An optical fingerprint module abnormal annular image detection method

Abstract

The application discloses an optical fingerprint module abnormal annular image detection method, which comprises the following steps: placing an optical fingerprint module in a preset range in front of a light source, with the end surface of the optical fingerprint module being parallel to the light source; loading a lens of the optical fingerprint module to a far view position, adjusting the gain of a sensor of the optical fingerprint module to 1x, and closing the light shielding and mirror image functions; setting the exposure value of the sensor of the optical fingerprint module to a preset value of the center brightness of a picture; capturing the picture under the irradiation 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, taking the centroid as an optical center, and calculating the radius of the minimum circumscribed circle of the picture; taking the radius as the abscissa, counting the average brightness of all image points at the same radius from the optical center, taking the average brightness as the ordinate, and establishing a variation curve of the center distance and the average brightness; and when a concave part appears on the variation curve, it is judged that the optical fingerprint module is damaged by static electricity.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical fingerprint module, in particular to an optical fingerprint module abnormal annular image detection method. BACKGROUND

[0002] With the development of the intelligent mobile terminal industry, the screen ratio has become an important selling point index, and optical fingerprint and side fingerprint have been widely used because they can improve the screen ratio. Among them, optical fingerprint has become the fingerprint unlocking scheme recognized by most users due to its convenience and stickiness to the user's use habit of capacitive fingerprint. However, the optical fingerprint module will appear an abnormal black dot after being damaged by static electricity, that is, the so-called abnormal annular image, as shown in Figure 1 , which affects the accuracy of fingerprint identification and becomes a defective product.

[0003] How to detect whether the optical fingerprint module is damaged by static electricity has become a technical problem to be solved in the industry. SUMMARY

[0004] In order to at least solve the above technical problems, the purpose of the present application is to provide an optical fingerprint module abnormal annular image detection method, which can intuitively judge whether the optical fingerprint module is damaged by static electricity through a curve graph.

[0005] In order to achieve the above purpose, the optical fingerprint module abnormal annular image detection method provided by the present application comprises:

[0006] Place the optical fingerprint module in a predetermined range in front of the light source, and the end face of the optical fingerprint module is in parallel relationship with the light source;

[0007] Load the lens of the optical fingerprint module to a long-distance position, adjust the gain of the sensor of the optical fingerprint module to 1x, and close the light shielding and mirror image functions;

[0008] Set the exposure value of the sensor of the optical fingerprint module to the center brightness of the picture to a predetermined value;

[0009] Capture the picture under the irradiation of the light source, count the brightness of the picture and establish a brightness histogram;

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

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

[0012] Take the radius as the abscissa, count the average brightness of all image points at the same radius from the optical center, take the average brightness as the ordinate, and establish a change curve of the center distance and the average brightness;

[0013] When the concave appears on the change curve, it is judged that the optical fingerprint module has static damage.

[0014] Further, the method further comprises: setting the optical fingerprint module in a preset test environment.

[0015] The preset test environment comprises that the color temperature of the test environment is 5000-5200K, and the brightness is 900-1100lux.

[0016] Further, the preset range includes 1cm in front of the light source.

[0017] Further, the preset value includes 128.

[0018] Further, the light source is uniform and stable.

[0019] Further, the method further comprises: taking the brightest area on the histogram, calculating the centroid of the brightest area, and taking the centroid as the optical center.

[0020] Further, when the concave does not appear on the change curve, it is judged that the optical fingerprint module does not have static damage.

[0021] Further, the method further comprises: filtering the change curve.

[0022] Further, it is judged whether the concave appears on the change curve after filtering, and when the concave appears on the change curve, it is judged that the optical fingerprint module has static damage.

[0023] Further, it is judged whether the concave appears on the change curve after filtering, and when the concave does not appear on the change curve, it is judged that the optical fingerprint module does not have static damage.

[0024] The optical fingerprint module abnormal annular image detection method of the embodiment of the application comprises the following steps: placing the optical fingerprint module in a preset range in front of a light source, the end surface of the optical fingerprint module being in parallel with the light source; loading the lens of the optical fingerprint module to a far view position, adjusting the gain of the sensor of the optical fingerprint module to 1x, and closing the light shielding and mirror image functions; setting the exposure value of the sensor of the optical fingerprint module to a preset value of the center brightness of a picture; capturing a picture under the irradiation 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 abscissa, counting the average brightness of all image points at the same radius from the optical center, taking the average brightness as the ordinate, and establishing a variation curve of the center distance and the average brightness; when a concave part appears on the variation curve, it is judged that the optical fingerprint module is damaged by static electricity. Through the curve, it can be directly judged whether the optical fingerprint module is damaged by static electricity, the detection efficiency is improved, and the yield of subsequent products is guaranteed. BRIEF DESCRIPTION OF DRAWINGS

[0025] The accompanying drawings are included to provide a further understanding of the application, and constitute a part of the specification, illustrate the application, and are used to explain the application, but do not constitute a limitation on the application. In the drawings:

[0026] Figure 1 is an abnormal annular image picture feature schematic diagram of the embodiment of the application;

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

[0028] Figure 3 is an equidistance average brightness curve diagram of the embodiment of the application;

[0029] Figure 4 is a flowchart of the optical fingerprint module abnormal annular image detection method of the embodiment of the application. DETAILED DESCRIPTION

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

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

[0032] The term "comprising" and variations thereof as used herein are used inclusively, i.e., "comprising, but not limited to." The term "based on" is "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." Related terms have corresponding meanings.

[0033] It should be noted that the use of "a", "an", "the" and similar referents in the application are intended to be illustrative of the application and are not intended to be limiting. It will be understood by those skilled in the art that, unless otherwise specified, "a", "an", "the" and similar referents are used in the context of the application to mean "one or more". "Multiple" is understood to mean two or more.

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

[0035] The optical fingerprint module anomaly annular image detection method provided by the embodiment of the present application comprises:

[0036] The optical fingerprint module is placed within a preset range in front of a light source, and the end face of the optical fingerprint module is in parallel relationship with the light source;

[0037] The lens of the optical fingerprint module is loaded to a far view position, the gain of the sensor of the optical fingerprint module is adjusted to 1x, and the light shielding and mirror image functions are closed;

[0038] The exposure value of the sensor of the optical fingerprint module is adjusted to a preset value of the center brightness of a picture;

[0039] The picture under the irradiation of the light source is captured, the brightness of the picture is counted, and a brightness histogram is established;

[0040] The brightest area on the histogram is taken, the centroid of the brightest area is calculated, and the centroid is taken as the optical center;

[0041] The radius of the minimum circumscribed circle of the picture is calculated with the centroid as the center;

[0042] The radius is taken as the abscissa, the average brightness of all image points on the same radius from the optical center is counted, the average brightness is taken as the ordinate, and a variation curve of the center distance and the average brightness is established;

[0043] When a concave part appears on the variation curve, it is judged that the optical fingerprint module is damaged by static electricity.

[0044] Embodiment 1

[0045] Figure 1 is a schematic diagram of an abnormal annular image picture feature of an embodiment of the present application, Figure 2 is a schematic diagram of optical center modeling of an embodiment of the present application, Figure 3 is an equidistant mean luminance curve diagram of an embodiment of the present application, Figure 4 is a schematic diagram of an optical fingerprint module abnormal annular image detection method of an embodiment of the present application, and Figures 1-4 The optical fingerprint module abnormal annular image detection method of an embodiment of the present application will be described in detail below.

[0046] In an exemplary embodiment, the optical fingerprint module abnormal annular image detection method of an embodiment of the present application is used to detect the optical fingerprint module abnormal annular image, so as to effectively screen out defective products damaged by static electricity, thereby meeting the needs of automatic 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 900-1100 lux, and the uniformity and stability of the light source brightness are ensured to avoid the influence of stray light on the test.

[0048] First, in step 101, the optical fingerprint module is placed in a predetermined range in front of the light source, and the end face of the optical fingerprint module is in parallel relationship with 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 telephoto position, adjust the gain of the sensor of the optical fingerprint module to 1x, and close the light shielding and mirror image functions.

[0051] In an exemplary embodiment, the lens of the optical fingerprint module is loaded to the telephoto position, and then the gain of the sensor of the optical fingerprint module is adjusted to 1x, and the light shielding and mirror image functions of the optical fingerprint module are closed.

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

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

[0054] Step 104, capture the picture under the irradiation of the light source, count the brightness of the picture, and establish a brightness histogram.

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

[0056] In step 105, the brightest area on the histogram is taken, the centroid of the brightest area is calculated, and the centroid is taken 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 taken as the optical center.

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

[0059] In step 106, the radius of the minimum circumscribed circle of the picture is calculated with the centroid as the center.

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

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

[0062] In step 107, the average brightness of all image points at the same radius from the optical center is counted with the radius as the abscissa, the average brightness is taken as the ordinate, and a variation curve of the distance from the center and the average brightness is established.

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

[0064] In an exemplary embodiment, the average brightness of all image points at the same radius from the optical center is counted.

[0065] In an exemplary embodiment, the average brightness is taken as the ordinate, and a variation curve of the distance from the center and the average brightness is established, as shown in Figure 3 .

[0066] In step 108, when a concave appears on the variation curve, it is judged that the optical fingerprint module is damaged by static electricity.

[0067] In an exemplary embodiment, due to the influence of the lens shadow, the picture as a whole presents a condition of bright in the middle and dark around, and the average brightness gradually decays with the increase of the distance from the optical center. However, due to the problem of the abnormal circular ring image of the optical fingerprint module sensor damaged by static electricity, a concave caused thereby will appear on the average brightness curve. Through the above conversion, when the abnormal concave of the brightness curve is identified, it can be determined that the optical fingerprint module is damaged by static electricity.

[0068] In an exemplary embodiment, the change curve can also be filtered as needed.

[0069] In an exemplary embodiment, the filtering is to calculate the inflection point of the curve and screen out the features at the concave part, and exclude the interference terms.

[0070] In an exemplary embodiment, after the filtering, it is determined whether a concave part appears on the filtered change curve. When the concave part appears on the change curve, it is determined that the optical fingerprint module has static damage.

[0071] In an exemplary embodiment, after the filtering, it is determined whether a concave part appears on the filtered change curve. When the concave part does not appear on the change curve, it is determined that the optical fingerprint module does not have static damage.

[0072] Although the embodiments of the present application are disclosed as above, the content is only the embodiments adopted for the purpose of facilitating the understanding of the present application, and is not intended to limit the present application. Any modification and change in the form and details can be made by any person skilled in the art without departing from the spirit and scope of the present application. The patent protection scope of the present application shall be subject to the scope defined by the appended claims.

Claims

1. An optical fingerprint module anomaly annular image detection method, characterized in that, The method comprises the following steps: placing the optical fingerprint module in a preset range in front of a light source, the end face of the optical fingerprint module being parallel to the light source; loading the lens of the optical fingerprint module to a far view position, adjusting the gain of the sensor of the optical fingerprint module to 1x, and closing the light shielding and mirror image functions; adjusting the exposure value of the sensor of the optical fingerprint module to the preset value of the center brightness of the picture; capturing the picture under the irradiation 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 radius of the minimum circumscribed circle of the picture as the abscissa, counting the average brightness of all image points at the same radius from the optical center, and establishing a variation curve of the center distance and the average brightness taking the average brightness as the ordinate; when a concave appears on the variation curve, it is judged that the optical fingerprint module is damaged by static electricity. The method further comprises the following steps:

2. The method according to claim 1, wherein, placing the optical fingerprint module in a preset test environment; the preset test environment comprises that the color temperature of the test environment is 5000-5200K, and the brightness is 900-1100lux. The step of placing the optical fingerprint module in a preset range in front of a light source comprises placing the optical fingerprint module at 1cm in front of the light source.

3. The method according to claim 2, wherein, The step of adjusting the exposure value of the sensor of the optical fingerprint module to the preset value of the center brightness of the picture comprises adjusting the exposure value of the sensor of the optical fingerprint module to the center brightness of the picture to 128.

4. The method according to claim 3, wherein, The brightness of the light source is uniform and stable.

5. The method according to claim 4, wherein, The step of taking the brightest area on the histogram, calculating the centroid of the brightest area, and taking the centroid as the optical center comprises taking the tenth brightest area on the histogram to calculate the centroid, and taking the centroid as the optical center.

6. The method according to claim 5, wherein the method further comprises: determining whether the abnormal annular image is a circular image or an elliptical image. When no concave appears on the variation curve, it is judged that the optical fingerprint module is not damaged by static electricity.

7. The method according to claim 1, wherein the method further comprises: determining whether the image is a circular image; and if the image is a circular image, determining whether the image is a circular image of a fingerprint. The method further comprises filtering the variation curve.

8. The method according to claim 1, wherein, It is judged whether a concave appears on the variation curve after the filtering, and when a concave appears on the variation curve, it is judged that the optical fingerprint module is damaged by static electricity.

9. The method according to claim 8, wherein the method further comprises: determining whether the abnormal annular image is a circular image or an elliptical image. It is judged whether a concave appears on the variation curve after the filtering, and when no concave appears on the variation curve, it is judged that the optical fingerprint module is not damaged by static electricity.

10. The method according to claim 9, wherein the method further comprises: determining whether the abnormal annular image is a circular image or an elliptical image. ​

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