Camera module and electronic device

Abstract

This invention provides a camera module and an electronic device. The camera module includes: a reflector for reflecting light incident along a first optical axis to exit along a second optical axis; and a dispersion-adjusting lens group and a focal length-adjusting lens group arranged sequentially along the second optical axis. The focal length-adjusting lens group is used to move along the second optical axis to adjust the focal length of the camera module. The dispersion-adjusting lens group includes a first lens, a negative power lens group, and a positive power lens group arranged sequentially along the second optical axis. The first lens is close to the reflector. The negative power lens group includes at least two negative lenses with different negative power and Abbe numbers. The positive power lens group includes at least two positive lenses with different positive power and Abbe numbers. This invention utilizes the characteristic that positive and negative power produce opposite chromatic aberrations and the difference in Abbe number adjusts the magnitude of chromatic aberration, causing positive and negative chromatic aberrations to cancel each other out within the camera module, significantly eliminating chromatic aberration and improving image quality.

Description

Technical Field

[0001] This invention relates to the field of camera module technology, specifically to a camera module and an electronic device. Background Technology

[0002] With the widespread adoption of smart devices, camera functionality has become a crucial factor for consumers when making purchasing decisions. Telephoto lenses, in particular, are a key component of smart device cameras due to their ability to produce clear images from a distance.

[0003] However, existing telephoto lenses have certain image quality issues, with some shots prone to color deviation, resulting in inconsistencies between the image and the actual colors of the scene. For example, in a scene with a grassy green background, pink or yellow lines may appear as edges in the image. This type of color difference is more pronounced in telephoto lenses, affecting image quality. Summary of the Invention

[0004] The present invention aims to provide a camera module and electronic device to solve the problem of color deviation in the captured images in the prior art.

[0005] To solve the above-mentioned technical problems, the present invention is implemented as follows: In a first aspect, the present invention provides a camera module, comprising: A reflector, used to reflect light rays incident along a first optical axis to exit along a second optical axis; In addition, a dispersion-adjusting lens group and a focal length-adjusting lens group are arranged sequentially along the second optical axis, wherein the focal length-adjusting lens group is used to move along the second optical axis to adjust the focal length of the camera module; The dispersion-adjusting lens group includes a first lens, a negative power lens group, and a positive power lens group arranged sequentially along the second optical axis. The first lens is close to the reflector. The negative power lens group includes at least two negative lenses, and the negative power and Abbe number of the at least two negative lenses are different. The positive power lens group includes at least two positive lenses, and the positive power and Abbe number of the at least two positive lenses are different.

[0006] Optionally, at least two negative light lenses are provided, including a second lens and a third lens arranged sequentially along the second optical axis, with the second lens close to the first lens; The Abbe number of the second lens is less than that of the first lens but greater than that of the third lens.

[0007] Optionally, the Abbe number Vd1 of the first lens satisfies: Vd1>75; The Abbe number Vd2 of the second lens satisfies: 40 <Vd2<60; The Abbe number Vd3 of the third lens satisfies: Vd3 < 40.

[0008] Optionally, at least two of the positive lenses include a fourth lens and a fifth lens arranged sequentially along the second optical axis, with the fourth lens being close to the negative power lens group; The Abbe number of the fourth lens is less than that of the fifth lens.

[0009] Optionally, the Abbe number Vd4 of the fourth lens satisfies: Vd4 < 40; The Abbe number Vd5 of the fifth lens satisfies: Vd5>50.

[0010] Optionally, the focal length adjustment lens group includes a sixth lens, a seventh lens, and an eighth lens arranged sequentially along the second optical axis, with the sixth lens close to the negative power lens group; The sixth and eighth lenses have negative optical power, the seventh lens has positive optical power, and the Abbe number of the seventh lens is less than that of the sixth lens and less than that of the eighth lens.

[0011] Optionally, the first lens is a spherical lens, and the negative power lens group, the positive power lens group, and the focal length adjustment lens group are all aspherical lenses.

[0012] Optionally, the reflector has an incident surface and an exit surface, and the camera module further includes an aperture stop connected to the incident surface.

[0013] Optionally, the camera module further includes an aperture stop connected to the side of the first lens near the reflector.

[0014] Secondly, the present invention also provides an electronic device, the electronic device comprising the camera module described in any one of the first aspects.

[0015] The camera module provided by this invention sets up positive and negative optical power lens groups in the dispersion adjustment lens group, and each lens group contains at least two lenses with the same optical power but different Abbe numbers. By utilizing the characteristics of positive and negative optical power to generate chromatic aberration in opposite directions and the difference in Abbe number to adjust the magnitude of chromatic aberration, the positive and negative chromatic aberrations cancel each other out in the camera module, significantly eliminating axial chromatic aberration and magnification chromatic aberration, improving color reproduction and image quality. Attached Figure Description

[0016] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a schematic diagram of the structure of a camera module provided by the present invention; Figure 2 yes Figure 1 Axial chromatic aberration diagram of the camera module shown; Figure 3 yes Figure 1 The out-of-focus MTF diagram of the camera module shown; Figure 4 This is a schematic diagram of another camera module provided by the present invention; Figure 5 yes Figure 4 Axial chromatic aberration diagram of the camera module shown; Figure 6 yes Figure 4 The out-of-focus MTF diagram of the camera module shown.

[0017] Figure label: 1-Reflector, 10-Incident surface, 11-Exit surface, 12-Reflecting surface; 2-First optical axis; 3-Second optical axis; 4-Dispersion adjustment lens group, 40-First lens, 41-Negative power lens group, 410-Second lens, 411-Third lens, 42-Positive power lens group, 420-Fourth lens, 421-Fifth lens; 5 - Focus adjustment lens group, 50 - Sixth lens, 51 - Seventh lens, 52 - Eighth lens; 6-Aperture. Detailed Implementation

[0018] 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 some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] It should be understood that the phrase "one embodiment" or "an embodiment" throughout the specification means that a specific feature, structure, or characteristic related to the embodiment is included in at least one embodiment of the invention. Therefore, "in one embodiment" or "in an embodiment" appearing throughout the specification do not necessarily refer to the same embodiment. Furthermore, these specific features, structures, or characteristics can be combined in any suitable manner in one or more embodiments.

[0020] In a first aspect, the present invention provides a method such as Figure 1 and Figure 4The camera module shown includes: a reflector 1 for reflecting light incident along the first optical axis 2 to be emitted along the second optical axis 3; and a dispersion adjustment lens group 4 and a focal length adjustment lens group 5 arranged sequentially along the second optical axis 3, the focal length adjustment lens group 5 being used to move along the second optical axis 3 to adjust the focal length of the camera module; wherein, the dispersion adjustment lens group 4 includes a first lens 40, a negative power lens group 41 and a positive power lens group 42 arranged sequentially along the second optical axis 3, the first lens 40 being close to the reflector 1, the negative power lens group 41 including at least two negative lenses having different negative power and Abbe number, and the positive power lens group 42 including at least two positive lenses having different positive power and Abbe number.

[0021] This invention utilizes the physical properties of positive and negative optical power lenses producing opposite chromatic aberrations, and lenses with different Abbe numbers producing different magnitudes of chromatic aberration. This allows for adjustable chromatic aberration within both the negative optical power lens group 41 and the positive optical power lens group 42, thereby canceling out the positive and negative chromatic aberrations. This significantly reduces axial and magnification chromatic aberration, effectively eliminating purple fringing and color fringing during imaging, and greatly improving color reproduction and image quality. Simultaneously, the positive and negative optical powers of the dispersion adjustment lens group 4 and the focal length adjustment lens group 5 work together to form a telescope structure, achieving telephoto imaging within a compact space. Furthermore, the focal length adjustment lens group 5 can move along the second optical axis 3 to adjust the focal length, ensuring clear imaging at different object distances. In addition, the folding effect of the reflector 1 allows the overall length of the camera module to exceed the thickness limitations of mobile devices, facilitating miniaturization and integration.

[0022] It should be noted that the term "at least two" used in the embodiments of this invention refers to a quantity of two, three, or more, and this invention does not impose a specific limitation in this regard. For ease of understanding and description, the structure of the negative optical power lens group 41 and the positive optical power lens group 42 will be described below using two lenses as an example. However, those skilled in the art should understand that, provided that "at least two lenses have different optical powers and Abbe numbers," alternative solutions using three or more lenses also fall within the protection scope of this invention.

[0023] Specifically, chromatic aberration (including axial chromatic aberration and magnification chromatic aberration) is the phenomenon in an optical system where light of different wavelengths cannot converge at the same point due to differences in refractive index. For a single lens, the magnitude of the chromatic aberration is directly proportional to the optical power and inversely proportional to the Abbe number, and the direction of chromatic aberration is determined by the sign of the optical power: a positive optical power lens produces positive chromatic aberration (blue light converges at a shorter distance than red light), and a negative optical power lens produces negative chromatic aberration (blue light converges at a longer distance than red light).

[0024] In this embodiment of the invention, the dispersion-adjusting lens group 4 is arranged along the second optical axis 3, consisting of a first lens 40, a negative power lens group 41, and a positive power lens group 42. Specifically: the negative power lens group 41 comprises at least two negative lenses, each with different negative power and Abbe number. Since their power is negative, the chromatic aberration directions they produce are all opposite, but the difference in Abbe number results in different magnitudes of the opposite chromatic aberration. By selecting different Abbe numbers (e.g., one with a higher Abbe number and the other with a lower Abbe number), the magnitude of the total opposite chromatic aberration produced by the negative power lens group 41 can be precisely adjusted. The positive power lens group 42 comprises at least two positive lenses, each with different positive power and Abbe number. Similarly, the chromatic aberration directions they produce are all positive, and the difference in Abbe number allows for adjustment of the magnitude of the positive chromatic aberration.

[0025] When the reverse chromatic aberration generated by the negative power lens group 41 is superimposed on the positive chromatic aberration generated by the positive power lens group 42, since their directions are opposite, they can cancel each other out by reasonably selecting the optical power and Abbe number of each lens to make the absolute values ​​of the positive and reverse chromatic aberrations equal or close. This mechanism does not rely on additional special materials or complex structures; it can significantly reduce the total chromatic aberration of the camera module over a wide spectral range using only a combination of conventional lenses, thereby avoiding color deviations such as purple fringing and chromatic aberration during imaging and improving the accuracy of color reproduction.

[0026] Furthermore, the first lens 40 is positioned close to the reflector 1, which allows for preliminary convergence or divergence of light in advance, and further optimizes chromatic aberration balance in conjunction with subsequent lens groups. Through the above-mentioned multi-level and multi-group Abbe number differentiation combination, the present invention achieves systematic correction of chromatic aberration, and is particularly suitable for scenes in telephoto shooting where chromatic aberration is highly sensitive.

[0027] Secondly, in this embodiment of the invention, the dispersion adjustment lens group 4 has a positive optical power, while the focal length adjustment lens group 5 has a negative optical power, and the focal length adjustment lens group 5 can move along the second optical axis 3. The combination of the positive and negative optical power lens groups constitutes a typical telescopic optical structure. In this structure, the total length of the camera module (along the direction of the second optical axis 3) is less than the focal length, thereby achieving a longer focal length within a limited physical space, meeting the needs of electronic devices for high-magnification telephoto shooting. At the same time, the reflector 1 folds the first optical axis 2 to the second optical axis 3, changing the optical path that originally needed to be arranged along the thickness direction of the mobile phone to be arranged along the length or width direction, further breaking through the thickness limitation, allowing the camera module to be built into a thin and light device in a periscope structure.

[0028] Simultaneously, the focus adjustment lens group 5 can move along the second optical axis 3 to adjust the focus. When the shooting distance changes from infinity to close, the image plane position will shift. By moving the focus adjustment lens group 5 along the second optical axis 3, the axial distance between it and the dispersive adjustment lens group 4 can be changed, compensating for the image plane displacement and ensuring that the image plane always falls accurately on the image sensor. This internal focusing method does not require moving the entire camera module, and has advantages such as fast focusing speed, low drive power consumption, and unchanged front-end size, and is also conducive to maintaining the stability of the chromatic aberration correction state.

[0029] Optionally, at least two negative light lenses are provided, including a second lens 410 and a third lens 411 arranged sequentially along the second optical axis 3, with the second lens 410 close to the first lens 40; wherein the Abbe number of the second lens 410 is less than the Abbe number of the first lens 40 but greater than the Abbe number of the third lens 411.

[0030] This invention achieves precise layered control of chromatic aberration by forming a progressively decreasing Abbe number gradient between the first lens 40, the second lens 410, and the third lens 411, combined with the optical power configuration of each lens. The synergistic effect of these three elements results in a gradual distribution of reverse chromatic aberration (smaller at the beginning, larger at the end) within the negative optical power lens group 41, which more precisely matches and cancels out the positive chromatic aberration generated by the subsequent positive optical power lens group 42. This significantly reduces axial and magnification chromatic aberration over a wide wavelength range, effectively eliminating purple fringing and color fringing during imaging, and improving color reproduction and image sharpness. Simultaneously, this Abbe number gradient design also helps balance off-axis aberrations and improves the imaging quality of the edge fields of view.

[0031] Specifically, the first lens 40 is positioned close to the reflector 1, and its Abbe number is greater than that of the second lens 410. As the first lens into the dispersion-adjusting lens group 4, the first lens 40 performs the initial converging or diverging function of the incident beam. By selecting a material with the highest Abbe number (lowest dispersion), the chromatic aberration generated by the first lens 40 itself is minimized, thereby controlling the accumulation of chromatic aberration at the front end of the camera module and creating favorable conditions for chromatic aberration correction in subsequent lens groups.

[0032] The second lens 410 has a negative optical power and a medium Abbe number, generating a medium-sized negative longitudinal chromatic aberration; the third lens 411 has a negative optical power and the lowest Abbe number, generating the largest negative longitudinal chromatic aberration. Since both the second lens 410 and the third lens 411 have negative optical powers, the chromatic aberration directions they generate are the same (both negative), but the difference in Abbe numbers results in different magnitudes of negative longitudinal chromatic aberration. By setting the second lens 410 to have a medium Abbe number and the third lens 411 to have the lowest Abbe number, the negative longitudinal chromatic aberration exhibits a "smaller in the front and larger in the back" progressive accumulation characteristic in the optical path propagation direction. This progressive distribution makes the total negative longitudinal chromatic aberration generated by the negative optical power lens group 41 no longer simply the sum of the chromatic aberrations of the two lenses, but rather the total negative longitudinal chromatic aberration can be continuously adjusted within a wide range by adjusting the optical power distribution and the Abbe number difference between the two lenses. When the subsequent positive optical power lens group 42 generates positive chromatic aberration, the two can achieve a more precise magnitude matching and direction cancellation, thereby significantly reducing the total chromatic aberration of the imaging module.

[0033] In addition to axial chromatic aberration, lateral chromatic aberration (i.e., the difference in magnification of light rays with different wavelengths on the image plane) is also an important factor affecting imaging quality. Lateral chromatic aberration is closely related to the incident height of the chief ray of the off-axis beam on each lens.

[0034] In the embodiment of the present application, the second lens 410 is disposed close to the first lens 40, and its Abbe number is between that of the first lens 40 and the third lens 411. This configuration enables the chief rays of light rays with different wavelengths to be gradually corrected in terms of the deflection angle when the off-axis beam sequentially passes through the first lens 40, the second lens 410, and the third lens 411 due to the gradient change in the Abbe numbers of each lens. Compared with the solution of directly using a single negative lens with a low Abbe number, this solution reduces the change rate of the incident angle of the off-axis beam on the lens surface through the gradient distribution of the Abbe numbers, thereby effectively suppressing the generation of lateral chromatic aberration. At the same time, this design is also beneficial for balancing other off-axis aberrations such as coma and astigmatism, making the imaging clarity of the edge field of view closer to that of the central field of view and improving the image quality of the entire field of view.

[0035] Optionally, the Abbe number Vd1 of the first lens 40 satisfies: Vd1 > 75; the Abbe number Vd2 of the second lens 410 satisfies: 40 < Vd2 < 60; the Abbe number Vd3 of the third lens 411 satisfies: Vd3 < 40.

[0036] In a telephoto lens, a large aperture (small F#) design poses higher requirements for chromatic aberration correction because increasing the aperture means increasing the entrance pupil diameter, expanding the incident height range of off-axis light beams, and making chromatic aberration more easily perceivable. Through precise grading with Vd1 > 75, 40 < Vd2 < 60, and Vd3 < 40, this solution enables the camera module to control chromatic aberration at an extremely low level while maintaining a relatively large aperture (such as around F#2.4). This allows the camera module to obtain sufficient light input in low-light environments, ensuring the shutter speed and signal-to-noise ratio, while avoiding the problem of chromatic aberration degradation caused by a large aperture.

[0037] Specifically, the first lens 40 has a positive optical power, and its Abbe number Vd1 > 75 belongs to an extremely low-dispersion material (such as glass). The extremely low-dispersion characteristic makes the positive chromatic aberration generated by the first lens 40 extremely small, avoiding introducing a large amount of chromatic aberration at the front end of the optical system, reducing the correction burden of the subsequent lens groups, and enabling the first lens 40 to almost not introduce chromatic aberration while performing the converging function, achieving a decoupled design of function and aberration.

[0038] Since both the second lens 410 and the third lens 411 have negative optical powers, the chromatic aberration they generate has the same direction (both are negative). By precisely setting the Abbe numbers of the three lenses, the negative chromatic aberration shows a distribution of "the first lens 40 (extremely small positive) - the second lens 410 (medium negative) - the third lens 411 (maximum negative)" in the optical path. When the subsequent positive optical power lens group 42 (such as the fourth lens 420 and the fifth lens 421) generates positive chromatic aberration, since the negative chromatic aberration has been made adjustable in magnitude through precise grading, the two can achieve high-precision matching and cancellation, making the total chromatic aberration approach zero. Compared with only using two negative lenses with different Abbe numbers, this solution provides more design freedom through the gradient design of three lenses and can achieve better chromatic aberration correction in a wider wavelength range.

[0039] Optionally, among at least two positive lenses, there are a fourth lens 420 and a fifth lens 421 arranged in sequence along the second optical axis 3, and the fourth lens 420 is closer to the negative optical power lens group 41; among them, the Abbe number of the fourth lens 420 is less than that of the fifth lens 421.

[0040] This invention, through the inclusion of a fourth lens 420 and a fifth lens 421 within a positive power lens group 42, and by limiting the Abbe number of the fourth lens 420 to be less than that of the fifth lens 421, and combining this with the power configuration of each lens (both the fourth lens 420 and the fifth lens 421 are positive power lenses), constructs an increasing Abbe number gradient within the positive power lens group 42, with "lower Abbe number (higher dispersion) in front, and higher Abbe number (lower dispersion) in the back." This design forms a symmetrical complement to the decreasing gradient of "higher Abbe number in front, lower Abbe number in the back" in the negative power lens group 41. This allows the reverse chromatic aberration (smaller in front, larger in back) generated by the negative power lens group 41 to precisely cancel out the positive chromatic aberration (larger in front, smaller in back) generated by the positive power lens group 42 in the direction of light propagation. Consequently, it significantly reduces axial chromatic aberration and magnification chromatic aberration over a wide wavelength range, effectively eliminates purple fringing and color fringing during imaging, and greatly improves color reproduction and image sharpness. Meanwhile, this Abbe number gradient also helps to optimize the large aperture design of the camera module, reduce off-axis aberrations, improve production yield, and enhance the camera module's adaptability to ambient temperature.

[0041] Specifically, since both the fourth lens 420 and the fifth lens 421 are positive power, they produce chromatic aberration in the same direction (both positive), but the difference in Abbe number results in different magnitudes of the positive chromatic aberration. By setting the fourth lens 420 to a low Abbe number (high dispersion) and the fifth lens 421 to a high Abbe number (low dispersion), the positive chromatic aberration exhibits a gradual distribution characteristic of "larger at the beginning and smaller at the end" along the optical path propagation direction. The reverse chromatic aberration is smaller at the beginning and larger at the end of the optical path, while the positive chromatic aberration is larger at the beginning and smaller at the end. The two match each other in different sections of the optical path, causing the chromatic aberration to continuously cancel each other out during propagation, eventually reaching an extremely low level at the image plane. When the two are superimposed in the system, the positive and reverse chromatic aberrations cancel each other out segment by segment at different positions in the optical path, rather than canceling each other out only once at the final image plane, thus significantly improving the accuracy of chromatic aberration correction and wide-band adaptability. Meanwhile, by independently adjusting the optical power distribution and Abbe number difference between the fourth lens 420 and the fifth lens 421, the magnitude distribution of positive chromatic aberration can be precisely controlled, so as to achieve optimal matching with the reverse chromatic aberration generated by the negative optical power lens group 41, thereby improving the flexibility and optimization space of the design.

[0042] Secondly, the fourth lens 420 is positioned close to the negative power lens group 41, and its Abbe number is lower than that of the fifth lens 421. This design makes the fourth lens 420 the main element generating positive chromatic aberration in the positive power lens group 42. Because the fourth lens 420 uses a low Abbe number (high dispersion) material, it can generate a large positive chromatic aberration at a relatively small power, which is beneficial for matching the large negative chromatic aberration generated by the negative power lens group 41 (mainly contributed by the third lens 411). This design concentrates the chromatic aberration correction function on a few lenses, reducing the system's sensitivity to the accumulation of tolerances from multiple lenses, while allowing the fifth lens 421 to take on more of the functions of aberration balancing and optical path transition, thus achieving functional division of labor.

[0043] In telephoto lenses, a large aperture (small F#) design increases the entrance pupil diameter, widening the range of incident heights of off-axis beams and making chromatic aberration (especially magnification chromatic aberration) more perceptible. This solution utilizes an increasing Abbe number gradient within the positive power lens group 42 to create a "larger at the front, smaller at the back" distribution of positive chromatic aberration, precisely matching the reverse chromatic aberration of the negative power lens group 41. This allows the system to maintain a relatively large aperture (around F#2.4) while keeping chromatic aberration at an extremely low level. This enables the camera module to obtain sufficient light in low-light environments, ensuring shutter speed and signal-to-noise ratio, while avoiding the chromatic aberration degradation problems associated with large apertures.

[0044] Furthermore, chromatic aberration is primarily affected by the incident height of the principal ray of the off-axis beam on the lens. In this design, the fourth lens 420 is positioned close to the negative power lens group 41. Its low Abbe number characteristic causes significant differences in the refraction angles of different wavelengths of light when the off-axis beam passes through the fourth lens 420; subsequently, when it passes through the high Abbe number fifth lens 421, the difference is partially compensated. This "difference first, compensation later" design helps reduce the accumulation of chromatic aberration on the image plane, resulting in more accurate color reproduction at the edges of the field of view. Simultaneously, this design also helps balance other off-axis aberrations such as coma and astigmatism, improving the overall image sharpness across the entire field of view.

[0045] Optionally, the Abbe number Vd4 of the fourth lens 420 satisfies: Vd4<40; the Abbe number Vd5 of the fifth lens 421 satisfies: Vd5>50.

[0046] Specifically, when the embodiments of the present invention are combined with the aforementioned first lens 40, second lens 410, and third lens 411, the Abbe number distribution of the entire dispersion-adjusting lens group 4 presents a complete "extremely high—medium—high—high—low" gradient. Through multi-level progressive cancellation, extremely low total chromatic aberration is achieved over a wide wavelength range, while also taking into account volume control, tolerance sensitivity, and temperature stability. Vd4 < 40 enables the fourth lens 420 to produce a large positive chromatic aberration with a small positive power, forming an order of magnitude match with the large reverse chromatic aberration produced by the third lens 411 (Vd3 < 40) in the negative power lens group 41, facilitating precise cancellation between the two in the system; Vd5 > 50 enables the fifth lens 421 to contribute positive power while introducing almost no additional chromatic aberration, effectively suppressing magnification chromatic aberration and improving the imaging quality of the edge field of view. The selection of this Abbe number range forms a system-level match with the Abbe number range of the negative power lens group 41, enabling high-precision cancellation of positive and negative chromatic aberration in the optical path. This significantly reduces axial and magnification chromatic aberration, effectively eliminates purple fringing and color fringing, and also facilitates large aperture design, reduces tolerance sensitivity, and improves temperature adaptability. Optionally, the focal length adjustment lens group 5 includes a sixth lens 50, a seventh lens 51, and an eighth lens 52 arranged sequentially along the second optical axis 3, with the sixth lens 50 close to the negative optical power lens group 41; wherein the sixth lens 50 and the eighth lens 52 have negative optical power, the seventh lens 51 has positive optical power, and the Abbe number of the seventh lens 51 is less than the Abbe number of the sixth lens 50 and less than the Abbe number of the eighth lens 52.

[0047] This invention employs a negative-positive-negative three-element structure in the focal length adjustment lens group 5, combined with a specific distribution of Abbe numbers, enabling the focal length adjustment lens group 5 to not only perform focusing functions but also assist in aberration correction and compensate for residual aberrations. Specifically, the seventh lens 51 uses a low Abbe number (high dispersion) material, producing a large positive chromatic aberration at positive power; the sixth lens 50 and the eighth lens 52 use higher Abbe number (low dispersion) materials, producing a smaller negative chromatic aberration at negative power. The combined effect of these three elements achieves partial cancellation of positive and negative chromatic aberrations within the focal length adjustment lens group 5, thereby assisting the dispersion correction lens group in further reducing total chromatic aberration at the system level. Simultaneously, the alternating negative-positive-negative power structure helps balance monochromatic aberrations such as spherical aberration and coma, ensuring stable image quality even when the focal length adjustment lens group 5 moves along the second optical axis 3 to achieve focusing at different object distances. Furthermore, this structure also helps control back intercept, reduce aberration fluctuations during focusing, and improve focusing sensitivity.

[0048] Specifically, the focal length adjustment lens group 5 can move along the second optical axis 3 to adjust the focal length, and its core function is to compensate for image plane displacement at different object distances. This scheme adopts a negative-positive-negative alternating optical power structure, which allows the entire lens group to maintain the required negative optical power while controlling aberration changes during focusing by adjusting the optical power distribution of each lens. Compared with single-lens or double-lens structures, the three-element structure provides more design freedom and can maintain image quality stability over a wider range of object distances; the alternating arrangement of positive and negative optical power allows spherical aberration to cancel each other out within the lens group, reducing the amount of spherical aberration change during focusing and ensuring consistent image sharpness at different object distances. At the same time, by optimizing the surface shape and aspherical coefficient of each lens, the negative-positive-negative structure can effectively control coma and astigmatism of off-axis beams, ensuring that the edge field of view maintains good image quality throughout the focusing process.

[0049] In an autofocus system, focusing sensitivity (i.e., the distance the image plane moves per unit distance when the lens group moves) is related to the optical power configuration of the lens group. In this design, the focal length adjustment lens group 5 has a negative optical power overall, which, in conjunction with the positive optical power of the dispersion adjustment lens group 4, allows the system to achieve significant image plane displacement compensation with a small movement stroke, thereby improving focusing sensitivity and reducing focusing time. Simultaneously, the negative-positive-negative three-element structure ensures a more balanced mass distribution within the lens group, which is beneficial for the rapid response and precise control of the drive motor.

[0050] When the focal length adjustment lens group 5 adopts the above structure and Abbe number distribution, it forms a complete five-group system with the dispersion adjustment lens group 4. Among them: the dispersion adjustment lens group 4 undertakes the main contribution of optical power and chromatic aberration correction function, and realizes the main cancellation of positive and negative chromatic aberration through the Abbe number gradient; the focal length adjustment lens group 5, while realizing the focusing function, assists in compensating for residual chromatic aberration through internal Abbe number distribution, and undertakes fine correction of monochromatic aberration; through optical power distribution and spacing design between the two lens groups, the total length of the system is less than the focal length (telescope structure), realizing compactness.

[0051] In a preferred embodiment, the Abbe number Vd6 of the sixth lens 50 satisfies: Vd6>40; the Abbe number Vd7 of the seventh lens 51 satisfies: Vd7<40; and the Abbe number Vd8 of the eighth lens 52 satisfies: Vd8>40.

[0052] Among them, the positive chromatic aberration generated by the seventh lens 51 and the negative chromatic aberration generated by the sixth and eighth lenses 52 form a stable proportional relationship in terms of magnitude, making the self-cancellation effect of chromatic aberration within the focal length adjustment lens group 5 quantitatively controllable. At the same time, this range strengthens the functional division of labor, making the seventh lens 51 clearly responsible for the main chromatic aberration adjustment function, while the sixth lens 50 and the eighth lens 52 undertake the auxiliary convergence function, improving the design accuracy. In addition, this range, together with the numerical ranges of the second lens 410 (40-60), the third lens 411 (<40), the fourth lens 420 (<40), and the fifth lens 421 (>50) in the dispersion adjustment lens group 4, forms a complete Abbe number gradient chain, enabling the positive and negative chromatic aberrations to be progressively canceled at multiple levels and points, effectively suppressing the generation of higher-order chromatic aberrations such as secondary spectra. Finally, the clear partition with 40 as the boundary allows designers to directly select standardized crown glass (>40) and flint glass (<40) grades, which is beneficial for controlling material costs, shortening the procurement cycle, and improving production yield.

[0053] Optionally, the first lens 40 is a spherical lens, while the negative power lens group 41, the positive power lens group 42, and the focal length adjustment lens group are all aspherical lenses.

[0054] In this embodiment of the invention, the first lens 40, as the first lens through which light enters the dispersion adjustment lens group 4, adopts a spherical design to reduce processing difficulty and manufacturing cost. Furthermore, due to its extremely high Abbe number (Vd1>75) and its primary converging function, the spherical design is sufficient to meet its requirements for low dispersion and low aberration, eliminating the need to introduce aspherical lenses to increase costs. Meanwhile, the negative power lens group 41, positive power lens group 42, and focus adjustment lens group, as the core execution units for chromatic aberration correction, aberration compensation, and focusing functions, all employ aspherical lenses. This allows for efficient correction of monochromatic aberrations such as spherical aberration, coma, astigmatism, and distortion using the aspherical degrees of freedom. Simultaneously, the Abbe number gradient design of each lens further optimizes the chromatic aberration correction effect, enabling the system to achieve high image quality while maintaining a relatively small number of lenses. In addition, the widespread use of aspherical lenses helps to compress the overall optical length and reduce the lens outer diameter, meeting the stringent compactness requirements of mobile devices. This configuration achieves an optimized balance between performance, cost, size, and process yield, ensuring image quality while controlling manufacturing costs and processing difficulty.

[0055] Specifically, spherical lenses have mature manufacturing processes, employing traditional grinding, polishing, or molding techniques. They require less equipment, have high yield rates, and are significantly cheaper to manufacture than aspherical lenses. This cost advantage is particularly pronounced in the mass production of mobile phone camera modules. The curvature radius and center thickness of spherical lenses are easy to measure, and they have higher tolerance for eccentricity and tilt during assembly, which helps improve production yield and assembly efficiency. The first lens 40 is positioned close to the reflector 1, possessing positive optical power and an extremely high Abbe number. Its primary function is to facilitate the initial convergence of light, and due to its low dispersion characteristics, it produces minimal chromatic aberration. The spherical design is sufficient to meet its low aberration requirements, eliminating the need to introduce aspherical lenses and incur unnecessary costs.

[0056] The negative power lens group 41 includes at least two negative lenses (such as the second lens 410 and the third lens 411), all of which are aspherical lenses. This offers the following technical advantages: Aspherical lenses can independently control the refraction of light in different aperture regions through higher-order coefficients. This allows the second lens 410 and the third lens 411 to finely adjust the chromatic aberration distribution across different aperture bands while generating reverse chromatic aberration. This ensures that the reverse chromatic aberration generated by the negative power lens group 41 precisely matches the positive chromatic aberration generated by the subsequent positive power lens group 42 across the entire aperture range. Simultaneously, the lenses in the negative power lens group 41 typically have large light refraction angles, making them prone to introducing spherical aberration. Aspherical lenses can counteract spherical aberration by changing the distribution of surface curvature with the aperture, ensuring consistent convergence of on-axis point beams and improving the sharpness of the central field of view.

[0057] The positive power lens group 42 includes at least two positive lenses (such as the fourth lens 420 and the fifth lens 421), all of which are aspherical lenses. It has the following technical advantages: the fourth lens 420 uses a low Abbe number (high dispersion) and the fifth lens 421 uses a high Abbe number (low dispersion). Combined with the aspherical surface shape, the contribution of chromatic aberration in different aperture areas can be independently controlled, so that the positive chromatic aberration presents an ideal distribution pattern on the aperture, achieving full aperture matching with the reverse chromatic aberration generated by the negative power lens group 41. At the same time, the aspherical lens can effectively control distortion (barrel distortion or pincushion distortion), so that the geometry of the captured image is accurate, which is especially suitable for distortion-sensitive scenes in telephoto lenses. Furthermore, the aspherical lens can achieve a large change in optical power while maintaining the thinness of the lens shape, which is convenient for constructing a telephoto structure in a limited space and compressing the total optical length.

[0058] The focus adjustment lens group includes a sixth lens 50, a seventh lens 51, and an eighth lens 52, all of which are aspherical lenses. This offers the following technical advantages: When the focus adjustment lens group moves along the second optical axis 3 to achieve different object distances for focusing, the distance between it and the dispersive adjustment lens group changes, and the aberration state of the system changes accordingly. Aspherical lenses, by optimizing their surface shape, minimize the changes in monochromatic aberrations such as spherical aberration, coma, and astigmatism with the moving position, ensuring consistent image quality at different object distances. Simultaneously, aspherical lenses can precisely control the light emission angle, ensuring the light beam reaches the photosensitive chip at a suitable incident angle, avoiding a decrease in chip microlens efficiency due to excessive incident angles, while also providing sufficient space for filters and chip packaging. Furthermore, aspherical lenses can achieve the required optical power with a smaller number of lenses, which helps to shorten the length of the focus adjustment lens group, reduce the load on the focusing drive mechanism, and improve focusing speed and accuracy.

[0059] At the same time, aspherical mirrors must satisfy the aspherical formula describing aspherical surfaces:

[0060] Where: c = 1 / R, which is the curvature corresponding to the radius; r is the perpendicular distance from a point on the optical surface to the optical axis; z represents the sag of the point along the optical axis; k is the quadratic surface coefficient of the surface; and Ai represents the i-th order aspherical coefficient.

[0061] Optionally, the reflector 1 has an incident surface 10 and an exit surface 11, and the camera module also includes an aperture 6 connected to the incident surface 10.

[0062] For reference Figure 1 In this embodiment of the invention, by directly connecting the aperture stop 6 to the incident surface 10 of the reflector 1, the aperture stop 6 is positioned at the very front of the camera module, achieving advance restriction of the incident beam and thus optimizing system performance in multiple dimensions. This design significantly reduces the lateral dimensions of the reflector 1 and subsequent optical elements, which is beneficial for the miniaturization and integration of the camera module. By integrating the aperture stop 6 with the reflector 1, the structural assembly is simplified, and the optical axis alignment accuracy and module stability are improved. At the same time, the front placement of the aperture stop 6 reduces the incident height of the principal ray of the off-axis beam on the subsequent lens, which is beneficial for reducing the design outer diameter of the focal length adjustment lens group 5 and improving the relative illumination of the edge field of view. In addition, the arrangement of the aperture stop 6, combined with the folding function of the reflector 1, provides more flexible space for the layout of the optical image stabilization mechanism and effectively suppresses the generation of stray light, thereby improving image quality.

[0063] In a preferred embodiment, the aperture stop 6 is directly connected to the incident surface 10 of the reflector 1, making the aperture stop 6 the entrance pupil of the entire optical system. Since the aperture stop 6 is located in front of the reflector 1, the reflector 1 only needs to cover the beam range defined by the aperture stop 6, without needing to be further expanded to accommodate off-axis beams. The incident surface 10 and the exit surface 11 of the reflector 1 can be optimized according to the aperture of the aperture stop 6, and its lateral dimension (i.e., the direction perpendicular to the first optical axis 2) is significantly reduced, which helps to reduce the processing difficulty and material cost of the reflector 1. For the scheme using a prism as the reflector 1, the volume of the prism is proportional to its light-transmitting aperture. The front placement of the aperture stop 6 allows the prism to be made smaller and thinner, which helps to reduce the overall thickness of the camera module. At the same time, since the incident beam is limited by the aperture stop 6 before entering the reflector 1, the beam aperture of the beam emitted from the reflector 1 is correspondingly reduced, so that the outer diameter of the lenses of the subsequent negative power lens group 41, positive power lens group 42 and focus adjustment lens group can be reduced proportionally, realizing the radial dimension optimization of the entire system.

[0064] Secondly, the principal ray of the off-axis field of view deflects at a smaller angle towards the optical axis after passing through aperture 6, significantly reducing its radial incident height on the subsequent negative power lens group 41, positive power lens group 42, and focus-adjusting lens group. This characteristic helps to reduce the design outer diameter of the focus-adjusting lens group 5, lowering the difficulty of lens manufacturing and assembly. Because the off-axis beam's obstruction at the lens edge is reduced, the vignetting effect at the edge of the field of view is alleviated, increasing the ratio of edge illumination to center illumination and improving vignetting. Furthermore, the magnitude of chromatic aberration is closely related to the incident height of the principal ray of the off-axis beam on the lens. Positioning aperture 6 forward lowers the principal ray's height, reducing the separation of different wavelengths of light on the image plane, thereby effectively suppressing chromatic aberration.

[0065] The basic specifications of the camera module in this embodiment are shown in Table 1; the surface type, radius of curvature, spacing between adjacent lenses, refractive index, and Abbe number of each lens in the camera module are shown in Table 2; the aspherical coefficients of the aspherical lenses are shown in Table 3. Table 1

[0066] Where: EFL is the focal length of the camera module, F# is the aperture of the camera module, DFOV is the field of view, f1 is the focal length of the dispersion adjustment lens group, f2 is the focal length of the focal length adjustment lens group, and L is the length of the camera module along the second optical axis 3.

[0067] Table 2

[0068] Wherein, S0 is the object plane, S1 is the incident surface 10 of the reflector 1, S2 is the reflecting surface 12 of the reflector 1, and S3 is the exit surface 11 of the reflector 1; S4 and S5 are two planes of the first lens 40 that are opposite to each other along the second optical axis 3, with S4 being closer to the reflector 1; similarly, the second lens 410 to the eighth lens 52 each have two planes that are opposite to each other along the second optical axis 3, namely S6 to S19 respectively; S20 and S21 are two planes of the filter that are opposite to each other along the second optical axis 3, and S22 is the image plane.

[0069] The signs of the radii of curvature in the table follow conventional optical design notation rules, indicating the position and direction of the surface center relative to the optical axis, not the magnitude of the curvature. A positive radius means the surface center is on the image side, and a negative radius means the surface center is on the object side. Taking the second lens 410 as an example: radius S6 is positive and radius S7 is negative, meaning the second lens 410 bulges towards the object side. The negative spacing in the table is a conventional symbol used by optical design software to represent reflected light paths and ray refraction positions; it is only used to indicate the relative position of surfaces and the direction of the light path, and does not represent a negative actual physical distance.

[0070] Table 3

[0071] The axial color difference diagram in this embodiment is as follows: Figure 2 As shown, the MTF defocus plot is as follows Figure 3 As shown, the defocus MTF represents the curve of how the lens sharpness / contrast changes with the amount of defocus as the image plane moves before and after the optimal focus.

[0072] The five solid curves in the chromatic aberration diagram represent wavelengths of 656nm, 587nm, 546nm, 486nm, and 435nm, respectively. It can be seen that the axial chromatic aberration of the lens in this embodiment is controlled within a very small range, and the chromatic aberration convergence is good. The MTF defocus diagram shows that at a spatial frequency of 89 lp / mm, the MTF across the entire field of view is greater than 0.6, indicating extremely high resolution.

[0073] Optionally, the camera module also includes an aperture 6, which is connected to the side of the first lens 40 near the reflector 1.

[0074] For reference Figure 4In another preferred embodiment, by setting the aperture stop 6 on the side of the first lens 40 close to the reflector 1 (i.e., the object side of the first lens 40), the position of the aperture stop 6 is moved forward to the surface of the first lens of the dispersion adjustment lens group 4, thereby achieving the advance restriction of the incident beam and thus optimizing the system performance in multiple dimensions. This design allows more off-axis light rays away from the optical axis to enter the aperture 6, while appropriately reducing the size of the focal length adjustment lens group 5 to intercept off-axis light rays close to the optical axis. This effectively compresses the outer diameter of the rear lens group while ensuring edge illumination, which is beneficial for the miniaturization and integration of the camera module. At the same time, the forward placement of the aperture 6 changes the incident height distribution of the off-axis principal rays on the subsequent lenses, which works synergistically with the Abbe number gradient design of the negative power lens group 41 and the positive power lens group 42 to further optimize the correction effect of magnification chromatic aberration and improve the relative illumination of the edge field of view. In addition, the aperture 6 setting method, in conjunction with the spherical or aspherical design of the first lens 40, simplifies the structural assembly, improves the optical axis alignment accuracy, and effectively suppresses the generation of stray light.

[0075] The basic specifications of the camera module in this embodiment are shown in Table 4; the surface type, radius of curvature, spacing between adjacent lenses, refractive index, and Abbe number of each lens in the camera module are shown in Table 5; the aspherical coefficients of the aspherical lenses are shown in Table 6. Table 4

[0076] Table 5

[0077] Table 6

[0078] The axial color difference diagram in this embodiment is as follows: Figure 5 As shown, the MTF defocus plot is as follows Figure 6 As shown in the diagram, the five solid curves in the chromatic aberration diagram represent wavelengths of 656nm, 587nm, 546nm, 486nm, and 435nm, respectively. It can be seen that the axial chromatic aberration of the lens in this embodiment is controlled within a very small range, and the chromatic aberration convergence is good. The MTF defocus diagram shows that at a spatial frequency of 89 lp / mm, the MTF across the entire field of view is greater than 0.6, indicating extremely high resolution.

[0079] In a second aspect, the present invention also provides an electronic device, which includes a camera module according to any one of the first aspects.

[0080] Specifically, the electronic device can be a smartphone, tablet, wearable device, action camera, drone, vehicle-mounted camera, or any other terminal product that requires integrated miniaturized telephoto imaging capabilities. By embedding the camera module provided by this invention into the electronic device, the device can overcome the thickness limitations by using the reflector 1 to fold the optical path, effectively eliminate chromatic aberration and improve color reproduction by using the combination of different Abbe number lenses in the dispersion adjustment lens group 4, and achieve fast and accurate focusing by using the focal length adjustment lens group 5 that can move along the optical axis. Thus, while maintaining a slim and lightweight device, it achieves high magnification and high image quality telephoto shooting capabilities, significantly improving the user's photography experience in different scenarios. In addition, due to the compact overall structure and controllable manufacturing cost of the camera module, this electronic device has good market competitiveness in mass production.

[0081] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0082] Although alternative embodiments of the present invention have been described, those skilled in the art, upon learning the basic inventive concept, can make further changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the alternative embodiments as well as all changes and modifications falling within the scope of the embodiments of the present invention.

[0083] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used merely to distinguish one entity from another, and do not necessarily require or imply any such actual relationship or order between these entities. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or terminal device. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or terminal device that includes that element.

[0084] The technical solution provided by the present invention has been described in detail above. Specific examples have been used to illustrate the principle and implementation of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the principle and implementation of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A camera module, characterized in that, The camera module includes: A reflector (1) is used to reflect light rays incident along the first optical axis (2) to be emitted along the second optical axis (3); In addition, a dispersion adjustment lens group (4) and a focal length adjustment lens group (5) are arranged sequentially along the second optical axis (3), the focal length adjustment lens group (5) being used to move along the second optical axis (3) to adjust the focal length of the camera module; The dispersion adjustment lens group (4) includes a first lens (40), a negative power lens group (41), and a positive power lens group (42) arranged sequentially along the second optical axis (3). The first lens (40) is close to the reflector (1). The negative power lens group (41) includes at least two negative lenses, and the negative power and Abbe number of the at least two negative lenses are different. The positive power lens group (42) includes at least two positive lenses, and the positive power and Abbe number of the at least two positive lenses are different.

2. The camera module according to claim 1, characterized in that, At least two negative light lenses, including a second lens (410) and a third lens (411) arranged sequentially along the second optical axis (3), with the second lens (410) close to the first lens (40). The Abbe number of the second lens (410) is less than that of the first lens (40) but greater than that of the third lens (411).

3. The camera module according to claim 2, characterized in that, The Abbe number Vd1 of the first lens (40) satisfies: Vd1>75; The Abbe number Vd2 of the second lens (410) satisfies: 40 <Vd2<60; The Abbe number Vd3 of the third lens (411) satisfies: Vd3<40.

4. The camera module according to claim 1, characterized in that, Among the at least two positive lenses, there are a fourth lens (420) and a fifth lens (421) arranged sequentially along the second optical axis (3), with the fourth lens (420) close to the negative power lens group (41). The Abbe number of the fourth lens (420) is less than that of the fifth lens (421).

5. The camera module according to claim 4, characterized in that, The Abbe number Vd4 of the fourth lens (420) satisfies: Vd4 < 40; The Abbe number Vd5 of the fifth lens (421) satisfies: Vd5>50.

6. The camera module according to claim 1, characterized in that, The focal length adjustment lens group (5) includes a sixth lens (50), a seventh lens (51) and an eighth lens (52) arranged sequentially along the second optical axis (3), with the sixth lens (50) close to the negative power lens group (41). The sixth lens (50) and the eighth lens (52) have negative optical power, the seventh lens (51) has positive optical power, and the Abbe number of the seventh lens (51) is less than the Abbe number of the sixth lens (50) and less than the Abbe number of the eighth lens (52).

7. The camera module according to claim 1, characterized in that, The first lens (40) is a spherical lens, and the negative power lens group (41), the positive power lens group (42) and the focal length adjustment lens group are all aspherical lenses.

8. The camera module according to any one of claims 1-7, characterized in that, The reflector (1) has an incident surface (10) and an exit surface (11), and the camera module further includes an aperture (6) connected to the incident surface (10).

9. The camera module according to any one of claims 1-7, characterized in that, The camera module also includes an aperture stop (6), which is connected to the side of the first lens (40) near the reflector (1).

10. An electronic device, characterized in that, The electronic device includes the camera module as described in any one of claims 1-9.

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