvature of the image side of the ninth lens is higher than the upper limit, the spherical aberration of the optical system decreases, but if it is lower than the lower limit, the spherical aberration of the optical system increases. In addition, in order to reliably obtain the effect of conditional equation 4), it is more preferred to set the value of conditional equation 4) to 3).

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

[0098] Conditional equation 4) defines the focal length ratio and the center thickness of the second lens and the third lens respectively. By setting the conditions appropriately, the spherical aberration of the optical system is corrected. If the two 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 it is lower than the lower limit, the residual spherical aberration of the optical system is also too large and the spot diameter increases. In addition, in order to reliably obtain the effect of conditional equation 4), it is more preferable to set the value of conditional equation 4) to 4) f2 = 48.6mm; f3 = -34mm; T3 = 9.05mm; T4 = 1.8mm; |f2 / f3| = 1.43; T3+T4 = 10.9;

[0099] Conditional equation 5) defines the distance from the aperture to the center of the image side of the seventh lens and the distance from the aperture to the object side of the eighth lens. The distance between the center of the surface is controlled by the position of the diaphragm and the front and rear lenses to facilitate the installation of the diaphragm components. If the aperture position is lower than the lower limit, the aperture position space is too small and cannot be placed. In order to reliably obtain the effect of the conditional expression 5), it is more preferable to set the value of the conditional expression 5) to 5)d7= 4.85mm; d8 = 3.33mm;

[0100] d7+d8=8.18mm.

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

[0102] Conditional formula 7) defines the thickness of the filter and the protective film respectively. By setting the conditions appropriately, 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. If it is higher than the upper limit, the flat plate aberration of the optical system has too much influence and does not match the actual situation. However, if it is lower than the lower limit, the flat plate aberration of the optical system has too little influence and does not match the actual situation. In addition, in order to reliably obtain the effect of conditional formula 7), it is more preferred to set the value of conditional formula 7) to T G1 =0.3mm; T G2 =1.1mm.

[0103] A detailed description will now be given of a day-night switching low-light imaging lens according to various examples.

[0104] For the optical structure of Example 1, please refer to Figure 1 , the specific parameters of Example 1 are shown in Table 1 below. In Example 1, the working band of the day and night switching low-light imaging lens is 400-1000nm, the F number is 1.0, and the lens focal length f=47mm. The conditional formula is 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 Parameters

[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 The third lens -128.2 1.80 Glass 1.7 29 5 29.1 6.53 6 The 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 The 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 The eighth lens 21.0 7.71 Low melting point glass 1.8 41 14 -78.1 0.55 15 The ninth lens -31.8 1.42 Glass 1.7 30 16 28.0 3.68 17 Optical Filters 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 Coefficient Table

[0115] Surface 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] See also Figure 3 Example 1: MTF curve for daily use; the horizontal axis is frequency, in line pairs. The vertical axis is MTF value, in units of none. As can be seen from the figure above: the wavelength is 435-650nm visible light band, filtering out the interference of infrared light, and the MTF value of the curve is greater than 0.4 at 40Lp / mm. The imaging quality is good and can meet the requirements of the matching sensor.

[0117] See also Figure 4 , Example 1: Field curvature distortion diagram under daily use; the left picture is the field curvature diagram, the horizontal axis is the field curvature value, the unit is millimeter; the vertical axis is the normalized field of view, the unit is infinite rigid. It can be intuitively concluded from the figure: the field curvature of the lens is within 0.2mm. The right picture is the optical relative distortion diagram, the horizontal axis is the percentage relative optical distortion value, the unit is %; the vertical axis is the normalized field of view, the unit is infinite rigid. It can be intuitively concluded from the figure: the relative optical distortion of the lens is about 1.3%, which can meet the direct observation needs of the human eye.

[0118] See also Figure 5 , Example 1 is a relative illumination diagram under daily use; it can be seen from the figure that the relative illumination of the entire field of view of the optical system is 56%, the brightness of the image is uniform, and there is no obvious dark corner phenomenon at the edge.

[0119] See also Figure 6 , Example 1: Energy concentration diagram for daily use; As can be seen from the figure, 80% of the energy in the central field of view is concentrated within 10um, and 80% of the energy in the full field of view is concentrated around 25um. The energy concentration of this optical system is high, and the system diffuse spot is relatively small.

[0120] See also Figure 7, Example 1: MTF curve for night use; the horizontal axis is frequency, in line pairs. The vertical axis is MTF value, in units. From the above figure, we can see that: the wavelength is 435-1000nm full band, and the focus is on infrared light at night while also considering the use of visible light. The MTF value of the curve is greater than 0.4 at 40Lp / mm. The imaging quality is good and can meet the use of the matching sensor.

[0121] See also Figure 8 , Example 1: Field curvature distortion diagram under night use; the left picture is the field curvature diagram, the horizontal axis is the field curvature value, the unit is millimeter; the vertical axis is the normalized field of view, the unit is infinite rigid. It can be intuitively concluded from the figure: the field curvature of the lens is within 0.2mm. The right picture is the optical relative distortion diagram, the horizontal axis is the percentage relative optical distortion value, the unit is %; the vertical axis is the normalized field of view, the unit is infinite rigid. It can be intuitively concluded from the figure: the relative optical distortion of the lens is about 1.4%, which can meet the direct observation needs of the human eye.

[0122] See also Fig. 9 , Example 1 is a relative illumination diagram under night use; it can be seen from the figure that the relative illumination of the entire field of view of the optical system is 57%, the brightness of the image is uniform, and there is no obvious dark corner phenomenon at the edge.

[0123] See also Fig.10 , Example 1: Energy concentration diagram for night use; As can be seen from the figure, 80% of the energy in the central field of view is concentrated within 10um, and 80% of the energy in the full field of view is concentrated around 23um. The energy concentration of this optical system is high, and the system diffuse spot is relatively small.

[0124] See also Fig.11 , the real-scene simulation diagram of Example 1; it can be seen from the figure that the optical system performs real-scene simulation, the imaging quality is good, the illumination is uniform, and there is no obvious vignetting.

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

[0126] 1. By adopting the equal-thickness ICR filter switching solution, using visible light during the day and visible and infrared light at night can effectively improve and enhance the use effect, so that the influence of infrared light can be avoided during daytime use, and dual-peak filters are used at night.

[0127] 2. By adding operands to control the back intercept of the optical system and digging a step on the last lens, the distance from the frame to the image plane is increased to meet the space requirements of the ICR filter and the camera and prevent interference between the components.

[0128] 3. Adding the thickness of the filter and the thickness of the protection optimizes the field curvature of the optical system and achieves high image quality output.

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

[0130] Example 2

[0131] Reference Fig.12 , a description will be given of an electronic device A according to Example 2 of the present invention. Fig.12 1 is a schematic diagram of an electronic device (industrial line scan camera) using any one of the day / night switching low-light imaging lenses according to Example 1 for an imaging optical system.

[0132] exist Fig.12 , reference numeral A2 denotes an electronic device body, and reference numeral A1 denotes an imaging optical system (interchangeable lens) including any one of the day-night switching low-light imaging lenses according to Example 1. Reference numeral A3 denotes 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 (optical image formed by the imaging optical system A1) from the imaging optical system A1 and performs photoelectric conversion. Reference numeral A4 denotes 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 for electronic equipment such as a digital still camera or the like, it is possible to obtain an electronic equipment having a day / night switching low-light imaging lens with high optical performance.

[0134] While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments.The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims

1. A day-night switching low-light imaging lens, characterized in that: From the object side to the image side, there are the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the aperture, the eighth lens, the ninth lens, the filter and the protective film; The first lens has positive refractive power and a convex object side surface; The second lens has positive refractive power, and its object side surface is convex, and its image side surface is convex; The third lens has negative refractive power, and its object side surface is concave and its image side surface is concave; The fourth lens element has negative refractive power, and its object side surface is concave and its image side surface is concave; The fifth lens element has positive refractive power, and its object side surface is convex, and its image side surface is convex; The sixth lens has positive refractive power, and its object-side surface is convex, and its image-side surface is convex; The seventh lens element has negative refractive power, and its object side surface is concave and its image side surface is concave; The eighth lens has positive refractive power, and its object-side surface is convex, and its image-side surface is convex; The ninth lens element has negative refractive power, and its object side surface is concave and its image side surface is concave; The image side surface of the second lens and the object side surface of the third lens are glued together to form a first glued lens; The image side surface of the fourth lens and the object side surface of the fifth lens are glued together to form a second glued lens; The image side surface of the sixth lens and the object side surface of the seventh lens are glued together to form a third glued lens; The filter adopts an ICR double filter switcher, which is equipped with a visible light filter and an infrared light filter of equal thickness; The lens satisfies the following conditional formula: 0.1 <BFL / y<1.2 Wherein, BFL is the optical back focus of the lens, and y is the half image height of the imaging surface of the lens on the image plane.

2. The day-night switching low-light imaging lens according to 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 according to claim 1, characterized in that: The lens satisfies the following conditional formula: 6 <TTL / y<10;2.8<f / y<7.6 Wherein, TTL is the total optical length of the lens, and f is the focal length of the lens.

4. The day-night switching low-light imaging lens according to claim 1, characterized in that: The lens satisfies the following conditional formula: 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 is the radius of curvature of the first lens object side, R 02 is the radius of curvature of the image side of the first lens, T1 is the center thickness of the first lens, R 15 is the radius of curvature of the object side of the ninth lens, R 16 is the curvature radius of the image side of the ninth lens, T 15 is the center thickness of the ninth lens.

5. The day-night switching low-light imaging lens as claimed in claim 1, characterized in that: The lens satisfies the following conditional formula: 1.0<|f2 / f3|<2.6; 7 <T3+T4<14 Wherein, 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. The day-night switching low-light imaging lens according to claim 1, characterized in that: The lens satisfies the following conditional formula: 6mm <d7+d8<14mm Wherein, d7 is the distance from the aperture to the center of the image side of the seventh lens, and d8 is the distance from the aperture to the center of the object side of the eighth lens.

7. The day-night switching low-light imaging lens according to claim 1, characterized in that: The lens satisfies the following conditional formula: |Vd4-Vd5|<5 Wherein, Vd4 is the Abbe number of the fourth lens, and Vd5 is the Abbe number of the fifth lens.

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

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

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