Test device and test method for camera module

Abstract

The present invention discloses a test device and a test method for a camera module. The test device includes: a working platform; a first test board having two opposite test surfaces; a second test board having at least one test pattern, the second test board and the first test board are oppositely arranged on the working platform along a first direction; a bracket assembly is arranged between the first test board and the second test board, the bracket assembly has a carrier for supporting the camera module, the carrier is movable in the first direction, the second direction and the third direction respectively, and the carrier is rotatable around the first direction, the second direction and the third direction respectively; the second direction is perpendicular to the working platform, and the first direction, the second direction and the third direction are perpendicular to each other pairwise. The test device of the present invention can adjust the orientation of the camera module to be tested towards a suitable test board or a selected test area, the types of the test boards are rich, and the integration degree of the device is high; the corresponding test method can complete a variety of test items, which is efficient and simple.

Description

Technical Field

[0001] The present invention generally relates to the technical field of camera testing, and particularly relates to a testing device and a testing method for a camera module. Background Art

[0002] At present, high-end flagship mobile phones and other electronic products already have 3D TOF (Time of flight) camera functions. 3D TOF cameras are an important 3D imaging technology, and the evaluation of cameras is particularly important. Currently, the evaluation equipment for 3D TOF cameras is relatively primitive, and there is no multi-functional integrated testing equipment. It can only evaluate single items one by one, with low efficiency and poor repeatability. Summary of the Invention

[0003] In view of the above defects or deficiencies in the prior art, it is desirable to provide a testing device and a testing method for a camera module.

[0004] In a first aspect, the present invention provides a testing device for a camera module. The camera module is a 3D TOF camera module, and the testing device includes:

[0005] A working platform, on which a first test board, a second test board, and a bracket assembly are provided;

[0006] The first test board has two opposite test surfaces;

[0007] The second test board has one test surface, and at least one test pattern is provided on the test surface of the second test board. The second test board and the first test board are oppositely arranged on the working platform along a first direction; and,

[0008] A bracket assembly, which is arranged between the first test board and the second test board. The bracket assembly has a carrier for supporting the camera module. The carrier is movable in the first direction, the second direction, and the third direction respectively, and the carrier is rotatable around the first direction, the second direction, and the third direction respectively;

[0009] The second direction is perpendicular to the working platform, and the first direction, the second direction, and the third direction are perpendicular to each other in pairs.

[0010] Optionally, the bracket assembly includes a first bracket, a second bracket, and a third bracket;

[0011] The first bracket is installed on the working platform, and the first bracket is movable along the first direction and rotatable around the second direction;

[0012] The second bracket is connected to the first bracket. The second bracket is movable along the second direction, movable along the third direction and rotatable about the first direction;

[0013] The third bracket is rotatably connected to the second bracket about the third direction, and the carrying platform is provided on the third bracket.

[0014] Optionally, the first test board has a first test surface and a second test surface facing away from each other. The first test surface is flat and has a uniform reflectivity everywhere, and the second test surface has multiple regions with different reflectivities.

[0015] Optionally, one or more of four test patterns are provided on the second test board. The four test patterns include:

[0016] A first test pattern, which includes a plurality of fan-shaped hollow areas distributed around a center point, and the fan angles of the respective fan-shaped hollow areas are different;

[0017] A second test pattern, which protrudes from the second test board. The projection of the second test pattern along the second direction includes a plurality of steps, and the heights of the plurality of steps increase or decrease in sequence;

[0018] A third test pattern, which protrudes from the second test board. The orthographic projection of the third test pattern along the second direction includes a plurality of sawtooth structures, and the included angles between any two adjacent sawteeth are different; and,

[0019] A fourth test pattern, which protrudes from the second test board. The orthographic projection of the fourth test pattern along the second direction includes a plurality of rectangular blocks arranged in parallel and evenly.

[0020] Optionally, it further includes at least one ambient light source facing the first test board. The ambient light source is arranged between the first test board and the second test board, and the ambient light source is arranged on one side of the bracket assembly.

[0021] Optionally, the carrying platform is a temperature control platform.

[0022] In a second aspect, the present invention provides a test method for a camera module. Using the above test device, the camera module is a 3D TOF camera module, and the test method includes:

[0023] Place the camera module on the carrying platform of the test device;

[0024] Adjust the lens of the camera module to face the first test surface of the first test board;

[0025] Obtain the depth image captured by the camera module facing the first test board, and determine the depth information of each pixel in the depth image;

[0026] Based on the depth information of each pixel in the depth image, calculate the depth average value of the depth image through the average value calculation formula, and calculate the depth standard deviation of the depth image through the standard deviation calculation formula;

[0027] According to the calculated average value and standard deviation, calculate the depth accuracy of the depth image through the accuracy calculation formula.

[0028] Optionally, the average value calculation formula is:

[0029]

[0030] The standard deviation calculation formula is:

[0031]

[0032] The accuracy calculation formula is:

[0033]

[0034] Where r is the depth average value, σ(r) is the depth standard deviation, and P precision is the depth accuracy. The depth image has N pixels, and x i represents the depth information of the i-th pixel in the depth image. N is a positive integer, and i ≤ N.

[0035] Optionally, before obtaining the depth image, the test method further includes: turning on the interference light source;

[0036] The interference light source includes any one of the following: the light source located on the first test surface, the light source located on the carrier, and the ambient light source of the test device. The light wave of the light source located on the first test surface or the light wave of the light source located on the carrier is the same as the light wave of the light emitted by the camera module.

[0037] Optionally, the test method of the camera module further includes:

[0038] Adjust the lens of the camera module to face the second test board;

[0039] Select a rectangular test area on the second test board, align the camera lens with the rectangular test area to take a picture, and determine that the pixel coordinates of the four corner points of the rectangular test area are (x A , y A , Z A ), (x B , y B , ZB ),(x c ,y C ,Z c ),(x D ,y D ,Z D );

[0040] Convert the pixel coordinates of the four corner points into spatial coordinates (X A , Y A , Z A ), (X B , Y B , Z B ), (X c , Y c , Z c ), (X D , Y D , Z D );

[0041] Calculate the measured width and measured length of the rectangular test area through the width calculation formula and the length calculation formula respectively;

[0042] Compare the measured width and the measured length with the actual width and actual length of the rectangular test area respectively.

[0043] Optionally, the width calculation formula is:

[0044]

[0045] The length calculation formula is:

[0046]

[0047] where Width is the measured width and Length is the measured length.

[0048] Optionally, the test method of the camera module further includes:

[0049] Adjust the lens of the camera module to face the second test board;

[0050] Align the camera lens with the first test pattern to take a photo to obtain a first depth image, and calculate the first depth accuracy of the first depth image through the average value calculation formula, the standard deviation calculation formula and the accuracy calculation formula in sequence. If the first depth accuracy is within the first preset threshold, it is determined that the camera has good resolution for the object angle.

[0051] Optionally, the test method of the camera module further includes:

[0052] Adjust the lens of the camera module to face the second test board;

[0053] Align the camera lens with the second test pattern to take a picture to obtain a second depth image. Then, calculate the second depth accuracy of the second depth image successively through the average value calculation formula, the standard deviation calculation formula, and the accuracy calculation formula. If the second depth accuracy is within the second preset threshold, it is determined that the resolution of the camera for the object is good.

[0054] Optionally, the test method for the camera module further includes:

[0055] Adjust the lens of the camera module to face the second test board;

[0056] Align the camera lens with the third test pattern to take a picture to obtain a third depth image. Then, calculate the third depth accuracy of the third depth image successively through the average value calculation formula, the standard deviation calculation formula, and the accuracy calculation formula. If the third accuracy is within the third preset threshold, it is determined that the multi-path accuracy of the camera is good.

[0057] Optionally, the test method for the camera module further includes:

[0058] Select a test area in the second test pattern;

[0059] Adjust the lens of the camera module to align with the test area of the second test board, and take a picture to obtain a still image;

[0060] Move the camera module along the first direction, and take pictures of the test area during the movement of the camera module to obtain a moving image;

[0061] Calculate the signal-to-noise ratio of the moving image through the signal-to-noise ratio calculation formula.

[0062] Optionally, the signal-to-noise ratio calculation formula is:

[0063]

[0064] SNR is the signal-to-noise ratio of the moving image, and g(i, j) and f(i, j) are the gray values of the moving image and the still image at the point (i, j) respectively.

[0065] Compared with the prior art, the test device for the camera module provided by the present invention can adjust the carrier platform at multiple angles, so as to adjust the camera module to be tested to face the appropriate test board or the selected test area. Moreover, the types of test boards are rich and the integration degree of the device is high; based on the corresponding test method for the camera module, multiple test items can be completed in one stop, which is efficient and simple. Description of the Drawings

[0066] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments read in conjunction with the accompanying drawings:

[0067] Figure 1 Schematic structural diagram of a test device for a camera module provided by an embodiment of the present invention;

[0068] Figure 2 Top view of a test device for a camera module provided by an embodiment of the present invention;

[0069] Figure 3 Side view of a test device for a camera module provided by an embodiment of the present invention;

[0070] Figure 4 Schematic structural diagram of a second test board provided by an embodiment of the present invention;

[0071] Figure 5 Top view of a second test board provided by an embodiment of the present invention;

[0072] Figure 6 Schematic structural diagram for testing the field of view angle on the first test surface based on the first test board provided by an embodiment of the present invention. Detailed implementation manners

[0073] The present invention will be further described in detail below in conjunction with the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the related invention and are not intended to limit the invention. Additionally, it should be noted that for the sake of description, only parts related to the invention are shown in the drawings.

[0074] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the drawings and embodiments.

[0075] As Figures 1 to 3 shown, an embodiment of the present invention provides a test device for a camera module, and the camera module is a 3D TOF camera module, including:

[0076] A working platform (not shown in the figure), on which a first test board 1, a second test board 2, and a bracket assembly are provided;

[0077] The first test board 1 has two opposite test surfaces;

[0078] The second test board 2 has one test surface, and at least one test pattern is provided on the test surface of the second test board 2. The test surface of the second test board 2 is disposed opposite to any test surface of the first test board 1 in a first direction; and,

[0079] The bracket assembly is arranged between the first test board 1 and the second test board 2. The bracket assembly has a carrier 3 for supporting the camera module. The carrier 3 is movable in the first direction, the second direction, and the third direction respectively, and the carrier 3 is rotatable around the first direction, the second direction, and the third direction respectively;

[0080] The second direction is perpendicular to the working platform, and the first direction, the second direction, and the third direction are perpendicular to each other in pairs.

[0081] Refer to Figure 1 , using mark A to represent the first direction, mark B to represent the second direction, and mark C to represent the third direction. The three directions are perpendicular to each other in pairs. Among them, the first test board 1 and the second test board 2 are arranged opposite to each other in the first direction, and the third direction C is parallel to any test surface of the first test board or the test surface of the second test board.

[0082] In the test device for the camera module provided in this embodiment, the carrier is used to clamp the camera module to be tested. Through the bracket assembly, the carrier can be moved in three directions, and through the bracket assembly, the carrier can also be rotated in three directions. Thus, the distance between the camera module and the first test board or the second test board can be adjusted in the first direction, and the camera module can also be adjusted to align with a certain area of the first test board or a certain area of the second test board. This test device has a high integration degree, and multiple performance tests can be carried out on the camera module through this test device, which is simple and efficient.

[0083] Optionally, the bracket assembly includes a first bracket, a second bracket, and a third bracket;

[0084] The first bracket is installed on the working platform. The first bracket is movable along the first direction and rotatable around the second direction;

[0085] The second bracket is connected to the first bracket. The second bracket is movable along the second direction, movable along the third direction, and rotatable around the first direction;

[0086] The third bracket is rotatably connected to the second bracket around the third direction, and a carrier 3 is provided on the third bracket.

[0087] Refer to Figures 1 to 3, preferably, a base 4 is arranged on the working platform. The first bracket 5 is connected to the base 4 through a first adapter block 6. Inside the base 4, there are a linear motor, a first pair of guide rails arranged along the first direction, a first lead screw arranged along the first direction, and a first slider passing through the first pair of guide rails and the first lead screw. The first adapter block 6 is fixedly connected to the first slider. Guided by the first pair of guide rails and driven by the linear motor, the first lead screw rotates, and the rotation of the first lead screw is converted into the linear motion of the first slider, that is, driving the first adapter block 6 to move in the first direction, and correspondingly driving the first bracket 5 to move in the first direction; inside the first adapter block 6, there is a linear motor driving the first bracket 5 to rotate around the second direction.

[0088] Refer to Figures 1 to 3 , preferably, the second bracket includes a second adapter block 7 connected to the first bracket 5, a displacement table 8 connected to the second adapter block 7, and a first support block 9 connected to the displacement table 8. On the first bracket 5, there are a second lead screw arranged along the second direction, a second pair of guide rails arranged along the second direction, a second slider passing through the second lead screw and the second pair of guide rails, and a linear motor driving the second lead screw to rotate. The second adapter block 7 is fixedly connected to the second slider. Guided by the second pair of guide rails and driven by the linear motor, the second lead screw rotates, and the rotation of the second lead screw is converted into the linear motion of the second slider along the second direction, that is, driving the second adapter block 7 to move in the second direction;

[0089] Inside the second adapter block 7, there is a linear motor driving the displacement table 8 to rotate around the first direction;

[0090] The length direction of the displacement table 8 is perpendicular to the second direction. Inside the displacement table 8, there are a third lead screw arranged along its length direction, a third pair of guide rails arranged along its length direction, a third slider passing through the third pair of guide rails and the third lead screw, and a linear motor driving the third lead screw to move along the length direction of the displacement table 8. The first support block 9 is fixedly connected to the third slider. Guided by the third pair of guide rails and driven by the linear motor, the third lead screw rotates, and the rotation of the third lead screw is converted into the linear motion of the third slider along the length direction of the displacement table 8, that is, driving the first support block 9 to move along the length direction of the displacement table 8.

[0091] Refer to Figures 1 to 3 , preferably, the third bracket includes a third adapter block 10 connected to the first support block 9 and a second support block 11 connected to the third adapter block 10. In the length direction of the displacement table 8, the third adapter block 10 is arranged on one side of the first support block 10. On the second support block 11, there is the above-mentioned carrier table 3, and the bearing surface of the carrier table 3 is parallel to the length direction of the displacement table 8. Inside the third adapter block 10, there is a linear motor driving the second support block 11 to rotate around the length direction of the displacement table 8.

[0092] Optionally, the first test board 1 has opposite first and second test surfaces. The first test surface is flat and has a uniform reflectivity everywhere, while the second test surface has multiple regions with different reflectivities. The first test board can be used to test the depth accuracy of the camera module, such as the depth accuracy tests under different distance conditions and different reflectivities.

[0093] Optionally, as Figure 4 and Figure 5 shown, one or more of four test patterns are provided on the second test board 2. The four test patterns include:

[0094] The first test pattern e, which includes multiple sector-shaped hollow areas distributed around a center point, and the sector angles of the respective sector-shaped hollow areas are different;

[0095] The second test pattern f, which protrudes from the second test board 2, and the projection of the second test pattern f in the second direction includes multiple steps, and the heights of the multiple steps increase or decrease in sequence;

[0096] The third test pattern g, which protrudes from the second test board 2, and the orthographic projection of the third test pattern g in the second direction includes multiple sawtooth structures, and the included angles between any two adjacent sawteeth are different; and,

[0097] The fourth test pattern h, which protrudes from the second test board 2, and the orthographic projection of the fourth test pattern h in the second direction includes multiple juxtaposed and evenly distributed rectangular blocks.

[0098] The second test can be used to test the resolution of the camera module for an object, such as the resolution of the object size, the resolution of the object angle, and the accuracy test of multiple paths.

[0099] Optionally, it further includes at least one ambient light source 12 facing the first test board 1. The ambient light source 12 is arranged between the first test board 1 and the second test board 2, and the ambient light source 12 is arranged on one side of the bracket assembly. As Figure 1 and Figure 2 shown, it is preferably to arrange two ambient light sources 12. The two ambient light sources 12 are located between the first test board 1 and the second test board 12, and in the direction perpendicular to the first direction, the two ambient light sources 12 are respectively located on both sides of the bracket assembly.

[0100] The ambient light source is used to simulate the working wavelength band existing in the environment, such as sunlight, etc.

[0101] Optionally, the carrier stage 3 is a temperature-controlled stage. That is, a heating wire and a temperature sensor can be arranged inside the carrier stage. By generating heat through the heating wire to a certain temperature, a certain temperature environment can be provided for the camera module to be tested, such as a normal temperature environment, a high temperature environment, etc., and the depth accuracy or other test items of the camera module under different temperature environments can be measured.

[0102] Based on the above test device for the camera module, an embodiment of the present invention further provides a test method for the camera module. The camera module is a 3D TOF camera, and the test method includes:

[0103] Place the camera module on the carrier stage of the test device;

[0104] Adjust the lens of the camera module to face the first test surface of the first test board;

[0105] Obtain the depth image captured by the camera module facing the first test board, and determine the depth information of each pixel in the depth image;

[0106] Based on the depth information of each pixel in the depth image, calculate the depth average value of the depth image through the average value calculation formula, and calculate the depth standard deviation of the depth image through the standard deviation calculation formula;

[0107] According to the calculated average value and standard deviation, calculate the depth accuracy of the depth image through the accuracy calculation formula.

[0108] Among them, the depth standard deviation is the most commonly used quantitative form to reflect the degree of dispersion of a set of data, and the depth accuracy, abbreviated as depth precision, is a physical quantity that describes the degree of change of the depth value on a specific object or within a specific area at a specific distance. Through the above test method, the depth accuracy under different distances, different external light sources, different reflectivities of the test board or different object structures can be determined.

[0109] Optionally, the average value calculation formula is:

[0110]

[0111] The standard deviation calculation formula is:

[0112]

[0113] The accuracy calculation formula is:

[0114]

[0115] Among them, r is the depth average value, σ(r) is the depth standard deviation, and P precision is the depth accuracy. The depth image has N pixels, and x iIt represents the depth information of the i-th pixel in the depth image, where N is a positive integer and i ≤ N.

[0116] Optionally, the camera module placed on the carrier platform faces the first test surface of the first test board. By adjusting the position of the support assembly in the test device in the first direction, the distance between the carrier platform and the first test board can be changed in the first direction, so as to measure the depth accuracy at different distances.

[0117] Furthermore, if the depth accuracy is controlled within an allowable range (such as 0.5%), the nearest distance and the farthest range within the allowable working range of the TOF camera can be obtained.

[0118] Optionally, adjust the second test surface of the first test board to face the camera module. The second test surface has multiple regions with different reflectivities. By taking pictures of different regions through the camera module, the depth accuracy corresponding to different regions (i.e., different reflectivities) can be measured.

[0119] Optionally, before obtaining the depth image, the test method further includes: turning on the interference light source.

[0120] The interference light source includes any one of the following: the light source located on the first test surface, the light source located on the carrier platform 3, and the ambient light source 12 of the test device. The light wave of the light source located on the first test surface or the light wave of the light source located on the carrier platform 3 and the light wave of the light emitted by the camera module.

[0121] Judging the anti-interference ability of the camera module by turning on the interference light source includes:

[0122] For example, install at least two identical mobile terminals on the carrier platform and face the first test surface. The mobile terminal has a 3D TOF camera. Control the mobile terminal to be tested to take pictures, and the other mobile terminals emit light for interference, and calculate the depth accuracy; or,

[0123] Place a mobile terminal on the carrier platform and face the first test surface. Fix at least one identical mobile terminal on the first test surface. The mobile terminal has a 3D TOF camera. Control the mobile terminal placed on the carrier platform to take pictures, and the mobile terminal on the first test surface emits light for interference, and calculate the depth accuracy; or,

[0124] Place a mobile terminal on the carrier platform and face the first test surface. The mobile terminal has a 3D TOF camera. Turn on the ambient light source. The ambient light source is in the wavelength range of 350nm - 1100nm, which can imitate the solar spectrum. The maximum illuminance of the ambient light source reaching the first test surface can reach 150000 lux. Control the mobile terminal placed on the carrier platform to take pictures. While calculating the depth accuracy, the pictures taken can be analyzed to determine the stray light of the camera.

[0125] Optionally, the test method for the camera module further includes:

[0126] Adjust the lens of the camera module to face the second test board 2;

[0127] Select a rectangular test area on the second test board 2, align the camera lens with the rectangular test area to take a photo, and determine that the pixel coordinates of the four corner points of the rectangular test area are respectively (x A , y A , Z A ), (x B , y B , Z B ), (x C , y c , Z c ), (x D , y D , Z D );

[0128] Convert the pixel coordinates of the four corner points into spatial coordinates (X A , Y A , Z A ), (X B , Y B , Z B ), (X C , Y c , Z c ), (X D , Y D , Z D );

[0129] Calculate the measured width and measured length of the rectangular test area respectively through the width calculation formula and the length calculation formula;

[0130] Compare the measured width and measured length with the actual width and actual length of the rectangular test area respectively.

[0131] Among them, by taking a photo of the selected rectangular test area through the camera module to obtain a depth image, the pixel coordinates of the four corner points can be determined, and the depth accuracy can be calculated;

[0132] The process of converting pixel coordinates into spatial coordinates is that the position of a point A in the depth image is (x, y, Z), where x and y are in pixels, and Z is in mm / cm, and it is converted into the coordinates (X, Y, Z) of point A in the spatial coordinate system with the depth camera as the coordinate origin, where both X and Y are in mm / cm.

[0133] Optionally, the width calculation formula is:

[0134]

[0135] The length calculation formula is as follows:

[0136]

[0137] Among them, Width is the measured width, and Length is the measured length.

[0138] Optionally, the test method of the camera module further includes:

[0139] Adjust the lens of the camera module to face the second test board 2;

[0140] Align the camera lens with the first test pattern e to take a photo to obtain a first depth image, and successively calculate the first depth accuracy of the first depth image through the average value calculation formula, the standard deviation calculation formula, and the accuracy calculation formula. If the first depth accuracy is within the first preset threshold, it is determined that the camera has good resolution for the object angle.

[0141] Optionally, the test method of the camera module further includes:

[0142] Adjust the lens of the camera module to face the second test board 2;

[0143] Align the camera lens with the second test pattern f to take a photo to obtain a second depth image, and successively calculate the second depth accuracy of the second depth image through the average value calculation formula, the standard deviation calculation formula, and the accuracy calculation formula. If the second depth accuracy is within the second preset threshold, it is determined that the camera has good resolution for the object.

[0144] Optionally, the test method of the camera module further includes:

[0145] Adjust the lens of the camera module to face the second test board 2;

[0146] Align the camera lens with the third test pattern g to take a photo to obtain a third depth image, and successively calculate the third depth accuracy of the third depth image through the average value calculation formula, the standard deviation calculation formula, and the accuracy calculation formula. If the third accuracy is within the third preset threshold, it is determined that the camera has good multi-path accuracy.

[0147] Optionally, the test method of the camera module further includes:

[0148] Select a test area in the second test pattern f;

[0149] Adjust the lens of the camera module to align with the test area of the second test board 2 and take a photo to obtain a still image;

[0150] Move the camera module along the first direction, and take a photo of the test area during the movement of the camera module to obtain a moving image;

[0151] Calculate the signal-to-noise ratio of the moving image through the signal-to-noise ratio calculation formula.

[0152] The quality of the moving image is evaluated by the signal-to-noise ratio. The larger the signal-to-noise ratio value, the better the image quality.

[0153] Furthermore, the calculation formula for the signal-to-noise ratio is:

[0154]

[0155] SNR is the signal-to-noise ratio of the moving image, and g(i, j) and f(i, j) are the gray values of the moving image and the static image at the point (i, j), respectively.

[0156] In this embodiment, using the above test device and based on the above test method, various performance tests can be performed on the camera module, which is convenient and efficient.

[0157] Optionally, as Figure 6 shown, the field of view angle is tested using the first test surface of the first test board. The horizontal length of the shooting area of the camera module is a, the vertical length is b, the diagonal length is c, and d represents the distance from the camera to the first test surface. d is a known distance.

[0158] The diagonal field of view angle α = 2 * arctan(c / d);

[0159] The horizontal field of view angle = 2 * arctan(a / d);

[0160] The vertical field of view angle = 2 * arctan(b / d).

[0161] It should be noted that in the embodiments of the present invention, the expressions of 3D TOF cameras or depth cameras involved are all equivalent to camera modules.

[0162] The above description is only a preferred embodiment of the present invention and an explanation of the applied technical principles. Those skilled in the art should understand that the scope of the invention involved in the present invention is not limited to the technical solutions formed by the specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the technical solutions formed by mutually replacing the above features with the (but not limited to) technical features with similar functions disclosed in the present invention.

Claims

1. A testing device for a camera module, characterized in that, The camera module is a 3D TOF camera module, and the test device includes: A working platform, on which a first test board, a second test board, and a bracket assembly are provided; The first test board has a first test surface and a second test surface facing away from each other. The first test surface is flat and has a uniform reflectivity everywhere, and the second test surface has multiple regions with different reflectivities. The first test board is used to test the depth accuracy of the camera module at different distances, the nearest distance and the farthest range within the allowable working range, the depth accuracy corresponding to different reflectivities, the anti-interference ability under interfering light sources, and the stray light situation; The second test board has a test surface, and at least one test pattern is provided on the test surface of the second test board. The test surface of the second test board is disposed opposite to any test surface of the first test board along a first direction. The test pattern of the second test board is a hollow structure or a protruding structure. The protruding heights of the protruding structures are different, or the structural angles are different, or there are multiple juxtaposed and evenly distributed rectangular blocks. The test pattern of the second test board is used to test the resolution of the camera module for the size of an object, the resolution for the angle of an object, and the accuracy test of multi-path, and A bracket assembly, which is disposed between the first test board and the second test board. The bracket assembly has a carrier for supporting the camera module. The carrier is movable in the first direction, the second direction, and the third direction respectively, and the carrier can rotate around the first direction, the second direction, and the third direction respectively; The second direction is perpendicular to the working platform, and the first direction, the second direction, and the third direction are perpendicular to each other in pairs.

2. The testing device for the camera module according to claim 1, wherein The bracket assembly includes a first bracket, a second bracket, and a third bracket; The first bracket is installed on the working platform. The first bracket is movable along the first direction and can rotate around the second direction; The second bracket is connected to the first bracket. The second bracket is movable along the second direction, movable along the third direction, and can rotate around the first direction; The third bracket is rotatably connected to the second bracket around the third direction, and the carrier is provided on the third bracket.

3. The test device for the camera module according to claim 1, characterized in that, One or more of four test patterns are provided on the second test board. The four test patterns include: A first test pattern, which includes a plurality of fan-shaped hollow areas distributed around a central point, and the fan angles of the respective fan-shaped hollow areas are different; A second test pattern, which protrudes from the second test board. The projection of the second test pattern along the second direction includes a plurality of steps, and the heights of the plurality of steps increase or decrease in sequence; A third test pattern, which protrudes from the second test board. The front projection of the third test pattern along the second direction includes a plurality of sawtooth structures, and the included angles between any two adjacent sawteeth are different; and A fourth test pattern, which protrudes from the second test board. The front projection of the fourth test pattern along the second direction includes a plurality of juxtaposed and evenly distributed rectangular blocks.

4. The testing device for a camera module according to claim 2, wherein, It further includes at least one ambient light source facing the first test board, the ambient light source is arranged between the first test board and the second test board, and the ambient light source is arranged on one side of the bracket assembly.

5. The test device for the camera module according to any one of claims 1-4, characterized in that, The carrier table is a temperature control table.

6. A test method for a camera module, characterized in that, Using the test device according to any one of claims 1-5, the camera module is a 3D TOF camera module, and the test method includes: Placing the camera module on the carrier table of the test device; Adjusting the lens of the camera module to face the first test surface of the first test board; Obtaining a depth image captured by the camera module facing the first test board, and determining the depth information of each pixel in the depth image; Based on the depth information of each pixel of the depth image, calculating the depth average value of the depth image through the average value calculation formula, and calculating the depth standard deviation of the depth image through the standard deviation calculation formula; According to the calculated average value and standard deviation, calculating the depth accuracy of the depth image through the accuracy calculation formula; the depth accuracy includes the depth accuracy of the camera module under different distances, different external light sources, different test board reflectivities, and different object structures; the depth accuracy is used to determine the nearest distance and the farthest range within the allowable working range of the camera module.

7. The test method of the camera module according to claim 6, wherein The average value calculation formula is: The standard deviation calculation formula is: The accuracy calculation formula is: wherein, is the depth average value, is the depth standard deviation, is the depth precision, the depth image has N pixels, represents the depth information of the i-th pixel in the depth image, N is a positive integer, and i ≤ N.

8. The testing method of the camera module according to claim 6, characterized in that, Before obtaining the depth image, the test method further includes: turning on the interference light source; The interference light source includes any one of the following: a light source located on the first test surface, a light source located on the carrier table, and the ambient light source of the test device, and the light wave of the light source located on the first test surface or the light wave of the light source located on the carrier table is the same as the light wave of the light emitted by the camera module.

9. The test method of the camera module according to claim 7, wherein, It further includes: Adjusting the lens of the camera module to face the second test board; Select a rectangular test area on the second test board, align the camera lens with the rectangular test area to take a photo, and determine that the pixel coordinates of the four corner points of the rectangular test area are respectively , , , ; Convert the pixel coordinates of the four corner points into spatial coordinates respectively , , , ; Calculating the measured width and measured length of the rectangular test area through the width calculation formula and the length calculation formula respectively; Comparing the measured width and the measured length with the actual width and actual length of the rectangular test area respectively.

10. The test method of the camera module according to claim 9, characterized in that, The width calculation formula is: ； The length calculation formula is: ； Among them, is for measuring the width, is for measuring the length.

11. The test method of the camera module according to claim 7, characterized in that, It further includes: Adjusting the lens of the camera module to face the second test board; Aligning the camera lens with the first test pattern to take a photo to obtain a first depth image, and successively calculating the first depth accuracy of the first depth image through the average value calculation formula, the standard deviation calculation formula, and the accuracy calculation formula. If the first depth accuracy is within the first preset threshold, it is determined that the camera has good resolution for the object angle.

12. The test method of the camera module according to claim 7, wherein, It further includes: Adjusting the lens of the camera module to face the second test board; Aligning the camera lens with the second test pattern to take a photo to obtain a second depth image, and successively calculating the second depth accuracy of the second depth image through the average value calculation formula, the standard deviation calculation formula, and the accuracy calculation formula. If the second depth accuracy is within the second preset threshold, it is determined that the camera has good resolution for the object.

13. The testing method of the camera module according to claim 7, wherein It further includes: Adjust the lens of the camera module to face the second test board; Align the camera lens with the third test pattern to take a photo to obtain a third depth image, and successively calculate the third depth accuracy of the third depth image through the average value calculation formula, the standard deviation calculation formula, and the accuracy calculation formula. If the third depth accuracy is within the third preset threshold, it is determined that the multi-path accuracy of the camera is good.

14. The test method of the camera module according to claim 7, characterized in that, It further includes: Select a test area in the second test pattern; Adjust the lens of the camera module to align with the test area of the second test board, and take a still image; Move the camera module along the first direction, and take a moving image of the test area during the movement of the camera module; Calculate the signal-to-noise ratio of the moving image through the signal-to-noise ratio calculation formula.

15. The test method of the camera module according to claim 14, wherein The signal-to-noise ratio calculation formula is: is the signal-to-noise ratio of the moving image, and the and are the gray values of the moving image and the still image at point respectively.

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