Method and device for determining glue shrinkage compensation amount of camera module

Abstract

The invention provides a method and device for determining the glue shrinkage compensation amount of a camera module, and the method comprises the steps: determining an MTF peak value from an MTF transformation curve after obtaining the MTF transformation curve before glue shrinkage operation, collecting a glue shrinkage MTF value of the camera module after glue shrinkage operation, and determining the glue shrinkage compensation amount based on the MTF peak value and the step value of the glue shrinkage MTF value in the MTF transformation curve. According to the method and the device, the MTF peak value is the MTF value when the imaging definition of the camera module is the highest before the glue shrinkage operation, the MTF peak value and the glue shrinkage MTF value are respectively the step pitch values in the MTF transformation curve, the step pitch difference condition of the same camera module, the MTF value after glue shrinkage and the MTF value when the imaging definition is the highest can be represented, and further the glue shrinkage compensation amount is determined based on the step pitch difference condition. The determined glue shrinkage compensation amount can correspond to the actual glue shrinkage condition of the camera module, so that the accuracy of the determined glue shrinkage compensation amount is relatively high.

Description

Technical Field

[0001] The present invention relates to the field of vehicle-mounted cameras, and more particularly to a method and device for determining a shrinkage compensation amount of a camera module. Background Art

[0002] MTF (Modulation Transfer Function) is one of the most important parameters of a camera module and is often used to evaluate the performance of a lens optical system. There are many factors that determine the MTF of a camera module, one of which is glue shrinkage. Glue shrinkage is a fixed and inevitable influencing factor. The fundamental reason is that the glue used to connect the lens and the imaging sensor in the camera module shrinks due to heat, which eventually causes the best imaging surface of the lens to deviate from the sensor, resulting in a decrease in MTF and a blurred image.

[0003] In order to avoid the impact of shrinkage on imaging, it is necessary to compensate the height of the lens module in advance so that the camera module is in the best imaging state after the glue shrinks. This compensation method is called shrinkage compensation. In order to determine the amount of shrinkage compensation, you can prepare a number of camera module materials (the quantity varies from 50Pcs to 100Pcs), and set the shrinkage compensation value to 0-15μm in turn. After AA (Active Alignment) and shrinkage are completed, compare the readback MTF of all camera modules involved in the verification with the MTF peak value in the corresponding AA process. The closer the MTF comparison result, the more appropriate the shrinkage compensation amount. This type of verification is mainly an exhaustive method. When the number of exhaustive methods is small, the most accurate shrinkage compensation amount cannot be obtained.

[0004] In addition, a finished camera module with preset shrinkage can be used. The MTF of the camera module at different object distances is obtained, and the corresponding relationship between MTF and object distance is obtained. The optimal image distance of the camera module is obtained based on the relationship between the object distance and the corresponding MTF at multiple different object distances. The onboard shrinkage compensation amount is obtained based on the optimal image distance, the theoretical optimal object distance and the set compensation amount. In this way, the object distance and other environments need to be adjusted repeatedly during the verification process, and there are no clear specifications for the adjustment of the object distance. The verification results of different personnel may vary greatly, resulting in low accuracy in determining the shrinkage compensation amount. Summary of the invention

[0005] In view of this, the present invention provides a method and device for determining the shrinkage compensation amount of a camera module to solve the problem of low accuracy in determining the shrinkage compensation amount.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A method for determining a shrinkage compensation amount of a camera module, comprising:

[0008] Before performing a shrinking operation on the camera module, obtaining a modulus transfer function (MTF) transformation curve obtained by performing an active alignment operation on the camera module;

[0009] Determine an MTF peak value from the MTF transformation curve, wherein the MTF peak value is an MTF value when the imaging clarity of the camera module is the highest before the shrinking operation;

[0010] Determine the shrinking MTF value of the camera module after the shrinking operation;

[0011] The shrinkage compensation amount is determined based on the step values ​​of the MTF peak value and the shrinkage MTF value in the MTF transformation curve.

[0012] Optionally, determining the shrinkage compensation amount based on the step values ​​of the MTF peak value and the shrinkage MTF value in the MTF transformation curve respectively includes:

[0013] Determine the first step value corresponding to the MTF peak from the MTF transformation curve, wherein the abscissa is the Z-axis moving distance according to the fixed step size change, and the ordinate is the MTF value;

[0014] Determine a second step value corresponding to the collimated MTF value from a descending portion of the MTF transformation curve;

[0015] Calculating a difference between the first step value and the second step value;

[0016] The product of the difference and the fixed step length used in the horizontal coordinate of the MTF conversion curve is used as the shrinkage compensation amount.

[0017] Optionally, if the first step value or the second step value is not a multiple of the fixed step value, the method for determining the shrinkage compensation amount of the camera module further includes:

[0018] Reduce the value of the fixed step length, return to execute the steps of obtaining the MTF transformation curve obtained by performing an active alignment operation on the camera module before performing the shrinking operation on the camera module, and determine the shrinkage compensation amount when the first step value or the second step value obtained is a multiple of the fixed step length.

[0019] Optionally, obtaining an MTF transformation curve obtained by performing an active alignment operation on the camera module includes:

[0020] Starting from the target position, a lens of the camera module is fixed by a fixing device to gradually approach the imaging sensor of the camera module according to a fixed step distance, and the MTF value is continuously detected during the approaching process to obtain an MTF conversion curve;

[0021] The target position is a position where the relative distance between the lens and the imaging sensor is greater than the lens image distance of the camera module.

[0022] Optionally, determining a shrinking MTF value of the camera module after the shrinking operation includes:

[0023] Performing a shrinking operation on the camera module;

[0024] Perform an MTF readback operation on the camera module after the shrinking operation to obtain the shrinking MTF value.

[0025] Optionally, performing a shrinking operation on the camera module includes:

[0026] Determine the curing temperature and curing time of the glue used in the shrinking operation;

[0027] The oven is controlled according to the curing temperature and the curing time to perform a curing and shrinking operation on the camera module.

[0028] Optionally, before acquiring the MTF transformation curve obtained by performing an active alignment operation on the camera module, the method further includes:

[0029] Adjust the object distance corresponding to the camera module.

[0030] Optionally, adjusting the object distance corresponding to the camera module includes:

[0031] Get the preset focus distance and object distance;

[0032] Based on the preset focusing distance and the object distance, a first distance between the camera module and the lower metal surface of the relay lens, and a second distance between the upper metal surface of the relay lens and the shooting target are determined, so as to adjust the relative positions of the camera module and the relay lens with respect to the shooting target based on the first distance and the second distance. The shooting target, the relay lens, and the camera module are arranged in sequence.

[0033] A device for determining a shrinkage compensation amount of a camera module, comprising:

[0034] A curve acquisition module, used for acquiring a modulus transfer function MTF transformation curve obtained by performing an active alignment operation on the camera module before performing a shrinking operation on the camera module;

[0035] A peak value determination module, used to determine an MTF peak value from the MTF transformation curve, wherein the MTF peak value is an MTF value when the imaging clarity of the camera module is the highest before the shrinking operation;

[0036] A shrinkage value determination module, used to determine the shrinkage MTF value of the camera module after the shrinkage operation;

[0037] The compensation amount determination module is used to determine the shrinkage compensation amount based on the step values ​​of the MTF peak value and the shrinkage MTF value in the MTF transformation curve.

[0038] Optionally, the compensation amount determination module includes:

[0039] A first step distance value determination submodule, used to determine the first step distance value corresponding to the MTF peak from the MTF transformation curve, in which the horizontal axis is the Z-axis movement distance that changes according to a fixed step distance, and the vertical axis is the MTF value;

[0040] A second step value determination submodule, used for determining a second step value corresponding to the shrinkage MTF value from a descending portion of the MTF transformation curve;

[0041] A difference calculation submodule, used for calculating the difference between the first step value and the second step value;

[0042] The compensation amount determination submodule is used to take the product of the difference and the fixed step length used by the horizontal coordinate in the MTF transformation curve as the shrinkage compensation amount.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] The present invention provides a method and device for determining the shrinkage compensation amount of a camera module. In the present invention, after obtaining the MTF transformation curve before the shrinkage operation, the MTF peak is determined from the MTF transformation curve, the shrinkage MTF value of the camera module after the shrinkage operation is collected, and the shrinkage compensation amount is determined based on the MTF peak and the step value of the shrinkage MTF value in the MTF transformation curve, thereby achieving the determination of the shrinkage compensation amount. In addition, in the present invention, the MTF peak is the MTF value when the imaging clarity of the camera module is the highest before the shrinkage operation, and the MTF peak and the step value of the shrinkage MTF value in the MTF transformation curve can characterize the step difference between the MTF after shrinkage and the MTF value when the imaging clarity is the highest for the same camera module, and then the shrinkage compensation amount is determined based on the step difference, so that the determined shrinkage compensation amount can correspond to the shrinkage situation of the actual camera module, so that the accuracy of the determined shrinkage compensation amount is high, and the imaging clarity after shrinkage compensation is guaranteed. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0046] Figure 1 A flowchart of a method for determining a shrinkage compensation amount of a camera module provided by an embodiment of the present invention;

[0047] Figure 2 A schematic diagram of a device layout scenario provided by an embodiment of the present invention;

[0048] Figure 3 A schematic diagram of an MTF conversion curve provided by an embodiment of the present invention;

[0049] Figure 4 A flow chart of a method for determining a shrinkage compensation amount provided by an embodiment of the present invention;

[0050] Figure 5 A schematic diagram of the structure of a device for determining the shrinkage compensation amount of a camera module provided by an embodiment of the present invention;

[0051] Figure 6 A schematic diagram of the structure of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0052] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0053] With the rapid development of the automotive industry, the development and application of autonomous driving related technologies are in full swing, and the role of vehicle-mounted cameras is crucial. In the AA (Active Alignment) process in the production and assembly of camera modules, MTF (Modulation Transfer Function) is one of the most important parameters of camera modules and is often used to evaluate the performance of lens optical systems. There are many factors that determine the MTF of a camera module, one of which is shrinkage.

[0054] Glue shrinkage is a fixed and inevitable influencing factor. The fundamental reason is that the glue used to connect the lens and the imaging sensor in the camera module shrinks due to heat, which eventually causes the best imaging surface of the lens to deviate from the sensor, resulting in a decrease in MTF and blurred images. The direct impact on manufacturers is a decrease in pass rate and yield, and an increase in manufacturing costs.

[0055] In order to avoid the impact of glue shrinkage on imaging, it is necessary to compensate the height of the lens module in advance so that after the glue shrinks, the camera module is in the best imaging state. This compensation method is called glue shrinkage compensation. Then, how to determine the glue shrinkage compensation amount (one of the important parameters in the optical system of enterprise cameras) is a technical problem that technicians in this field need to solve urgently.

[0056] In order to determine the shrinkage compensation amount, a finished camera module with preset shrinkage can be used. The MTF of the camera module at different object distances is obtained, and the corresponding relationship between MTF and object distance is obtained. The optimal image distance of the camera module is obtained according to the relationship between the object distance and the corresponding MTF at multiple different object distances. The shrinkage compensation amount is obtained according to the optimal image distance, the theoretical optimal object distance and the set compensation amount.

[0057] This method requires repeated adjustments of the object distance and other environments during the verification process, and there are no clear specifications for the adjustment of the object distance. The verification results of different personnel may vary greatly. In addition, this method can only be used for camera modules with a short focus distance and is not suitable for medium and long-distance pan-focus camera modules. Therefore, this method has too many unstable factors and is applicable to fewer types of cameras.

[0058] To this end, you can also prepare a number of camera module materials (the quantity varies from 50Pcs to 100Pcs), and set the shrinkage compensation values ​​to 0-15μm respectively. After AA and shrinkage are completed, compare the readback MTF of all camera modules involved in the verification with the MTF peak value in the corresponding AA process. The closer the MTF comparison results are, the more appropriate the shrinkage compensation amount is.

[0059] This verification is mainly an exhaustive method, which consumes a lot of materials and time to verify the shrinkage amount. The verification is cumbersome, and when the number of exhaustive verification is small, the most accurate shrinkage compensation amount cannot be obtained. That is, this method is inefficient, inaccurate and costly.

[0060] In order to improve efficiency and accuracy and reduce costs, in this embodiment, after obtaining the MTF transformation curve before the shrinking operation, the MTF peak is determined from the MTF transformation curve, the shrinking MTF value of the camera module after the shrinking operation is collected, and the shrinking compensation amount is determined based on the MTF peak and the step value of the shrinking MTF value in the MTF transformation curve, thereby achieving the determination of the shrinking compensation amount. In addition, in the present invention, the MTF peak is the MTF value when the imaging clarity of the camera module is the highest before the shrinking operation, and the MTF peak and the step value of the shrinking MTF value in the MTF transformation curve can characterize the step difference between the MTF after shrinking and the MTF value when the imaging clarity is the highest for the same camera module, and then the shrinking compensation amount is determined based on the step difference, so that the determined shrinking compensation amount can correspond to the shrinking situation of the actual camera module, so that the accuracy of the determined shrinking compensation amount is high, and the imaging clarity after shrinking compensation is guaranteed.

[0061] In addition, since only one operation is required to determine the shrinkage compensation amount, multiple repeated operations are not required, which can improve efficiency and reduce costs.

[0062] Based on the above content, an embodiment of the present invention provides a method for determining the shrinkage compensation amount of a camera module, and the execution subject may be a controller, a server, and other devices. The camera module in the embodiment of the present invention may be a vehicle-mounted camera, including but not limited to a vehicle surround view camera, a rear view camera, a side view camera, a built-in infrared camera, a driving recorder, a panoramic camera, and other types of vehicle-mounted camera modules on the market.

[0063] Reference Figure 1 A method for determining a shrinkage compensation amount of a camera module may include:

[0064] S11. Before performing a shrinking operation on the camera module, an MTF transformation curve obtained by performing an active alignment operation on the camera module is obtained.

[0065] In practical applications, before performing the active alignment operation in step S11 of this embodiment, corresponding preparations for the active alignment operation need to be performed. The materials required to be prepared in advance are: 1 pc of camera module assembly material, the state is: the sensor and the support base have been assembled, the lens is not assembled, that is, the AA state, the matching sensor fixing fixture and the lighting module for subsequent use.

[0066] During the preparation, the object distance corresponding to the camera module needs to be adjusted. When the focusing distance is far, a relay lens (teleconverter) is required. The relay lens is usually set between the chart and the camera module, that is, the chart image is transferred once through the relay lens and projected to the camera module. Its optical principle is to generate an upright and enlarged virtual image of a close object (actual shooting target) at a farther distance, so as to meet the ultra-long-distance focusing requirements.

[0067] Among them, the chart is a graphic of the shooting target photographed by the camera module. After the camera module shoots, the chart is calculated by an algorithm to reflect the MTF level. The distance from the position where the chart is carried to the entrance pupil of the camera lens is called the object distance. The object distance is usually set according to the use scenario of the camera. For example, for ADAS cameras, most intelligent recognition solutions require a distance of 100m.

[0068] In order to meet the requirement of focusing at a longer distance, the shooting target, the relay lens and the camera module are arranged in sequence. Figure 2 As shown, the position of the shooting target is the position of the chart.

[0069] Although the three are set in sequence, the relative distances between them need to be calculated. That is, when setting up the AA environment, in order to restore the scene in AA based on the actual use scenario of the product, it is necessary to set the distance from the chart to the relay lens, and the distance from the relay lens to the camera module.

[0070] When setting up, first obtain the preset focus distance and object distance. For example, the camera module of a certain ADAS (Advanced Driving Assistance System) system requires a focus distance of 100m, a FOV (Field of view) of 100°, and an object distance of 100m.

[0071] Then, based on the preset focus distance and the object distance, a first distance between the camera module and the lower metal surface of the relay lens and a second distance between the upper metal surface of the relay lens and the shooting target are determined.

[0072] Specifically, taking the relay lens model RL19130 as an example, a distance simulation comparison table of the relay lens can be obtained, and the comparison table includes the correspondence between the object distance, the focus distance, the first distance and the second distance. From the comparison table, the first distance and the second distance corresponding to the pre-acquired object distance and the focus distance are found, and the distance is the distance required in this embodiment. Then, the relative position of the camera module and the relay lens relative to the shooting target can be adjusted manually or using a mobile device based on the first distance and the second distance. For example, the mobile device is a mobile robot that can drive the chart and the relay lens to move, so that the distance between the camera module and the lower metal surface of the relay lens is the first distance, and the distance between the upper metal surface of the relay lens and the shooting target is the second distance.

[0073] For example, the first distance from the camera module to the metal surface under the relay lens is 20 mm, and the second distance from the metal surface on the relay lens to the chart is 458.9 mm. The simulated distance is exactly 100 m.

[0074] If the camera module requires a shorter focusing distance, you can also avoid using a relay lens and directly adjust the relative distance between the camera module and the target to meet the object distance requirement. For example, in a fatigue detection scenario, the focusing distance requirement of the camera used for fatigue monitoring is about 1m (the distance between a normal sitting driver and the camera module is approximately 0.8m-1.2m). Without a relay lens, the chart can be adjusted to a distance of 1m from the camera module to meet the object distance requirement. The present invention is configured with an object distance adjustment method when the focusing distance is relatively close or relatively far, so that the adjustment method is flexible and changeable and is not limited by the site.

[0075] After the AA environment is prepared, active alignment can be performed to obtain the MTF transformation curve.

[0076] During the alignment operation, a starting target position is first determined to control the lens of the camera module to gradually approach the imaging sensor of the camera module starting from the target position.

[0077] In practical applications, the target position is: the relative distance between the lens and the imaging sensor is greater than the lens image distance of the camera module to ensure that the imaging effect changes from blur to clear and then to blur, and the corresponding MTF value changes from low to high and then from high to low, so that there is enough MTF data.

[0078] Still taking the camera module of a certain ADAS system mentioned above as an example, the focal length of this lens is 6.29mm, and the six-axis Z-axis height needs to be set to be slightly larger than this image distance, such as 6.5mm, so that the relative distance between the lens and the imaging sensor is larger than the lens image distance of the camera module.

[0079] Starting from the target position, a fixing device is used to fix the lens of the camera module, such as using a six-axis clamp to hold the lens of the camera module, and then gradually approaching the imaging sensor of the camera module according to a fixed step length, wherein the fixed step length can be the same as the fixed step length used for the horizontal axis in the MTF transformation curve, such as 3μm. During the approach process, the MTF value is measured once for each step length, and all the MTF values ​​are plotted according to the step length to obtain the MTF transformation curve. Among them, the six-axis clamp is an AA six-axis system, and the six axes can adjust the tilt angle, horizontal displacement, and vertical displacement between the lens and the sensor through six degrees of freedom in space to ensure the imaging quality of the finished camera module to achieve the best imaging quality.

[0080] After AA is completed, the MTF data in the AA process log can be drawn into a parabola, such as Figure 3 The MTF transformation curve shown in the figure records all MTF change values ​​during the AA process.

[0081] The MTF transformation curve can be expressed as Figure 3 As shown, the horizontal axis, that is, the X direction, is the Z-axis moving distance that changes according to a fixed step size (such as 3μm). Each grid represents one Z-axis movement, and the distance that the Z-axis moves once is a fixed amount, that is, the fixed step size. The moving distance is the product of the number of grids and the fixed step size. For example, 2 in the horizontal axis represents 2*fixed step size. If the fixed step size is 3μm, then 2 represents a movement of 6μm. The vertical axis, that is, the Y direction, is the MTF value. According to the change of MTF, the optimal resolution of this camera module, that is, the MTF peak value, can be found.

[0082] Taking the camera module of a certain ADAS system mentioned above as an example, the six-axis Z-axis step distance is set to 3μm, that is, one grid in the X direction of the coordinate system represents 3μm, and the obtained MTF peak value is 0.71. Other concrete MTF change values ​​in the AA process are as follows: Figure 3 shown.

[0083] The Y-axis peak value and X-axis step distance in the coordinate system are important parameters and are the key to finding the shrinkage compensation amount.

[0084] S12. Determine an MTF peak value from the MTF transformation curve.

[0085] The MTF peak is the MTF value when the imaging clarity of the camera module is the highest before the shrinking operation. Figure 3 As shown, the MTF peak value (MTF @峰值 ) is 0.71.

[0086] S13, determining the shrinking MTF value of the camera module after the shrinking operation.

[0087] Specifically, since the camera module needs to be compensated for shrinkage, a shrinkage operation needs to be performed on the camera module. After the shrinkage operation, the MTF value after shrinkage needs to be collected to determine the shrinkage compensation amount of the MTF.

[0088] For the camera module after the shrinking operation, the MTF value of the current camera module after the shrinking is completed can be obtained by using the MTF readback operation.

[0089] The MTF readback operation uses the above-mentioned AA operation to obtain the shrinkage MTF value (MTF @胶缩 ).

[0090] During the shrinking operation, high temperature baking is required to achieve the effect of heat shrinkage of the glue. During high temperature baking, the baking time and baking temperature need to be determined. Since the glue solidifies during baking, the baking time can also be called the curing time, and the baking temperature can be called the curing temperature.

[0091] After the curing time and curing temperature are obtained, the oven can be set remotely or manually, such as the operation time of the high-temperature oven is the curing time, and the temperature is the curing temperature.

[0092] Then the oven is controlled to start running to perform a curing and shrinking operation on the camera module.

[0093] For example, the camera module that has been pre-cured after AA is sent to a high-temperature oven for baking. The purpose of this step is to completely cure and shrink the glue used to assemble the camera module. The time and temperature required for UV (UVglue, shadowless glue) glue curing are set according to different UV glues. The temperature is usually between 75℃-95℃, and the time is usually between 60min-80min.

[0094] S14, determining the shrinkage compensation amount based on the step values ​​of the MTF peak value and the shrinkage MTF value in the MTF transformation curve.

[0095] In this embodiment, the step values ​​of the MTF peak value and the shrinkage MTF value in the MTF transformation curve are different, indicating that the MTF changes due to the shrinkage operation. At this time, the shrinkage compensation amount can be calculated according to the difference between the two step values.

[0096] In this embodiment, after obtaining the MTF transformation curve before the shrinking operation, the MTF peak is determined from the MTF transformation curve, the shrinking MTF value of the camera module after the shrinking operation is collected, and the shrinking compensation amount is determined based on the MTF peak and the step value of the shrinking MTF value in the MTF transformation curve, thereby achieving the determination of the shrinking compensation amount. In addition, in the present invention, the MTF peak is the MTF value when the imaging clarity of the camera module is the highest before the shrinking operation, and the MTF peak and the step value of the shrinking MTF value in the MTF transformation curve can characterize the step difference between the MTF after shrinking and the MTF value when the imaging clarity is the highest for the same camera module, and then the shrinking compensation amount is determined based on the step difference, so that the determined shrinking compensation amount can correspond to the shrinking situation of the actual camera module, so that the accuracy of the determined shrinking compensation amount is high, and the imaging clarity after shrinking compensation is guaranteed.

[0097] In addition, since only one operation is required to determine the amount of shrinkage compensation, there is no need for repeated operations. This is simple and efficient, and reduces costs, which is of great help to enterprises in increasing efficiency and reducing costs, and improving direct pass rate and yield.

[0098] In another implementation of the present invention, a process for determining the shrinkage compensation amount is provided. Specifically, referring to Figure 4 “Determining the shrinkage compensation amount based on the step values ​​of the MTF peak value and the shrinkage MTF value in the MTF transformation curve” may include:

[0099] S21, determining the first step distance value corresponding to the MTF peak from the MTF transformation curve.

[0100] In practical applications, Figure 3 From the MTF transformation curve, it can be seen that the MTF peak value is 0.71, and the corresponding first step length is 11.

[0101] S22: Determine a second step value corresponding to the collimated MTF value from a descending portion of the MTF transformation curve.

[0102] In practical applications, after shrinking, the distance between the lens and the imaging sensor decreases. The reduced distance makes the MTF after shrinking smaller than the MTF peak value. In this case, the second step value corresponding to the shrinking MTF value should be found in the descending part of the MTF transformation curve.

[0103] If the MTF peak value of the camera module is known to be 0.71 according to the AA record, and the MTF value of the camera module after shrinking is measured to be 0.64, then the second step value corresponding to 0.64 is found to be 13 from the descending part of the curve.

[0104] S23, calculating the difference between the first step value and the second step value.

[0105] According to the above, the first step value is 11, and the second step value is 13, which differs by 2 steps, which means that the MTF changes by two steps due to shrinkage.

[0106] S24, taking the product of the difference and the fixed step length used in the horizontal coordinate of the MTF conversion curve as the shrinkage compensation amount.

[0107] Taking a fixed step size of 3μm as an example, 2step represents 2*3μm=6μm, that is, due to the shrinkage operation, the height changes by 6μm, that is, due to the 6μm Z-axis change, the MTF value changes from 0.71 to 0.64. Therefore, 6μm should be compensated, that is, the shrinkage compensation amount is 6μm.

[0108] In an optional implementation of the present invention, the fixed step size can be set based on experience, such as being set to any one of 1, 2, 3 or 4 μm. In addition, in order to ensure accuracy, it can be directly set to 1 μm.

[0109] After the MTF conversion curve is obtained by measuring the fixed step size mentioned above, when the first step size value or the second step size value is determined based on the MTF conversion curve, there may be a situation where it is not a multiple of the fixed step size, that is, it is not a certain grid on the horizontal axis. At this time, the MTF peak value and the shrinkage MTF value are not a certain black point on the curve, which will result in the inability to accurately obtain the first step size and the second step size value. In order to solve this problem, the value of the fixed step size can be reduced, such as reducing the originally used 3μm to 2μm, and then returning to execute step S11, and again judging whether the first step size value or the second step size value is a multiple of the fixed step size. If not, continue to reduce the fixed step size, and repeat the above operation again until the first step size value or the second step size value obtained is a multiple of the fixed step size, and then determine the shrinkage compensation amount according to the above steps.

[0110] In this embodiment, the shrinkage compensation amount can be accurately obtained according to the MTF peak value and the step value corresponding to the shrinkage MTF value. In addition, the fixed step size can be adaptively adjusted according to the actual situation so that the first step size and the second step size can be accurately obtained, thereby obtaining the accurate optimal shrinkage compensation amount.

[0111] The embodiments of the present invention can obtain corresponding shrinkage compensation data for non-test camera modules, that is, camera modules in mass production. It is suitable for application scenarios where production enterprises need to regularly verify the shrinkage compensation amount, need to verify the consistency of material or glue batches, or need to reconfirm the shrinkage compensation amount for other reasons, so as to achieve "zero material loss" verification.

[0112] Based on the above-mentioned embodiment of the method for determining the shrinkage compensation amount of the camera module, another embodiment of the present invention provides a device for determining the shrinkage compensation amount of the camera module, referring to Figure 5 , which may include:

[0113] The curve acquisition module 11 is used to acquire the modulus transfer function MTF transformation curve obtained by performing an active alignment operation on the camera module before performing a shrinking operation on the camera module;

[0114] A peak value determination module 12, used to determine an MTF peak value from the MTF transformation curve, wherein the MTF peak value is an MTF value when the imaging clarity of the camera module is the highest before the shrinking operation;

[0115] The shrinkage value determination module 13 is used to determine the shrinkage MTF value of the camera module after the shrinkage operation;

[0116] The compensation amount determination module 14 is used to determine the shrinkage compensation amount based on the step values ​​of the MTF peak value and the shrinkage MTF value in the MTF transformation curve.

[0117] In one implementation, the compensation amount determination module 14 includes:

[0118] A first step distance value determination submodule, used to determine the first step distance value corresponding to the MTF peak from the MTF transformation curve, in which the horizontal axis is the Z-axis movement distance that changes according to a fixed step distance, and the vertical axis is the MTF value;

[0119] A second step value determination submodule, used for determining a second step value corresponding to the shrinkage MTF value from a descending portion of the MTF transformation curve;

[0120] A difference calculation submodule, used for calculating the difference between the first step value and the second step value;

[0121] The compensation amount determination submodule is used to take the product of the difference and the fixed step length used by the horizontal coordinate in the MTF transformation curve as the shrinkage compensation amount.

[0122] In one implementation, if the first step value or the second step value is not a multiple of the fixed step value, the device for determining the shrinkage compensation amount of the camera module further includes:

[0123] A numerical adjustment module, used for reducing the numerical value of the fixed step;

[0124] The curve acquisition module 11 is used to execute the step of acquiring the MTF transformation curve obtained by performing an active alignment operation on the camera module before performing a shrinking operation on the camera module after the adjustment module reduces the value of the fixed step length, until the first step length value or the second step length value obtained is a multiple of the fixed step length to determine the shrinkage compensation amount.

[0125] In one implementation, the curve acquisition module 11 is specifically used for:

[0126] Starting from the target position, a lens of the camera module is fixed by a fixing device to gradually approach the imaging sensor of the camera module according to a fixed step distance, and the MTF value is continuously detected during the approaching process to obtain an MTF conversion curve;

[0127] The target position is a position where the relative distance between the lens and the imaging sensor is greater than the lens image distance of the camera module.

[0128] In one implementation, the shrinkage value determination module 13 includes:

[0129] A shrinking operation submodule, used for performing shrinking operation on the camera module;

[0130] The shrinkage value determination submodule is used to perform an MTF readback operation on the camera module after the shrinkage operation to obtain the shrinkage MTF value.

[0131] In one implementation, the shrinking operation submodule includes:

[0132] A parameter determination unit, used to determine the curing temperature and curing time of the glue used in the shrinking operation;

[0133] The shrinking operation unit is used to control the oven to perform a shrinking operation on the camera module according to the curing temperature and the curing time.

[0134] In one implementation, the method further includes:

[0135] The object distance adjustment module is used to adjust the object distance corresponding to the camera module.

[0136] In one implementation, the object distance adjustment module includes:

[0137] A parameter acquisition submodule is used to obtain a preset focus distance and object distance;

[0138] A distance adjustment submodule is used to determine a first distance between the camera module and the lower metal surface of the relay lens, and a second distance between the upper metal surface of the relay lens and the shooting target based on the preset focus distance and the object distance, so as to adjust the relative positions of the camera module and the relay lens with respect to the shooting target based on the first distance and the second distance, and the shooting target, the relay lens, and the camera module are arranged in sequence.

[0139] In this embodiment, after obtaining the MTF transformation curve before the shrinking operation, the MTF peak is determined from the MTF transformation curve, the shrinking MTF value of the camera module after the shrinking operation is collected, and the shrinking compensation amount is determined based on the MTF peak and the step value of the shrinking MTF value in the MTF transformation curve, thereby achieving the determination of the shrinking compensation amount. In addition, in the present invention, the MTF peak is the MTF value when the imaging clarity of the camera module is the highest before the shrinking operation, and the MTF peak and the step value of the shrinking MTF value in the MTF transformation curve can characterize the step difference between the MTF after shrinking and the MTF value when the imaging clarity is the highest for the same camera module, and then the shrinking compensation amount is determined based on the step difference, so that the determined shrinking compensation amount can correspond to the shrinking situation of the actual camera module, so that the accuracy of the determined shrinking compensation amount is high, and the imaging clarity after shrinking compensation is guaranteed.

[0140] It should be noted that, for the working process of each module, sub-module and unit in the embodiment of the present invention, please refer to the corresponding description in the above embodiment, which will not be repeated here.

[0141] The present application also provides an electronic device in an embodiment. Figure 6 As shown, it shows a schematic diagram of the structure of an electronic device suitable for implementing the embodiment of the present application. The electronic device in the embodiment of the present application may include but is not limited to fixed terminals such as mobile phones, laptops, PDAs (personal digital assistants), PADs (tablet computers), desktop computers, etc. Figure 6 The electronic device shown is merely an example and should not bring any limitation to the functions and scope of use of the embodiments of the present application.

[0142] like Figure 6As shown, the electronic device may include a processing device (such as a central processing unit, a graphics processing unit, etc.) 601, which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM) 602 or a program loaded from a storage device 608 to a random access memory (RAM) 603 to implement the above-mentioned method for determining the shrinkage compensation amount of the camera module. When the electronic device is powered on, various programs and data required for the operation of the electronic device are also stored in the RAM 603. The processing device 601, the ROM 602, and the RAM 603 are connected to each other via a bus 604. An input / output (I / O) interface 605 is also connected to the bus 604.

[0143] Typically, the following devices may be connected to the I / O interface 605: an input device 606 including, for example, a touch screen, a touch pad, a keyboard, a mouse, a camera, a microphone, an accelerometer, a gyroscope, etc.; an output device 607 including, for example, a liquid crystal display (LCD), a speaker, a vibrator, etc.; a storage device 608 including, for example, a memory card, a hard disk, etc.; and a communication device 609. The communication device 609 may allow the electronic device to communicate with other devices wirelessly or by wire to exchange data. Although Figure 6 An electronic device having various devices is shown, but it should be understood that it is not required to implement or possess all the devices shown. More or fewer devices may be implemented or possessed instead.

[0144] Also provided in an embodiment of the present application is a computer program product including computer-readable instructions. When the computer-readable instructions are executed on an electronic device, the electronic device implements any method for determining the shrinkage compensation amount of a camera module provided in an embodiment of the present application.

[0145] A computer-readable storage medium is also provided in an embodiment of the present application. The storage medium carries one or more computer programs. When one or more computer programs are executed by an electronic device, the electronic device can implement any method for determining the shrinkage compensation amount of a camera module provided in an embodiment of the present application.

[0146] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for determining the shrinkage compensation amount of a camera module, characterized in that: include: Before performing a shrinking operation on the camera module, obtaining a modulus transfer function (MTF) transformation curve obtained by performing an active alignment operation on the camera module; Determine an MTF peak value from the MTF transformation curve, wherein the MTF peak value is an MTF value when the imaging clarity of the camera module is the highest before the shrinking operation; Determine the shrinking MTF value of the camera module after the shrinking operation; The shrinkage compensation amount is determined based on the step values ​​of the MTF peak value and the shrinkage MTF value in the MTF transformation curve.

2. The method for determining the shrinkage compensation amount of the camera module according to claim 1, characterized in that: Determining the shrinkage compensation amount based on the step values ​​of the MTF peak value and the shrinkage MTF value in the MTF transformation curve, respectively, includes: Determine the first step value corresponding to the MTF peak from the MTF transformation curve, wherein the abscissa is the Z-axis moving distance according to the fixed step size change, and the ordinate is the MTF value; Determine a second step value corresponding to the collimated MTF value from a descending portion of the MTF transformation curve; Calculating a difference between the first step value and the second step value; The product of the difference and the fixed step length used in the horizontal coordinate of the MTF conversion curve is used as the shrinkage compensation amount.

3. The method for determining the shrinkage compensation amount of the camera module according to claim 2, characterized in that: If the first step value or the second step value is not a multiple of the fixed step value, the method for determining the shrinkage compensation amount of the camera module further includes: Reduce the value of the fixed step length, return to execute the steps of obtaining the MTF transformation curve obtained by performing an active alignment operation on the camera module before performing the shrinking operation on the camera module, and determine the shrinkage compensation amount when the first step value or the second step value obtained is a multiple of the fixed step length.

4. The method for determining the shrinkage compensation amount of the camera module according to claim 1, characterized in that: Obtaining an MTF transformation curve obtained by performing an active alignment operation on the camera module, including: Starting from the target position, a lens of the camera module is fixed by a fixing device to gradually approach the imaging sensor of the camera module according to a fixed step distance, and the MTF value is continuously detected during the approaching process to obtain an MTF conversion curve; The target position is a position where the relative distance between the lens and the imaging sensor is greater than the lens image distance of the camera module.

5. The method for determining the shrinkage compensation amount of the camera module according to claim 1, characterized in that: Determining the shrinkage MTF value of the camera module after the shrinkage operation, including: Performing a shrinking operation on the camera module; Perform an MTF readback operation on the camera module after the shrinking operation to obtain the shrinking MTF value.

6. The method for determining the shrinkage compensation amount of the camera module according to claim 5, characterized in that: The camera module is subjected to a shrinking operation, comprising: Determine the curing temperature and curing time of the glue used in the shrinking operation; The oven is controlled according to the curing temperature and the curing time to perform a curing and shrinking operation on the camera module.

7. The method for determining the shrinkage compensation amount of the camera module according to claim 1, characterized in that: Before obtaining the MTF transformation curve obtained by performing an active alignment operation on the camera module, the method further includes: Adjust the object distance corresponding to the camera module.

8. The method for determining the shrinkage compensation amount of the camera module according to claim 7, characterized in that: Adjusting the object distance corresponding to the camera module includes: Get the preset focus distance and object distance; Based on the preset focusing distance and the object distance, a first distance between the camera module and the lower metal surface of the relay lens, and a second distance between the upper metal surface of the relay lens and the shooting target are determined, so as to adjust the relative positions of the camera module and the relay lens with respect to the shooting target based on the first distance and the second distance. The shooting target, the relay lens, and the camera module are arranged in sequence.

9. A device for determining the shrinkage compensation amount of a camera module, characterized in that: include: A curve acquisition module, used for acquiring a modulus transfer function MTF transformation curve obtained by performing an active alignment operation on the camera module before performing a shrinking operation on the camera module; A peak value determination module, used to determine an MTF peak value from the MTF transformation curve, wherein the MTF peak value is an MTF value when the imaging clarity of the camera module is the highest before the shrinking operation; A shrinkage value determination module, used to determine the shrinkage MTF value of the camera module after the shrinkage operation; The compensation amount determination module is used to determine the shrinkage compensation amount based on the step values ​​of the MTF peak value and the shrinkage MTF value in the MTF transformation curve.

10. The device for determining the shrinkage compensation amount of the camera module according to claim 9, characterized in that: The compensation amount determination module comprises: A first step distance value determination submodule, used to determine the first step distance value corresponding to the MTF peak from the MTF transformation curve, in which the horizontal axis is the Z-axis movement distance that changes according to a fixed step distance, and the vertical axis is the MTF value; A second step value determination submodule, used for determining a second step value corresponding to the shrinkage MTF value from a descending portion of the MTF transformation curve; A difference calculation submodule, used for calculating the difference between the first step value and the second step value; The compensation amount determination submodule is used to take the product of the difference and the fixed step length used by the horizontal coordinate in the MTF transformation curve as the shrinkage compensation amount.

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