Optical system and projection device

Abstract

This invention discloses an optical system and a projection device. The optical system has an object side and an image side arranged opposite each other along the optical axis. From the object side to the image side, the optical system sequentially includes a zoom lens assembly and a focusing lens assembly. The zoom lens assembly includes a first lens assembly with negative optical power, an aperture stop, a second lens assembly with positive optical power, and a third lens assembly with positive optical power, arranged sequentially from the object side to the image side. The aperture stop and the second lens assembly are fixed in position relative to the image side. The first lens assembly and the third lens assembly can move closer to each other or further away from each other along the optical axis to enable the optical system to zoom. The focusing lens assembly has positive optical power and can move to a corresponding position along the optical axis to enable the optical system to focus, thus solving the problem of low zoom efficiency in existing optical lenses.

Description

Technical Field

[0001] This invention relates to the field of optical lens technology, and in particular to an optical system and projection device. Background Technology

[0002] Currently, to meet the demands of the surveillance market, zoom lenses are widely used in people's daily lives. Simultaneously, zoom lens designs are evolving towards ease of operation and lower costs. Furthermore, with the improvement of network speeds, high-quality, high-resolution images can be transmitted quickly. However, current security and traffic monitoring devices suffer from the following drawbacks: in low-light environments, the captured image is not generally clear, with some corners always appearing blurry; high-magnification lenses on the market generally have low pixel counts, and existing zoom lenses often cannot achieve high magnification while maintaining a compact size, as increasing magnification causes a drastic change in lens size; additionally, existing zoom lenses generally suffer from low zoom efficiency. Summary of the Invention

[0003] The main objective of this invention is to propose an optical system and projection device that aims to solve the problems of low zoom efficiency and large system size in existing zoom lenses.

[0004] To achieve the above objectives, the optical system proposed in this invention has an object side and an image side arranged opposite to each other along the optical axis. From the object side to the image side, the optical system sequentially includes:

[0005] A zoom lens assembly includes a first lens assembly with negative optical power, an aperture stop, a second lens assembly with positive optical power, and a third lens assembly with positive optical power, arranged sequentially from the object side to the image side. The aperture stop and the second lens assembly are fixed in position relative to the image side. The first lens assembly and the third lens assembly can move closer to or further away from each other along the optical axis to enable zooming of the optical system.

[0006] A focusing lens assembly having positive optical power and movable to a corresponding position along the optical axis so that the optical system can focus.

[0007] Optionally, the first lens assembly includes a first lens with negative optical power, a second lens with negative optical power, and a third lens with positive optical power, arranged sequentially from the object side to the image side; and / or,

[0008] The second lens assembly includes a fourth lens having positive optical power; and / or,

[0009] The third lens assembly includes, sequentially arranged from the object side to the image side, a fifth lens with positive optical power, a sixth lens with positive optical power, a seventh lens with positive optical power, and an eighth lens with negative optical power; and / or,

[0010] The focusing lens assembly includes a ninth lens with positive optical power, a tenth lens with negative optical power, an eleventh lens with positive optical power, and a twelfth lens with negative optical power, arranged sequentially from the object side to the image side.

[0011] Optionally, at least one of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, the ninth lens, the tenth lens, the eleventh lens, and the twelfth lens is made of glass.

[0012] Optionally, at least three of the first lens, second lens, third lens, fourth lens, fifth lens, sixth lens, seventh lens, eighth lens, ninth lens, tenth lens, eleventh lens, and twelfth lens are made of low-dispersion material; and / or,

[0013] Of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, the ninth lens, the tenth lens, the eleventh lens, and the twelfth lens, at least two are made of a high refractive index material.

[0014] Optionally, at least four of the fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, and twelfth lenses are configured as aspherical lenses.

[0015] Optionally, the fourth lens, the fifth lens, the ninth lens, and the eleventh lens are all configured as aspherical lenses.

[0016] Optionally, the second lens is cemented with the third lens to form a first cemented lens; and / or,

[0017] The seventh lens and the eighth lens are cemented together to form a second cemented lens.

[0018] Optionally, the focal length of the optical system is f, where 6.5mm ≤ f ≤ 19.5mm.

[0019] Optionally, the aperture coefficient of the optical system is F, where 1.0≤F≤1.2.

[0020] The present invention also provides a projection device, including the optical system described above.

[0021] In the technical solution provided by this invention, by fixing the second lens assembly and the aperture together relative to the image side, and then setting the first lens assembly and the third lens assembly to be close to or far from each other along the optical axis, the system can perform efficient zoom adjustment at the near-focal end and the far-focal end, reducing the overall length of the system. At the same time, by driving the focusing lens assembly to move along the optical axis to the focusing position by external force, clear imaging is ensured during zooming. Moreover, through the reasonable setting of the structure, position and material of the first lens assembly with negative optical power, the second lens assembly with positive optical power, the third lens assembly with positive optical power and the focusing lens assembly with positive optical power, the optical system has the effects of low magnification, large angle, large aperture, large image plane and high resolution. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0023] Figure 1 A schematic diagram of an embodiment of the optical system provided by the present invention.

[0024] Explanation of icon numbers:

[0025] label name label name 100 Optical system 142 Sixth lens 1 zoom lens assembly 143 Seventh Lens 11 First lens assembly 144 Eighth lens 111 First lens 2 Focusing lens assembly 112 Second lens 21 Ninth Lens 113 Third lens 22 Tenth Lens 12 aperture 23 Eleventh Lens 13 Second lens assembly 24 The Twelfth Lens 131 Fourth lens 3 Photosensitive component 14 Third lens assembly 31 Photosensitive chip 141 Fifth lens 32 Filter

[0026] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0028] It should be noted that if the embodiments of the present invention involve directional indication, the directional indication is only used to explain the relative positional relationship and movement of the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0029] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0030] Currently, to meet the demands of the surveillance market, zoom lenses are widely used in people's daily lives. Simultaneously, zoom lens designs are evolving towards ease of operation and lower costs. Furthermore, with the improvement of network speeds, high-quality, high-resolution images can be transmitted quickly. However, current security and traffic monitoring devices suffer from the following drawbacks: in low-light environments, the captured image is not generally clear, with some corners always appearing blurry; high-magnification lenses on the market generally have low pixel counts, and existing zoom lenses often cannot achieve high magnification while maintaining a compact size, as increasing magnification causes a drastic change in lens size; additionally, existing zoom lenses generally suffer from low zoom efficiency.

[0031] In view of this, the present invention proposes an optical system aimed at solving the problems of low zoom efficiency and large system size in existing zoom lenses, wherein... Figure 1 A simplified structural diagram of an embodiment of the present invention.

[0032] Please see Figure 1 The optical system 100 has an object side and an image side arranged opposite each other along the optical axis. From the object side to the image side, the optical system 100 sequentially includes a zoom lens assembly 1 and a focusing lens assembly 2. The zoom lens assembly 1 includes a first lens assembly 11 with negative optical power, an aperture stop 12, a second lens assembly 13 with positive optical power, and a third lens assembly 14 with positive optical power, arranged sequentially from the object side to the image side. The aperture stop 12 and the second lens assembly 13 are fixed in position relative to the image side. The first lens assembly 11 and the third lens assembly 14 can move closer to each other or further away from each other along the optical axis to enable the optical system 100 to zoom. The focusing lens assembly 2 has positive optical power and can move to a corresponding position along the optical axis to enable the optical system 100 to focus.

[0033] In the technical solution provided by the present invention, by fixing the second lens assembly 13 and the aperture stop 12 together relative to the image side, and then setting the first lens assembly 11 and the third lens assembly 14 to be close to or far from each other along the optical axis, the system can perform efficient zoom adjustment at the near-focal end and the far-focal end, reducing the overall length of the system. At the same time, by driving the focusing lens assembly 2 to move along the optical axis to the focusing position by external force, clear imaging is ensured during zooming. Moreover, through the reasonable setting of the structure, position and material of the first lens assembly 11 with negative optical power, the second lens assembly 13 with positive optical power, the third lens assembly 14 with positive optical power and the focusing lens assembly 2 with positive optical power, the optical system 100 has the effects of low magnification, large angle, large aperture, large image plane and high resolution.

[0034] In this embodiment, the first lens assembly 11 has a movement range of 33.55 mm between the near focal end and the far focal end, the third lens assembly 14 has a movement range of 13.4 mm between the near focal end and the far focal end, and the focusing lens assembly 2 has a focusing movement range of 11.5 mm, thus realizing a small-volume optical system 100.

[0035] Furthermore, in this embodiment, the first lens assembly 11 includes a first lens 111 with negative optical power, a second lens 112 with negative optical power, and a third lens 113 with positive optical power arranged sequentially from the object side to the image side.

[0036] In another embodiment, the second lens assembly 13 includes a fourth lens 131 having positive optical power.

[0037] In another embodiment, the third lens assembly 14 includes a fifth lens 141 with positive optical power, a sixth lens 142 with positive optical power, a seventh lens 143 with positive optical power, and an eighth lens 144 with negative optical power, arranged sequentially from the object side to the image side.

[0038] In another embodiment, the focusing lens assembly 2 includes a ninth lens 21 with positive optical power, a tenth lens 22 with negative optical power, an eleventh lens 23 with positive optical power, and a twelfth lens 24 with negative optical power, arranged sequentially from the object side to the image side.

[0039] It should be noted that the above four parallel technical features can be set individually, in twos, in threes, or simultaneously. By appropriately arranging multiple lenses, the system can ensure clear imaging and eliminate chromatic aberration.

[0040] Furthermore, in this embodiment, at least one of the first lens 111, the second lens 112, the third lens 113, the fourth lens 131, the fifth lens 141, the sixth lens 142, the seventh lens 143, the eighth lens 144, the ninth lens 21, the tenth lens 22, the eleventh lens 23, and the twelfth lens 24 is made of glass.

[0041] Specifically, the first lens 111, the second lens 112, the third lens 113, the fourth lens 131, the fifth lens 141, the sixth lens 142, the seventh lens 143, the eighth lens 144, the ninth lens 21, the tenth lens 22, the eleventh lens 23, and the twelfth lens 24 are all made of glass. This design minimizes the impact of temperature changes on lens performance, ensuring stable performance in environments ranging from -35℃ to 80℃ with minimal need for refocusing.

[0042] In this embodiment, at least three of the first lens 111, the second lens 112, the third lens 113, the fourth lens 131, the fifth lens 141, the sixth lens 142, the seventh lens 143, the eighth lens 144, the ninth lens 21, the tenth lens 22, the eleventh lens 23, and the twelfth lens 24 are made of low dispersion material.

[0043] In another embodiment, at least two of the first lens 111, the second lens 112, the third lens 113, the fourth lens 131, the fifth lens 141, the sixth lens 142, the seventh lens 143, the eighth lens 144, the ninth lens 21, the tenth lens 22, the eleventh lens 23, and the twelfth lens 24 are made of a high refractive index material.

[0044] It should be noted that the two parallel technical features mentioned above can be set individually or simultaneously. Obviously, setting them simultaneously will have a better effect, and can more effectively eliminate chromatic aberration and color difference, with an effective imaging diameter of up to Φ13.1mm.

[0045] The characteristic of aspherical lenses is that their curvature changes continuously from the center to the periphery, unlike spherical lenses which have a constant curvature from the center to the periphery. Aspherical lenses have better curvature radius characteristics, which has the advantages of improving distortion aberrations and astigmatism aberrations. Based on this, in this embodiment, at least four of the fourth lens 131, the fifth lens 141, the sixth lens 142, the seventh lens 143, the eighth lens 144, the ninth lens 21, the tenth lens 22, the eleventh lens 23, and the twelfth lens 24 are set aspherical lenses. By setting at least four aspherical lenses, aberrations that occur during imaging can be eliminated as much as possible, thereby improving the imaging quality of the system, while greatly reducing the number of spherical lenses required and reducing the system size.

[0046] Specifically, in this embodiment, the fourth lens 131, the fifth lens 141, the ninth lens 21, and the eleventh lens 23 are all configured as aspherical lenses.

[0047] Furthermore, in this embodiment, the second lens 112 and the third lens 113 are cemented together to form a first cemented lens. By setting the first cemented lens, chromatic aberration can be minimized or eliminated, resulting in clearer imaging.

[0048] In another embodiment, the seventh lens 143 and the eighth lens 144 are cemented together to form a second cemented lens. By setting the second cemented lens, chromatic aberration is further reduced or eliminated, resulting in a clearer image.

[0049] It should be noted that the two parallel technical features mentioned above, "the second lens 112 and the third lens 113 are cemented together to form a first cemented lens" and "the seventh lens 143 and the eighth lens 144 are cemented together to form a second cemented lens", can be set simultaneously or one of them can be set. Obviously, setting them simultaneously will have a better effect on eliminating chromatic aberration.

[0050] As the first lens assembly 11, the third lens assembly 14 and the focusing lens assembly 2 move, the focal length changes. In this embodiment, the focal length of the optical system 100 is f, where 6.5mm≤f≤19.5mm, making it suitable for use in various environments.

[0051] Specifically, in this embodiment, the shooting angle of the optical system 100 can vary between 30° and 110°, and the shooting distance can be as close as 0.5m.

[0052] In this embodiment, the aperture coefficient of the optical system 100 is F, where 1.0≤F≤1.2. By adjusting the setting to achieve an F value of 1.0 at the near focal end and an F value of 1.2 at the far focal end, the optical system 100 can have excellent light sensitivity and can still capture clear full-color images in darker environments.

[0053] Furthermore, in this embodiment, the optical system 100 further includes a photosensitive component 3, which includes a photosensitive chip 31 disposed on the image side and a filter 32 disposed between the photosensitive chip 31 and the twelfth lens 24; wherein the positions of the aperture 12 and the second lens assembly 13 relative to the photosensitive chip 31 are fixed.

[0054] Furthermore, in this embodiment, the distance between the aperture 12 and the photosensitive chip 31 is 53.35 mm.

[0055] The present invention can achieve a resolution higher than 8M (8 million pixels). Taking a 1 / 1.2” CCD with a diameter of 12.8mm as an example, the present invention can achieve a center resolution higher than 1900 TV lines and a peripheral 0.7H (70% diagonal position) resolution higher than 1700 TV lines.

[0056] Specifically, in this embodiment, the parameters of each lens of the optical system 100 are shown in the table below.

[0057] Parameters of each lens in the optical system described in Table 1

[0058]

[0059]

[0060] Furthermore, in this embodiment, the aspherical surface shape of the aspherical lens satisfies the following condition:

[0061]

[0062] Wherein, parameter c is the curvature corresponding to the radius, y is the radial coordinate (its unit is the same as the lens length unit), and k is the conic conic coefficient. When the coefficient k is less than -1, the surface curve is a hyperbola; when it is equal to -1, it is a parabola; when it is between -1 and 0, it is an ellipse; when it is equal to 0, it is a circle; and when it is greater than 0, it is an oval. α1 to α8 represent the coefficients corresponding to each radial coordinate. These parameters allow for precise setting of the shape and dimensions of the aspherical surface.

[0063] Specifically, in this embodiment, the aspherical coefficients corresponding to the aspherical lens are shown in the table below.

[0064] Table 2 Aspheric coefficients for aspheric lenses

[0065]

[0066] Furthermore, the present invention also provides a projection device, which includes the optical system 100 described above. It should be noted that the structure of the optical system 100 in the projection device can refer to the embodiments of the optical system 100 described above, and will not be repeated here. Since the optical system 100 described above is used in the projection device provided by the present invention, the embodiments of the projection device provided by the present invention include all the technical solutions of all embodiments of the optical system 100 described above, and the technical effects achieved are also completely the same, and will not be repeated here.

[0067] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention specification and drawings under the concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. An optical system having an object side and an image side arranged opposite to each other along the optical axis, characterized in that, The optical system, in the direction from the object side to the image side, sequentially comprises: A zoom lens assembly includes a first lens assembly with negative optical power, an aperture stop, a second lens assembly with positive optical power, and a third lens assembly with positive optical power, arranged sequentially from the object side to the image side. The aperture stop and the second lens assembly are fixed in position relative to the image side. The first lens assembly and the third lens assembly can move closer to or further away from each other along the optical axis to enable zooming of the optical system. A focusing lens assembly having positive optical power and being movable to a corresponding position along the optical axis so that the optical system can focus; The first lens assembly includes a first lens with negative optical power, a second lens with negative optical power, and a third lens with positive optical power, arranged sequentially from the object side to the image side; the second lens assembly includes a fourth lens with positive optical power; the third lens assembly includes a fifth lens with positive optical power, a sixth lens with positive optical power, a seventh lens with positive optical power, and an eighth lens with negative optical power, arranged sequentially from the object side to the image side; the focusing lens assembly includes a ninth lens with positive optical power, a tenth lens with negative optical power, an eleventh lens with positive optical power, and a twelfth lens with negative optical power, arranged sequentially from the object side to the image side. The focal length of the optical system is f, where 6.5mm ≤ f ≤ 19.5mm.

2. The optical system as described in claim 1, characterized in that, Of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, the ninth lens, the tenth lens, the eleventh lens, and the twelfth lens, at least one is made of glass.

3. The optical system as described in claim 1, characterized in that, Of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, the ninth lens, the tenth lens, the eleventh lens, and the twelfth lens, at least three are made of a low-dispersion material; and / or, Of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, the ninth lens, the tenth lens, the eleventh lens, and the twelfth lens, at least two are made of a high refractive index material.

4. The optical system as claimed in claim 1, characterized in that, Of the fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, and twelfth lenses, at least four are configured as aspherical lenses.

5. The optical system as described in claim 4, characterized in that, The fourth lens, the fifth lens, the ninth lens, and the eleventh lens are all configured as aspherical lenses.

6. The optical system as claimed in claim 1, characterized in that, The second lens is cemented with the third lens to form a first cemented lens; and / or, The seventh lens and the eighth lens are cemented together to form a second cemented lens.

7. The optical system as claimed in claim 1, characterized in that, The aperture coefficient of the optical system is F, where 1.0≤F≤1.

2.

8. A projection device, characterized in that, Includes the optical system as described in any one of claims 1 to 7.

Images