Optical lens system and surveillance camera equipment

Abstract

The present invention discloses an optical lens system and surveillance camera equipment. The optical lens system includes a plurality of lens groups arranged sequentially from the object side to the image side, with an optical axis formed between the plurality of lens groups. The plurality of lens groups include a first lens group and a second lens group. The first lens group has negative optical focal length and is movable along the extension direction of the optical axis; the second lens group has positive optical focal length and is movable along the extension direction of the optical axis. By arranging the first lens group and the second lens group, the refractive index and Abbe number of light from the object side to the image side are complementary, ensuring a resolution effect in the infrared band while ensuring minimal chromatic aberration in the visible band. By adjusting the positions of the first lens group and the second lens group, the change in the conjugate distance of the first lens group and the change in the conjugate distance after magnification of the second lens group are offset, achieving image plane compensation, thereby providing an ultra-low-cost, glass-plastic hybrid, high-reliability zoom optical lens system.

Description

Technical Field

[0001] The present invention relates to the field of optical technology, in particular to an optical lens system and a monitoring camera device. Background Art

[0002] Current surveillance zoom optical systems suffer from common drawbacks: high cost, inability to achieve infrared parfocality at every zoom magnification, lens inoperability or reduced resolution in extreme environments, and so on. Currently, no lens on the market fully addresses these shortcomings. A few improve certain aspects at the expense of others. For example, to achieve ultra-low costs, all-plastic lenses are used, resulting in either failure to guarantee infrared parfocality at every magnification or inability to operate in extreme environments. Some lenses also employ multiple glass elements to achieve required resolution and withstand extreme conditions, increasing costs and hindering their widespread adoption. Summary of the Invention

[0003] The main purpose of the present invention is to propose an optical lens system and a surveillance camera device, aiming to provide an ultra-low-cost, glass-plastic hybrid, high-reliability zoom optical lens system.

[0004] To achieve the above objectives, the present invention provides an optical lens system, wherein the optical lens system includes a plurality of lens groups arranged sequentially from the object side to the image side, wherein an optical axis is formed between the plurality of lens groups, wherein the plurality of lens groups include:

[0005] a first lens group having negative optical power and being movably arranged along the extension direction of the optical axis; and

[0006] The second lens group has positive refractive power and is movably arranged along the extension direction of the optical axis;

[0007] Image plane compensation is achieved by changing the positions of the first lens group and the second lens group.

[0008] Optionally, a stop is provided between the first lens group and the second lens group.

[0009] Optionally, a distance between a side of the first lens group facing the image side and the aperture is L1, wherein 0.93 mm ≤ L1 ≤ 12.67 mm.

[0010] Optionally, a distance between a side of the second lens group facing the object side and the aperture stop is L2, wherein 0.335 mm ≤ L2 ≤ 6.96 mm.

[0011] Optionally, the first lens group includes a first lens, a second lens and a third lens arranged in sequence from the object side to the image side; and / or,

[0012] The second lens group includes a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens arranged in sequence from the object side to the image side, wherein the optical focal power of the fourth lens is positive or negative, the optical focal power of the fifth lens is positive, the optical focal power of the sixth lens is negative, the optical focal power of the seventh lens is positive, and the optical focal power of the eighth lens is positive or negative.

[0013] Optionally, the first lens is a glass spherical lens, and the second lens and the third lens are plastic aspherical lenses.

[0014] Optionally, the fourth lens is a glass spherical lens, and the fifth lens, the sixth lens, the seventh lens and the eighth lens are plastic aspherical lenses.

[0015] Optionally, the optical lens system further includes a photosensitive chip, which is arranged on the side of the second lens group facing the image side, and the photosensitive surface of the photosensitive chip is arranged toward the second lens group.

[0016] Optionally, a filter is provided between the photosensitive chip and the second lens group.

[0017] The present invention further provides a surveillance camera device, comprising an optical lens system, wherein the optical lens system comprises a plurality of lens groups arranged sequentially from the object side to the image side, wherein an optical axis is formed between the plurality of lens groups, wherein the plurality of lens groups comprise:

[0018] a first lens group having negative optical power and being movably arranged along the extension direction of the optical axis; and

[0019] The second lens group has positive refractive power and is movably arranged along the extension direction of the optical axis;

[0020] Image plane compensation is achieved by changing the positions of the first lens group and the second lens group.

[0021] In the technical solution provided by the present invention, by arranging the first lens group and the second lens group, the refractive index and the Abbe number of the light from the object side to the image side are complementary, and the resolution effect of the infrared band is guaranteed while ensuring small chromatic aberration in the visible band. By adjusting the positions of the first lens group and the second lens group, the change in the conjugate distance of the first lens group and the change in the conjugate distance after magnification of the second lens group are offset, thereby achieving image plane compensation, thereby providing an ultra-low-cost, glass-plastic hybrid, high-reliability zoom optical lens system. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. 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 the structures shown in these drawings without paying any creative work.

[0023] Figure 1 This is a structural schematic diagram of an embodiment of the optical lens system provided by the present invention.

[0024] Description of Figure Numbers:

[0025] Label name Label name 100 Optical lens system 5 Fifth lens 10 First lens group 6 Sixth lens 1 First lens 7 Seventh lens 2 Second lens 8 Eighth lens 3 The third lens 30 aperture 20 Second lens group 40 Photosensitive chip 4 Fourth lens 50 Filters

[0026] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0027] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0028] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly.

[0029] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the meaning of "and / or" appearing throughout the text includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme in which A and B are satisfied at the same time. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0030] Current surveillance zoom optical systems suffer from common drawbacks: high cost, inability to achieve infrared parfocality at every zoom magnification, lens inoperability or reduced resolution in extreme environments, and so on. Currently, no lens on the market fully addresses these shortcomings. A few improve certain aspects at the expense of others. For example, to achieve ultra-low costs, all-plastic lenses are used, resulting in either failure to guarantee infrared parfocality at every magnification or inability to operate in extreme environments. Some lenses also employ multiple glass elements to achieve required resolution and withstand extreme conditions, increasing costs and hindering their widespread adoption.

[0031] In order to solve the above problems, the present invention provides an optical lens system 100. Figure 1 This is a specific embodiment of the optical lens system 100 provided by the present invention.

[0032] See also Figure 1 The optical lens system 100 includes a plurality of lens groups arranged in sequence from the object side to the image side, and an optical axis is formed between the plurality of lens groups. The plurality of lens groups include a first lens group 10 and a second lens group 20. The first lens group 10 has negative optical power and is movably arranged along the extension direction of the optical axis; the second lens group 20 has positive optical power and is movably arranged along the extension direction of the optical axis. Image plane compensation is achieved by changing the positions of the first lens group 10 and the second lens group 20.

[0033] In the technical solution provided by the present invention, by arranging the first lens group 10 and the second lens group 20, the refractive index and the Abbe number of the light from the object side to the image side are complementary, thereby ensuring the resolution effect in the infrared band while ensuring small chromatic aberration in the visible band. By adjusting the positions of the first lens group 10 and the second lens group 20, the change in the conjugate distance of the first lens group 10 and the change in the conjugate distance after magnification of the second lens group 20 are offset, thereby achieving image plane compensation, thereby providing an ultra-low-cost, glass-plastic hybrid, high-reliability zoom optical lens system 100.

[0034] It should be noted that optical power is equal to the difference between the image-side and object-side convergence of a beam, and it characterizes the ability of an optical system to deflect light. The negative optical power of the first lens group 10 and the positive optical power of the second lens group 20 enable the beam to be projected in the desired direction.

[0035] Furthermore, to improve imaging quality, in this embodiment, an aperture 30 is provided between the first lens group 10 and the second lens group 20. The aperture 30 limits the aperture of the on-axis light beam and blocks some light during the zooming process, thereby reducing light spots, improving image contrast, and helping to improve image quality.

[0036] Specifically, the change in the conjugate distance of the first lens group 10 is offset by the change in the conjugate distance of the second lens group 20 after longitudinal magnification, thereby achieving image plane compensation. To specifically control the range of motion of the first lens group 10 and the second lens group 20, in this embodiment, the distance between the image-side side of the first lens group 10 and the aperture 30 is L1, where 0.93mm≤L1≤12.67mm; the distance between the object-side side of the second lens group 20 and the aperture 30 is L2, where 0.335mm≤L2≤6.96mm. It should be noted that the above two related technical features can be provided simultaneously or alternatively.

[0037] Furthermore, during the optical design process, the lens groups are grouped according to the functions and tasks they achieve. The first lens group 10 includes a first lens 1, a second lens 2, and a third lens 3 arranged in sequence from the object side to the image side; the second lens group 20 includes a fourth lens 4, a fifth lens 5, a sixth lens 6, a seventh lens 7, and an eighth lens 8 arranged in sequence from the object side to the image side, wherein the optical power of the fourth lens 4 is positive or negative, the optical power of the fifth lens 5 is positive, the optical power of the sixth lens 6 is negative, the optical power of the seventh lens 7 is positive, and the optical power of the eighth lens 8 is positive or negative. The surface shape of any of the above lenses needs to satisfy the following formula:

[0038]

[0039] Wherein, c corresponds to the reciprocal of the radius R, y is the radial coordinate, k is the conic quadratic curve coefficient, and a1 to a8 are the coefficients corresponding to each radial coordinate.

[0040] Furthermore, in the prior art, similar optical lens systems 100 employ plastic aspheric surfaces to achieve confocality and control costs. This results in poor lens reliability and inability to adapt to environments with large temperature differences. To enhance the stability of the optical lens system 100, in this embodiment, the first lens 1 is a glass spherical lens, while the second lens 2 and the third lens 3 are plastic aspheric lenses. This arrangement effectively corrects lens chromatic aberration, achieving infrared confocality while ensuring control of lens purple fringing, while also correcting spherical aberration and sinusoidal aberration at high magnification positions.

[0041] In this embodiment, the fourth lens element 4 is a glass spherical lens, while the fifth lens element 5, the sixth lens element 6, the seventh lens element 7, and the eighth lens element 8 are plastic aspherical lenses. The second lens group 20 diverges light of different colors, and the fifth lens element 5, the sixth lens element 6, and the seventh lens element 7 correct for higher-order aberrations, balancing the aberrations of the entire system. Vignetting is also implemented on each lens element to block peripheral stray light without affecting illumination, ensuring consistent resolution at the center and edges of the image plane.

[0042] Thus, by rationally designing the optical parameters and materials of each lens, the optical lens system 100 can maintain clear image resolution in extreme environments (high temperature of 70°C, low temperature of -40°C, or relative humidity of 90%) without the need for refocusing. The system uses a plastic material with extremely low water absorption and fully considers the changes in the refractive index and Abbe number of various lens materials at high and low temperatures, matching the surface shape and changes in air spacing, achieving positive and negative matching of the changes in the various factors of high and low temperatures and humidity, ensuring synchronization and clarity of the image plane in high and low temperature and different humidity environments.

[0043] Furthermore, to reduce or eliminate chromatic aberration, in this embodiment, the second lens 2 and the third lens 3 are quasi-cemented. To minimize or eliminate chromatic aberration, in this embodiment, the fifth lens 5, the sixth lens 6, and the seventh lens 7 are also quasi-cemented. Lens cementing, by gluing two lenses made of different materials together, corrects for glass dispersion and achieves further improvements in polychromatic (white light) imaging performance compared to single lenses.

[0044] Specifically, in this embodiment, the optical lens system 100 further includes a photosensitive chip 40, which is disposed on the side of the second lens group 20 facing the image side, and the photosensitive surface of the photosensitive chip 40 is disposed toward the second lens group 20, so as to receive an image on the image side and process the received image through the photosensitive chip 40.

[0045] Furthermore, a filter 50 is disposed between the photosensitive chip 40 and the second lens assembly 20. This filter 50 effectively filters out stray light in non-operating wavelengths, reducing optical noise and simplifying subsequent photoelectric module processing. This filter 50 can also be used to adjust the color saturation of the final image.

[0046] It should be noted that the basic parameters of the optical lens system 100 in this embodiment are shown in Table 1, where the units of curvature radius and thickness are both millimeters (mm).

[0047] Table 1

[0048]

[0049]

[0050] Among them, the aspheric coefficients of each surface are shown in Table 2:

[0051] Table 2

[0052]

[0053]

[0054] The present invention further provides a surveillance camera device, comprising the optical lens system 100. Since the surveillance camera device comprises the optical lens system 100, the specific structure of the optical lens system 100 is similar to that of the above-mentioned embodiments. Since the optical lens system 100 of the surveillance camera device employs all the technical solutions of all the above-mentioned embodiments, it at least has all the beneficial effects brought about by the technical solutions of the above-mentioned embodiments, which will not be described in detail here.

[0055] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention description and drawings under the inventive concept of the present invention, or direct / indirect application in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. An optical lens system, characterized in that: The invention comprises two lens groups arranged in sequence from the object side to the image side, wherein an optical axis is formed between the two lens groups, wherein the two lens groups are configured as follows: a first lens group having negative optical power and being movably arranged along the extension direction of the optical axis; and The second lens group has positive refractive power and is movably arranged along the extension direction of the optical axis; Wherein, image plane compensation is achieved by changing the positions of the first lens group and the second lens group; The first lens group includes a first lens, a second lens, and a third lens arranged in sequence from the object side to the image side; The second lens group is configured to include a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens arranged in order from the object side to the image side, wherein the fourth lens has a positive optical power, the fifth lens has a positive optical power, the sixth lens has a negative optical power, the seventh lens has a positive optical power, and the eighth lens has a negative optical power; The radius of curvature of the object side of the first lens is 51.832 mm, the thickness of the first lens is 0.756 mm, the radius of curvature of the image side of the first lens is 7.848 mm, the distance from the image side of the first lens to the object side of the second lens is 5.261 mm, the radius of curvature of the object side of the second lens is -15.2 mm, the thickness of the second lens is 2.09 mm, the radius of curvature of the image side of the second lens is 13.734 mm, and the distance from the image side of the second lens to the object side of the third lens is 0.0 87mm, the radius of curvature of the object side of the third lens is 12.3378mm, the thickness of the third lens is 2.531mm, the radius of curvature of the image side of the third lens is -244.369mm, the distance from the image side of the third lens to the object side of the fourth lens is 12.671mm, the radius of curvature of the object side of the fourth lens is 7.675mm, the thickness of the fourth lens is 2.967mm, the radius of curvature of the image side of the fourth lens is -21.975mm, and the distance from the image side of the fourth lens to the object side of the fifth lens is 12.671mm. The distance from the mirror object side is 0.081mm, the curvature radius of the fifth lens object side is 20.734mm, the thickness of the fifth lens is 2.203mm, the curvature radius of the image side of the fifth lens is -11.106mm, the distance from the image side of the fifth lens to the object side of the sixth lens is 0.175mm, the curvature radius of the object side of the sixth lens is -7.786mm, the thickness of the sixth lens is 1.824mm, the curvature radius of the image side of the sixth lens is 3.869mm, and the sixth lens image The distance from the side surface to the objective side surface of the seventh lens is 0.207 mm, the radius of curvature of the objective side surface of the seventh lens is 4.204 mm, the thickness of the seventh lens is 3.369 mm, the radius of curvature of the image side surface of the seventh lens is -16.436 mm, the distance from the image side surface of the seventh lens to the objective side surface of the eighth lens is 0.561 mm, the radius of curvature of the objective side surface of the eighth lens is 19.020 mm, the thickness of the eighth lens is 3.196 mm, and the radius of curvature of the image side surface of the eighth lens is 21.443 mm.

2. The optical lens system according to claim 1, wherein: A stop is provided between the first lens group and the second lens group.

3. The optical lens system according to claim 2, wherein: A distance between a side of the first lens group facing the image side and the aperture is L1, wherein 0.93 mm ≤ L1 ≤ 12.67 mm.

4. The optical lens system according to claim 2, wherein: A distance between a side of the second lens group facing the object side and the aperture is L2, wherein 0.335 mm ≤ L2 ≤ 6.96 mm.

5. The optical lens system according to claim 1, wherein: The first lens is a glass spherical lens, and the second lens and the third lens are plastic aspherical lenses.

6. The optical lens system according to claim 1, wherein: The fourth lens is a glass spherical lens, and the fifth lens, the sixth lens, the seventh lens, and the eighth lens are plastic aspherical lenses.

7. The optical lens system according to claim 1, wherein: The optical lens system further includes a photosensitive chip, which is disposed on a side of the second lens group facing the image side, and a photosensitive surface of the photosensitive chip is disposed toward the second lens group.

8. The optical lens system according to claim 7, wherein: A filter is provided between the photosensitive chip and the second lens group.

9. A surveillance camera device, characterized in that: Comprising the optical lens system according to any one of claims 1 to 8.

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