An optical sensor

Abstract

The embodiment of the present specification provides an optical sensor. The optical sensor comprises a microlens array composed of at least two microlenses and a sensor chip; the sensor chip is provided with photosensitive elements corresponding to the microlenses respectively; the microlens converges the light irradiated to the microlens to the photosensitive element corresponding to the microlens; the microlenses in the microlens array located at different field positions on the sensor chip have different lens structures, so as to improve the ratio of the illumination intensity of the light received by the photosensitive element corresponding to the microlens at the edge position to the illumination intensity of the light received by the photosensitive element corresponding to the microlens at the center position; and the photosensitive element is used for generating a corresponding photosensitive electrical signal according to the illumination intensity of the received light. The above-mentioned optical sensor improves the relative illumination of the array as a whole, and further improves the presentation effect of the finally obtained image.

Description

Technical Field

[0001] The embodiments in this specification relate to the field of optical sensing technology, and in particular to an optical sensor. Background Technology

[0002] With technological advancements and growing user demands, optical sensors have found widespread application in photography, measurement, and identity authentication. Based on the photoelectric effect, optical sensors convert light into electrical signals, which are then converted into voltage signals. Processing circuits, using pre-defined logic, synthesize these voltage signals from various optical sensors to create a corresponding image. Optical sensors require adjustments depending on the application environment. Under-display optical sensor technology has developed rapidly in recent years, providing guidance for the practical application of technologies such as under-display fingerprint recognition.

[0003] However, due to the limitations of under-display optical sensors in various applications, the light intensity and propagation direction differ across different areas of the under-display optical lens. This causes the illumination on the sensor chip to gradually decrease from the center outwards, resulting in uneven brightness distribution in the final image. The edges of the image are darker than the center, and in some cases, the edges may not even display the image correctly, severely impacting practical applications. Therefore, there is an urgent need for a technical solution that can effectively achieve uniform illumination of the optical lens. Summary of the Invention

[0004] The purpose of the embodiments in this specification is to provide an optical sensor that addresses the problem of how to improve the overall relative illumination of an optical sensor.

[0005] To address the aforementioned technical problems, this specification provides an optical sensor comprising a microlens array consisting of at least two microlenses and a sensor chip. The sensor chip is equipped with photosensitive elements corresponding to each microlens. Each microlens converges light incident upon it onto the corresponding photosensitive element. Microlenses located at different field-of-view positions on the sensor chip within the microlens array possess different lens structures to increase the ratio of light intensity received by the photosensitive element corresponding to the microlens at the edge to that received by the photosensitive element corresponding to the microlens at the center. The photosensitive element generates a corresponding photoelectric signal based on the received light intensity.

[0006] As can be seen from the technical solutions provided in the embodiments of this specification above, when arranging the microlenses in the microlens array, the microlenses positioned at different field-of-view locations on the sensor chip have different lens structures. This increases the ratio of the light intensity received by the photosensitive elements corresponding to the microlenses at the edges to the light intensity received by the photosensitive elements corresponding to the microlenses at the center. This ensures that when the light illuminating the microlenses is focused onto the photosensitive elements corresponding to the microlenses, even if the angle and intensity of the incident light differ among the microlenses in the microlens array, the light can be effectively focused and the light intensity compensated based on their respective lens structures. This guarantees the light intensity received by the photosensitive elements corresponding to the microlenses at the edges, improves the overall relative illumination of the array, and ultimately improves the final image presentation. Simultaneously, it enhances the sensitivity of the photosensitive elements located at the edges, reducing the burden of subsequent light intensity compensation. Attached Figure Description

[0007] To more clearly illustrate the technical solutions in the embodiments or prior art of this specification, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this specification. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0008] Figure 1 This is a structural diagram of an optical sensor according to an embodiment of this specification;

[0009] Figure 2 This is a schematic diagram of the structure of an optical lens according to an embodiment of this specification;

[0010] Figure 3A This is a schematic diagram of light convergence from a microlens at the central field of view in an embodiment of this specification.

[0011] Figure 3B This is a schematic diagram of light convergence from a microlens at an edge field of view, as described in an embodiment of this specification.

[0012] Figure 4A This is a schematic diagram of a lens structure for a microlens according to an embodiment of this specification;

[0013] Figure 4B This is a schematic diagram of a lens structure for a microlens according to an embodiment of this specification;

[0014] Figure 4C This is a schematic diagram of a lens structure for a microlens according to an embodiment of this specification;

[0015] Figure 5This is a comparative schematic diagram of a light intensity variation curve according to an embodiment of this specification;

[0016] Figure 6 This is a flowchart illustrating a method for adjusting the surface profile coefficient of each lens structure in a microlens array, as described in this specification. Detailed Implementation

[0017] The technical solutions in the embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this specification, and not all embodiments. Based on the embodiments in this specification, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this specification.

[0018] To address the aforementioned technical problems, this specification introduces an embodiment of an optical sensor. For example... Figure 1 As shown, the optical sensor includes at least a microlens array 110 and a sensor chip 130. The microlens array 110 may include at least two microlenses 111; the sensor chip 130 typically has photosensitive elements 131 corresponding to each microlens 111 disposed on its active area (AA). In some embodiments, the optical sensing system further includes a light-shielding layer 120 disposed between the microlens array 110 and the sensor chip 130. The light-shielding layer 120 may have light-transmitting holes 121 corresponding to each microlens 111, so that light collected by the microlenses 111 shines onto the corresponding photosensitive element 131 through the corresponding light-transmitting hole 121, and prevents crosstalk between light received by different photosensitive elements 121.

[0019] In some embodiments, a plurality of photosensitive elements 131 are disposed on the active area (AA) of the sensor chip 130, each photosensitive element 131 being a pixel unit. The sensor chip 130 may include a pixel array composed of multiple pixel units arranged in an array. Correspondingly, these microlenses 111 may also be combined into an array according to the arrangement of the pixel units. The microlens array can have different arrangement forms. For example, the microlenses 111 can be arranged in a rectangular form in a square array, or in a circular array with the center of the array of the sensor chip 130 as the center, or in a radial form radiating outward from the center of the array. In practical applications, the arrangement of the microlenses in the microlens array 110 can be designed based on the actual situation, taking into account the incident light range and the structure of the sensor itself, and will not be elaborated further here.

[0020] The microlenses 111 in the microlens array 110 can focus the light they receive onto the corresponding photosensitive element 131, so that the photosensitive element 131 generates a corresponding charge signal based on the different light intensities received, which is then converted into a voltage signal for processing by the corresponding processing logic in the electronic circuit, and finally realizes the generation of an image.

[0021] In some embodiments, an optical lens is also disposed above the microlens array 110. Figure 1 (Not shown). The scene above the lens (taking an optical fingerprint sensor as an example, the scene above the lens is the ridges and valleys on a person's fingerprint) reflects light, and the reflected light is received by the optical lens. Then, the light received by different areas of the optical lens and different incident directions is converged to different positions of the microlens array 110. Thus, the light received by different microlenses 111 is reflected by different parts of the scene. Based on the processing logic of the subsequent digital circuit, the image information of the object in front of the optical lens can be restored by integrating the images of each part.

[0022] Based on the appendix Figure 2 Further explanation is needed regarding the above situation. For example... Figure 2 The diagram shown is a schematic of the optical lens 140 in front of the microlens array 110. The optical lens 140 includes multiple lenses and aperture stops. This invention does not limit the structure of the optical lens 140, as... Figure 2 The optical lens shown includes three lenses, which can be either convex or concave, designed according to specific optical requirements. In the geometric optical system design of the optical lens 140, the principal ray originates from the object side (e.g., a fingerprint), passes through the center of the pupil, and reaches the edge of the image, determining the image height on the sensor chip 130. The edge rays originate from the center of the object side, pass through the edge of the pupil, and reach the center of the sensing area of ​​the sensor chip 130, determining the image position on the sensor chip 130. The sensor chip 130 is divided into different field-of-view positions according to different image heights (or by field-of-view angle; the division of field-of-view positions will be detailed later). Rays incident on the central region of the optical lens 140 (i.e., edge rays) need to be received by the microlens 111 located in the central region of the field-of-view position, while rays incident on the edge region of the optical lens 140 (i.e., principal rays) and rays received at large angles of tilt need to be received by the microlens 111 located in the edge region of the field-of-view position. The microlenses 111 are arranged according to the above principles to form a microlens array 110.

[0023] However, in the above-described situation, if the microlenses 111 in the microlens array 110 adopt a uniform lens structure, the light intensity corresponding to the microlenses 111 in the central region of the microlens array 110 is generally higher, and after being focused onto the corresponding photosensitive element 131, the photosensitive element 131 also has a higher illuminance. Meanwhile, the light intensity received by the microlenses 111 in the edge region of the microlens array 110 is generally lower, and due to the aforementioned reason, the direction of light received by the microlenses 111 in the edge region is more oblique. Therefore, the microlenses 111 in a normal configuration may not be able to focus the light directly downwards after receiving it, and there may even be a situation where the focal length cannot correspond to the photosensitive element 131.

[0024] like Figure 3A and Figure 3B The diagrams illustrate the two scenarios described above. Figure 3A The microlens 111 corresponding to the central region of the microlens array 110 can better focus light at a normal angle onto the photosensitive element 131; Figure 3B The microlens 111 corresponding to the edge region of the microlens array 110 cannot effectively focus the light onto the photosensitive element 131 because the light received is at an angle. The angle of the converged light is too large, and it may not be able to correspond to the photosensitive element 131.

[0025] In the above situation, the illuminance corresponding to the photosensitive element 131 in the center of the sensor chip 130 may be much higher than that of the photosensitive element 131 in the edge part, resulting in an excessively large difference in overall relative illuminance. This ultimately leads to the generated image having high brightness in the middle and low brightness around the edges, which seriously affects the subsequent use of the image.

[0026] To address the aforementioned issues, in the embodiments of this specification, the microlenses 111 arranged on the sensor chip 130 at different field-of-view positions in the microlens array 110 have different lens structures. The optical path system of the aforementioned microlens array 110 with different lens structures arranged at different field-of-view positions is tested to achieve the following: compared to the original microlens array 110 (e.g., the same lens structure is arranged at different field-of-view positions), the ratio of the light intensity received by the photosensitive element 131 corresponding to the microlens 111 arranged at the edge position to the light intensity received by the photosensitive element 131 corresponding to the microlens 111 arranged at the center position can be increased, thereby effectively improving the illuminance of the photosensitive element 131 in the edge region relative to the photosensitive element 131 in the center region, that is, increasing the relative illuminance of the edge region relative to the center region, and improving the overall image presentation effect.

[0027] Specifically, the microlens 111 can be an aspherical structure to adapt to the converging effect of light from different directions. For example... Figure 4A , Figure 4B and Figure 4C The diagram shows a schematic representation of a microlens 111 with different aspherical structures. Based on the different aspherical structures of the microlens 111, light rays from tilted directions can be converged to the photosensitive element 131 directly below the microlens 111 according to the needs of different field-of-view positions, thereby ensuring the overall image presentation effect. It should be noted that in practical applications, the structure of the microlens 111 is not limited to the example shown in the diagram and can be adjusted based on the specific application.

[0028] In some embodiments, the lens structure of the microlens 111 has multiple aspect ratios. Different microlenses 111 can correspond to different aspect ratio values. That is, there is at least one different aspect ratio among microlenses 111 with different lens structures. The aspect ratio is used to adjust the refraction effect of the microlens 111 on light to ensure that the microlens 111 can focus light onto the corresponding photosensitive element 131 according to the needs of different field positions. In other words, the lens structure selection of the microlens 111 needs to meet preset conditions.

[0029] In some specific embodiments, the goal of adjusting the different aspect ratios of different lens structures is to achieve the following: in different field-of-view positions, the ratio of the illumination intensity of the photosensitive element 131 corresponding to the microlens 111 at the edge position to the illumination intensity of the photosensitive element 131 corresponding to the microlens 111 at the center position is greater than the relative illuminance threshold. For example, if all microlenses 111 have a conventional spherical structure before adjustment, the ratio of the illumination intensity received by the photosensitive element 131 at the edge position to that at the center position (i.e., the relative illuminance RI) is 20%. The goal of adjusting the different aspect ratios of different lens structures is to increase this ratio (i.e., the relative illuminance RI) to 43%, where the relative illuminance threshold is 43%. Specifically, the aspect ratio of the microlens 111 at the edge position can be adjusted to converge the originally deflected light onto the corresponding photosensitive element 131, thereby increasing the illumination intensity of the photosensitive element 131 at the edge position, thus achieving the aforementioned goal of adjusting the different aspect ratios of different lens structures (meeting preset conditions). Assuming that the light intensity of the photosensitive element 131 at the edge position is increased to a limit of 30%, the aspect ratio of the microlens 111 at the center position needs to be further adjusted to sacrifice the light that would originally be received by the photosensitive element 131 at the center position, thereby reducing the light intensity of the photosensitive element 131 at the center position, for example, to 70% of the original (0.3 divided by 0.7 = 43%), thus achieving the aforementioned goal of adjusting the different aspect ratios of different lens structures (satisfying the preset condition). Since the light intensity received by the photosensitive element 131 corresponding to the microlens 111 at the edge position is usually the lowest, the aforementioned preset condition is equivalent to: making the ratio of the light intensity received by the photosensitive element 131 corresponding to the microlens 111 at all field positions to that received by the photosensitive element 131 at the center position (i.e., relative illuminance RI) greater than this relative illuminance threshold (for example, 43%), thereby making the relative illuminance curve region of the entire optical system smooth.

[0030] In another specific embodiment, the adjustment method is to reduce the light intensity of the photosensitive element 131 corresponding to the microlens 111 at the center position to a threshold light intensity. The center position refers to a location within a preset center distance from the center of the sensor chip 130. As mentioned earlier, the sensor chip 130 is divided into different field-of-view positions based on its center as the origin, according to different image heights or field angles (how this division is done will be detailed later). This adjustment method involves reducing and equalizing the light intensity of the photosensitive elements 131 corresponding to all microlenses 111 within the preset center distance range to the same value (threshold light intensity). For example, if all microlenses 111 have a traditional spherical lens structure before adjustment, the light intensity received by the photosensitive element 131 at the center position gradually decreases. Figure 5On the "original" curve, the distance between the 0.3F field of view and the origin is the preset center distance. The illumination intensity before adjustment from 0 to 0.3F is gradually reduced. The adjustment method can be achieved by gradually adjusting the surface coefficient of each microlens 111 in the 0 to 0.3F (center position) range, thereby reducing and equalizing the illumination intensity of the photosensitive element 131 within the center position range to the threshold light intensity (e.g., ...). Figure 5 The “0.3F” curve (the threshold light intensity is 90% of the original maximum light intensity) is used to achieve the aforementioned adjustment target (meeting the preset conditions) and increase the relative illumination of the photosensitive element 131 at the edge position.

[0031] In a specific example, the lens structure of microlens 111 is an axisymmetric high-order aspherical surface. Therefore, in order to achieve a quantitative description of the lens structure of microlens 111, the structure of microlens 111 can be based on the formula under the influence of the surface shape coefficient. In the formula, Z represents the sag of the microlens 111 along the optical axis, c represents the paraxial curvature of the surface of the microlens 111, and h represents the coordinate position of the point on the surface of the microlens 111. 2 =x 2 +y 2 x and y are the coordinates of the corresponding planar positions, k is the quadratic surface coefficient, a2, a4, a6, a8, a 10 This refers to the surface coefficient that needs to be adjusted according to the aforementioned objectives.

[0032] It should be noted that, based on the optimized accuracy of microlens 111, the effects of other surface coefficients can be added after the above formula, for example, it could be a. 12 h 12 a 14 h 14 The specific optimizations can be adjusted based on the actual application requirements, and will not be elaborated here.

[0033] Now for reference Figure 6 , Figure 6 This is a flowchart illustrating a method for adjusting the surface profile coefficients of each lens structure in a microlens array, as described in this specification. First, step S601 is executed: To ensure the adjustment of the surface profile coefficients a2, a4, a6, a8, a... 10 The actual application effect of the adjusted microlens 111 is determined by the different surface coefficients [a12 a14 a16 a18 a1] of each microlens 111 in the microlens array 110. 10 ]、[a22 a24 a26 a28 a2 10 ]、[a32 a34 a36 a38 a3 10When..., a set of candidate surface shape coefficients can be proposed first (including candidate surface shape coefficients of multiple microlenses 111 [a1′2 a1′4 a1′6 a1′8 a1′...). 10 ], [a2′2 a2′4a2′6 a2′8 a2′ 10 ], [a3′2 a3′4 a3′6 a3′8 a3′ 10 ...and so on), in step S601, the candidate surface shape coefficients [a1′2 a1′4 a1′6 a1′8 a1′] of each microlens 111 will be determined based on the results of subsequent measurements. 10 ], [a2′2 a2′4a2′6 a2′8 a2′ 10 ], [a3′2 a3′4 a3′6 a3′8 a3′ 10 Adjustments are made for the candidate surface type coefficients [a1′2 a2′4 a1′6 a1′8 a1′...]. It is worth noting that the candidate surface type coefficients [a1′2 a2′4 a1′6 a1′8 a1′...] are adjusted accordingly. 10 ], [a2′2 a2′4 a2′6 a2′8 a2′ 10 ], [a3′2 a3′4 a3′6 a3′8a3′ 10 ...These can be pre-generated variable parameters using the corresponding program, or parameters formulated based on the developer's experience; there are no restrictions on this. The initial microlens can be a predefined microlens with a uniform structure, and the initial microlens in subsequent loops is the microlens to be tested after the previous adjustment.

[0034] Then, step S602 is executed: using the candidate surface shape coefficients (including the candidate surface shape coefficients of multiple microlenses 111 [a1′2 a2′4 a1′6 a1′8 a1′]) 10 ], [a2′2 a2′4 a2′6 a2′8 a2′ 10 ], [a3′2 a3′4 a3′6 a3′8 a3′ 10 (...and so on) the lens structure of the initial microlens is adjusted to obtain the structure of the microlens to be tested.

[0035] After completing the adjustment in step S602, step S603 is executed to measure the characteristic parameters corresponding to the microlens structure under test. The measurement process can involve placing the microlens under test at the corresponding position in the microlens array 110 for actual measurement, or obtaining the characteristic parameters through simulation using optical system simulation software such as ZMAX. The characteristic parameters can be used to represent the effect of the microlens under test on the convergence of corresponding light rays onto the corresponding photosensitive element 131. Specifically, they can include at least one of focal length F, relative illuminance RI, illumination intensity, incident light angle, and emitted light area, wherein the relative illuminance can be the result of comparing the illuminance of a specific microlens with a predetermined value.

[0036] Next, step S604 is executed, which compares the measured characteristic parameters with the boundary conditions to determine whether the characteristic parameters meet the boundary conditions. If these characteristic parameters meet the boundary conditions, step S605 is executed to determine whether the relative illumination RI meets the aforementioned preset conditions (e.g., the adjustment target of the RI curve).

[0037] If the judgment result obtained based on step S605 is yes, then step S606 is executed to determine the current candidate surface type coefficients [a1′2 a2′4 a1′6 a1′8 a1′ 10 ], [a2′2 a2′4 a2′6 a2′8 a2′ 10 ], [a3′2 a3′4a3′6 a3′8 a3′ 10 ... represents the surface profile coefficients of each microlens 111 [a12 a14 a16 a18 a1] 10 ]、[a22 a24a26 a28 a2 10 ]、[a32 a34 a36 a38 a3 10 ... Accordingly, the microlens structure to be tested corresponding to the current candidate surface shape coefficient can be used as the lens structure in each of the microlens array 110 for adjusting the output, and the adjustment process for the lens structure of microlens 111 ends.

[0038] Specifically, the boundary conditions in step S604 may include the following: the focal length F of the microlens 111 falls on the photosensitive element 131 of the sensor chip 130; the overall relative illuminance RI of all photosensitive elements 131 meets the target relative illuminance requirement; the light intensity is greater than the light intensity threshold; and the emitted light area is within at least one of the following areas of the photosensitive element 131. The incident light angle corresponding to the microlens under test can be used to adjust the specific parameters of the boundary conditions. The preset conditions in step S605, for example, are determined by a specific evaluation function. Figure 5Whether the relative illuminance curve shown meets the requirements of the target RI curve, so as to achieve that the ratio of the light intensity of the photosensitive element 131 at the edge position to the light intensity of the photosensitive element 131 at the center position is greater than the relative illuminance threshold, or to bring the light intensity of the photosensitive element 131 at the center position to the threshold light intensity, so as to ensure the uniformity of illuminance and improve the overall quality of the final image.

[0039] If the measured characteristic parameters do not meet the boundary conditions (No in step S604) or the relative illumination RI does not meet the preset conditions (No in step S605), the process of adjusting the candidate surface shape coefficient (step S601), adjusting the microlens structure under test using the adjusted candidate surface shape coefficient (step S602), and measuring the characteristic parameters corresponding to the adjusted microlens structure under test (step S603) can be repeated until the characteristic parameters meet the boundary conditions and the preset conditions are also met. Then, the final candidate surface shape coefficient is determined as the surface shape coefficient.

[0040] In practical applications, the light received by the microlens 111 is generally from the optical lens 140 in front of the microlens array 110 (e.g., Figure 2 As shown, the light rays converged by the optical lens 140 correspond to a field of view, which describes the field of view range of the optical lens 140. Typically, the field of view is designed to cover the area (AA region) where all photosensitive elements 131 on the sensor chip 130 are located. The coverage area is a circle with the diagonal of the area (AA region) where the photosensitive elements 131 on the sensor chip 130 are located as its diameter; that is, the outer circle of the area (AA region) where the photosensitive elements 131 on the sensor chip 130 are located. This is because the imaging circle needs to be larger than the AA region to ensure that all photosensitive elements 131 (e.g., all pixel units of the pixel array) can receive light. The field of view coverage of the optical lens 140 is divided into different field of view positions: For example, half of the diagonal of the AA area of ​​the sensor chip 130 can be divided into 11 field of view positions [0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0] based on the field of view of the optical lens 140; Alternatively, the field of view can be divided into different positions. Figure 2The image height mentioned in the description is divided into, for example, 11 field-of-view positions [0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0], where each field-of-view position corresponds to an image height. The image height at field-of-view position 1.0 is half the diagonal of the sensor chip 130, representing the field-of-view position with the maximum image height. Correspondingly, microlenses 111 with corresponding lens structures can be set at different field-of-view positions. One microlens 111 or multiple microlenses 111 may be set within the same field-of-view position; this invention does not impose any limitations. Therefore, to ensure overall consistency in relative illumination, the microlenses 111 within the same field of view can correspond to a uniform lens structure. However, when installing the microlenses 111, the installation orientation needs to be adjusted based on the installation location to ensure that the incident light is effectively focused onto the photosensitive element 131, thereby ensuring overall relative illumination balance and optimizing the overall image presentation effect.

[0041] In practical applications, due to the overall structure of the optical sensor and the application environment, the light intensity of the microlenses 111 illuminating different areas naturally varies. For example, the light intensity of the incident light corresponding to the center of the pixel array (i.e., the 0 field of view position) is 1.0, while the light intensity of the incident light corresponding to the edge of the pixel array (i.e., the 1.0 field of view position) is only 0.3. In this case, no matter how much the lens structure of the microlenses 111 at the edge of the pixel array (i.e., the 1.0 field of view position) is optimized, the light intensity of the outgoing light from the microlenses 111 at the edge of the pixel array can only be made infinitely close to 0.3. The relative illumination of the photosensitive element 131 at the edge position compared to the photosensitive element 131 at the center is still too small, and the resulting image still cannot present a good overall presentation effect.

[0042] To address the aforementioned issues, in some embodiments, at least one microlens 111 located within a preset center distance from the pixel array center (i.e., the 0 field-of-view position) can be designated as a central microlens. Microlenses 111 encompassed within a radius centered on the 0 field-of-view position and extending to the preset center distance can all be considered central microlenses. For example, microlenses 111 at field-of-view positions of [0, 0.1, 0.2, 0.3] can be designated as central microlenses.

[0043] Because the incident light intensity corresponding to the central microlens is relatively high, and the converged light rays can generally be well focused onto the photosensitive element 131, the illuminance of the photosensitive element 131 corresponding to the central microlens is greater than that of the other photosensitive elements 131. Therefore, in order to balance the relative illuminance, the lens structure of the central microlens can be adjusted to reduce the light intensity of the converged light rays, and the degree of reduction decreases as the distance between the central microlens and the 0 field of view position increases.

[0044] Based on the above example, assuming the incident light intensity at the 0 field-of-view position is 1.0 and the incident light intensity at the 1.0 field-of-view position is 0.3, after optimizing the lens structure of the microlens at the edge field-of-view positions, the outgoing light intensity of the microlens at the edge field-of-view positions can reach 0.29. Without adjusting the lens structure of the central microlens, assuming the outgoing light intensity of microlens 111 at the 0 field-of-view position is 0.9, the relative illumination is 0.29 / 0.9 = 0.32. However, by reducing the light intensity of the light from the central microlens, assuming the outgoing light intensity is 0.7, the relative illumination increases to 0.29 / 0.7 = 0.41, thereby improving the overall image presentation.

[0045] Since the light intensity received by microlens 111 generally decreases gradually from the center outwards, when using the central microlens to reduce the light intensity, preferably, the degree of light reduction decreases as the distance between the central microlens and the 0 field-of-view position increases. That is, the microlens 111 at the 0 field-of-view position has the greatest light reduction, while the microlens at the outermost edge of the 0 field-of-view position, for example, at a 0.3 field-of-view position, has the smallest light reduction. This balance ensures that the emitted light corresponding to the central microlens has a basically consistent light intensity, thereby further improving the relative illumination between the photosensitive elements 131 and optimizing the overall image presentation.

[0046] Specifically, the microlens in the center can reduce the light intensity by adjusting the microlens structure to deflect light that is not perpendicularly incident on the photosensitive element 131. This deflected light prevents it from reaching the photosensitive element 131, resulting in the final emitted light consisting only of perpendicularly incident light and a portion of the non-perpendicularly incident light, thus reducing light intensity. Specific application methods can be adjusted based on actual needs and will not be elaborated further here. It is worth noting that the deflected light is absorbed by a metal layer or blackened area placed between the photosensitive units 131 (e.g., different pixel units) to prevent crosstalk to adjacent photosensitive units 131.

[0047] In some embodiments, the specific degree to which the central microlens reduces the light intensity can be adjusted based on the relative illuminance requirements. Specifically, a relative illuminance threshold can be preset, which limits the minimum relative illuminance between the light intensities of the emitted light corresponding to different microlenses 111. By adjusting the central microlens, the light intensity of the emitted light from the central microlens is reduced, so that the relative illuminance of the photosensitive elements 131 corresponding to the photosensitive elements 131 of microlenses other than the central microlens is increased to a level greater than the relative illuminance threshold.

[0048] Since the microlenses 111 at the edge of the microlens array 110 generally have the minimum illuminance, the relative illuminance of the microlens at the 0 field of view position can be directly compared with that of the microlens at the 1.0 field of view position. Based on the comparison result between the minimum relative illuminance and the relative illuminance threshold, the overall surface shape can be adjusted so that the minimum relative illuminance is greater than the relative illuminance threshold, thus ensuring the convenience of the adjustment process.

[0049] To illustrate the above effect, let's take a concrete example, such as... Figure 5 The diagram shows the variation in light intensity. The horizontal axis represents the field-of-view position of the microlens 111. In this example, 11 field-of-view positions are obtained based on the field-of-view angle or image height of the optical lens 140, corresponding to 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and 1 on the horizontal axis. Field-of-view position 0 corresponds to the center of the AA area of ​​the sensor chip 130, and field-of-view position 1 corresponds to the position of the photosensitive unit 131 at the outermost edge of the AA area of ​​the sensor chip 130. The vertical axis represents the light intensity corresponding to the microlens 111 (note that...). Figure 5 Normalization was performed using the maximum illuminance in the 0 field of view before adjustment as the denominator (therefore, illuminance is expressed as a percentage). Without adjusting the lens structure of microlens 111, the relative illuminance curves of each field of view relative to the initial illuminance are shown in the original curve in the figure, exhibiting a gradually declining trend. In this case, the relative illuminance at field position 1 is approximately 30% compared to field position 0, resulting in a relatively uneven overall relative illuminance distribution. If the above method is adopted, by setting microlenses of different surface shapes at the 0, 0.1, 0.2, and 0.3 field positions, the illuminance within the 0.3F field position is brought to 90% of the initial illuminance at the 0 field position, thus significantly improving the overall relative illuminance effect. The curves after bringing the illuminance within the 0.5F and 0.7F field positions together can also be seen from... Figure 5 The sensor's overall relative illumination changes are relatively smooth, which ensures the consistency of the overall presentation effect.

[0050] It should be noted that, since the photosensitive element 131 needs to meet the condition that the light intensity is greater than a certain threshold when generating charge based on the photoelectric effect, when adjusting the degree of light reduction by the central microlens, the effective excitation of charge by the photosensitive element 131 should also be considered to ensure the normal operation of the sensor.

[0051] When light is focused onto the photosensitive element 131 using the microlens 111, the photodiode in the photosensitive element 131 generates a corresponding signal charge based on the photoelectric effect. After exposure, the transmission electrode gate opens, allowing the generated signal charge to be transferred to the floating diffusion layer for accumulation. The charge is then picked up by the MOSFET electrode gate and converted into a voltage signal, which is the photoelectric signal. This photoelectric signal can be used to reflect relevant parameters of the received light, such as illuminance and frequency. After the optical sensor transmits the signal to the corresponding electronic circuit, the processing logic in the electronic circuit comprehensively processes the photoelectric signal to generate a corresponding image.

[0052] Optical sensors can be applied to a range of image sensing fields, such as identity authentication, where they can authenticate users by capturing images of their biometric information. Specifically, optical sensors can be used in under-display fingerprint recognition devices, where they capture the image of a user's fingerprint under illumination to authenticate the user and ensure information security. In practical applications, optical sensors can also be used in other specific devices to achieve similar functions, which will not be elaborated upon here.

[0053] As can be seen from the above embodiments, when arranging microlenses in a microlens array, the microlenses positioned at different field-of-view locations on the sensor chip have different lens structures. This ensures that the ratio of the light intensity received by the photosensitive element corresponding to the microlens at the edge to the light intensity received by the photosensitive element corresponding to the microlens at the center is greater than a threshold. When the light illuminating the microlens is focused onto the photosensitive element corresponding to the microlens, even if the angle and intensity of the incident light corresponding to each microlens in the microlens array differ, the light can be effectively focused and the light intensity compensated based on its respective lens structure. This ensures the light intensity received by the photosensitive elements corresponding to the microlenses at the edge, improves the overall relative illumination of the array, and thus improves the final image presentation. Simultaneously, it increases the sensitivity of the photosensitive elements located at the edges, reducing the burden of subsequent light intensity compensation.

[0054] Although the process described above includes multiple operations that appear in a specific order, it should be clearly understood that these processes may include more or fewer operations, which may be executed sequentially or in parallel (e.g., using parallel processors or a multithreaded environment).

[0055] Although the process described above includes multiple operations that appear in a specific order, it should be clearly understood that these processes may include more or fewer operations, which may be executed sequentially or in parallel (e.g., using parallel processors or a multithreaded environment).

[0056] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this specification. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0057] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0058] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0059] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0060] Memory may include non-persistent storage in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0061] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0062] Those skilled in the art will understand that the embodiments of this specification can be provided as methods, systems, or computer program products. Therefore, the embodiments of this specification can take the form of entirely hardware embodiments, entirely software embodiments, or embodiments combining software and hardware aspects. Furthermore, the embodiments of this specification can take the form of computer program products implemented on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0063] The embodiments described in this specification can be described in the general context of computer-executable instructions, such as program modules, that are executed by a computer. Generally, program modules include routines, programs, objects, components, data structures, etc., that perform a specific task or implement a specific abstract data type. The embodiments of this specification can also be practiced in distributed computing environments where tasks are performed by remote processing devices connected via a communication network. In distributed computing environments, program modules can reside in local and remote computer storage media, including storage devices.

[0064] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, system embodiments are basically similar to method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments. In the description of this specification, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the embodiments in this specification. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0065] The above description is merely an embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of this application should be included within the scope of the claims of this application.

Claims

1. An optical sensor, characterized in that, It includes a microlens array consisting of at least two microlenses and a sensor chip; the sensor chip is provided with photosensitive elements corresponding to each microlens; The microlens converges the light incident on the microlens onto the corresponding photosensitive element. The microlenses located at different field-of-view positions on the sensor chip in the microlens array have different lens structures to increase the ratio of the light intensity received by the photosensitive element corresponding to the microlens at the edge position to the light intensity received by the photosensitive element corresponding to the microlens at the center position. The lens structure is an aspherical structure with multiple aspect ratios, and there is at least one different aspect ratio among the different lens structures. The surface shape coefficient is determined in the following way: The initial microlens structure is adjusted based on the candidate surface shape coefficient to obtain the microlens structure to be tested; Measure the characteristic parameters corresponding to the microlens structure under test; the characteristic parameters include at least one of focal length, overall relative illuminance, light intensity, incident light angle, and outgoing light area; If the characteristic parameters meet the boundary conditions, determine whether the relative illumination meets the preset conditions; If the relative illumination meets the preset conditions, the candidate surface coefficient is determined to be a surface coefficient; The preset conditions include: the ratio of the light intensity of the photosensitive element corresponding to the microlens at the edge position to the light intensity of the photosensitive element corresponding to the microlens at the center position is greater than the relative illuminance threshold; and / or the light intensity of the photosensitive element corresponding to the microlens at the center position is reduced to the threshold light intensity, wherein the distance between the center position and the center of the sensor chip is within a preset center distance. Among them, at least one microlens that is within a preset center distance from the center of the sensor chip is a central microlens; the lens structure of the central microlens is used to reduce the light intensity of the collected light, and the degree of reduction decreases as the distance between the central microlens and the center of the sensor chip increases; The photosensitive element is used to generate a corresponding photoelectric signal based on the light intensity of the received light.

2. The optical sensor as described in claim 1, characterized in that, The surface shape coefficient is used to change the deflection effect of the microlens on light to meet preset conditions.

3. The optical sensor as described in claim 2, characterized in that, After measuring the characteristic parameters corresponding to the microlens structure under test, the method further includes: If the feature parameters do not meet the boundary conditions or the relative illumination does not meet the preset conditions, the steps of adjusting the candidate surface shape coefficient, adjusting the microlens structure under test using the adjusted candidate surface shape coefficient, and measuring the feature parameters corresponding to the adjusted microlens structure under test are repeated until the feature parameters meet the boundary conditions and the relative illumination meets the preset conditions. The candidate surface shape coefficients are determined to be surface shape coefficients.

4. The optical sensor as described in claim 3, characterized in that, The boundary conditions include: The focal length of the microlens is on the photosensitive element, and / or The overall relative illuminance meets the target relative illuminance requirements, and / or The light intensity is greater than the light intensity threshold, and / or The emitted light area is within the area of ​​the photosensitive element.

5. The optical sensor as described in claim 2, characterized in that, The lens structure is an axisymmetric aspherical structure, and the lens structure of the microlens is based on the formula... In other words, in the formula, Let be the sagittal height of the microlens along the optical axis. The paraxial curvature of the microlens surface is given by [the value of the value]. The coordinates of the points on the surface of the microlens are given. For quadratic surface coefficients, , , , , is the surface shape coefficient.

6. The optical sensor as described in claim 5, characterized in that, The reduction of the light intensity of the received light includes: Light rays that are not incident perpendicularly on the corresponding photosensitive element are deflected so that the deflected light rays cannot illuminate the corresponding photosensitive element.

7. The optical sensor as described in claim 6, characterized in that, The central microlens reduces the light intensity of the collected light so that the ratio of the light intensity of the photosensitive element corresponding to the microlens other than the central microlens to the light intensity of the photosensitive element corresponding to the central microlens is increased.

8. The optical sensor as described in claim 1, characterized in that, The light received by the microlens includes light converged by an optical lens in front of the microlens array; the optical lens has a field of view that covers the area where the photosensitive element is located on the sensor chip; the field of view coverage is divided into different field of view positions.

9. The optical sensor as claimed in claim 1, characterized in that, The optical sensor also includes a light-shielding layer disposed between the microlens array and the sensor chip; the light-shielding layer has a light-transmitting hole so that the light collected by the microlens shines on the corresponding photosensitive element through the light-transmitting hole.

10. The optical sensor as claimed in claim 1, characterized in that, The optical sensor is used in under-display fingerprint recognition devices.

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