Method and device for testing whether secondary slope exists in VCM of camera module

Abstract

The invention discloses a method for testing whether a VCM of a camera module has a secondary slope, and the method comprises the steps: judging the slope of the VCM of the camera module through comparing whether the variable quantities of the distance between two mark points after the same driving current is added are the same, and achieving the automatic testing of whether the VCM of the camera module has the secondary slope. The defects of low accuracy and low efficiency of an experiment result caused by a manual judgment mode are overcome, so that the accuracy and the efficiency of testing are improved. The invention further discloses a device for testing whether the VCM of the camera module has the secondary slope or not.

Description

Technical Field

[0001] The present invention relates to the technical field of camera modules, and in particular to a method and device for testing whether a VCM of a camera module has a quadratic slope. Background Art

[0002] VCM, or voice coil motor, is a special linear drive device. VCM has the characteristics of fast response speed, high positioning accuracy, large driving force, wide travel range and easy control. In the field of camera modules, the linear region of the normal VCM characteristic curve is linear, that is, the slope is unique. If there are two straight line segments with different slopes at both ends of the linear region, that is, there is a quadratic slope, the focus function of the camera module will be affected, causing the camera module to have a focus blur problem. At present, for the problem of whether the camera module VCM has a quadratic slope, a laser rangefinder is usually used for testing, and then the VCM curve is manually determined to be normal. The manual determination method is prone to errors in the experimental results, resulting in low accuracy of the experimental results, and the manual determination method has the problem of low efficiency. Summary of the invention

[0003] The purpose of the present invention is to overcome the deficiencies in the prior art and to provide a method and device for testing whether the VCM of a camera module has a quadratic slope.

[0004] The object of the present invention is achieved through the following technical solution: a method for testing whether the VCM of a camera module has a quadratic slope, characterized in that it includes:

[0005] Step 1: Preset two mark points on the Chart so that the lens of the camera module faces the Chart;

[0006] Step 2: Use a camera module to shoot the Chart, obtain the coordinates of the two Mark points on the Chart when imaging the chip, and calculate the coordinate distance between the two Mark points;

[0007] Step 3: Continue to drive the VCM according to a preset current increase, and obtain the coordinate distance between the two corresponding Mark points;

[0008] Step 4: Calculate the ratio between the change in distance between two adjacent coordinates and the corresponding change in driving current;

[0009] Step 5: Determine whether the ratio between the change in the distance between two adjacent coordinates and the change in the corresponding driving current is stable.

[0010] In one embodiment, step 1 is specifically:

[0011] Step 1.1: Ensure that the size, resolution and clarity of the Chart are suitable for the requirements of the camera module;

[0012] Step 1.2: Setting the two Mark points on the Chart relatively;

[0013] Step 1.3: Fix the camera module and direct the lens of the camera module toward the Chart;

[0014] Step 1.4: Adjust the focal length of the camera module to ensure that the lens of the camera module can clearly capture the two Mark points on the Chart.

[0015] In one embodiment, step 2 is specifically:

[0016] Step 2.1: Use the module to take multiple photos of the Chart, and select the photo with the highest definition as the experimental object;

[0017] Step 2.2: Obtain the coordinates of the two Mark points on the Chart in the chip imaging through image processing software, and calculate the coordinate distance between the two Mark points;

[0018] Step 2.3: Save the coordinate distance between the two Mark points.

[0019] In one embodiment, step 3 is specifically:

[0020] Step 3.1: Continue to drive the VCM to move the lens according to the preset current increase amount;

[0021] Step 3.2: When the lens stops moving, the Chart is photographed, and the coordinate distance between the two corresponding Mark points is obtained;

[0022] Step 3.3: Save the coordinate distances of the two Mark points obtained in order of current magnitude.

[0023] In one embodiment, step 4 is specifically:

[0024] Step 4.1: Calculate the change in the distance between two adjacent coordinates saved;

[0025] Step 4.2: Calculate the ratio of the change in distance between two adjacent coordinates to the corresponding change in driving current and save it.

[0026] In one embodiment, step 5 is specifically:

[0027] Step 5.1: Setting a comparison interval to determine the ratio between the change in distance between two adjacent coordinates and the change in the corresponding driving current;

[0028] Step 5.2: If the ratio between the change in distance between two adjacent coordinates and the change in the corresponding driving current is within the comparison interval, it is determined that the VCM of the camera module does not have a quadratic slope;

[0029] Step 5.3: If the ratio between the change in distance between two adjacent coordinates and the change in the corresponding driving current is not within the comparison interval, it is determined that the VCM of the camera module has a quadratic slope.

[0030] In one of the embodiments, it also includes: if the VCM of the camera module has a quadratic slope, an alarm is given.

[0031] A device for testing whether the VCM of a camera module has a quadratic slope, and a method for executing the above-mentioned test whether the VCM of a camera module has a quadratic slope, comprising: a driving module, a storage module and a judgment module, wherein the driving module is used to continuously drive the VCM to drive the lens to move according to a preset current increase; the storage module is used to save the coordinate distance of the two Mark points corresponding to each current magnitude, and save the ratio of the change in the distance between two adjacent coordinates to the corresponding change in the driving current; the judgment module is used to judge whether the ratio between the change in the distance between two adjacent coordinates and the change in the corresponding driving current is within a comparison interval.

[0032] In one of the embodiments, an alarm module is also included for giving an alarm when a quadratic slope exists in the VCM of the camera module.

[0033] In one of the embodiments, it also includes a statistical module for collecting statistics on the camera modules whose VCM does not have a quadratic slope.

[0034] Compared with the prior art, the present invention has at least the following advantages:

[0035] The method of testing whether the VCM of the camera module has a quadratic slope of the present invention determines the slope of the VCM of the camera module by comparing whether the change in the distance between two mark points after adding the same driving current is the same, thereby automatically testing whether the VCM of the camera module has a quadratic slope, overcoming the low accuracy and low efficiency of the experimental results caused by the manual judgment method, thereby improving the accuracy and efficiency of the test BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0037] Figure 1 A flow chart of a method for testing whether a VCM of a camera module has a quadratic slope in one embodiment of the present invention;

[0038] Figure 2 Schematic diagram of imaging of a camera module in one embodiment of the present invention;

[0039] Figure 3 is a VCM characteristic curve diagram in one embodiment of the present invention;

[0040] Figure 4 is a VCM characteristic curve diagram with a quadratic slope in one embodiment of the present invention;

[0041] Description of the drawings: 100, Chart; 200, lens; 300, chip; DETAILED DESCRIPTION

[0042] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thoroughly understood.

[0043] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0045] See also Figures 1 to 4, a method for testing whether a VCM of a camera module has a quadratic slope, comprising:

[0046] Step 1: Preset two Mark points on the Chart 100 so that the lens 200 of the camera module faces the Chart 100;

[0047] Step 2: Use a camera module to shoot the Chart 100, obtain the coordinates of the two Mark points on the Chart 100 imaged on the chip 300, and calculate the coordinate distance between the two Mark points;

[0048] Step 3: Continue to drive the VCM according to the preset current increase amount, and obtain the coordinate distance between the two corresponding mark points;

[0049] Step 4: Calculate the ratio between the change in distance between two adjacent coordinates and the corresponding change in driving current;

[0050] Step 5: Determine whether the ratio between the change in the distance between two adjacent coordinates and the change in the corresponding driving current is stable.

[0051] It should be noted that by using the camera module to shoot the Chart 100, the distance L1 between the two Marks on the Chart 100 is obtained, and then the coordinate distance L2 of the two Mark points on the Chart 100 in the chip 300 is obtained, the distance from the lens 200 to the Chart 100 is set to U, and the distance from the lens 200 to the chip 300 is set to V. According to the related theorem of similar triangles L1:L2=U:V, the height from the bottom of the camera module to the Chart 100 is obtained to be H=U+V, and thus L2:V=L1:HV is obtained. The VCM of the camera module pushes the lens 200 to move, so that the distance V from the lens 200 to the chip 300 changes, and the change amplitude of the distance V value from the lens 200 to the chip 300 caused by the displacement of the lens 200 is much smaller than the change amplitude of the distance V value from the bottom of the camera module to the Chart 100. 0, so HV can be considered as a constant, that is, the coordinate distance L2 of the two mark points on the chip 300 is proportional to the distance V from the lens 200 to the chip 300; in the linear region of VCM, VCM drives the lens 200 to move, and the driving force F and the displacement x of the lens 200 satisfy F=Kx, where K is a fixed value, and the driving force F and the current I satisfy Ampere's law F=BIL, where B and L are fixed values, so x:I=BL:K, that is, the displacement x of the lens 200 is proportional to the current I; because the lens 200 moves toward the Chart 100, the larger the displacement x of the lens 200, the smaller the distance U from the lens 200 to the Chart 100, and the larger the distance V from the lens 200 to the chip 300, that is, the distance V from the lens 200 to the chip 300 is proportional to the displacement x of the lens 200;Since the coordinate distance L2 of the two Mark points imaged on the chip 300 is proportional to the distance V from the lens 200 to the chip 300, the displacement x of the lens 200 is proportional to the current I, and the distance V from the lens 200 to the chip 300 is proportional to the displacement x of the lens 200, it can be concluded that the coordinate distance L2 of the two Mark points imaged on the chip 300 is proportional to the current I. When the camera module shoots the Chart 100, the preset current increase continuously drives the VCM to obtain the corresponding coordinate distance value L2 of the two Mark points imaged on the chip 300, and obtain the relationship curve between L2 and I. When the value of L2 changes continuously, it indicates that the VCM linear region begins to enter. Until the value of L2 no longer changes, in the interval of continuous change of L2, the ratio between the change in the distance between two adjacent coordinates and the corresponding change in the driving current is calculated, and then the change in the distance between two adjacent coordinates is determined. Whether the ratio between the change in the distance between two adjacent coordinates and the change in the corresponding driving current is stable, if the ratio between the change in the distance between two adjacent coordinates and the change in the corresponding driving current is within the comparison interval, there is a straight line from the starting point A to the end point C of the VCM linear region, then it is judged that the VCM of the camera module does not have a quadratic slope, if the ratio between the change in the distance between two adjacent coordinates and the change in the corresponding driving current is not within the comparison interval, there are two straight lines with different slopes from the starting point A to the end point C of the VCM linear region, and the characteristic curve of the VCM has a quadratic slope, so that the method judges the slope of the VCM of the camera module by comparing whether the change in the distance between the two mark points after adding the same driving current is the same, and realizes automatic testing of whether the VCM of the camera module has a quadratic slope, overcoming the low accuracy and low efficiency of the experimental results caused by manual judgment, thereby improving the accuracy and efficiency of the test. ;

[0052] In one embodiment, step 1 is specifically as follows: Step 1.1: ensure that the size, resolution and clarity of the Chart 100 are suitable for the requirements of the camera module; Step 1.2: set two Mark points relatively on the Chart; Step 1.3: fix the camera module and point the lens 200 of the camera module toward the Chart 100; Step 1.4: adjust the focal length of the camera module to ensure that the lens 200 of the camera module can clearly capture the two Mark points on the Chart 100. With such a setting, the test error caused by the experimental environment and equipment factors can be tested.

[0053] In one embodiment, step 2 is specifically as follows: Step 2.1: Use the module to take multiple photos of the Chart 100, and select the picture with the highest clarity as the experimental object; Step 2.2: Obtain the coordinates of the two Mark points on the Chart 100 imaged on the chip 300 through image processing software, and calculate the coordinate distance between the two Mark points; Step 2.3: Save the coordinate distance between the two Mark points.

[0054] In one embodiment, step 3 is specifically as follows: step 3.1: continuously driving the VCM to move the lens 200 according to a preset current increase; step 3.2: when the lens 200 stops moving, photographing the Chart 100 and obtaining the coordinate distances of the two corresponding Mark points; step 3.3: saving the obtained coordinate distances of the two corresponding Mark points in order of current size.

[0055] In one implementation, step 4 is specifically as follows: step 4.1: calculating the change in the distance between two adjacent coordinates that are saved; step 4.2: calculating and saving the ratio of the change in the distance between two adjacent coordinates to the corresponding change in the driving current.

[0056] In one embodiment, step 5 is specifically as follows: step 5.1: setting a comparison interval for determining the ratio between the change in the distance between two adjacent coordinates and the corresponding change in the driving current; step 5.2: if the ratio between the change in the distance between two adjacent coordinates and the corresponding change in the driving current is within the comparison interval, then determining that the VCM of the camera module does not have a quadratic slope; step 5.3: if the ratio between the change in the distance between two adjacent coordinates and the corresponding change in the driving current is not within the comparison interval, then determining that the VCM of the camera module has a quadratic slope.

[0057] In one embodiment, it also includes: if the VCM of the camera module has a quadratic slope, an alarm is issued.

[0058] A device for testing whether a VCM of a camera module has a quadratic slope, and a method for executing the above-mentioned test whether a VCM of a camera module has a quadratic slope, comprising: a driving module, a storage module and a judgment module, wherein the driving module is used to continuously drive the VCM to drive the lens 200 to move according to a preset current increase; the storage module is used to save the coordinate distance of two Mark points corresponding to each current magnitude, and save the ratio of the change in the distance between two adjacent coordinates to the corresponding change in the driving current; the judgment module is used to judge whether the ratio between the change in the distance between two adjacent coordinates and the change in the corresponding driving current is within a comparison interval.

[0059] In one embodiment, an alarm module is also included to issue an alarm prompt when the VCM of the camera module has a quadratic slope.

[0060] In one embodiment, a statistical module is further included to collect statistics on camera modules whose VCM does not have a quadratic slope, so as to facilitate the management of normal camera modules.

[0061] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be based on the attached claims.

Claims

1. A method for testing whether the VCM of a camera module has a quadratic slope, characterized in that: include: Step 1: Preset two mark points on the Chart so that the lens of the camera module faces the Chart; Step 2: Use a camera module to shoot the Chart, obtain the coordinates of the two Mark points on the Chart when imaging the chip, and calculate the coordinate distance between the two Mark points; Step 3: Continue to drive the VCM according to a preset current increase, and obtain the coordinate distance between the two corresponding Mark points; Step 4: Calculate the ratio between the change in distance between two adjacent coordinates and the corresponding change in driving current; Step 5: Determine whether the ratio between the change in the distance between two adjacent coordinates and the change in the corresponding driving current is stable.

2. A method for testing whether the VCM of a camera module has a quadratic slope according to claim 1, characterized in that: Step 1 is as follows: Step 1.1: Ensure that the size, resolution and clarity of the Chart are suitable for the requirements of the camera module; Step 1.2: Setting the two Mark points on the Chart relatively; Step 1.3: Fix the camera module and direct the lens of the camera module toward the Chart; Step 1.4: Adjust the focal length of the camera module to ensure that the lens of the camera module can clearly capture the two Mark points on the Chart.

3. A method for testing whether the VCM of a camera module has a quadratic slope according to claim 2, characterized in that: Step 2 is as follows: Step 2.1: Use the module to take multiple photos of the Chart, and select the photo with the highest definition as the experimental object; Step 2.2: Obtain the coordinates of the two Mark points on the Chart in the chip imaging through image processing software, and calculate the coordinate distance between the two Mark points; Step 2.3: Save the coordinate distance between the two Mark points.

4. A method for testing whether the VCM of a camera module has a quadratic slope according to claim 3, characterized in that: Step 3 is as follows: Step 3.1: Continue to drive the VCM to move the lens according to the preset current increase amount; Step 3.2: When the lens stops moving, the Chart is photographed, and the coordinate distance between the two corresponding Mark points is obtained; Step 3.3: Save the coordinate distances of the two Mark points obtained in order of current magnitude.

5. A method for testing whether the VCM of a camera module has a quadratic slope according to claim 4, characterized in that: Step 4 is as follows: Step 4.1: Calculate the change in the distance between two adjacent coordinates saved; Step 4.2: Calculate the ratio of the change in distance between two adjacent coordinates to the corresponding change in driving current and save it.

6. A method for testing whether the VCM of a camera module has a quadratic slope according to claim 5, characterized in that: Step 5 is as follows: Step 5.1: Setting a comparison interval to determine the ratio between the change in distance between two adjacent coordinates and the change in the corresponding driving current; Step 5.2: If the ratio between the change in distance between two adjacent coordinates and the change in the corresponding driving current is within the comparison interval, it is determined that the VCM of the camera module does not have a quadratic slope; Step 5.3: If the ratio between the change in distance between two adjacent coordinates and the change in the corresponding driving current is not within the comparison interval, it is determined that the VCM of the camera module has a quadratic slope.

7. A method for testing whether the VCM of a camera module has a quadratic slope according to claim 6, characterized in that: Also includes: The VCM of the camera module has a quadratic slope, which gives an alarm.

8. A device for testing whether the VCM of a camera module has a quadratic slope, characterized in that: The method for testing whether the VCM of a camera module has a quadratic slope according to any one of claims 1 to 7 comprises: A driving module, the driving module is used to continuously drive the VCM to drive the lens to move according to a preset current increase; A storage module, the storage module is used to store the coordinate distance between the two Mark points corresponding to each current magnitude, and store the ratio of the change in the distance between two adjacent coordinates to the corresponding change in the driving current; and A judgment module is used to judge whether the ratio between the change in distance between two adjacent coordinates and the change in the corresponding driving current is within a comparison interval.

9. A device for testing whether the VCM of a camera module has a quadratic slope according to claim 8, characterized in that: It also includes an alarm module, which is used to issue an alarm prompt when the VCM of the camera module has a quadratic slope.

10. The device for testing whether the VCM of a camera module has a quadratic slope according to claim 8, characterized in that: It also includes a statistical module for collecting statistics on the camera modules whose VCM does not have a quadratic slope.

Images