Camera module and image quality compensation method thereof

Abstract

This invention discloses a camera module and its image quality compensation method, comprising: when the module to be calibrated is in a scene where a checkerboard image is acquired at a target object distance, controlling the compensation lens driving component of the module to drive the compensation lens group to move to achieve focusing operation, and determining the resolution curve of the module to be calibrated; determining the tilt characteristics of the compensation lens group after focusing operation based on the resolution curve; determining the compensation characteristics of the photosensitive chip of the module to be calibrated based on the tilt characteristics, and controlling the chip driving component of the module to drive the photosensitive chip to adjust according to the compensation characteristics; updating the resolution curve based on the adjusted photosensitive chip, and when the updated resolution curve meets the resolution requirements, establishing the correlation between the target object distance, the focusing position of the compensation lens group, and the compensation characteristics. This invention compensates for the image plane tilt caused by the movement of the compensation lens group during internal focusing by adjusting the tilt degree of the photosensitive chip, thereby improving image quality.

Description

Technical Field

[0001] This invention relates to the field of optical technology, and in particular to a camera module and its image quality compensation method. Background Technology

[0002] Internal focusing can significantly reduce lens thickness and improve lens resolution at close range. However, in optical systems with strict tolerance requirements, such as mobile phone lenses, internal focusing has the following technical drawbacks:

[0003] When a drive component (such as a motor) moves the compensation lens assembly, the motor will tilt, which in turn causes the compensation lens assembly to tilt, resulting in a decrease in the image quality on the image sensor.

[0004] Therefore, improving the imaging quality of in-lens focusing is an urgent problem to be solved. Summary of the Invention

[0005] This application provides a camera module and its image quality compensation method, which solves the technical problem in the prior art where the driving component causes the compensation lens group to tilt, resulting in a decrease in the image quality on the photosensitive chip, and achieves the technical effect of improving the image quality of in-lens focusing.

[0006] Firstly, this application provides a method for image quality compensation of a camera module, the method comprising:

[0007] When the module to be calibrated is in a scene where a checkerboard image is acquired at the target object distance, the compensation lens drive assembly of the module to be calibrated is controlled to drive the compensation lens group to move to achieve focusing operation and determine the resolution curve of the module to be calibrated.

[0008] The tilt characteristics of the compensation lens group after focusing operation are determined based on the resolving power curve.

[0009] The compensation characteristics of the photosensitive chip of the module to be calibrated are determined based on the tilt characteristics, and the chip driving component of the module to be calibrated is controlled to drive the photosensitive chip to adjust according to the compensation characteristics.

[0010] Based on the updated resolution curve of the image sensor, when the updated resolution curve meets the resolution requirements, a correlation is established between the target object distance, the focus position of the compensation lens group, and the compensation features. This correlation is used to perform image quality compensation during the shooting process when the module to be calibrated is at the target object distance.

[0011] Furthermore, after establishing the correlation between the target object distance, the focus position of the compensation lens group, and the compensation features, the method also includes:

[0012] Determine the correlation relationships corresponding to multiple different target distances;

[0013] The correlation between multiple different target distances is fitted to construct a continuous relationship between the focus position and compensation features of the module to be calibrated at different continuous object distances. This continuous relationship is used to perform image quality compensation during the shooting process of the module to be calibrated at different object distances.

[0014] Furthermore, after constructing the continuous relationship between the focus position and compensation features of the module to be calibrated at continuously different object distances, the method also includes:

[0015] When shooting with the module to be calibrated, the continuity relationship is queried based on the focus position of the compensation lens group in the module to be calibrated to determine the actual compensation characteristics of the image sensor in the current state.

[0016] The image sensor is adjusted according to the actual compensation characteristics to compensate for the image quality of the module to be calibrated.

[0017] Furthermore, the distance to the target object is greater than or equal to 3 centimeters.

[0018] Furthermore, the compensation characteristics of the photosensitive chip of the module to be calibrated are determined based on the tilt characteristics, and the chip driving assembly of the module to be calibrated is controlled to drive the photosensitive chip to adjust according to the compensation characteristics, including:

[0019] The height variation characteristics of the photosensitive chip in at least three directions are determined based on the tilt characteristics; the compensation characteristics include the height variation characteristics in at least three directions.

[0020] The control chip driving component changes the height of the photosensitive chip in the corresponding direction according to the height change characteristics in at least three directions, so that the photosensitive chip is adjusted according to the compensation characteristics.

[0021] Furthermore, controlling the compensation lens drive assembly of the module to be calibrated to drive the compensation lens group to move to achieve focusing operation includes:

[0022] Move the compensation lens group at least twice according to the initial step size of the module to be calibrated, and determine the first characteristic group of the change in the resolving power of the module to be calibrated before and after the two most recent moves of the compensation lens group.

[0023] When the first set of change features indicates that the resolving power is increasing, the movement step size is determined according to the first set of change features, the compensation lens group is moved according to the movement step size, and the second set of change features of the resolving power of the module to be calibrated before and after the two most recent movements of the compensation lens group is determined.

[0024] Determine whether the second set of change features indicates an increase in analytical power;

[0025] When the second change feature group indicates that the resolving power is increasing, the movement step size is updated according to the second change feature group, and the compensation lens group is moved according to the updated movement step size.

[0026] The second change feature group is updated based on the resolution before and after the two most recent moves of the compensation lens group, and the process returns to the step of determining whether the second change feature group indicates that the resolution is increasing, until the updated second change feature group indicates that the resolution is unchanged or decreases for the first time. The focus position of the compensation lens group when the resolution is unchanged or decreases for the first time is recorded.

[0027] Furthermore, both the first and second change feature groups include analytical force momentum features and analytical force acceleration features;

[0028] The resolving force momentum characteristic refers to the ratio between the difference in resolving force before and after the nth movement of the compensating lens group and the resolving force after the (n-1)th movement; n is a positive integer greater than 2.

[0029] The resolving force acceleration characteristic refers to the difference between the first ratio and the second ratio. The first ratio is the ratio between the difference in resolving force before and after the nth movement of the compensating lens group and the resolving force after the nth movement. The second ratio is the ratio between the difference in resolving force before and after the (n-2)th movement of the compensating lens group and the resolving force after the (n-1)th movement.

[0030] Further, the movement step size is updated based on the second set of change features, including:

[0031] Based on the initial step size and the resolving force momentum and resolving force acceleration characteristics corresponding to the most recent movement, update the current movement step size corresponding to the compensation lens group.

[0032] Furthermore, the tilt characteristics of the compensation lens group after focusing are determined based on the resolving power curve, including:

[0033] The central field curve of the central field of view and the peripheral field curves of multiple peripheral fields of view of the module to be calibrated are determined based on the resolving power curve.

[0034] The tilt of the compensation lens group in each peripheral field of view is determined based on the difference between the peripheral field curvature and the central field curvature after focusing. The tilt characteristics include the tilt of the compensation lens group in each peripheral field of view.

[0035] Secondly, this application provides a camera module, which includes:

[0036] Lens assembly, including compensating lens group and fixed lens group;

[0037] The compensating lens drive assembly is used to drive the compensating lens group to move to achieve focusing operation;

[0038] Photosensitive chip;

[0039] The chip driver component is used to drive the photosensitive chip to adjust according to the compensation features, so that the adjusted photosensitive chip compensates for the tilt features of the compensation lens group after focusing operation.

[0040] One or more technical solutions provided in the embodiments of this application have at least the following technical effects or advantages:

[0041] This embodiment utilizes the module under test to acquire a checkerboard image at the target object distance, controls the compensation lens drive assembly to move the compensation lens group to achieve focusing operation, and determines the resolution curve of the module under test. Based on the resolution curve, the tilt characteristics caused by the focusing operation are obtained, and the compensation characteristics of the image sensor are determined based on the tilt characteristics. Then, the tilt degree of the image sensor is adjusted according to the compensation characteristics. The target object distance, the focusing position of the compensation lens group, and the compensation characteristics of the image sensor are bound together to obtain a correlation relationship, which can be called by the module under test during actual shooting to improve the problem of resolution reduction during the focusing process of the internal focusing lens. Adjusting the tilt degree of the image sensor compensates for the image plane tilt caused by the movement of the compensation lens group during internal focusing, thereby improving image sharpness and image quality. As can be seen, the solution provided in this embodiment can calibrate the assembled module to be calibrated. It mainly relies on the checkerboard image and the resolution curve of the module to be calibrated during the process of capturing the checkerboard image to obtain the correlation between the target object distance, the focus position of the compensation lens group and the compensation characteristics of the photosensitive chip. This correlation is stored in the module to be calibrated so that the module to be calibrated can compensate for the image plane tilt caused by the movement of the compensation lens group during the internal focusing process by adjusting the tilt of the photosensitive chip during the shooting process, thereby improving the image sharpness and image quality. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0043] Figure 1 (a) shows the initial state of the compensation lens group when it is not in focus.

[0044] Figure 1 (b) shows a schematic diagram of the state after the compensation lens group has moved to perform a focusing operation;

[0045] Figure 2 A schematic diagram showing the state of a photosensitive chip tilted;

[0046] Figure 3 This is a cross-sectional view of the camera module provided in this embodiment;

[0047] Figure 4 This is an axial sectional view of the camera module provided in this embodiment;

[0048] Figure 5 This is an exploded view of the camera module provided in this embodiment;

[0049] Figure 6 This is a schematic diagram of the FPC provided in this embodiment;

[0050] Figure 7 This is a flowchart illustrating a camera module image quality compensation method provided in this embodiment;

[0051] Figure 8 This is a schematic diagram of a calibration scenario provided in this embodiment;

[0052] Figure 9 This is a schematic diagram showing the relationship between the central field of view and the peripheral field of view provided in this embodiment;

[0053] Figure 10 for Figure 9 The diagram shows the resolving power curves corresponding to the central field of view and the four peripheral fields of view.

[0054] Figure 11 This is a schematic diagram showing the adjustment of the height change characteristics corresponding to the four sides of the photosensitive chip in this embodiment;

[0055] Figure 12 This is a schematic diagram of the continuous relationship curves corresponding to different object distances obtained by fitting multiple correlation relationships corresponding to the four sides of the photosensitive chip.

[0056] Figure label:

[0057] 1-Fixed lens group, 2-Compensation lens group, 3-AF coil, 4-AF magnet, 5-Chip displacement magnet, 6-Filter holder, 7-Photosensitive chip, 8-Motor housing, 9-Carrier, 10-AF group holder, 11-Chip displacement coil, 12-Filter, 13-FPC, 131-Moving side, 132-Drive circuit, 133-Control interface, 21-Checkerboard pattern, 22-Module to be calibrated, 23-Drive module, 24-Computer system. Detailed Implementation

[0058] This application provides a camera module and its image quality compensation method, which solves the technical problem in the prior art where the driving component causes the compensation lens group to tilt, resulting in a decrease in the image quality on the photosensitive chip.

[0059] The technical solution of this application embodiment is to solve the above-mentioned technical problems, and the general idea is as follows:

[0060] A method for image quality compensation of a camera module includes: when the module 22 to be calibrated is in a scene where an image of a checkerboard pattern 21 is acquired at a target object distance, controlling the compensation lens driving component of the module 22 to drive the compensation lens group 2 to move to achieve focusing operation, and determining the resolution curve of the module 22 to be calibrated; determining the tilt characteristics of the compensation lens group 2 after focusing operation based on the resolution curve; determining the compensation characteristics of the photosensitive chip 7 of the module 22 to be calibrated based on the tilt characteristics, and controlling the chip driving component of the module 22 to drive the photosensitive chip 7 to adjust according to the compensation characteristics; updating the resolution curve based on the adjusted photosensitive chip 7; when the updated resolution curve meets the resolution requirements, constructing a correlation between the target object distance, the focusing position of the compensation lens group 2, and the compensation characteristics, the correlation being used for image quality compensation during the shooting process of the module 22 at the target object distance.

[0061] In this embodiment, the calibration module 22 acquires an image of the checkerboard pattern 21 at the target object distance, controls the compensation lens drive assembly to move the compensation lens group 2 to achieve focusing, and determines the resolution curve of the calibration module 22. Based on the resolution curve, the tilt characteristics caused by the focusing operation are obtained, and the compensation characteristics of the photosensitive chip 7 are determined based on the tilt characteristics. Then, the tilt degree of the photosensitive chip 7 is adjusted according to the compensation characteristics. The target object distance, the focusing position of the compensation lens group 2, and the compensation characteristics of the photosensitive chip 7 are bound to obtain a correlation relationship, which can be called by the calibration module 22 during actual shooting to improve the problem of resolution reduction during the focusing process of the internal focusing lens. The tilt degree of the photosensitive chip 7 is adjusted to compensate for the image plane tilt caused by the movement of the compensation lens group 2 during the internal focusing process, thereby improving image sharpness and image quality.

[0062] As can be seen, the solution provided in this embodiment can calibrate the assembled calibration module 22. It mainly relies on the checkerboard image 21 and the resolution curve of the calibration module 22 during the process of shooting the checkerboard image 21 to obtain the correlation between the target object distance, the focus position of the compensation lens group 2 and the compensation features of the photosensitive chip 7. This correlation is stored in the calibration module 22 so that the calibration module 22 can compensate for the image plane tilt caused by the movement of the compensation lens group 2 during the internal focusing process by adjusting the tilt of the photosensitive chip 7 during the shooting process, thereby improving the image sharpness and image quality.

[0063] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0064] First, it should be clarified that the term "and / or" in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0065] Internal focusing can significantly reduce lens thickness and improve lens resolution at close range. However, in optical systems with strict tolerance requirements, such as mobile phone lenses, internal focusing has the following technical drawbacks:

[0066] When a drive (such as a motor) moves the compensation lens group 2, the motor will tilt, which will cause the compensation lens group 2 to tilt, ultimately resulting in a decrease in the image quality on the image sensor 7.

[0067] like Figure 1 As shown, Figure 1 Including Figure 1 (a) and Figure 1 (b), Figure 1 (a) indicates the initial state where the compensation lens group 2 has not been focused. Figure 1 (b) indicates the state after the compensation lens group 2 has moved to perform a focusing operation. From Figure 1 As can be seen in (a), when the compensating lens group 2 is not moved, the optical axes of the fixed lens group 1 and the compensating lens group 2 are coincident, and the optical axis is... Figure 1 The vertical line in (a). From Figure 1 As can be seen in (b), after the compensation lens group 2 moves, the optical axis of the compensation lens group 2 tilts, and the optical axis of the compensation lens group 2 is... Figure 1 The dashed line in (b) represents the optical axis of fixed lens group 1. Figure 1 The vertical line in (b) causes the optical axes of the fixed lens group 1 and the compensation lens group 2 to not coincide. In this case, the image on the photosensitive chip 7 is not clear and uneven, resulting in relatively poor image quality.

[0068] To improve the imaging quality of in-lens focusing, this embodiment provides a camera module and its image quality compensation method. This mainly involves changing the tilt of the imaging chip to compensate for the tilt of the compensation lens group 2, thereby improving the imaging quality of in-lens focusing. In other words, it provides a tilt compensation amount to the image on the photosensitive chip 7, restoring the imaging system to a clear state. Figure 2 As shown, Figure 2 The dashed lines in the vertical direction represent the optical axis of compensation lens group 2. Figure 2 The dashed lines in the left-right direction represent the photosensitive chip 7 after it has been tilted. By adjusting the tilt of the photosensitive chip 7, the optical axis of the compensating lens group 2 is placed in the center field of view of the photosensitive chip 7 to improve image quality.

[0069] First, the camera module provided in this embodiment will be described.

[0070] This embodiment provides a camera module for reference. Figures 3-5 Mainly includes:

[0071] The lens assembly includes a compensating lens group 2 and a fixed lens group 1;

[0072] The compensation lens drive assembly is used to drive the compensation lens group 2 to move to achieve focusing operation;

[0073] Image sensor 7;

[0074] The chip driver component is used to drive the photosensitive chip 7 to adjust according to the compensation features, so that the adjusted photosensitive chip 7 compensates for the tilt features of the compensation lens group 2 after the focusing operation.

[0075] like Figure 3 , Figure 4 and Figure 5 As shown, Figure 3 This is a cross-sectional view of the camera module provided in this embodiment. Figure 4 This is an axial sectional view of the camera module provided in this embodiment. Figure 5 This is an exploded view of the camera module provided in this embodiment.

[0076] like Figure 3 , Figure 4 and Figure 5 As shown, the lens assembly includes a compensating lens group 2 and a fixed lens group 1, which are stacked in contact with each other. The fixed lens group 1 is located on the side closer to the object being photographed, and the compensating lens group 2 is located on the side closer to the image sensor 7. Figures 3-5 As shown, the compensating lens group 2 is located below the fixed lens group 1.

[0077] like Figure 3 , Figure 4 and Figure 5 As shown, the compensating lens drive assembly includes a motor housing 8, a carrier 9, an AF (AC / DC) coil 3, an AF magnet 4, and an AF group support 10. The AF magnet 4 and the AF coil 3 (equivalent to a motor) drive the compensating lens group 2 to move up and down for focusing. The motor housing 8 covers the outside of the lens assembly, with the light-receiving side of the fixed lens group 1 protruding from a hole at the top of the motor housing 8 to be exposed and to receive ambient light. The carrier 9 is located on the lower side of the compensating lens group 2 and supports the AF coil 3 and the AF magnet 4. The AF group support 10 is located on the lower side of the carrier 9.

[0078] like Figure 3 , Figure 4 and Figure 5 As shown, the chip driving assembly includes a chip displacement magnet 5, a chip displacement coil 11, and a spring plate (also known as FPC 13). The chip displacement magnet 5 is disposed on the lower side or inside of the AF group bracket 10. The camera module also includes a filter 12 and a filter bracket 6. The filter bracket 6 is disposed on the lower side of the AF group bracket 10, the chip displacement coil 11 is disposed inside or on the lower side of the filter bracket 6, and the filter 12 is disposed in the hole in the middle of the filter bracket 6. The photosensitive chip 7 is disposed on the FPC 13, and the photosensitive chip 7 is located below the filter 12, so that the light transmitted by the lens assembly passes through the filter 12 and is projected onto the photosensitive chip 7. The FPC 13 is as follows: Figure 6 As shown, the photosensitive chip 7 is disposed on the upper surface of the movable side 131 of the FPC 13. The chip displacement magnet 5 and the chip displacement coil 11 cooperate with each other. That is, when the photosensitive chip 7 needs to move, current is input to the chip displacement coil 11 to generate magnetic force, which pushes the photosensitive chip 7 to move up and down, so that the plane on the movable side 131 of the FPC 13 is tilted, thereby achieving the purpose of adjusting the tilt degree of the photosensitive chip 7. In this way, the optical axis of the compensation lens group 2 can be placed in the center field of view of the photosensitive chip 7 to improve image quality. The specific adjustment process of the photosensitive chip 7 will be described in the description of the image quality compensation method of the camera module, and will not be described in detail here.

[0079] like Figure 6 As shown, the active side 131 of FPC13 includes four sides, each corresponding to a driving circuit 132. The four driving circuits 132 can be controlled independently. Different magnitudes of current can be input to generate different magnitudes of thrust. By inputting the same or different currents to the driving circuits 132 of the four sides, the height of each side of the active side 131 of FPC13 can be changed, thereby controlling the plane on which the photosensitive chip 7 is located to change the degree of tilt.

[0080] It should be noted that the shape of the movable side 131 of FPC13 can be set according to the actual situation, and the number of its corresponding drive circuits 132 can also be adjusted according to the different shapes, as long as the plane on which the movable side 131 is located is tilted according to the tilt of the compensation lens group 2. For example, Figure 6 The movable side 131 is square and has four sides. A driving circuit 132 can be set for each of the four sides, or a driving circuit 132 can be set for any three sides. The driving circuit 132 can be set in the middle of the side of the movable side 131 or at the end of the movable side 131.

[0081] In other words, the chip driving component is used to drive the photosensitive chip 7 to be height adjusted in at least three directions according to the compensation features, so that the adjusted photosensitive chip 7 compensates for the tilt features of the compensation lens group 2 after the focusing operation.

[0082] The camera module provided in this embodiment adopts an in-lens focusing method, which can reduce the size of the camera module and achieve miniaturization. More importantly, by changing the tilt of the photosensitive chip 7, the problem of reduced resolution during the focusing process of the in-lens focusing lens can be improved, and the image quality can be significantly improved.

[0083] Next, the image quality compensation method for the camera module provided in this embodiment will be explained.

[0084] This embodiment provides, for example Figure 7 The method shown is a camera module image quality compensation method, which includes steps S71-S74.

[0085] Step S71: When the module to be calibrated 22 is in the scene of acquiring the chessboard 21 image at the target object distance, control the compensation lens driving assembly of the module to be calibrated 22 to drive the compensation lens group 2 to move to achieve focusing operation, and determine the resolution curve of the module to be calibrated 22.

[0086] Step S72: Determine the tilt characteristics of the compensation lens group 2 after focusing operation based on the resolving power curve;

[0087] Step S73: Determine the compensation features of the photosensitive chip 7 of the module to be calibrated 22 based on the tilt characteristics, and control the chip driving component of the module to be calibrated 22 to drive the photosensitive chip 7 to adjust according to the compensation features.

[0088] Step S74: Update the resolution curve based on the adjusted image sensor 7. When the updated resolution curve meets the resolution requirements, construct the correlation between the target object distance, the focus position of the compensation lens group 2, and the compensation features. The correlation is used to perform image quality compensation during the shooting process when the module to be calibrated 22 is at the target object distance.

[0089] Regarding step S71, when the module to be calibrated 22 is in the scene of acquiring the image of the checkerboard 21 at the target object distance, the compensation lens driving assembly of the module to be calibrated 22 is controlled to drive the compensation lens group 2 to move to achieve focusing operation, and the resolution curve of the module to be calibrated 22 is determined.

[0090] The calibration module 22 is an in-lens focusing module. In this embodiment, it is used as... Figures 3-5 The camera module shown is module 22 to be calibrated, which will be explained later.

[0091] First, construct a calibration scenario, such as Figure 8As shown, the system includes a test checkerboard 21 (also called a chart), a calibration module 22, a drive module 23, and a computer system 24. The checkerboard 21 is the object being photographed, and the distance between the checkerboard 21 and the calibration module 22 is called the object distance, which is usually greater than or equal to 3 cm. The calibration module 22 is connected to the drive module 23, which controls the operation of the compensation lens drive assembly and the chip drive assembly within the calibration module 22. The computer system 24 records the object distance between the checkerboard 21 and the calibration module 22, the focus position of the compensation lens group 2 within the calibration module 22, and the compensation characteristics of the tilt of the image sensor 7.

[0092] Determine the object distance between the checkerboard 21 to be measured and the module 22 to be calibrated, and record it as the target object distance. The target object distance is a distance greater than or equal to 3cm.

[0093] The calibration module 22 acquires the checkerboard 21 image at the target object distance, and drives the compensation lens group 2 to move the compensation lens by controlling the compensation lens drive assembly to change the focal length and achieve focusing operation.

[0094] The focusing operation can be performed in two ways. Method one involves gradually moving the compensation lens group 2 according to the initial step size until a relatively optimal focusing position is reached. Method two includes steps S7111-S7115.

[0095] Step S7111: Move the compensation lens group 2 at least twice according to the initial step size of the module to be calibrated 22, and determine the first change characteristic group of the resolving power of the module to be calibrated 22 before and after the two most recent moves of the compensation lens group 2.

[0096] Step S7112: When the first change feature group indicates that the resolving power is increasing, determine the movement step size according to the first change feature group, move the compensation lens group 2 according to the movement step size, and determine the second change feature group of the resolving power of the module 22 to be calibrated before and after the two most recent movements of the compensation lens group 2.

[0097] Step S7113: Determine whether the second set of change features indicates an increase in analytical power;

[0098] Step S7114: When the second change feature group indicates that the resolving power is increasing, update the movement step size according to the second change feature group, and move the compensation lens group 2 according to the updated movement step size.

[0099] Step S7115: Update the second change feature group based on the resolution before and after the two most recent moves of the compensation lens group 2, and return to the step of determining whether the second change feature group indicates that the resolution is increasing, until the updated second change feature group indicates that the resolution is unchanged or decreases for the first time, and record the focus position of the compensation lens group 2 when the resolution is unchanged or decreases for the first time.

[0100] Regarding step S7111, the compensation lens group 2 in the calibration module 22 moves in steps. The initial step size is related to the system characteristics of the calibration module 22, and can be determined according to the system characteristics of the calibration module 22, for example, 1 mm.

[0101] Move the compensation lens group 2 at least twice according to the initial step size, and record the resolving power before and after each move. The resolving power can be represented by the MTF value or the SFR value, whichever is more appropriate for the specific situation. Determine the first change feature group based on the resolving power before and after the two most recent moves of the compensation lens group 2.

[0102] The first set of change characteristics includes analytical force momentum characteristics and analytical force acceleration characteristics.

[0103] The resolving force momentum characteristic refers to the ratio between the difference in resolving force before and after the nth movement of the compensation lens group 2 and the resolving force after the (n-1)th movement. See Formula 1 for details. n is a positive integer greater than 2.

[0104]

[0105] Where m is the analytical force-momentum characteristic, f n f is the analytical force corresponding to the nth movement; n-1 This is the analytical force corresponding to the (n-1)th move, and it is also the analytical force corresponding to the nth move. In other words, the analytical force corresponding to the (n-1)th move and the analytical force corresponding to the nth move are the same.

[0106] The resolving force acceleration characteristic refers to the difference between the first ratio and the second ratio. The first ratio is the ratio between the difference in resolving force before and after the nth movement of the compensation lens group 2 and the resolving force after the nth movement. The second ratio is the ratio between the difference in resolving force before and after the (n-2)th movement of the compensation lens group 2 and the resolving force after the (n-1)th movement. For details, please refer to Formula 2.

[0107]

[0108] Where a represents the analytical force acceleration characteristic, f n f is the analytical force corresponding to the nth movement; n-1 f is the analytical force corresponding to the (n-1)th move, and also the analytical force corresponding to the nth move. In other words, the analytical force corresponding to the (n-1)th move and the analytical force corresponding to the nth move are the same. n-2This is the analytical force corresponding to the (n-2)th move, and it is also the analytical force corresponding to the (n-1)th move. In other words, the analytical force corresponding to the (n-2)th move and the analytical force corresponding to the (n-1)th move are the same analytical force.

[0109] For example, when the compensation lens group 2 is moved twice according to the initial step size, the first change feature group includes m1, m2, and a2. However, m1 is not used in actual operation, so the first change feature group can also include only m2 and a2. Determine whether the first change feature group indicates that the resolving power is increasing.

[0110] When the first change feature group indicates that the resolution remains unchanged or decreases, it is considered that the module 22 to be calibrated is in a relatively optimal focusing position. The correlation between the target object distance and the focusing position of the compensation lens group 2 can be established, indicating that the tilt of the compensation lens group 2 at the target object distance has a negligible impact on the image quality, and therefore there is no need to adjust the tilt of the photosensitive chip 7.

[0111] When the first change feature group indicates that the resolving power is increasing, it means that the module 22 to be calibrated is not yet in a relatively optimal focusing position, and step S7112 needs to be continued.

[0112] Regarding step S7112, the movement step size of the compensation lens group 2 for refocusing is determined according to the first change feature group. Specifically, the movement step size corresponding to the current movement of the compensation lens group 2 is updated according to the initial step size and the resolving momentum feature and resolving acceleration feature corresponding to the most recent movement. For details, please refer to Formula 3.

[0113] s n =s b +αm n-1 +βa n-1 Formula 3

[0114] Among them, s n To compensate for the movement step size corresponding to the nth focusing movement of lens group 2, s b Let m be the initial step size, α and β be coefficients, and m be the value of m. n-1 The analytical force-momentum characteristic corresponding to the (n-1)th movement, a n-1 This represents the analytical force acceleration characteristic corresponding to the (n-1)th movement.

[0115] For example, in step S7111, when the compensation lens group 2 is moved twice according to the initial step size, the first change feature group includes m2 and a2. If the first change feature group indicates that the resolving power is increasing, then based on m2 and a2 and in combination with formula 3, the moving step size s3 corresponding to the third movement of the compensation lens group 2 can be determined. b +αm2+βa2.

[0116] The control compensation lens drive assembly drives the compensation lens group 2 to move according to the movement step size, and determines the second change feature group of the resolving force of the module 22 to be calibrated before and after the two most recent movements. The second change feature group also includes the resolving force momentum feature and the resolving force acceleration feature, which can be referred to in the relevant description of the first change feature group, and will not be repeated here in this embodiment.

[0117] Regarding step S7113, it is determined whether the second change feature group indicates an increase in resolving power. If the second change feature group indicates that the resolving power remains unchanged or decreases, then the module 22 to be calibrated is considered to be in a relatively optimal focusing position, and step S73 can be continued. If the second change feature group indicates that the resolving power is increasing, it means that the module 22 to be calibrated is not yet in a relatively optimal focusing position, and step S7114 needs to be continued.

[0118] Regarding step S7114, when the second change feature group indicates an increase in resolving power, a new movement step size is recalculated based on the second change feature group. The principle is similar to that of determining the movement step size based on the first change feature group in step S7112; please refer to the relevant description of step S7112 for details, which will not be elaborated upon here. After updating the movement step size, the compensation lens group 2 is moved according to the updated movement step size, and step S7115 continues.

[0119] Regarding step S7115, after moving the compensation lens group 2 according to the updated movement step size, the second change feature group is recalculated to update it, and the process returns to step S7113 to determine whether the updated second change feature group indicates an increase in resolving power. If the updated second change feature group indicates an increase in resolving power, steps S7114 and S7115 are executed, and this process is repeated until the updated second change feature group indicates that the resolving power remains unchanged or decreases for the first time. If the updated second change feature group indicates that the resolving power remains unchanged or decreases for the first time, step S72 is executed.

[0120] Regarding the focusing operation in this embodiment involving Method 1 and Method 2, Method 1 is relatively simple, but its focusing efficiency is low, requiring further focusing steps following the initial step. Method 2 is relatively complex, but its focusing efficiency is high. It determines the next movement step size based on the changes in the compensation lens group 2 after the last two movements, and moves according to the new step size. This allows for adjustment of the focusing step size according to actual conditions, shortening focusing time and improving focusing efficiency. For example, if the initial step size is 1mm, and focusing at the current target distance requires a 10mm movement to find the relatively optimal focusing position, then Method 1 requires 10 movements. In Method 2, the first two movements are 1mm each, and after re-determining the step size, if the step size is 3mm, then only two or three more movements are needed to find the relatively optimal focusing position. In other words, Method 1 requires 10 movements, while Method 2 only requires about 5 movements, demonstrating that Method 2 has much higher focusing efficiency. In actual operation, the specific focusing operation can be selected from Method 1 and Method 2 according to the actual focusing efficiency requirements.

[0121] Regarding step S72, the tilt characteristics of the compensation lens group 2 after focusing are determined based on the resolving power curve.

[0122] Based on the system characteristics of the module 22 to be calibrated and the parameters of the checkerboard 21, the central field of view and the peripheral field of view of the module 22 to be calibrated can be distinguished. For example... Figure 9 As shown, the central field of view f0 and four peripheral fields of view f1, f2, f3, and f4 are illustrated. Each field of view corresponds to a different resolving power curve, as shown below. Figure 10 As shown, Figure 9 The diagram shows the resolving power curves corresponding to the central field of view and the four peripheral fields of view. The horizontal axis represents the distance of the image plane's deviation forward and backward, and the vertical axis represents the MTF value. The greater the deviation of the image plane, the smaller the MTF value, and the worse the image quality. In this embodiment, the number and location of the peripheral fields of view can be determined according to the actual situation, and this embodiment does not impose any restrictions on this.

[0123] The central field curve of the central field of view and the peripheral field curves of multiple peripheral fields of view of the module 22 to be calibrated are determined based on the resolution curve; the central field curve and the peripheral field curve can be obtained from the resolution curve.

[0124] The tilt of the compensation lens group 2 in each peripheral field of view is determined based on the difference between the peripheral field curvature and the central field curvature after focusing. The tilt characteristics include the tilt of the compensation lens group 2 in each peripheral field of view.

[0125] When the compensation lens group 2 is tilted, the imaging quality on the image sensor 7 will differ in different peripheral fields of view. The imaging quality in the central field of view is relatively better. Therefore, the difference between the peripheral field curvature and the central field curvature of each peripheral field of view can be determined based on the central field curvature of the central field of view. Based on these difference values, the tilt degree of the compensation lens group 2 in each peripheral field of view can be determined. The tilt degree of each peripheral field of view can reflect the tilt characteristics of the compensation lens group 2 during the focusing process.

[0126] For example, suppose Figure 9 The field curvature values ​​of the central field of view and the four peripheral fields of view are Z0, Z1, Z2, Z3, and Z4, respectively. Taking the field curvature Z0 of the central field of view as the reference point, the field curvature difference values ​​of the peripheral fields of view are Z1-Z0, Z2-Z0, Z3-Z0, and Z4-Z0, respectively. Using the plane where the photosensitive chip 7 is located as the XOY plane (the X and Y directions can be the length and width of the photosensitive chip 7), and establishing a three-dimensional coordinate system with the field curvature as the Z-axis, and with the center of the photosensitive chip 7 as point O, and setting the length and width of the photosensitive chip 7 as X1 and Y1, respectively, the plane coordinate points after the compensation lens group 2 tilts can be constructed in the three-dimensional coordinate system as follows:

[0127] (0,-Y1 / 2,Z1-Z0), (0,Y1 / 2,Z2-Z0), (-X1 / 2,0,Z3-Z0), (X1 / 2,0,Z4-Z0).

[0128] These four points can be used to determine the plane where the compensation lens group 2 is located after it tilts. These four points are also the tilt characteristics of the compensation lens group 2 after it tilts.

[0129] Regarding step S73, the compensation characteristics of the photosensitive chip 7 of the module to be calibrated 22 are determined according to the tilt characteristics, and the chip driving component of the module to be calibrated 22 is controlled to drive the photosensitive chip 7 to adjust according to the compensation characteristics.

[0130] Ideally, the tilt of the compensation lens group 2 during focusing should correspond to the tilt of the image sensor 7; in other words, the compensation lens group 2 and the image sensor 7 should remain balanced. Therefore, the tilt characteristics of the compensation lens group 2 can be directly used as the compensation characteristics of the image sensor 7, allowing the image sensor 7 to completely compensate for the tilt of the compensation lens group 2. The tilt characteristics of the compensation lens group 2 are converted into compensation characteristics of the image sensor 7, and then these compensation characteristics are further converted into control current for the chip driver assembly. This control current then drives the image sensor 7 to adjust according to the compensation characteristics.

[0131] Specifically, the height variation characteristics of the photosensitive chip 7 in at least three directions can be determined based on the tilt characteristics; the compensation characteristics include the height variation characteristics in at least three directions. The control chip driving component changes the height of the photosensitive chip 7 in the corresponding directions according to the height variation characteristics in at least three directions, so that the photosensitive chip 7 is adjusted according to the compensation characteristics.

[0132] For example, such as Figure 6 As shown, four driving circuits 132 are provided on the active side 131 of FPC13. The different driving currents of the four driving circuits 132 can be determined according to the compensation characteristics, thereby changing the tilt of the plane where the photosensitive chip 7 is located.

[0133] The height of each of the four sides of the photosensitive chip 7 is independently controllable (at least three sides need to be height-adjustable to create a height difference between the four sides). As shown earlier, assuming the tilt characteristics of the compensation lens group 2 are (0, -Y1 / 2, Z1-Z0), (0, Y1 / 2, Z2-Z0), (-X1 / 2, 0, Z3-Z0), (X1 / 2, 0, Z4-Z0), then the compensation characteristics are (0, -Y1 / 2, Z1-Z0), (0, Y1 / 2, Z2-Z0), (-X1 / 2, 0, Z3-Z0), (X1 / 2, 0, Z4-Z0). Converting these into corresponding control currents I1, I2, I3, and I4 allows control of the corresponding sides of the photosensitive chip 7 to change their heights H1, H2, H3, and H4. Figure 11 As shown, the four sides of the photosensitive chip 7 can correspond to height change characteristics H1, H2, H3, and H4 respectively. By adjusting the height of the four sides of the photosensitive chip 7, the tilt of the compensation lens group 2 can be compensated.

[0134] Regarding step S74, the resolution curve is updated based on the adjusted image sensor 7. When the updated resolution curve meets the resolution requirements, the correlation between the target object distance, the focus position of the compensation lens group 2, and the compensation features is constructed. The correlation is used to perform image quality compensation during the shooting process when the module to be calibrated 22 is at the target object distance.

[0135] Ideally, after the tilt of the photosensitive chip 7 is adjusted, the plane of the compensating lens group 2 should remain parallel to the plane of the photosensitive chip 7. However, in actual operation, while the image quality is optimal when the planes of the compensating lens group 2 and the photosensitive chip 7 are balanced, the conditions for achieving this are relatively stringent, and it is difficult to determine whether they are parallel. Therefore, this embodiment determines whether the tilt of the photosensitive chip 7 has achieved the purpose of tilt compensation for the compensating lens group 2 by checking whether the resolution is improved.

[0136] Specifically, after adjusting the tilt of the photosensitive chip 7, the resolution can be determined by a gradient algorithm, such as the Tenengrad algorithm (see Formula 4).

[0137]

[0138] Where S1(x,y), S2(x,y), S3(x,y), and S4(x,y) are the first-order differences between a pixel and its eight neighboring pixels in the chessboard image 21 obtained from the calibration module 22 in the horizontal, vertical, left diagonal, and right diagonal directions, respectively, which can be expressed as follows:

[0139] Where g1, g2, g3, and g4 are constants, and f(x,y) is the grayscale value of the target pixel, which can be defined as a constant. g1, g2, g3, and g4 can be defined as follows.

[0140]

[0141] Based on the updated resolution curve of the adjusted image sensor 7, a gradient algorithm is used to determine whether the updated resolution curve meets the resolution requirements. If it does, the target object distance, the focus position of the compensation lens group 2, and the compensation features of the image sensor 7 are bound together to establish a correlation and store the record. In actual use, when the object distance is the target object distance, the calibration module 22 can determine the corresponding compensation features of the image sensor 7 based on the correlation, and then control the tilt adjustment of the image sensor 7 to improve image quality.

[0142] It should be noted that the compensation feature in the correlation can be the compensation feature itself, the tilt feature, or the current value of each drive circuit 132 in the chip driver component corresponding to the compensation feature. In actual operation, the appropriate option can be selected according to the actual situation.

[0143] Furthermore, after establishing the correlation between the target object distance, the focus position of the compensation lens group 2, and the compensation features, the method also includes steps S81-S82.

[0144] Step S81: Determine the correlation relationships corresponding to multiple different target distances;

[0145] Step S82: Fit the correlation relationships corresponding to multiple different target object distances to construct a continuous relationship between the focus position and compensation features of the module to be calibrated 22 at different object distances. The continuous relationship is used to perform image quality compensation during the shooting process of the module to be calibrated 22 at different object distances.

[0146] Regarding step S81, multiple different target object distances are all greater than or equal to 3 cm, and the number can be more than three. The more distances, the more accurate the final continuity relationship will be. The target object distance can be infinity, but in the actual calibration process, 5 meters (or other distances) can be used to represent infinity. For example, within the range of 3 cm to 5 meters, nine target object distances are selected: 10 cm, 50 cm, 1 meter, 1.5 meters, 2 meters, 2.5 meters, 3 meters, 4 meters, and 5 meters. For each target object distance, the correlation relationship corresponding to each target object distance is determined using the methods in steps S71-S74.

[0147] Regarding step S82, the correlation relationships corresponding to multiple target object distances are fitted with data to obtain a continuous relationship between the focus position of the compensation lens group 2 and the compensation features of the image sensor 7 under continuously different object distances. For example... Figure 12 As shown, this is a schematic diagram of the continuous relationship curves corresponding to different object distances obtained after fitting multiple correlation relationships corresponding to the four sides of the photosensitive chip. The horizontal axis is the object distance, and the vertical axis is the displacement height distance.

[0148] By fitting the correlation relationships corresponding to multiple different object distances, the continuous relationship corresponding to consecutive different object distances can be determined. This can reduce the number of times steps S71-S74 are executed, save calibration time, and improve calibration efficiency.

[0149] After establishing a continuous relationship between the focus position and compensation features of the module to be calibrated 22 at different object distances, the continuous relationship is recorded in the drive module 23 of the module to be calibrated 22, thus becoming a calibrated module, which can then be directly put into use. That is, when shooting with the module to be calibrated 22 (here referring to the calibrated module), the continuous relationship is queried based on the focus position of the compensation lens group 2 in the module to be calibrated 22 to determine the actual compensation features corresponding to the image sensor 7 in the current state; then the image sensor 7 is controlled to adjust according to the actual compensation features to compensate for the image quality of the module to be calibrated 22.

[0150] In addition, when shooting with the module to be calibrated 22 (referring to the calibrated module), the actual object distance between the module and the object being photographed can be obtained. Based on the actual object distance, the continuous relationship is queried to determine the actual focus position corresponding to the current state of the module and the actual compensation feature corresponding to the current state of the image sensor 7. Then, the compensation lens group 2 is controlled to reach the actual focus position to complete the focusing operation, and the image sensor 7 is controlled to adjust according to the actual compensation feature in order to compensate for the image quality of the module to be calibrated 22.

[0151] In summary, this embodiment utilizes the calibration module 22 to acquire a checkerboard 21 image at the target object distance, controls the compensation lens drive assembly to drive the compensation lens group 2 to move to achieve focusing operation, and determines the resolution curve of the calibration module 22. Based on the resolution curve, the tilt characteristics caused by the focusing operation are obtained, and the compensation characteristics of the photosensitive chip 7 are determined based on the tilt characteristics. Then, the tilt degree of the photosensitive chip 7 is adjusted according to the compensation characteristics. The target object distance, the focusing position of the compensation lens group 2, and the compensation characteristics of the photosensitive chip 7 are bound to obtain a correlation relationship, which can be called by the calibration module 22 during actual shooting to improve the problem of resolution reduction during the focusing process of the internal focusing lens. The tilt degree of the photosensitive chip 7 is adjusted to compensate for the image plane tilt caused by the movement of the compensation lens group 2 during the internal focusing process, thereby improving image sharpness and image quality.

[0152] As can be seen, the solution provided in this embodiment can calibrate the assembled calibration module 22. It mainly relies on the checkerboard image 21 and the resolution curve of the calibration module 22 during the process of shooting the checkerboard image 21 to obtain the correlation between the target object distance, the focus position of the compensation lens group 2 and the compensation features of the photosensitive chip 7. This correlation is stored in the calibration module 22 so that the calibration module 22 can compensate for the image plane tilt caused by the movement of the compensation lens group 2 during the internal focusing process by adjusting the tilt of the photosensitive chip 7 during the shooting process, thereby improving the image sharpness and image quality.

[0153] Since the electronic device described in this embodiment is an electronic device used to implement the information processing method in the embodiments of this application, those skilled in the art can understand the specific implementation methods and various variations of the electronic device in this embodiment based on the information processing method described in the embodiments of this application. Therefore, how the electronic device implements the method in the embodiments of this application will not be described in detail here. Any electronic device used by those skilled in the art to implement the information processing method in the embodiments of this application falls within the scope of protection of this application.

[0154] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0155] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0156] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0157] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0158] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0159] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for image quality compensation in a camera module, characterized in that, The method includes: When the module to be calibrated is in a scenario where a checkerboard image is acquired at a target object distance, the compensating lens driving component of the module to be calibrated is controlled to drive the compensating lens group to move to achieve focusing operation, and the resolution curve of the module to be calibrated is determined. The tilt characteristics of the compensation lens group after focusing operation are determined based on the resolution curve. The compensation characteristics of the photosensitive chip of the module to be calibrated are determined based on the tilt characteristics, and the chip driving component of the module to be calibrated is controlled to drive the photosensitive chip to adjust according to the compensation characteristics. The resolution curve is updated based on the adjusted image sensor. When the updated resolution curve meets the resolution requirements, a correlation is established between the target object distance, the focus position of the compensation lens group, and the compensation feature. This correlation is used to perform image quality compensation during the shooting process when the module to be calibrated is at the target object distance.

2. The method as described in claim 1, characterized in that, After establishing the correlation between the target object distance, the focus position of the compensation lens group, and the compensation feature, the method further includes: Determine the correlation relationships corresponding to multiple different target object distances; The correlation relationships corresponding to multiple different target object distances are fitted to construct a continuous relationship between the focus position and compensation features of the module to be calibrated at different object distances. The continuous relationship is used to perform image quality compensation during the shooting process of the module to be calibrated at different object distances.

3. The method as described in claim 2, characterized in that, After establishing the continuous relationship between the focus position and compensation features of the module to be calibrated at continuously different object distances, the method further includes: When shooting with the module to be calibrated, the continuity relationship is queried according to the focus position of the compensation lens group in the module to be calibrated, and the actual compensation feature of the photosensitive chip in the current state is determined. The photosensitive chip is controlled to adjust according to the actual compensation characteristics in order to compensate for the image quality of the module to be calibrated.

4. The method as described in claim 1 or 2, characterized in that, The distance to the target object is greater than or equal to 3 centimeters.

5. The method as described in claim 1, characterized in that, The step of determining the compensation characteristics of the photosensitive chip of the module to be calibrated based on the tilt characteristics, and controlling the chip driving component of the module to be calibrated to drive the photosensitive chip to adjust according to the compensation characteristics, includes: The height variation characteristics of the photosensitive chip in at least three directions are determined based on the tilt characteristics; the compensation characteristics include the height variation characteristics in at least three directions. The chip driving component is controlled to change the height of the photosensitive chip in the corresponding direction according to the height change characteristics in at least three directions, so that the photosensitive chip is adjusted according to the compensation characteristics.

6. The method as described in claim 1, characterized in that, The control assembly for the compensation lens drive of the module to be calibrated drives the compensation lens group to move to achieve focusing operation, including: Move the compensation lens group at least twice according to the initial step size of the module to be calibrated, and determine the first change feature group of the resolving power of the module to be calibrated before and after the two most recent moves of the compensation lens group; When the first set of change features indicates that the resolving power is increasing, the movement step size is determined according to the first set of change features, the compensation lens group is moved according to the movement step size, and the second set of change features of the resolving power of the module to be calibrated before and after the two most recent movements of the compensation lens group is determined. Determine whether the second set of change features indicates an increase in analytical power; When the second change feature group indicates that the resolving power is increasing, the movement step size is updated according to the second change feature group, and the compensation lens group is moved according to the updated movement step size. The second change feature group is updated based on the resolution before and after the two most recent moves of the compensation lens group, and the process returns to the step of determining whether the second change feature group indicates that the resolution is increasing, until the updated second change feature group indicates that the resolution is unchanged or decreases for the first time. The focus position of the compensation lens group when the resolution is unchanged or decreases for the first time is recorded.

7. The method as described in claim 6, characterized in that, Both the first group of change features and the second group of change features include analytical force momentum features and analytical force acceleration features; The resolving force momentum characteristic refers to the ratio between the difference in resolving force before and after the nth movement of the compensation lens group and the resolving force after the (n-1)th movement; n is a positive integer greater than 2. The resolving force acceleration characteristic refers to the difference between the first ratio and the second ratio. The first ratio is the ratio between the difference in resolving force before and after the nth movement of the compensation lens group and the resolving force after the nth movement. The second ratio is the ratio between the difference in resolving force before and after the (n-2)th movement of the compensation lens group and the resolving force after the (n-1)th movement.

8. The method as described in claim 7, characterized in that, Updating the movement step size based on the second set of change features includes: Based on the initial step size and the resolving force momentum and resolving force acceleration characteristics corresponding to the most recent movement, the movement step size corresponding to the current movement of the compensation lens group is updated.

9. The method as described in claim 1, characterized in that, Determining the tilt characteristics of the compensation lens group after focusing operation based on the resolving power curve includes: The central field curve of the central field of view and the peripheral field curves of multiple peripheral fields of view of the module to be calibrated are determined based on the resolution curve. The tilt of the compensation lens group in each peripheral field of view after focusing is determined based on the difference between each peripheral field curvature and the central field curvature. The tilt feature includes the tilt of the compensation lens group in each peripheral field of view.

10. A camera module, characterized in that, The camera module includes: Lens assembly, including compensating lens group and fixed lens group; A compensation lens drive assembly is used to drive the compensation lens group to move to achieve focusing operation; Photosensitive chip; A chip driving component is used to drive the photosensitive chip to adjust according to the compensation features, so that the adjusted photosensitive chip compensates for the tilt features of the compensation lens group after focusing operation. The compensation features are obtained based on the correlation relationship when the object distance of the camera module is the target object distance. The correlation relationship is obtained based on the image quality compensation method of the camera module as described in any one of claims 1-9.

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