A method and system for active focusing of a drone camera module

Abstract

The application discloses a kind of unmanned aerial vehicle camera module active focusing method and system, method includes the following steps: using camera module to obtain output image;Using the definition of output image to obtain the relative position of lens assembly and CMOS chip;Adjust the first position of lens assembly in camera module, so that when lens assembly is driven to second position, the image of best definition is obtained.Through design and manufacture multiple size specifications thickness high-precision steel sheet, the first position of lens assembly is adjusted, compensate the tolerance that appears in lens position due to transportation or tooling, and using active focusing equipment after camera module stepping motor is powered off, it is moved to specified position, after stepping motor is powered on, the problem that camera module cannot be moved to specified distance for focusing is solved, so that the focusing position of camera module for shipment exists difference.

Description

Technical Field

[0001] This invention relates to the field of camera module technology, and in particular to an active focusing method and system for a drone camera module. Background Technology

[0002] As the demand for drones expands, the requirements for cameras in drones are also increasing. In the manufacturing process, when the lens in the camera module is assembled, the optical axis is already offset when the lenses are stacked, and it is not absolutely on the center axis of the lens. Furthermore, when assembling the lens and image sensor (CMOS), due to the tolerances of the lenses, lens barrel, and image sensor, it is impossible to use the traditional two-dimensional focusing process to create a perfect camera module. Imperfect cameras produce blurry images in the corners of the captured images, and cannot effectively utilize high pixels.

[0003] Active alignment (AA) has emerged as a solution, using a stepper motor to drive the camera module for AA focusing, compensating for tolerances. Chinese patent CN 101950063 B discloses an autofocus system and method that focuses based on the optimized focus position corresponding to the minimum variance value calculated by the computing unit to improve image clarity.

[0004] However, the aforementioned patent documents did not take into account that: on the one hand, vibration during transportation causes changes in the lens position; on the other hand, lens manufacturers and module manufacturers have different assembly positions for the lenses; in order to obtain a clear image, customers encode the driving distance of the stepper motor of the camera module in a consistent manner, but due to the above two reasons, when the stepper motor fails to be powered on, the camera module is driven to the specified distance for focusing. Summary of the Invention

[0005] Existing drone camera modules have lens position tolerances due to transportation or tooling issues. When the stepper motor fails to power on, the camera module cannot be moved to the specified distance for focusing, resulting in differences in the focus position of the camera modules shipped from the factory, which cannot meet customer requirements.

[0006] To address the aforementioned issues, a method and system for active focusing of UAV camera modules is proposed. By designing and manufacturing multiple high-precision steel sheets of various sizes and thicknesses, the first position of the lens assembly is adjusted to compensate for tolerances in the lens position caused by transportation or tooling. Furthermore, an active focusing device is used to move the camera module to a designated position after the stepper motor is powered off. This solves the problem that the camera module cannot be moved to the designated distance for focusing when the stepper motor is not powered on, resulting in differences in the focus position of camera modules shipped from the factory.

[0007] Firstly, a method for active focusing of a drone camera module includes the following steps:

[0008] Step 100: Use the camera module to acquire the output image;

[0009] Step 200: Obtain the relative position of the lens assembly and the CMOS chip using the sharpness of the output image;

[0010] Step 300: Adjust the first position of the lens assembly in the camera module so that when the lens assembly is driven to the second position, an image with the best clarity is obtained;

[0011] The relative position refers to the relative position between the central axis of the lens assembly and the central axis of the CMOS chip.

[0012] In conjunction with the active focusing method for drone camera modules described in this invention, in a first possible implementation, step 100 includes:

[0013] Step 110: Take and output images sequentially from near to far using different focal lengths.

[0014] In conjunction with the first possible embodiment of the present invention, in the second possible embodiment, step 200 includes:

[0015] Step 210: Detect the edges and colors of the output image to obtain its sharpness;

[0016] Step 220: Determine the relative position using the resolution.

[0017] In conjunction with the second possible embodiment of the present invention, in the third possible embodiment, step 210 includes:

[0018] Step 211: Perform edge detection on each output image using the Candy algorithm, and then filter the output images.

[0019] Step 212: Obtain the image contrast and image entropy of each output image;

[0020] Step 213: Obtain the sharpness of the output image using the image contrast and image entropy.

[0021] In conjunction with the third possible implementation of the present invention, in the fourth possible implementation, step 211 includes:

[0022] Step 2111: Perform Gaussian filtering on the output image;

[0023] Step 2112: Calculate the angle image and gradient image of the output image;

[0024] The gradient image is subjected to non-maximum suppression processing.

[0025] In conjunction with the second possible embodiment of the present invention, in the fifth possible embodiment, step 300 includes:

[0026] Step 310: Fabricate high-precision steel sheets of various sizes and thicknesses;

[0027] Step 320: Adjust the first distance between the lens assembly and the filter assembly using the high-precision steel sheet to adjust the first position.

[0028] In conjunction with the fifth possible implementation of the present invention, in the sixth possible implementation, step 320 includes:

[0029] Step 321: Obtain the first distance using the relative position;

[0030] Step 322: Adjust the first distance by setting multiple high-precision steel sheets of different sizes and thicknesses between the lens assembly and the filter assembly.

[0031] In conjunction with the sixth possible implementation of the present invention, in the seventh possible implementation, step 300 further includes:

[0032] Step 330: Drive the lens assembly to the second position using an active focusing device.

[0033] Secondly, an active focusing system for a drone camera module, employing the focusing method described in the first aspect, includes:

[0034] Unit 1;

[0035] Unit Two;

[0036] Unit 3;

[0037] The first unit is used to acquire an output image using a camera module and transmit the output image to the second unit;

[0038] The second unit is used to obtain the relative position of the lens assembly and the CMOS chip using the sharpness of the output image, and transmit the relative position information to the third unit;

[0039] The third unit is used to obtain the first position of the lens assembly using the relative position, and adjust the first position so that when the lens assembly is driven to the second position, an image with the best clarity is obtained;

[0040] The relative position refers to the relative position between the central axis of the lens assembly and the central axis of the CMOS chip.

[0041] In conjunction with the active focusing system described in the second aspect of the present invention, in a first possible embodiment, the second unit includes:

[0042] First module;

[0043] Module Two;

[0044] The first module is used to detect the edges and colors of the output image, obtain the sharpness, and transmit the sharpness to the second module;

[0045] The second module is used to determine the relative position using the resolution;

[0046] The third unit includes:

[0047] Active focusing equipment;

[0048] The active focusing device is used to drive the lens assembly to the second position.

[0049] Compared with the prior art, the present invention has the following beneficial effects:

[0050] The present invention provides an active focusing method and system for a drone camera module. By designing and manufacturing multiple high-precision steel sheets of various sizes and thicknesses, the first position of the lens assembly is adjusted to compensate for tolerances in the lens position caused by transportation or tooling. Furthermore, by utilizing an active focusing device to move the camera module to a designated position after the stepper motor of the camera module is powered off, the problem of not being able to move the camera module to a designated distance for focusing when the stepper motor is not powered on, resulting in differences in the focus position of camera modules shipped from the factory, is solved. Attached Figure Description

[0051] 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 only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0052] Figure 1 This is a first schematic diagram of the active focusing method for a drone camera module according to the present invention;

[0053] Figure 2 This is a second schematic diagram illustrating the steps of an active focusing method for a drone camera module according to the present invention;

[0054] Figure 3 This is a third schematic diagram of the active focusing method for a drone camera module according to the present invention;

[0055] Figure 4This is a schematic diagram of the fourth step of the active focusing method for a drone camera module according to the present invention;

[0056] Figure 5 This is a schematic diagram of the fifth step of the active focusing method for a drone camera module according to the present invention;

[0057] Figure 6 This is a schematic diagram of the sixth step in the active focusing method of a drone camera module according to the present invention;

[0058] Figure 7 This is a first schematic diagram of a drone camera module according to the present invention;

[0059] Figure 8 This is a second schematic diagram of a drone camera module according to the present invention; Detailed Implementation

[0060] The technical solutions of this invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are all within the scope of protection of this invention.

[0061] Existing drone camera modules have lens position tolerances due to transportation or tooling issues. When the stepper motor fails to power on, the camera module cannot be moved to the specified distance for focusing, resulting in differences in the focus position of the camera modules shipped from the factory, which cannot meet customer requirements.

[0062] To address the aforementioned issues, a method and system for active focusing of drone camera modules are proposed.

[0063] Example 1

[0064] An active focusing method for drone camera modules, such as Figure 1 , Figure 1 This is a first schematic diagram of the active focusing method for a drone camera module according to the present invention; including:

[0065] Step 100: Acquire an output image using the camera module; Step 200: Obtain the relative position of the lens assembly 10 and the CMOS chip 30 using the clarity of the output image; Step 300: Adjust the first position of the lens assembly 10 in the camera module so that when the lens assembly 10 is driven to the second position, an image with the best clarity is acquired; wherein, the relative position is the relative position between the central axis of the lens assembly 10 and the central axis of the CMOS chip 30.

[0066] In this embodiment, the camera module includes a stepper motor. Ideally, the central axis of the lens assembly 10 overlaps with the central axis of the CMOS chip 30 (image sensor). However, during production assembly or transportation, the central axes of the two components may shift, resulting in a relative position. This shift can easily lead to image blurring and degraded module performance.

[0067] In this embodiment, the first position is adjustable, and the second position is a predetermined position required by the customer. In order to obtain the best clarity when driving the lens assembly 10 to the second position, the first position needs to be adjusted.

[0068] In this embodiment, the first position is the position of the lens assembly 10 relative to the CMOS chip 30 (image sensor) in the camera module.

[0069] Furthermore, when acquiring the output image, step 100 includes: step 110, sequentially capturing output images from different focal lengths, from near to far. During image capture, output images are captured sequentially from the closest focal length to the farthest focal length. By designing and manufacturing high-precision steel sheets 40 of multiple sizes and thicknesses, the first position of the lens assembly 10 is adjusted to compensate for tolerances in the lens position caused by transportation or tooling. Furthermore, by utilizing an active focusing device to move the camera module to a designated position after the stepper motor is powered off, the problem of not being able to move the camera module to a designated distance for focusing when the stepper motor is not powered on, resulting in differences in the focus position of the camera modules shipped from the factory, is solved.

[0070] Example 2

[0071] Image sharpness is determined by detecting edge and color changes. If the image is blurry, it means the camera is not in focus and the focus position needs to be adjusted. Specifically, for example... Figure 2 , Figure 2 This is a second schematic diagram of the active focusing method for a drone camera module according to the present invention; it can be implemented as follows:

[0072] Step 200 includes:

[0073] Step 210: Detect the edges and colors of the output image to obtain sharpness; Step 220: Use the sharpness to determine the relative position.

[0074] Furthermore, when acquiring image sharpness, such as Figure 3 , Figure 3 This is a third schematic diagram of the active focusing method for a drone camera module according to the present invention; step 210 includes:

[0075] Step 211: Perform edge detection on each output image using the Candy algorithm and filter the output image; Step 212: Obtain the image contrast and image entropy of each output image; Step 213: Obtain the sharpness of the output image using the image contrast and image entropy.

[0076] Furthermore, such as Figure 4 , Figure 4 This is a schematic diagram of the fourth step of the active focusing method for a drone camera module according to the present invention; during edge detection, step 211 includes:

[0077] Step 2111: Perform Gaussian filtering on the output image; Step 2112: Calculate the angle image and gradient image of the output image; Step 2113: Perform non-maximum suppression processing on the gradient image.

[0078] By weighting the gray values ​​of the pixel to be filtered and its neighbors according to the parameters generated by the Gaussian formula, high-frequency noise superimposed on the ideal image can be effectively filtered out. Gradient calculation is performed using a gradient detection operator, with pixels closer to the center point receiving greater weight. An angular image provides guidance for the direction of non-maximum suppression; setting the gray values ​​corresponding to non-maximums to 0 can eliminate a large portion of non-edge pixels.

[0079] When adjusting the first position, such as Figure 5 , Figure 5 This is a schematic diagram of the fifth step in the active focusing method for a drone camera module according to the present invention; it can be implemented as follows: Step 300 includes:

[0080] Step 310: Fabricate high-precision steel sheets 40 of multiple sizes and thicknesses; Step 320: Use the high-precision steel sheets 40 to adjust the first distance between the lens assembly 10 and the filter assembly 20 to adjust the first position.

[0081] The high-precision steel sheet 40 is made of thin steel sheet and consists of several high-precision steel sheets 40 of different thicknesses. The thickness of each high-precision steel sheet 40 can be marked on its own thickness in millimeters. The specifications of the high-precision steel sheet 40 can range from 0.01mm to 1mm.

[0082] In this embodiment, the first distance is the distance between one end of the lens assembly 10 and one end of the filter assembly 20 (IR assembly). By adjusting the first distance, the first position is adjusted, thereby changing the relative position of the central axis of the lens assembly 10 and the central axis of the CMOS chip 30 (image sensor), making their central axes infinitely close, so that the clarity of the output image is optimal when the lens assembly 10 is driven to the second position.

[0083] Furthermore, when obtaining the first distance, such as Figure 6 , Figure 6 This is a schematic diagram of the sixth step in the active focusing method for a drone camera module according to the present invention; it can be implemented as follows:

[0084] Step 320 includes:

[0085] Step 321: Obtain the first distance using relative position; Step 322: Adjust the first distance by setting multiple high-precision steel sheets 40 of different sizes and thicknesses between the lens assembly 10 and the filter assembly 20.

[0086] The distance between one end of the lens assembly 10 and one end of the filter assembly 20 (IR assembly) is obtained by optical calculation. Based on the first distance, a high-precision steel sheet 40 is set between the lens assembly 10 and the filter assembly 20 so that the central axis of the lens assembly 10 and the central axis of the CMOS chip 30 (image sensor) are infinitely close to overlap, thereby compensating for the tolerance.

[0087] After the first position is determined, the lens assembly 10 is driven to the second position using an active focusing device. Step 300 also includes:

[0088] Step 330: Drive the lens assembly 10 to the second position using an active focusing device.

[0089] In this embodiment, the filter assembly 20 may include two types of visible light filters: an IR filter and blue glass. In some embodiments, it may also include white glass (a fully transparent filter).

[0090] Example 3

[0091] An active focusing system for a drone camera module employs a first aspect of the focusing method, comprising a first unit, a second unit, and a third unit. The first unit is used to acquire an output image using the camera module and transmit the output image to the second unit. The second unit is used to acquire the relative position of a lens assembly 10 and a CMOS chip 30 using the sharpness of the output image and transmit the relative position information to the third unit. The third unit is used to acquire a first position of the lens assembly 10 using the relative position and adjust the first position so that when the lens assembly 10 is driven to a second position, an image with optimal sharpness is acquired. The relative position is the relative position between the central axis of the lens assembly 10 and the central axis of the CMOS chip 30.

[0092] Furthermore, the second unit includes a first module and a second module; the first module is used to detect the edges and colors of the output image, obtain the sharpness, and transmit the sharpness to the second module; the second module is used to determine the relative position using the sharpness; the third unit includes an active focusing device; the active focusing device is used to drive the lens assembly 10 to a second position.

[0093] The present invention discloses an active focusing method and system for a drone camera module. By designing and manufacturing multiple high-precision steel sheets 40 of various sizes and thicknesses, the first position of the lens assembly 10 is adjusted to compensate for tolerances in the lens position caused by transportation or tooling. The active focusing device moves the camera module to a designated position after the stepper motor is powered off, thus solving the problem that the camera module cannot be moved to a designated distance for focusing when the stepper motor is not powered on, resulting in differences in the focus position of the camera modules shipped from the factory.

[0094] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for active focusing of a drone camera module, characterized in that, include: Step 100: Use the camera module to acquire the output image; Step 200: Obtain the relative position of the lens assembly and the CMOS chip using the sharpness of the output image; Step 300: Adjust the first position of the lens assembly in the camera module so that when the lens assembly is driven to the second position, an image with the best clarity is obtained; Wherein, the relative position is the relative position between the central axis of the lens assembly and the central axis of the CMOS chip; Step 300 includes: Step 310: Fabricate high-precision steel sheets of various sizes and thicknesses; Step 320: Adjust the first distance between the lens assembly and the filter assembly using the high-precision steel sheet to adjust the first position, specifically including: Step 321: Obtain the first distance using the relative position; Step 322: Adjust the first distance by setting multiple high-precision steel sheets of different sizes and thicknesses between the lens assembly and the filter assembly; The first distance is the distance between one end of the lens assembly and one end of the filter assembly; The distance between one end of the lens assembly and one end of the filter assembly is obtained through optical calculations.

2. The active focusing method for a drone camera module according to claim 1, characterized in that, Step 100 includes: Step 110: Take and output images sequentially from near to far using different focal lengths.

3. The active focusing method for a drone camera module according to claim 2, characterized in that, Step 200 includes: Step 210: Detect the edges and colors of the output image to obtain its sharpness; Step 220: Determine the relative position using the resolution.

4. The active focusing method for a drone camera module according to claim 3, characterized in that, Step 210 includes: Step 211: Perform edge detection on each output image using the Candy algorithm, and then filter the output images. Step 212: Obtain the image contrast and image entropy of each output image; Step 213: Obtain the sharpness of the output image using the image contrast and image entropy.

5. The active focusing method for a drone camera module according to claim 4, characterized in that, Step 211 includes: Step 2111: Perform Gaussian filtering on the output image; Step 2112: Calculate the angle image and gradient image of the output image; The gradient image is subjected to non-maximum suppression processing.

6. The active focusing method for a drone camera module according to claim 5, characterized in that, Step 300 further includes: Step 330: Drive the lens assembly to the second position using an active focusing device.

7. An active focusing system for a drone camera module, employing the focusing method described in any one of claims 1-6, characterized in that, include: Unit 1; Unit Two; Unit 3; The first unit is used to acquire an output image using a camera module and transmit the output image to the second unit; The second unit is used to obtain the relative position of the lens assembly and the CMOS chip using the sharpness of the output image, and transmit the relative position information to the third unit; The third unit is used to obtain the first position of the lens assembly using the relative position, and adjust the first position so that when the lens assembly is driven to the second position, an image with the best clarity is obtained; The relative position refers to the relative position between the central axis of the lens assembly and the central axis of the CMOS chip.

8. The active focusing system for a drone camera module according to claim 7, characterized in that, The second unit includes: First module; Module Two; The first module is used to detect the edges and colors of the output image, obtain the sharpness, and transmit the sharpness to the second module; The second module is used to determine the relative position using the resolution; The third unit includes: Active focusing equipment; The active focusing device is used to drive the lens assembly to the second position.

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