Electric focusing lens

Abstract

The utility model relates to the technical field of optical lenses, in particular to an electric focusing lens. The electric focusing lens comprises a first lens unit, a second lens unit, a liquid lens module and a third lens unit which are sequentially arranged in the light path direction, the first lens unit is of negative focal power, the second lens unit and the third lens unit are of positive focal power, and the liquid lens module and the third lens unit are of positive focal power. The liquid lens module comprises a first window piece and a second window piece which are arranged in parallel, a sealed cavity is formed between the first window piece and the second window piece, a diaphragm is arranged in the sealed cavity, first liquid is packaged between the diaphragm and the first window piece, second liquid is packaged between the diaphragm and the second window piece, and the first window piece and the second window piece are arranged in a sealed mode. And voltage is applied between the first window sheet and the second window sheet so as to change the curvature radius of the diaphragm. By the adoption of the mode, the lens is simple in structure, real-time electric focusing can be conducted on different object distances, the object distance observation range is widened, and the resolution ratio is improved.

Description

Technical Field

[0001] The present application relates to the technical field of optical lenses, and in particular to an electric focusing lens. Background Art

[0002] In the fields of industrial slit detection, pipeline monitoring, and minimally invasive medical surgery, the bulky surveillance and industrial lenses commonly used on the market predominantly require electronic endoscopes, which facilitate easy access to tiny holes. However, due to these size limitations, endoscopes cannot be equipped with various motors to drive the lens assembly for electric focusing. Therefore, once the endoscope is installed, its focus distance is fixed and cannot be adjusted. This makes it impossible to freely observe objects at different distances within a small space, limiting its observation range.

[0003] In order to avoid the observation inconvenience caused by the above problems, traditional endoscopes on the market today often use a small aperture system with an aperture greater than 5.0 to increase the depth of field of the lens. In this way, even if the lens is not focused, a larger object distance range can be observed at the same time. However, this method has limited improvement in depth of field, and the clear object distance range is only a few tens of millimeters. In addition, the small aperture system introduces new problems. First, the amount of light entering is too small, requiring strong fill light. On the other hand, due to the diffraction effect, the resolution of the lens is limited, which is not conducive to seeing a clear image. Utility Model Content

[0004] The technical problem to be solved by the embodiments of the present application is to provide an electric focus lens that can perform real-time electric focus adjustment for different object distances, thereby increasing the observation object distance range and improving the resolution.

[0005] The present application discloses an electric focus lens, comprising a first lens unit, a second lens unit, a liquid lens module and a third lens unit arranged in sequence along an optical path, wherein the first lens unit has a negative optical focal length, the second lens unit and the third lens unit have a positive optical focal length, the liquid lens module comprises a first window and a second window arranged in parallel, a sealed chamber is formed between the first window and the second window, a diaphragm is provided in the sealed chamber, a first liquid is encapsulated between the diaphragm and the first window, and a second liquid is encapsulated between the diaphragm and the second window, and a voltage is applied between the first window and the second window to change the curvature radius of the diaphragm.

[0006] Optionally, the first lens unit is a first single lens with negative optical power, and the first single lens is a meniscus lens.

[0007] Optionally, the second lens unit is a second single lens with positive optical power.

[0008] Optionally, the second lens unit is a combination lens group of a parallel flat glass with no optical power and a second single lens with positive optical power corresponding to the parallel flat glass.

[0009] Optionally, the second lens unit is a combination lens group of a turning prism and a second single lens with positive optical power corresponding to the turning prism.

[0010] Optionally, the turning prism includes a first prism, a second prism and a third prism glued together, and the upper and lower parts of the bonding surface of the first prism and the second prism are respectively provided with an incident area and a first reflection area, and the bonding surface of the third prism and the second prism is provided with a second reflection area, so that the light emitted from the first lens unit is incident on the incident area, and after being reflected in turn by the second reflection area and the first reflection area, it is emitted from the second prism, and the direction of the light incident on the turning prism and the direction of the light exiting the turning prism form a preset angle.

[0011] Optionally, the third lens unit is a first cemented lens with positive refractive power, or the third lens unit includes a first cemented lens and a second cemented lens with positive refractive power that are arranged opposite to each other.

[0012] Optionally, the electric focus lens can focus on an object distance range of 20 mm to 150 mm, and the electric focus lens satisfies the following conditional formula:

[0013] -1.3 <fG1 / f<-0.9 (1)

[0014] 1.6 <fG2 / f<2.6 (2)

[0015] Wherein, fG1 is the focal length of the first lens unit, fG2 is the focal length of the second lens unit, and f is the total focal length of the electric focus lens when the object distance is 150 mm.

[0016] Optionally, the electric focus lens further satisfies the following conditional formula:

[0017] 1.76 <nG1<2.06 (3)

[0018] Wherein, nG1 is the refractive index of the first monomer lens.

[0019] Optionally, the electric focus lens further includes a lens barrel, the first lens unit, the second lens unit, the liquid lens module and the third lens unit are all located in the lens barrel, and the outer diameter of the lens barrel is less than or equal to 8.5 mm.

[0020] Compared with the prior art, the beneficial effect of the electric focus lens provided by the embodiment of the present application is that: by utilizing a liquid lens module to achieve real-time electric focusing of the electric focus lens, there are no protrusions of any motor, gear or other structures on the outer surface of the structure, and no moving parts are required. It is simple and compact, achieving the purpose of miniaturization of the electric focus lens. At the same time, a first lens unit with negative optical focal length is used to form a reverse telephoto optical structure with a large field of view. Since the electric focus lens can focus on different object distances at any time, it is not necessary to consider a large depth of field in the optical path design. The lens aperture can be F4.0 or even larger, which helps to reduce the influence of the diffraction effect. Compared with a lens with a fixed focus object distance, it has a higher resolution. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The technical solution of the present application will be further described in detail below with reference to the accompanying drawings and embodiments, in which:

[0022] Figure 1 This is one of the structural schematic diagrams of the electric focus lens provided in the embodiment of the present application;

[0023] Figure 2 This is the second structural diagram of the electric focus lens provided in an embodiment of the present application;

[0024] Figure 3 This is the third structural diagram of the electric focus lens provided in the embodiment of the present application;

[0025] Figure 4 This is the fourth structural diagram of the electric focus lens provided in an embodiment of the present application;

[0026] Figure 5 This is the fifth structural diagram of the electric focus lens provided in the embodiment of the present application;

[0027] Figure 6 yes Figure 1 Spherical aberration, astigmatism, and optical distortion curves when the object distance is 20 mm in the structure shown;

[0028] Figure 7 yes Figure 1 Spherical aberration, astigmatism, and optical distortion curves for the structure shown when the object distance is 150mm;

[0029] Figure 8 yes Figure 2 Graphs of spherical aberration, astigmatism, and optical distortion when the first single lens in the structure shown is a spherical lens and the object distance is 20 mm;

[0030] Figure 9 yes Figure 2 Graphs of spherical aberration, astigmatism, and optical distortion when the object distance is 150 mm when the first single lens in the structure shown is a spherical lens;

[0031] Figure 10 yes Figure 2 Graphs of spherical aberration, astigmatism, and optical distortion when the first single lens in the structure shown is an aspherical lens and the object distance is 20 mm;

[0032] Figure 11 yes Figure 2 Graphs of spherical aberration, astigmatism, and optical distortion when the object distance is 150 mm when the first single lens in the structure shown is an aspherical lens;

[0033] Figure 12 yes Figure 4 Spherical aberration, astigmatism, and optical distortion curves when the object distance is 20 mm in the structure shown;

[0034] Figure 13 yes Figure 4 Spherical aberration, astigmatism, and optical distortion curves at an object distance of 150mm for the shown configuration.

[0035] The reference numerals in the figures are:

[0036] 100. Electric focus lens; 110. First lens unit; 112. First monomer lens; 120. Second lens unit; 122. Second monomer lens; 124. Parallel plate glass; 126. Turning prism; 1262. First prism; 1264. Second prism; 1266. Third prism; 130. Liquid lens module; 132. First window; 134. Second window; 136. Diaphragm; 140. Third lens unit; 142. First cemented lens; 144. Second cemented lens. DETAILED DESCRIPTION

[0037] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present application can be combined with each other. Now, in conjunction with the accompanying drawings, the preferred embodiments of the present application are described in detail.

[0038] like Figures 1 to 5 As shown, an embodiment of the present application provides an electric focus lens 100, including a first lens unit 110, a second lens unit 120, a liquid lens module 130 and a third lens unit 140 arranged in sequence along the optical path direction, wherein the first lens unit 110 has a negative optical focal length, the second lens unit 120 and the third lens unit 140 have a positive optical focal length, and the liquid lens module 130 includes a first window 132 and a second window 134 arranged in parallel, a sealed chamber is formed between the first window 132 and the second window 134, a diaphragm 136 is provided in the sealed chamber, a first liquid is encapsulated between the diaphragm 136 and the first window 132, and a second liquid is encapsulated between the diaphragm 136 and the second window 134, and a voltage is applied between the first window 132 and the second window 134 to change the curvature radius of the diaphragm 136.

[0039] Specifically, the first lens unit 110 is configured to have a negative optical power, enabling the electric focus lens 100 to form a reverse telephoto structure. Light rays incident at large angles outside the field of view are deflected after passing through the first lens unit 110, reducing their angle with the optical axis. This facilitates aberration correction in the rear optical path, allowing the electric focus lens 100 to have a larger field of view. The second lens unit 120 has a positive optical power and is primarily responsible for correcting the spherical aberration of the electric focus lens 100. The first liquid and the second liquid are made of different materials and are separated by a diaphragm 136. To ensure normal light transmission, the diaphragm 136 must be transparent. When the voltage applied between the first window 132 and the second window 134 changes, the curvature of the diaphragm 136 changes due to the electrowetting effect. This curvature and the applied voltage have a clear correspondence, resulting in a one-to-one correspondence between the lens's focal distance and the voltage. The optical power of the liquid lens module 130 can be adjusted using the voltage. The third lens unit 140 has positive refractive power and is used to correct chromatic aberration of the electric focus lens.

[0040] The electric focusing lens 100 provided in the embodiment of the present application realizes real-time electric focusing of the electric focusing lens 100 by utilizing a liquid lens module 130. The outer surface of the structure does not have any protrusions of motors, gears or other structures, does not require any moving parts, is simple and compact, and achieves the purpose of miniaturization of the electric focusing lens 100. At the same time, a first lens unit 110 with negative optical focal length is adopted to form a reverse telephoto optical structure with a larger field of view. Since the electric focusing lens 100 can focus on different object distances at any time, it is not necessary to consider a large depth of field in the optical path design. The lens aperture can be F4.0 or even larger, which helps to reduce the influence of the diffraction effect and has a higher resolution than a lens with an immutable focusing object distance. The above-mentioned form can improve the observation object distance range of the lens and improve the resolution.

[0041] like Figures 1 to 5 As shown, the first lens unit 110 is a first single lens 112 with negative optical power, and the first single lens 112 is a meniscus lens.

[0042] Specifically, the first lens unit 110 uses a first single lens 112 with negative optical power, which is beneficial for increasing the field of view while ensuring the desired imaging effect. In practical applications, a meniscus lens can be used, which can be a spherical lens or an aspherical lens, and this embodiment of the application does not impose specific limitations on this.

[0043] When the first single lens 112 is in the form of an aspheric lens, the optical distortion of the system can be reduced, and richer image information can be retained at the edge of the field of view, which is very valuable for medical observation. The surface shape of the aspheric surface satisfies the following formula:

[0044]

[0045] Among them, c = 1 / R, R represents the curvature radius of the reference sphere of the aspheric surface, r represents the radial coordinate of the aspheric lens starting from the optical axis, z represents the sag corresponding to the radial coordinate r of the aspheric lens, k represents the cone coefficient, and A, B, C, D, E, and F represent aspheric coefficients of different orders, respectively.

[0046] like Figure 1 As shown, the second lens unit 120 is a second single lens 122 with positive refractive power.

[0047] Specifically, the second single lens 122 may be a plano-convex lens or a biconvex lens to correct the spherical aberration of the electric focus lens 100 .

[0048] use Figure 1 The scheme shown constitutes an electric focus lens 100, and the lens data used is shown in the following table:

[0049] Face number Curvature radius R(mm) Thickness interval d(mm) Refractive index nd Abbe coefficient vd 1 9.697 0.85 1.9108 35.26 2 2.1 3.835 3 16.95 3.3 1.9004 37.37 4 6.17 0.66 5 ∞ 0.4 1.5233 54.52 6 ∞ D(6) 1.4882 38.39 7 R(7) D(7) 1.4293 62.16 8 ∞ 0.5 1.5233 54.52 9 ∞ 0.5 10 8.11 1.509 1.6968 56.2 11 -3.0 0.51 1.9460 17.94 12 -9.4 4.83

[0050] It should be noted that surface numbers 1 to 12 are the numbers of the optical surfaces arranged in order from the object side to the image side. In addition, when the object distance is 20mm and 150mm respectively, the parameter changes of D(6), D(7) and R(7) are shown in the following table:

[0051] Object distance (mm) 20 150 D(6) 0.35 0.28 D(7) 0.45 0.52 R(7) -12.03 42.06

[0052] Among them, the use of Figure 1 In the embodiment shown, the corresponding optical indicators (when the object distance is 150 mm) are as follows: focal length f: 2.65 mm; aperture Fno: F4.1; half field angle ω: 45°; optical distortion: -24.0%.

[0053] like Figure 2 and Figure 4 As shown, the second lens unit 120 is a combination of a parallel plate glass 124 with no optical power and a second single lens 122 with positive optical power corresponding to the parallel plate glass 124 .

[0054] Specifically, when the second monomer lens 122 is a biconvex lens, there may be a certain distance between the second monomer lens 122 and the parallel plate glass 124 (see Figure 2 When the second monomer lens 122 is a plano-convex lens, it can be directly glued to the parallel plate glass 124 (see Figure 4 ), in this case, there is no air gap between the parallel flat glass 124 and the second monomer lens 122, and a spacer can be omitted in the structure, making the assembly steps simpler.

[0055] use Figure 2 The scheme shown constitutes the electric focus lens 100, and when the first single lens 112 is a spherical lens, the lens data used are shown in the following table:

[0056] Face number Curvature radius R(mm) Thickness interval d(mm) Refractive index nd Abbe coefficient vd 1 16.75 1.0 2.0010 29.13 2 2.44 0.47 3 ∞ 8.6 1.9108 35.26 4 ∞ 0.11 5 7.852 1.25 1.9108 35.26 6 -10.665 0.643 7 ∞ 0.4 1.5233 54.52 8 ∞ D(8) 1.4882 38.39 9 R(9) D(9) 1.4293 62.16 10 ∞ 0.5 1.5233 54.52 11 ∞ 0.3 12 9.954 1.756 1.5928 68.62 13 -2.589 0.53 1.9229 20.88 14 -7.051 5.55

[0057] It should be noted that surface numbers 1 to 14 are the numbers of the optical surfaces arranged in order from the object side to the image side. In addition, when the object distance is 20mm and 150mm respectively, the parameter changes of D(8), D(9) and R(9) are shown in the following table:

[0058] Object distance (mm) 20 150 D(8) 0.35 0.28 D(9) 0.45 0.52 R(9) -13.02 62.03

[0059] Among them, the use of Figure 2 In the embodiment shown, the corresponding optical indicators (when the object distance is 150 mm) are as follows: focal length f: 2.92 mm; aperture Fno: F4.1; half field angle ω: 40°; optical distortion: -18.5%.

[0060] use Figure 2 The scheme shown constitutes the electric focus lens 100, and when the first single lens 112 is an aspherical lens, the lens data used are shown in the following table:

[0061]

[0062]

[0063] It should be noted that surface numbers 1 to 14 are the numbers of the optical surfaces arranged in order from the object side to the image side. In addition, when the object distance is 20mm and 150mm respectively, the parameter changes of D(8), D(9) and R(9) are shown in the following table:

[0064] Object distance (mm) 20 150 D(8) 0.34 0.29 D(9) 0.46 0.51 R(9) -13.818 50.122

[0065] The aspheric lens adopts the parameters in the following table:

[0066] Face number k A B C D E F 1 0 6.0245E-03 3.5537E-03 -2.6859E-03 7.8835E-04 -1.0951E-04 5.8310E-06 2 -3.1587E-01 2.8378E-03 3.7565E-02 -3.9933E-02 2.1796E-02 -5.7326E-03 5.5118E-04

[0067] In the above table, surface number 1 and surface number 2 are the numbers of two optical surfaces of the first single lens 112 arranged in sequence from the object side to the image side.

[0068] At this time, the corresponding optical indicators (when the object distance is 150 mm) are as follows: focal length f: 2.66 mm; aperture Fno: F4.1; half field angle ω: 40°; optical distortion: -10.0%.

[0069] exist Figure 2 and Figure 4In the embodiment, the parallel plate glass 124 has no optical power and does not participate in correcting the aberration in the system. In actual applications, it can be transformed into a turning prism 126 with the same optical path as the parallel plate glass 124 by the prism expansion method.

[0070] like Figure 3 and Figure 5 As shown, in an optional embodiment of the present application, the second lens unit 120 is a combination lens group of a turning prism 126 and a second single lens 122 with positive optical power corresponding to the turning prism 126 .

[0071] Specifically, by cooperating with the steering prism 126 and the second single lens 122, the optical axis of the optical path is changed, enabling the electric focus lens 100 to have different viewing angles. This approach facilitates changing the lens's viewing angle to meet the needs of different observation angles. When the lens is within a small space, it can be viewed in different directions simply by rotating it around the optical axis.

[0072] like Figure 3 As shown, the turning prism 126 includes a first prism 1262, a second prism 1264 and a third prism 1266 that are glued together. The upper and lower parts of the bonding surface of the first prism 1262 and the second prism 1264 are respectively provided with a first reflection area and an incident area, and the bonding surface of the third prism 1266 and the second prism 1264 is provided with a second reflection area, so that the light emitted from the first lens unit 110 is incident on the incident area of ​​the first prism 1262, and then reflected by the second reflection area and the first reflection area in sequence, and then emitted from the second prism 1264 to the rear light path, and the direction of the light incident on the turning prism 126 is at a preset angle to the direction of the light exiting the turning prism 126.

[0073] Specifically, the incident area may not be coated with any functional film. After the light emitted from the first lens unit 110 is incident on the incident area, it can directly pass through the first prism 1262 and the second prism 1264 to the second reflection area, or an anti-reflection film can be coated on the incident area to improve the utilization rate of the light. After the light is incident on the second reflection area, the light is reflected to the first reflection area, wherein the bonding surfaces of the third prism 1266 and the second prism 1264 are all provided with a reflective film to improve the utilization rate of the light during reflection. After the light is reflected to the first reflection area, it is finally emitted from the second prism 1264. Using the above form, the direction of the light incident on the steering prism 126 and the direction of the exit steering prism 126 are at a preset angle to change the optical axis direction of the light path, so that the lens has a different viewing angle. For example, the first lens unit 110 can be set to a certain deflection angle as needed, such as a 30° viewing angle.

[0074] like Figures 1 to 5As shown, the third lens unit 140 is a first cemented lens 142 with positive refractive power, or the third lens unit 140 includes a first cemented lens 142 and a second cemented lens 144 with positive refractive power that are arranged opposite to each other.

[0075] Specifically, first cemented lens 142 can be formed by cementing a positive-power lens and a negative-power lens. The positive-power lens is made of extra-low dispersion glass, which helps correct system chromatic aberration. Furthermore, second cemented lens 144 is also formed by cementing a positive-power lens and a negative-power lens. The positive-power lens is also made of extra-low dispersion glass, which further helps correct system chromatic aberration. When first cemented lens 142 and second cemented lens 144 are combined, aberrations in the optical system, such as spherical aberration and chromatic aberration, can be reduced, thereby improving the imaging quality and clarity of the optical system.

[0076] use Figure 4 When the electric focus lens 100 is constructed according to the solution shown, the lens data used are shown in the following table:

[0077] Face number Curvature radius R Thickness interval d Refractive index nd Abbe coefficient vd 1 17.086 0.75 2.0010 29.13 2 2.52 0.488 3 ∞ 8.6 1.9108 35.26 4 ∞ 1.142 1.9537 32.32 5 -6.258 1.021 6 ∞ 0.4 1.5233 54.52 7 ∞ D(7) 1.4882 38.39 8 R(8) D(8) 1.4293 62.16 9 ∞ 0.5 1.5233 54.52 10 ∞ 0.29 11 3.65 1.332 1.5928 68.62 12 64.02 0.54 1.7618 26.61 13 3.614 0.13 14 6.333 2.611 1.5928 68.62 15 -2.4 0.695 1.9037 31.32 16 -5.281 4.27

[0078] It should be noted that surface numbers 1 to 16 are the numbers of the optical surfaces arranged in order from the object side to the image side. In addition, when the object distance is 20mm and 150mm respectively, the parameter changes of D(7), D(8) and R(8) are shown in the following table:

[0079] Object distance 20 150 D(7) 0.34 0.29 D(8) 0.46 0.51 R(8) -13.011 170.02

[0080] At this time, the corresponding optical indicators (when the object distance is 150mm) are as follows: focal length f: 2.89mm; aperture Fno: F4.05; half field angle ω: 40°; optical distortion: -17.3%.

[0081] In an optional embodiment of the present application, the object distance range that the electric focus lens 100 can focus on is 20 mm to 150 mm, and the electric focus lens 100 satisfies the following conditional formula:

[0082] -1.3 <fG1 / f<-0.9 (1)

[0083] 1.6 <fG2 / f<2.6 (2)

[0084] Wherein, fG1 is the focal length of the first lens unit 110 , fG2 is the focal length of the second lens unit 120 , and f is the total focal length of the electric focus lens 100 when the object distance is 150 mm.

[0085] Specifically, through the cooperation of the first lens unit 110, the second lens unit 120 and the third lens unit 140, and relying on the electric focus of the liquid lens module 130, clear focus can be achieved within the object distance range of 20mm to 150mm, thereby improving the observation effect. Figures 6 to 13 Figures 2 and 3 show the spherical aberration, astigmatism, and optical distortion of the electric focus lens 100 in different configurations. Spherical aberration represents spherical aberration, with its ordinate representing the height of the light above the aperture stop; astigmatic field curves represent astigmatism, with their ordinate representing the image plane height; and distortion represents optical distortion, with its ordinate also representing the image plane height. As can be seen, the electric focus lens 100 achieves excellent correction for various aberrations at various object distances, enabling high-definition imaging over a wide range of working object distances.

[0086] In an optional embodiment of the present application, the electric focus lens 100 further satisfies the following conditional formula:

[0087] 1.76 <nG1<2.06 (3)

[0088] Wherein, nG1 is the refractive index of the first single lens 112 .

[0089] With this configuration, light incident at large angles outside the field of view is deflected after passing through the first individual lens 112, reducing its angle with the optical axis. This facilitates aberration correction in the subsequent optical path, resulting in a wider field of view. Furthermore, the height of the light incident on the first individual lens 112 is reduced, which helps control the lens diameter and ensures a compact overall diameter of the electric focus lens 100.

[0090] The conditional values ​​corresponding to the embodiments of this application are summarized as follows:

[0091]

[0092]

[0093] In an optional embodiment of the present application, the electric focus lens 100 further includes a lens barrel, and the first lens unit 110, the second lens unit 120, the liquid lens module 130 and the third lens unit 140 are all located in the lens barrel, and the outer diameter of the lens barrel is less than or equal to 8.5 mm.

[0094] Specifically, using the above method, in actual applications, the electric focusing lens 100 has a small overall diameter and can easily enter tiny holes and cavities, and perform electric focusing on different object distances, thereby expanding the observation range of the electric focusing lens 100, which is conducive to its application in micro lenses such as endoscopes.

[0095] It should be understood that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Those skilled in the art may modify, scale, or replace some of the technical features described in the above embodiments with equivalents; and all these modifications, scaling, and replacements shall fall within the scope of protection of the claims attached to this application.

Claims

1. An electric focus lens, characterized in that: The invention comprises a first lens unit, a second lens unit, a liquid lens module and a third lens unit arranged in sequence along the optical path, wherein the first lens unit has a negative optical focal length, the second lens unit and the third lens unit have a positive optical focal length, the liquid lens module comprises a first window and a second window arranged in parallel, a sealed chamber is formed between the first window and the second window, a diaphragm is provided in the sealed chamber, a first liquid is encapsulated between the diaphragm and the first window, a second liquid is encapsulated between the diaphragm and the second window, and a voltage is applied between the first window and the second window to change the curvature radius of the diaphragm.

2. The electric focus lens according to claim 1, wherein: The first lens unit is a first single lens with negative optical power, and the first single lens is a meniscus lens.

3. The electric focus lens according to claim 2, wherein: The second lens unit is a second single lens with positive refractive power.

4. The electric focus lens according to claim 2, wherein: The second lens unit is a combination of a parallel flat glass with no optical power and a second single lens with positive optical power corresponding to the parallel flat glass.

5. The electric focus lens according to claim 2, wherein: The second lens unit is a combination lens group of a turning prism and a second single lens with positive optical power corresponding to the turning prism.

6. The electric focus lens according to claim 5, characterized in that: The turning prism includes a first prism, a second prism and a third prism that are glued together. The upper and lower parts of the bonding surface of the first prism and the second prism are respectively provided with a first reflection area and an incident area. The bonding surface of the third prism and the second prism is provided with a second reflection area, so that the light emitted from the first lens unit is incident on the incident area, and after being reflected in turn by the second reflection area and the first reflection area, it is emitted from the second prism, and the direction in which the light enters the turning prism and the direction in which the light exits the turning prism form a preset angle.

7. The electric focus lens according to any one of claims 2 to 6, wherein: The third lens unit is a first cemented lens with positive refractive power, or the third lens unit includes a first cemented lens and a second cemented lens with positive refractive power that are arranged opposite to each other.

8. The electric focus lens according to claim 7, wherein: The object distance range that the electric focus lens can focus on is 20mm to 150mm, and the electric focus lens meets the following conditional formula: -1.3 <fG1 / f<-0.9 (1) 1.6 <fG2 / f<2.6 (2) Wherein, fG1 is the focal length of the first lens unit, fG2 is the focal length of the second lens unit, and f is the total focal length of the electric focus lens when the object distance is 150 mm.

9. The electric focus lens according to claim 8, wherein: The electric focus lens also satisfies the following conditional formula: 1.76 <nG1<2.06 (3) Wherein, nG1 is the refractive index of the first monomer lens.

10. The electric focus lens according to any one of claims 1 to 6, characterized in that: The electric focus lens further includes a lens barrel, the first lens unit, the second lens unit, the liquid lens module and the third lens unit are all located in the lens barrel, and the outer diameter of the lens barrel is less than or equal to 8.5 mm.

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