Camera module resolution test chart

Abstract

The application provides a camera module resolution test chart, which comprises a center test block and a plurality of corner test blocks, the corner test blocks are adjacent to each other and surround and adjoin the center test block; the center test block and the corner test blocks each comprise a plurality of color blocks arranged in an array, the colors of any two color blocks adjacent to each other are different; each color block comprises at least two first straight edges and second straight edges perpendicular to each other, the straight edges are arranged obliquely relative to a first direction and a second direction perpendicular to the first direction; in any one corner test block, the oblique direction and the oblique angle of the first straight edge are symmetrical relative to the first direction and the second direction to the oblique direction and the oblique angle of the first straight edge in the adjacent other corner test block.

Description

Technical Field

[0001] This application relates to the field of optics, and more particularly to a camera module resolution test chart. Background Technology

[0002] To improve production efficiency, current camera module manufacturers often employ multiple camera modules simultaneously for SFR resolution testing, especially testing SFR. Furthermore, to facilitate testing different camera module models, the resolution test chart patterns are often set as follows: Figure 1 The diagram shows a checkerboard layout with multiple arrayed color blocks 50A, consisting of alternating white and black blocks. Testing SFR resolution typically requires measuring the horizontal and vertical resolution scores in the central and four corner areas of a resolution test chart. However, because all color blocks in the existing checkerboard layout have the same deflection direction and angle, the horizontal and vertical components of the measured SFR resolution at individual corners can differ significantly. This leads to variations in the measured SFR resolution between different corners, affecting the overall analysis of the corner area resolution and consequently, the overall resolution analysis of the camera module. Summary of the Invention

[0003] This application provides a camera module resolution test chart, which includes:

[0004] A central test block and multiple corner test blocks, wherein the multiple corner test blocks are adjacent to each other and surround and are adjacent to the central test block;

[0005] The central test block and each of the corner test blocks each include an array of multiple color blocks arranged side by side, and the colors of any two adjacent color blocks are different.

[0006] Each color block includes at least two straight edges, and any of the straight edges are inclined relative to a first direction and a second direction perpendicular to the first direction; each of the two straight edges of each color block includes a pair of mutually perpendicular first straight edges and second straight edges;

[0007] In any two adjacent corner test blocks, the tilt direction and tilt angle of the first straight edge in one corner test block are symmetrical with respect to both the first direction and the second direction as are the tilt direction and tilt angle of the first straight edge in the other corner test block.

[0008] In one embodiment, the tilt angle of the straight edge relative to the first or second direction of the camera module resolution test chart is in the range of 3-10 degrees.

[0009] In one embodiment, the plurality of color blocks includes white blocks and black blocks that are alternately arranged in both the direction extending along the first straight edge and the direction extending along the second straight edge.

[0010] In one embodiment, the plurality of color blocks are rectangular in shape and have the same size.

[0011] In one embodiment, in the central test block, each of the first straight edges has the same tilt direction and tilt angle relative to the first direction or the second direction, and each of the second straight edges has the same tilt direction and tilt angle relative to the first direction or the second direction; in the same corner test block, each of the first straight edges has the same tilt direction and tilt angle relative to the first direction or the second direction, and each of the second straight edges has the same tilt direction and tilt angle relative to the first direction or the second direction.

[0012] In one embodiment, the camera module resolution test chart is rectangular in shape, with the long side of the rectangle parallel to the first direction and the short side of the rectangle parallel to the second direction; the geometric center of the central test block coincides with the geometric center of the camera module resolution test chart, and the first direction is defined as the right side of the geometric center, and the second direction is defined as the top of the geometric center.

[0013] In one embodiment, there are four corner test blocks, which are respectively located in the upper left, lower left, upper right and lower right directions of the central test block.

[0014] In one embodiment, the tilt direction and tilt angle of the first straight edge in the central test block are the same as the tilt direction and tilt angle of the first straight edge in any of the corner test blocks.

[0015] In one embodiment, a line segment from the geometric center of the camera module resolution test chart to any vertex is defined as a field of view; in the direction from the geometric center of the camera module resolution test chart to any vertex, the boundary of the central test block is located at a position not exceeding 0.3 times the field of view.

[0016] In one embodiment, the side length of the color block does not exceed 0.08 times the side length of the long side of the camera module resolution test chart.

[0017] The camera module resolution test chart provided in this application provides a way to correct the differences in resolution scores measured from different corners by setting the tilt direction and tilt angle of the first straight side of the color block in adjacent corners to be symmetrical along the first direction or the second direction. This ensures that the final resolution value matches the actual situation and improves the accuracy of the camera module resolution test results. Attached Figure Description

[0018] Figure 1 This is a structural schematic diagram of an existing camera module resolution test chart.

[0019] Figure 2A for Figure 1 Enlarged schematic diagram of the middle IIA section (one corner part).

[0020] Figure 2B for Figure 1 Enlarged view of section IIB (the other corner).

[0021] Figure 3 This is a schematic diagram of the structure of the camera module resolution test chart according to an embodiment of this application.

[0022] Figure 4 This is a schematic diagram of the field of view and region distribution of the camera module resolution test chart according to an embodiment of this application.

[0023] Figure 5 This is a cross-sectional schematic diagram of the camera module resolution test chart according to an embodiment of this application.

[0024] Figure 6 This is a comparison chart of the resolution of test charts with different resolutions.

[0025] Explanation of main component symbols

[0026] Camera module resolution test charts 100 and 900

[0027] Central test block 10

[0028] Corner test blocks 30, 30a, 30b, 30c, 30d

[0029] Color blocks 50A, 50, 51, 53

[0030] First straight side 50V

[0031] Second straight edge 50H

[0032] First direction X

[0033] Second direction Y

[0034] Radial S

[0035] Tangential T

[0036] First angle VS

[0037] Second angle VT

[0038] Third angle HS

[0039] Fourth angle HT

[0040] First tilt angle α

[0041] Second tilt angle β

[0042] Field of view F

[0043] Substrate 110

[0044] Functional layer 130

[0045] The following detailed description, in conjunction with the accompanying drawings, will further illustrate this application. Detailed Implementation

[0046] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0047] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in this application's specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0048] To further illustrate the technical means and effects adopted by this application in achieving its intended purpose, the following detailed description of this application is provided in conjunction with the accompanying drawings and preferred embodiments.

[0049] Typical electronic products, such as smartphones, usually include camera modules. Before these modules are applied to a product, their performance typically needs to be tested to ensure they meet the expected shooting requirements. The resolution of a camera module is one of the key indicators for evaluating its performance; resolution refers to the sharpness of the images captured by the camera module. Methods for obtaining resolution can include Modulation Transfer Function (MTF) detection and SFR detection. This application uses SFR detection as an example to exemplarily describe the test charts used in the detection process, as well as their principles and usage methods.

[0050] During the camera module manufacturing process, the lens needs to be fixed to the sensor. To maintain good resolution in the camera module, the SFR resolution of the corresponding camera module needs to be calculated in advance based on the lens's resolution before assembly. This allows for adaptive alignment (AA) compensation, meaning the optimal relative position between the lens and the sensor is calculated before assembly. In this process, since the lens's resolution is divided into radial (S) and tangential (T) values, while the camera module's SFR resolution is divided into V values ​​calculated over a selected area in the horizontal direction and H values ​​calculated over a selected area in the vertical direction, the lens's S and T values ​​need to be converted into V and H values ​​for the SFR resolution during calculation.

[0051] Please refer to the following: Figure 1 , Figure 2A and Figure 2B ,in Figure 1 The camera module resolution test chart 900, commonly used for SFR resolution testing, consists of staggered black and white blocks, each block 50A being rectangular and having the same tilt direction and tilt angle. Figure 2A and Figure 2B These are enlarged views of different corners of the camera module resolution test chart 900. Color block 50A includes a first straight edge 50V and a second straight edge 50H that are perpendicular to each other. Radial direction S specifically refers to the direction extending outwards from the center of the lens; on the camera module resolution test chart 900, this corresponds to the direction from the geometric center of the chart to one of its vertices, i.e., along a diagonal of the chart. Tangential direction T is specifically perpendicular to radial direction S. Radial direction S forms a first angle VS and a third angle HS with the first straight edge 50V and the second straight edge 50H of color block 50A, respectively. Tangential direction T forms a second angle VT and a fourth angle HT with the first straight edge 50V and the second straight edge 50H of color block 50A, respectively. Since radial direction S and tangential direction T are perpendicular to each other, and the first straight edge 50V and the second straight edge 50H are perpendicular to each other, it is easy to conclude that the first angle VS equals the fourth angle HT, and the second angle VT equals the third angle HS. Let the resolution component of the lens along the radial direction S be S0, and the resolution component along the tangential direction T be T0 at a certain point. Then the H-value of the SFR resolution at this point can be expressed as:

[0052] H0=cosHT*T0+cosHS*S0 (1);

[0053] The V score of SFR resolution can be expressed as:

[0054] V0=cosVT*T0+cosVS*S0=cosHS*T0+cosHT*S0 (2).

[0055] From formulas (1) and (2), it can be seen that the H and V scores of SFR resolution are related to the third included angle HS and the fourth included angle HT, as well as the scores S0 and T0. Ideally, the lens is located at a certain corner (e.g., Figure 2A and Figure 2B As shown, the resolving power scores along the radial direction S and the tangential direction T are the same, and the H and V scores of the SFR resolving power are also the same. However, in practical applications, the resolving power scores along the radial direction S and the tangential direction T of the lens usually differ. In this case, the H and V scores of the SFR resolving power are also affected by the angles of the third included angle HS and the fourth included angle HT, and the greater the difference between the third included angle HS and the fourth included angle HT, the greater the impact on the H and V scores.

[0056] Please continue reading. Figure 2A and Figure 2B , Figure 2A The following describes the situation where the third included angle HS and the fourth included angle HT are both 45° at a certain corner of the camera module resolution test chart 900. In this case, the H score and V score of the SFR resolution can be expressed as:

[0057] H0=V0=cos45°*(T0+S0) (3),

[0058] That is, the influence of scores S0 and T0 on the H and V scores of SFR resolution is minimized. Figure 2B The situation at the other corner of the camera module resolution test chart 900 is given. At this time, the third included angle HS and the fourth included angle HT are not equal. The H score and V score of the SFR resolution are affected by the third included angle HS and the fourth included angle HT, as well as the score S0 and the score T0, thus affecting the value of the SFR resolution at this corner.

[0059] It can be seen that when the tilt direction and tilt angle of all color blocks 50A are the same, the SFR resolution calculation method of the same camera module on different corners of the camera module resolution test chart 900 is also different, which affects the analysis of the overall SFR resolution.

[0060] Based on the above, this application provides a camera module resolution test chart, which helps to eliminate the above problems.

[0061] Please refer to the following: Figure 3 and Figure 4The camera module resolution test chart 100 includes a central test block 10 and four corner test blocks 30. Corner test blocks 30a, 30b, 30c, and 30d surround the central test block 10 and are adjacent to each other. Both the central test block 10 and each corner test block 30 include an array of multiple color blocks 50 arranged closely without gaps. Any two adjacent color blocks 50 have different colors. "Adjacent" means that two color blocks 50 share a common edge. Each color block 50 includes at least two mutually perpendicular first straight edges 50V and second straight edges 50H. The first straight edge 50V is inclined relative to the first direction X and the second direction Y, and the second straight edge 50H is also inclined relative to the first direction X and the second direction Y. The first direction X is perpendicular to the second direction Y. In any two adjacent corner test blocks 30, the tilt direction and tilt angle of the first straight edge 50V in one corner test block 30 are symmetrical with respect to the first direction X and the second direction Y.

[0062] By setting the above, the calculation formulas for the H and V scores of SFR resolution in each corner test block 30 can be kept consistent, avoiding differences in SFR resolution scores caused by using different formulas for calculation.

[0063] In one embodiment, the first straight edge 50V of each color block 50 is inclined at 3°-10° relative to the first direction X, and a preferred embodiment is inclined at 8°; the second straight edge 50H of each color block 50 is inclined at 3°-10° relative to the second direction Y, and a preferred embodiment is inclined at 8°.

[0064] In one embodiment, the color block 50 includes black color blocks 51 and white color blocks 53 that are alternately arranged in the direction extending along the first straight edge 50V and the direction extending along the second straight edge 50H. In other embodiments, color blocks 51 and 53 may also be two other different colors, preferably with a high contrast difference between different color blocks 50.

[0065] In one embodiment, each color block 50 is rectangular and of the same size; a preferred embodiment is that each color block 50 is square.

[0066] In one embodiment, the first straight edge 50V of each color block 50 in the central test block 10 has the same tilt direction and tilt angle relative to the first direction X, and the second straight edge 50H of each color block 50 has the same tilt direction and tilt angle relative to the second direction Y; in the same corner test block 30, the first straight edge 50V of each color block 50 has the same tilt direction and tilt angle relative to the first direction X, and the second straight edge 50H of each color block 50 has the same tilt direction and tilt angle relative to the second direction Y.

[0067] In one embodiment, the camera module resolution test chart 100 is rectangular in shape, with a first direction X parallel to the direction of the long side of the rectangle and a second direction Y parallel to the direction of the short side of the rectangle. The geometric center of the central test block 10 coincides with the geometric center of the camera module resolution test chart 100, and the first direction X is defined as the right side of the geometric center, and the second direction Y is defined as the top of the geometric center. In a preferred embodiment, the aspect ratio of the camera module resolution test chart 100 is 4:3. In this case, the angle between the diagonal of the camera module resolution test chart 100 and the first direction X or the second direction Y is 37° or 53°, i.e., 45°±8°.

[0068] In one embodiment, the corner test block 30 includes a corner test block 30a located to the upper left of the central test block 10 relative to the first direction X and the second direction Y, a corner test block 30b located to the upper right, a corner test block 30c located to the lower left, and a corner test block 30d located to the lower right.

[0069] In one embodiment, with the orientation of the top-view camera module resolution test chart 100 as a reference, the first straight edge 50V of each color block 50 located in the corner test blocks 30a and 30d has a first tilt angle α that is counterclockwise relative to the first direction X, and the second straight edge 50H of each color block 50 has a first tilt angle α that is counterclockwise relative to the second direction Y; the first straight edge 50V of each color block 50 located in the center test block 10, corner test blocks 30b and 30c has a second tilt angle β that is clockwise relative to the first direction X, and the second straight edge 50H of each color block 50 has a second tilt angle β that is clockwise relative to the second direction Y. The first tilt angle α and the second tilt angle β are numerically equal, and a preferred embodiment is 8°. In other embodiments, the tilt direction and angle of the first straight edge 50V and the second straight edge 50H of each color block 50 in the central test block 10 may also be the same as the tilt direction and angle of the first straight edge 50V and the second straight edge 50H of each color block 50 in the corner test blocks 30a and 30d.

[0070] With the above settings, the radial direction S extending along any diagonal on the camera module resolution test chart 100 can be 45° with the first straight edge 50V and the second straight edge 50H of each color block 50 on the central test block 10 and the arbitrary corner test block 30. Therefore, when calculating the H score and V score of SFR resolution, formula (3) can be used directly to calculate, thereby minimizing the influence of the lens score S0 and score T0 on the H score and V score, so as to facilitate AA compensation and optimize the overall resolution of the camera module.

[0071] Please continue reading. Figure 4 In one embodiment, the field of view (F) of the camera module being tested is defined as the distance from the geometric center of the camera module resolution test chart 100 to any vertex. Within each vertex test block 30, the SFR resolution at 0.3x, 0.5x, and 0.8x F is tested respectively. Therefore, the boundary of the central test block 10 does not exceed 0.3x F. In other embodiments, only the SFR resolution at 0.5x and 0.8x F needs to be tested; therefore, the boundary of the central test block 10 can also be located between 0.3x and 0.5x F.

[0072] In one embodiment, the side length of any side of each color block 50 does not exceed 0.08 times the side length of the long side of the camera module resolution test chart 100, and a preferred embodiment is 0.064 times the side length of the long side.

[0073] In one embodiment, please refer to Figure 5 The camera module resolution test chart 100 includes a substrate 110 and a functional layer 130 disposed on the substrate 110. The substrate 110 can be cardboard, film, or other materials, and the functional layer 130 can be a printed layer, or a nested structure or a filling structure based on the substrate 110. The specific configuration can achieve, for example... Figure 3 The arrangement of the color blocks shown is sufficient; this application does not impose any specific restrictions on this arrangement.

[0074] The camera module resolution test chart 100 provided in this application embodiment sets up a central test block 10 and four corner test blocks 30, and makes the first straight edge 50V and the second straight edge 50H of the color block 50 in each test block have symmetrical tilt directions and tilt angles. This makes the calculation formulas for the H score and V score of SFR resolution consistent at each location, reducing the influence of the lens's own resolution on the camera module's resolution. This is beneficial for AA compensation of the camera module, thereby reducing the difference in H score and V score at each location when measuring SFR resolution in the subsequent process, and improving the overall resolution of the camera module.

[0075] In one embodiment, please refer to Figure 6Where 10, 10_L, 10_T, 10_R, and 10_B represent the resolution measured at various locations within the central test block 10; 30a_0.5_H represents the H score of the SFR resolution at 0.5 times the field of view F for the corner test block 30a; and 30a_0.5_V represents the V score of the SFR resolution at 0.5 times the field of view F for the corner test block 30a. The rest are similarly calculated. It can be seen that using the camera module resolution test chart 100 provided in this embodiment can effectively reduce the differences between the H and V scores of the SFR resolution in each corner test block 30. After online verification, using the camera module resolution test chart 100 provided in this embodiment can reduce the far-field defect rate of the camera module from 0.4% to 0.3%, the near-field defect rate from 0.15% to 0.07%, and the overall yield from 96.98% to 97.16%.

[0076] Those skilled in the art should recognize that the above embodiments are only used to illustrate this application and are not intended to limit this application. Any appropriate changes and variations made to the above embodiments within the essential spirit and scope of this application fall within the scope of protection claimed in this application.

Claims

1. A camera module resolution test chart, characterized in that, include: substrate; A central test block and multiple corner test blocks are disposed on the substrate, wherein the multiple corner test blocks are adjacent to each other and surround and are adjacent to the central test block; The central test block and each of the corner test blocks each include an array of multiple color blocks arranged side by side, and the colors of any two adjacent color blocks are different. Each color block includes at least two straight edges, and any of the straight edges are inclined relative to a first direction and a second direction perpendicular to the first direction; each of the two straight edges of each color block includes a pair of mutually perpendicular first straight edges and second straight edges; In any two adjacent corner test blocks, the tilt direction and tilt angle of the first straight edge in one corner test block are symmetrical with respect to both the first direction and the second direction as are the tilt direction and tilt angle of the first straight edge in the other corner test block.

2. The camera module resolution test chart as described in claim 1, characterized in that, The tilt angle of the straight edge relative to the first or second direction of the camera module resolution test chart is in the range of 3-10 degrees.

3. The camera module resolution test chart as described in claim 1, characterized in that, The plurality of color blocks include white blocks and black blocks that are alternately arranged in both the direction extending along the first straight edge and the direction extending along the second straight edge.

4. The camera module resolution test chart as described in any one of claims 1-3, characterized in that, The multiple color blocks are rectangular in shape and have the same size.

5. The camera module resolution test chart as described in claim 1, characterized in that, In the central test block, each of the first straight edges has the same tilt direction and tilt angle relative to the first direction or the second direction, and each of the second straight edges has the same tilt direction and tilt angle relative to the first direction or the second direction; in the same corner test block, each of the first straight edges has the same tilt direction and tilt angle relative to the first direction or the second direction, and each of the second straight edges has the same tilt direction and tilt angle relative to the first direction or the second direction.

6. The camera module resolution test chart as described in claim 1, characterized in that, The camera module resolution test chart is rectangular in shape, with the long side of the rectangle parallel to the first direction and the short side of the rectangle parallel to the second direction; the geometric center of the central test block coincides with the geometric center of the camera module resolution test chart, and the first direction is to the right of the geometric center, and the second direction is above the geometric center.

7. The camera module resolution test chart as described in claim 6, characterized in that, The number of corner test blocks is 4, which are respectively set in the upper left, lower left, upper right and lower right directions of the central test block.

8. The camera module resolution test chart as described in claim 7, characterized in that, The tilt direction and tilt angle of the first straight edge in the central test block are the same as the tilt direction and tilt angle of the first straight edge in any of the corner test blocks.

9. The camera module resolution test chart as described in claim 6, characterized in that, Let the line segment from the geometric center of the camera module resolution test chart to any vertex be a field of view; in the direction from the geometric center of the camera module resolution test chart to any vertex, the boundary of the central test block is no more than 0.3 times the field of view.

10. The camera module resolution test chart as described in claim 6, characterized in that, The side length of the color block does not exceed 0.08 times the side length of the long side of the camera module resolution test chart.

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