Abnormal circular ring image detection method for optical fingerprint module

Abstract

The invention discloses an optical fingerprint module abnormal circular image detection method, which comprises the steps that an optical fingerprint module is arranged in a preset range in front of a light source, and the end face of the optical fingerprint module is parallel to the light source; a lens of the optical fingerprint module is loaded to a distant view position, the gain of a sensor of the optical fingerprint module is adjusted to be 1x, and shading and mirroring functions are closed; setting the exposure value of the sensor of the optical fingerprint module to the picture center brightness to a preset value; capturing a picture irradiated by a light source, counting the brightness of the picture and establishing a brightness histogram; taking the brightest area on the histogram, calculating the centroid of the brightest area, taking the centroid as an optical center, and calculating the radius of the minimum circumcircle of the picture; taking the radius as a horizontal coordinate, counting a brightness average value of all image points on the same radius away from the optical center, and establishing a change curve of the center distance and the brightness average value by taking the brightness average value as a vertical coordinate; and when a recess appears on the change curve, judging that the optical fingerprint module has electrostatic damage.

Description

Technical Field

[0001] The present invention relates to the technical field of optical fingerprint modules, and in particular to a method for detecting abnormal circular ring images of optical fingerprint modules. Background Art

[0002] With the development of the smart mobile terminal industry, screen-to-body ratio has become an important selling point indicator. Optical fingerprint and side fingerprint have been widely used because they can increase the screen-to-body ratio. Among them, optical fingerprint has become the fingerprint unlocking solution recognized by most users due to its convenience of use and stickiness to the usage habits of capacitive fingerprint users. However, after the optical fingerprint module is damaged by static electricity, a circle of abnormal black dots will appear, which is the so-called abnormal ring image, such as Figure 1 As shown, it affects the accuracy of fingerprint recognition and becomes a defective product.

[0003] How to detect whether the optical fingerprint module has been damaged by electrostatic discharge has become a technical problem that needs to be solved urgently in the industry. Summary of the invention

[0004] In order to at least solve the above technical problems, the purpose of the present invention is to provide a method for detecting abnormal circular ring images of an optical fingerprint module. Through the curve graph, it can be intuitively determined whether the optical fingerprint module suffers from electrostatic damage.

[0005] In order to achieve the above-mentioned purpose, the optical fingerprint module abnormal ring image detection method provided in the present application includes:

[0006] Place the optical fingerprint module in a preset range in front of the light source, with the end face of the optical fingerprint module parallel to the light source;

[0007] Load the lens of the optical fingerprint module to the far-view position, adjust the gain of the sensor of the optical fingerprint module to 1x, and turn off the shading and mirroring functions;

[0008] Change the exposure value of the optical fingerprint module's sensor to the center brightness of the picture to the preset value;

[0009] Capture the image under the light source, count the brightness of the image and create a brightness histogram;

[0010] Take the brightest area on the histogram, calculate the centroid of the brightest area, and use the centroid as the optical center;

[0011] Taking the centroid as the center, calculate the radius of the minimum circumscribed circle of the picture;

[0012] Take the radius as the horizontal coordinate, count the average brightness of all image points at the same radius from the optical center, take the average brightness as the vertical coordinate, and establish a curve of center distance and average brightness.

[0013] When a depression appears on the change curve, it is determined that the optical fingerprint module has electrostatic damage.

[0014] Furthermore, it also includes: placing the optical fingerprint module in a preset test environment;

[0015] The preset test environment includes a color temperature of 5000-5200K and a brightness of 900-1100lux.

[0016] Furthermore, placing the optical fingerprint module within a preset range in front of the light source includes placing the optical fingerprint module 1 cm in front of the light source.

[0017] Furthermore, changing the exposure value of the sensor of the optical fingerprint module to the brightness at the center of the picture to a preset value includes changing the exposure value of the sensor of the optical fingerprint module to the brightness at the center of the picture to 128.

[0018] Furthermore, the brightness of the light source is uniform and stable.

[0019] Further, the brightest area on the histogram is taken, the centroid of the brightest area is calculated, and the centroid is used as the optical center, including taking the brightest one-tenth area on the histogram to calculate the centroid, and using the centroid as the optical center.

[0020] Furthermore, when no depression appears on the change curve, it is determined that the optical fingerprint module has no electrostatic damage.

[0021] Furthermore, the method also includes filtering the change curve.

[0022] Furthermore, it is determined whether a depression appears on the change curve after filtering. When a depression appears on the change curve, it is determined that the optical fingerprint module has electrostatic damage.

[0023] Further, it is determined whether a depression appears on the change curve after filtering. When no depression appears on the change curve, it is determined that there is no electrostatic damage to the optical fingerprint module.

[0024] The optical fingerprint module abnormal annular image detection method of the embodiment of the present application includes: placing the optical fingerprint module in a preset range in front of the light source, and the end face of the optical fingerprint module is parallel to the light source; loading the lens of the optical fingerprint module to the long-range position, adjusting the gain of the sensor of the optical fingerprint module to 1x, and turning off the shading and mirroring functions; adjusting the exposure value of the sensor of the optical fingerprint module to the center brightness of the picture to the preset value; capturing the picture under the illumination of the light source, counting the brightness of the picture and establishing a brightness histogram; taking the brightest area on the histogram, calculating the centroid of the brightest area, and taking the centroid as the optical center; taking the centroid as the center, calculating the radius of the minimum circumscribed circle of the picture; taking the radius as the horizontal coordinate, counting the brightness average of all image points on the same radius from the optical center, taking the brightness average as the vertical coordinate, and establishing a change curve of the center distance and the brightness average; when a depression appears on the change curve, it is judged that the optical fingerprint module has electrostatic damage. Through the curve graph, it can be intuitively judged whether the optical fingerprint module suffers from electrostatic damage, which improves the efficiency of detection and provides a guarantee for the yield rate of subsequent products. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings are used to provide a further understanding of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the present application and do not constitute a limitation of the present application. In the accompanying drawings:

[0026] Figure 1 This is a schematic diagram of the abnormal circular ring image characteristics of an embodiment of the present application;

[0027] Figure 2 is a schematic diagram of optical center modeling in an embodiment of the present application;

[0028] Figure 3 is an equidistant mean brightness curve diagram of an embodiment of the present application;

[0029] Figure 4 It is a schematic flow chart of an abnormal circular image detection method of an optical fingerprint module according to an embodiment of the present application. DETAILED DESCRIPTION

[0030] The embodiments of the present application will be described in more detail below with reference to the accompanying drawings. Although certain embodiments of the present application are shown in the accompanying drawings, it should be understood that the present application can be implemented in various forms and should not be construed as being limited to the embodiments described herein. Instead, these embodiments are provided to provide a more thorough and complete understanding of the present application. It should be understood that the drawings and embodiments of the present application are only for exemplary purposes and are not intended to limit the scope of protection of the present application.

[0031] It should be understood that the various steps described in the method implementation of the present application can be performed in different orders and / or performed in parallel. In addition, the method implementation may include additional steps and / or omit the steps shown. The scope of the present application is not limited in this respect.

[0032] The term "including" and its variations used herein are open inclusions, i.e., "including but not limited to". The term "based on" means "based at least in part on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments". The relevant definitions of other terms will be given in the following description.

[0033] It should be noted that the modifications of "one" and "plurality" mentioned in this application are illustrative rather than restrictive, and those skilled in the art should understand that unless otherwise clearly indicated in the context, it should be understood as "one or more". "Plurality" should be understood as two or more.

[0034] Embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0035] The present application embodiment provides a method for detecting abnormal circular ring images of an optical fingerprint module, comprising:

[0036] Place the optical fingerprint module in a preset range in front of the light source, with the end face of the optical fingerprint module parallel to the light source;

[0037] Load the lens of the optical fingerprint module to the far-view position, adjust the gain of the sensor of the optical fingerprint module to 1x, and turn off the shading and mirroring functions;

[0038] Change the exposure value of the optical fingerprint module's sensor to the center brightness of the picture to the preset value;

[0039] Capture the image under the light source, count the brightness of the image and create a brightness histogram;

[0040] Take the brightest area on the histogram, calculate the centroid of the brightest area, and use the centroid as the optical center;

[0041] Taking the centroid as the center, calculate the radius of the minimum circumscribed circle of the picture;

[0042] Take the radius as the horizontal coordinate, count the average brightness of all image points at the same radius from the optical center, take the average brightness as the vertical coordinate, and establish a curve of center distance and average brightness.

[0043] When a depression appears on the change curve, it is determined that the optical fingerprint module has electrostatic damage.

[0044] Example 1

[0045] Figure 1 is a schematic diagram of abnormal circular ring image characteristics of an embodiment of the present application, Figure 2 is a schematic diagram of optical center modeling in an embodiment of the present application, Figure 3 is an equidistant mean brightness curve diagram of an embodiment of the present application, Figure 4 This is a flow chart of the abnormal circular image detection method of the optical fingerprint module according to the embodiment of the present application. Figure 1-4 , the abnormal circular ring image detection method of the optical fingerprint module of the embodiment of the present application is described in detail.

[0046] In an exemplary embodiment, the optical fingerprint module abnormal circular ring image detection method of the embodiment of this application is used to detect the abnormal circular ring image of the optical fingerprint module, so as to effectively screen out defective products damaged by electrostatic discharge to meet the needs of automated production.

[0047] In an exemplary embodiment, first, the optical fingerprint module is placed in a test environment, the color temperature in the test environment is 5000-5200K, the brightness of the light source is 900-1100lux, and the brightness of the light source is ensured to be uniform and stable to avoid stray light affecting the test.

[0048] First, in step 101, the optical fingerprint module is placed in a preset range in front of a light source, and the end face of the optical fingerprint module is parallel to the light source.

[0049] In an exemplary embodiment, after the test environment meets the standard, the optical fingerprint module is first placed 1 cm in front of the light source, and the end face of the optical fingerprint module is kept parallel to the light source.

[0050] Step 102, load the lens of the optical fingerprint module to the perspective position, adjust the gain of the sensor of the optical fingerprint module to 1x, and turn off the shading and mirroring functions.

[0051] In an exemplary embodiment, the lens of the optical fingerprint module is loaded to a telephoto position, and then the gain of the sensor of the optical fingerprint module is adjusted to 1x, and the shading and mirroring functions of the optical fingerprint module are turned off.

[0052] Step 103, adjusting the exposure value of the sensor of the optical fingerprint module to the brightness of the center of the picture to a preset value.

[0053] In an exemplary embodiment, the exposure value of the sensor of the optical fingerprint module is adjusted to a preset value of the brightness at the center of the picture, for example ... 128.

[0054] Step 104, capturing the picture under the illumination of the light source, counting the brightness of the picture and establishing a brightness histogram.

[0055] In an exemplary embodiment, an optical fingerprint module image under the illumination of a light source is captured, the brightness of the image is counted and a brightness histogram is established.

[0056] Step 105, taking the brightest area on the histogram, calculating the centroid of the brightest area, and taking the centroid as the optical center.

[0057] In an exemplary embodiment, the brightest area on the brightness histogram is taken, the centroid of the brightest area is calculated, and the centroid is used as the optical center.

[0058] In an exemplary embodiment, the brightest tenth area on the brightness histogram is taken to calculate the centroid, and the centroid is used as the optical center.

[0059] Step 106, calculating the radius of the minimum circumscribed circle of the picture with the centroid as the center.

[0060] In an exemplary implementation, the radius of the minimum circumscribed circle of the picture is calculated with the centroid as the center.

[0061] In an exemplary embodiment, the minimum circumscribed circle radius of the screen is Lmax, where the calculation formula of Lmax is: Lmax=Max(L1, L2, L3, L4), such as Figure 2 shown.

[0062] Step 107, taking the radius as the horizontal coordinate, calculating the average brightness of all image points on the same radius from the optical center, taking the average brightness as the vertical coordinate, and establishing a curve of center distance and average brightness.

[0063] In an exemplary embodiment, the radius is taken as the horizontal coordinate, and the value range of the radius is 0-Lmax.

[0064] In an exemplary embodiment, the brightness average value of all image points on the same radius of the optical center is calculated.

[0065] In an exemplary embodiment, a change curve of center distance and brightness average value is established with the brightness average value as the ordinate, such as Figure 3 shown.

[0066] Step 108: When a depression appears on the change curve, it is determined that the optical fingerprint module has electrostatic damage.

[0067] In an exemplary embodiment, due to the influence of the lens shadow, the overall picture appears to be bright in the middle and dark around, and the average brightness gradually decays with the increase of the optical center distance. Since the optical fingerprint module sensor damaged by static electricity has an abnormal circular image problem, a depression caused by this will appear on the brightness average curve. Through the above conversion, when an abnormal depression in the brightness curve is identified, it can be determined that the optical fingerprint module has been damaged by static electricity.

[0068] In an exemplary implementation, the change curve may be filtered as needed.

[0069] In an exemplary embodiment, the filtering process is to calculate the inflection point of the curve and filter and separate the concave features to eliminate interference items.

[0070] In an exemplary embodiment, after filtering, it is determined whether a depression appears on the variation curve after filtering. When a depression appears on the variation curve, it is determined that the optical fingerprint module has electrostatic damage.

[0071] In an exemplary embodiment, after filtering, it is determined whether a depression appears on the filtered variation curve. When no depression appears on the variation curve, it is determined that the optical fingerprint module does not have electrostatic damage.

[0072] Although the embodiments disclosed in the present invention are as above, the contents are only embodiments adopted to facilitate understanding of the present invention and are not intended to limit the present invention. Any technician in the field to which the present invention belongs can make any modifications and changes in the form and details of implementation without departing from the spirit and scope disclosed in the present invention, but the patent protection scope of the present invention shall still be subject to the scope defined in the attached claims.

Claims

1. A method for detecting abnormal circular ring images of an optical fingerprint module, characterized in that: include: Placing the optical fingerprint module in a preset range in front of the light source, with the end surface of the optical fingerprint module being parallel to the light source; Load the lens of the optical fingerprint module to the perspective position, adjust the gain of the sensor of the optical fingerprint module to 1x, and turn off the shading and mirroring functions; Adjust the exposure value of the sensor of the optical fingerprint module to the brightness of the center of the picture to a preset value; Capturing a picture illuminated by the light source, counting the brightness of the picture and establishing a brightness histogram; Taking the brightest area on the histogram, calculating the centroid of the brightest area, and taking the centroid as the optical center; Taking the centroid as the center, calculating the radius of the minimum circumscribed circle of the picture; Taking the radius as the abscissa, calculating the average brightness of all image points on the same radius from the optical center, taking the average brightness as the ordinate, establishing a curve of center distance and average brightness; When a depression appears on the change curve, it is determined that the optical fingerprint module has electrostatic damage.

2. The optical fingerprint module abnormal circular ring image detection method according to claim 1, characterized in that: Also includes: Placing the optical fingerprint module in a preset test environment; The preset test environment includes a color temperature of 5000-5200K and a brightness of 900-1100lux.

3. The optical fingerprint module abnormal circular ring image detection method according to claim 2, characterized in that: Placing the optical fingerprint module within a preset range in front of the light source includes placing the optical fingerprint module 1 cm in front of the light source.

4. The optical fingerprint module abnormal circular ring image detection method according to claim 3, characterized in that: The step of changing the exposure value of the sensor of the optical fingerprint module to a preset value of the brightness at the center of the picture includes changing the exposure value of the sensor of the optical fingerprint module to a brightness at the center of the picture of 128.

5. The optical fingerprint module abnormal circular ring image detection method according to claim 4, characterized in that: The brightness of the light source is uniform and stable.

6. The optical fingerprint module abnormal circular ring image detection method according to claim 5, characterized in that: The taking the brightest area on the histogram, calculating the centroid of the brightest area, and taking the centroid as the optical center includes taking the brightest one-tenth area on the histogram, calculating the centroid, and taking the centroid as the optical center.

7. The optical fingerprint module abnormal circular ring image detection method according to claim 1, characterized in that: When no depression appears on the change curve, it is determined that the optical fingerprint module has no electrostatic damage.

8. The optical fingerprint module abnormal circular ring image detection method according to claim 1, characterized in that: The method also includes filtering the change curve.

9. The optical fingerprint module abnormal circular ring image detection method according to claim 8, characterized in that: It is determined whether a depression appears on the change curve after the filtering process. When a depression appears on the change curve, it is determined that the optical fingerprint module has electrostatic damage.

10. The optical fingerprint module abnormal circular ring image detection method according to claim 9, characterized in that: It is determined whether a depression appears on the change curve after the filtering process. When no depression appears on the change curve, it is determined that the optical fingerprint module does not have electrostatic damage.

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