Dark count rate mitigation on avalanche photodiode-based ambient light sensors

Abstract

Embodiments of the present disclosure relate to dark count rate mitigation on avalanche photodiode based ambient light sensors. An example apparatus, a computer-implemented method, and an electronic device including an ambient light sensor configured to mitigate effects of a dark count rate associated with an avalanche photodiode are provided. The example apparatus includes an exposed avalanche photodiode array, a dark avalanche photodiode array, and a controller. The exposed avalanche photodiode array is positioned to receive ambient light from an external environment. The dark avalanche photodiode array is shielded by ambient light. The controller is configured to receive an exposure illuminometer corresponding to ambient light received at the exposed avalanche photodiode array. The controller is further configured to receive a dark illuminometer number corresponding to a dark count at the dark avalanche photodiode array. The controller determines an ambient light value based on a difference between the exposure illuminometer number and the darkness illuminometer number.

Description

TECHNICAL FIELD

[0001] Embodiments of the present disclosure generally relate to avalanche photodiode-based ambient light sensors, and more particularly, to mitigating dark count rates on avalanche photodiode-based ambient light sensors. BACKGROUND

[0002] Many electronic devices can adjust settings based on ambient light in a surrounding environment. For example, a digital camera can adjust capture settings based on ambient light in a surrounding environment, or a digital display can adjust brightness settings. One common technique is to measure ambient light in an environment, and then adjust settings of the electronic device based on the ambient light measurement.

[0003] Applicants identified a number of technical challenges and difficulties associated with ambient light measurement. Through efforts, ingenuity, and innovation, Applicants have solved problems associated with measuring ambient light in a surrounding environment by developing solutions embodied in the present disclosure, which will be described in detail below. SUMMARY

[0004] Various embodiments are directed to example apparatuses, computer-implemented methods, and electronic devices including ambient light sensors configured to mitigate effects of dark count rates associated with avalanche photodiodes.

[0005] An example apparatus is provided. In some embodiments, the example apparatus includes an exposed avalanche photodiode array, a dark avalanche photodiode array, and a controller. The exposed avalanche photodiode array is positioned to receive ambient light from an external environment. The dark avalanche photodiode array is shielded from the ambient light. The controller is configured to receive an exposed illumination count corresponding to the ambient light received at the exposed avalanche photodiode array; receive a dark illumination count corresponding to a dark count at the dark avalanche photodiode array; and determine an ambient light value based on a difference between the exposed illumination count and the dark illumination count.

[0006] In some embodiments, the controller is further configured to: disable a first portion of avalanche photodiodes including the exposed avalanche photodiode array; and disable a second portion of avalanche photodiodes including the dark avalanche photodiode array.

[0007] In some embodiments, a first portion size of the first portion corresponding to the avalanche photodiodes is equal to a second portion size corresponding to the second portion of the avalanche photodiodes.

[0008] In some embodiments, the first portion size is based on an exposed avalanche photodiode array size.

[0009] In some embodiments, the first portion size is a percentage of an exposed avalanche photodiode array size.

[0010] In some embodiments, the percentage is between 15% and 35% of the first avalanche portion size.

[0011] In some embodiments, the first portion of avalanche photodiodes is based on a dark count rate associated with each exposed avalanche photodiode comprising the exposed avalanche photodiode array; and the second portion of avalanche photodiodes is based on a dark count rate associated with each dark avalanche photodiode comprising the dark avalanche photodiode array.

[0012] In some embodiments, the dark count rate associated with each avalanche photodiode corresponds to a number of dark count events generated by the avalanche photodiode.

[0013] In some embodiments, the apparatus further comprises an avalanche photodiode memory map configured to store a dark count rate of one or more avalanche photodiodes comprising the exposed avalanche photodiode array and the dark avalanche photodiode array.

[0014] In some embodiments, the controller is further configured to dynamically update the first portion size.

[0015] In some embodiments, the controller is further configured to dynamically enable and dynamically disable the avalanche photodiodes comprising the first portion of avalanche photodiodes and the second portion of avalanche photodiodes based on the first portion size and the second portion size.

[0016] In some embodiments, the avalanche photodiode memory map is initialized during a configuration process.

[0017] In some embodiments, the exposed avalanche photodiode array and the dark avalanche photodiode array comprise single-photon avalanche photodiodes (SPADs).

[0018] In some embodiments, the exposed illumination count corresponds to a total number of exposed photon events generated by one or more exposed avalanche photodiodes of the exposed avalanche photodiode array during the capture, and the dark illumination count corresponds to a total number of dark photon events generated by one or more dark avalanche photodiodes of the dark avalanche photodiode array during the capture.

[0019] In some embodiments, the ambient light value for the capture period is determined based at least in part on a difference between the exposed illumination count and the dark illumination count.

[0020] In some embodiments, the apparatus further comprises a metal layer that shields the dark avalanche photodiode array.

[0021] A computer-implemented method for determining an ambient light value is also provided. In some embodiments, the computer-implemented method includes receiving an exposure lux count corresponding to ambient light received at an exposure avalanche photodiode array, where the exposure avalanche photodiode array is positioned to receive ambient light from an external environment; receiving a dark lux count corresponding to a dark count at a dark avalanche photodiode array, where the dark avalanche photodiode array is shielded from ambient light; and determining the ambient light value based on a difference between the exposure lux count and the dark lux count.

[0022] In some embodiments, the computer-implemented method further includes disabling a first portion of avalanche photodiodes including the exposure avalanche photodiode array; and disabling a second portion of avalanche photodiodes including the dark avalanche photodiode array.

[0023] In some embodiments, the first portion of avalanche photodiodes is based on a dark count rate associated with each exposure avalanche photodiode including the exposure avalanche photodiode array; and the second portion of avalanche photodiodes is based on a dark count rate associated with each dark avalanche photodiode including the dark avalanche photodiode array.

[0024] An example electronic device is also provided. In some embodiments, the example electronic device includes a housing, a display screen, and an ambient light sensor. The display screen is attached to the housing, and the display screen includes a first side configured to emit transmissive light into an external environment via a plurality of display pixels. The ambient light sensor is disposed within the housing, opposite the first side of the display screen, and the ambient light sensor includes an exposure avalanche photodiode array, a dark avalanche photodiode array, and a controller. The exposure avalanche photodiode array is positioned to receive ambient light from the external environment. The dark avalanche photodiode array is shielded from ambient light. The controller is configured to receive an exposure lux count corresponding to ambient light received at the exposure avalanche photodiode array; receive a dark lux count corresponding to a dark count at the dark avalanche photodiode array; and determine an ambient light value based on a difference between the exposure lux count and the dark lux count. BRIEF DESCRIPTION OF DRAWINGS

[0025] Reference will now be made to the figures. Components shown in the figures can or can not be present in certain embodiments described herein. Some embodiments can include fewer (or more) components than shown in the figures, according to example embodiments of the present disclosure.

[0026] Figure 1 An example block diagram of an ambient light sensor configured to mitigate a dark count rate is illustrated, according to example embodiments of the present disclosure.

[0027] Figure 2Example embodiments of ambient light sensors configured to mitigate dark count rates are illustrated in accordance with example embodiments of the present disclosure.

[0028] Figure 3 Example dark count rate distributions for a plurality of avalanche photodiodes are illustrated.

[0029] Figure 4 Example embodiments of ambient light sensors including avalanche photodiode memory mapping are illustrated in accordance with example embodiments of the present disclosure.

[0030] Figure 5 A plurality of example thresholds for disabling avalanche photodiodes having high dark count rates are illustrated in accordance with example embodiments of the present disclosure.

[0031] Figure 6 An example flowchart of a method for determining an ambient light value is depicted in accordance with example embodiments of the present disclosure.

[0032] Figure 7 A cross-section of an example electronic device including an ambient light sensor is illustrated in accordance with example embodiments of the present disclosure.

[0033] Figure 8 A block diagram of a controller example component is illustrated in accordance with example embodiments of the present disclosure. DETAILED DESCRIPTION

[0034] Example embodiments will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the inventive subject matter described herein are shown. Indeed, the embodiments of the present disclosure can be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout.

[0035] Various example embodiments address technical problems associated with dark count rates of avalanche photodiodes in ambient light sensors. As understood by those skilled in the art, dark count rates in ambient light sensors can greatly affect the accuracy, sensitivity, and reliability of ambient light sensors. As such, there are many example scenarios that can benefit from enhanced performance of ambient light sensors by mitigating the effects of dark count rates.

[0036] For example, many electronic devices can adjust settings based on ambient light in the surrounding environment. For example, a digital camera can adjust capture settings based on ambient light in the environment in which an image is captured. Similarly, a mobile device can adjust the brightness of a digital display based on ambient light in the display environment. A common technique among many of these devices is to measure ambient light intensity in the surrounding environment, and then adjust the relevant settings based on the ambient light measurement.

[0037] Enabling dynamic setting adjustments requires continuous measurement of ambient light of the surrounding environment. Further, in some embodiments, an ambient light sensor can be required to operate in low light conditions. For example, the ambient light sensor can be placed underneath a digital display. In instances where the ambient light sensor is placed underneath a digital display, the amount of ambient light received at the ambient light sensor can be greatly reduced. Further, the received ambient light can be affected by light generated by the digital display.

[0038] In some examples, single-photon avalanche diode (SPAD) arrays have been used for ambient light sensors. The design of SPADs is such that even the absorption of a single photon can cause impact ionization, prompting the development of an avalanche current. The avalanche current can be detected and counted for each SPAD in a SPAD array. The counts output by the SPADs can be used to determine the intensity of light received by the ambient light sensor. Numerous modifications have been made to conventional integrated photodiodes and SPAD arrays to enable detection of ambient light from underneath a digital display. However, recently, there has been an increased demand for ambient light sensors configured to detect ambient light at lower minimum illuminance.

[0039] Various example embodiments described herein utilize various techniques to mitigate the effects of dark count rates on ambient light sensors. In accordance with the present disclosure, an exposed avalanche photodiode array and a dark avalanche photodiode array each comprising a plurality of avalanche photodiodes can be used to mitigate the effects of dark count rates in an ambient light sensor. For example, the exposed avalanche photodiode array can be positioned to receive ambient light from an external environment and capture illuminance counts. The illuminance counts captured by the exposed avalanche photodiode array include photon events and dark count events. The dark count events correspond to instances in which the avalanche photodiodes generate false positive photon detections without light impinging on the avalanche photodiodes.

[0040] The dark avalanche photodiode array can be shielded from ambient light (e.g., by a metal layer). Illuminance counts corresponding to the dark avalanche photodiode array are also captured. The illuminance counts associated with the dark avalanche photodiode array can include only dark rate counts. Thus, by subtracting the shielded illuminance counts from the exposed illuminance counts, the noise floor of the ambient light sensor can be reduced, increasing the sensitivity of the ambient light sensor to low light. Further, the dark count rate of the avalanche photodiodes can vary with temperature and time. Thus, by subtracting the shielded illuminance counts from the exposed illuminance counts, the ambient light sensor can be more resilient to changes in temperature and aging.

[0041] In some embodiments, portions of the exposed avalanche photodiode array and the dark avalanche photodiode array can be disabled based on measured dark rate counts. For example, during a configuration period, dark rate counts for each avalanche photodiode in the exposed avalanche photodiode array and the dark avalanche photodiode array can be measured and stored in an avalanche photodiode memory map. Depending on a desired level of sensitivity, portions of avalanche photodiodes that disproportionately contribute to the total dark rate counts can be disabled. For example, the top 25% of avalanche photodiodes with the highest measured dark count rate can be disabled. By disabling avalanche photodiodes that generate the most dark counts, the amount of noise generated by the exposed avalanche photodiode array and the dark avalanche photodiode array can be greatly reduced, enabling measurement of ambient light at lower light levels.

[0042] As a result of the example embodiments described herein, and in some examples, the accuracy, reliability, and lifetime of an ambient light sensor can be greatly improved. For example, determining a difference between exposed illuminance counts and shielded illuminance counts can make the ambient light sensor more resilient to changes in device components over time (e.g., reliability drift). In addition, determining a difference between exposed illuminance counts and shielded illuminance counts can make the ambient light sensor more resilient to temperature changes. Furthermore, reducing the noise floor by disabling underperforming avalanche photodiodes can improve the performance of the ambient light sensor in low light conditions, such as under a display of an electronic device.

[0043] Reference is now made to Figure 1 , an example block diagram of an ambient light sensor 100 is provided. As Figure 1 depicted, the example ambient light sensor 100 includes an exposed avalanche photodiode array 102 configured to transmit exposed illuminance counts 110 to an electrically connected controller 106. The example ambient light sensor 100 also includes a dark avalanche photodiode array 104 configured to transmit dark illuminance counts 111 to the electrically connected controller 106. Also as Figure 1 depicted, the controller 106 is configured to transmit a disable avalanche photodiode signal 112 to the exposed avalanche photodiode array 102 and the dark avalanche photodiode array 104 based on an accessible avalanche photodiode memory map 108.

[0044] As Figure 1As depicted, the example ambient light sensor 100 includes an exposed avalanche photodiode array 102. The exposed avalanche photodiode array 102 includes any number of avalanche photodiodes exposed to an external environment and configured to generate an output voltage pulse in an instance in which one or more photons encounter an avalanche photodiode of the number of avalanche photodiodes. In some embodiments, the number of avalanche photodiodes can be arranged in a pattern across a surface (e.g., in a two-dimensional array). The exposed avalanche photodiode array 102 is exposed to the external environment such that ambient light or other light in the external environment can be received at the number of avalanche photodiodes. In some embodiments, the exposed avalanche photodiode array 102 can be positioned beneath a transparent or semi-transparent optical structure that allows at least a portion of the light to pass through, e.g., a lens, a screen, or a digital display.

[0045] As also depicted Figure 1 As depicted, the exposed avalanche photodiode array 102 is configured to generate an exposed illuminance count 110. The exposed illuminance count 110 includes any signal or value representative of an intensity of light received at the exposed avalanche photodiode array 102. In some embodiments, the exposed avalanche photodiode array 102 can receive, count, and / or accumulate the output voltage pulses generated by the number of avalanche photodiodes during an exposure window. The counted and / or accumulated output voltage pulses can be proportional to the intensity of light received at the exposed avalanche photodiode array 102.

[0046] As also depicted Figure 1 As depicted, the example ambient light sensor 100 includes a dark avalanche photodiode array 104. The dark avalanche photodiode array 104 includes any number of avalanche photodiodes that become obscured from exposure to ambient light in the external environment. In some embodiments, the dark avalanche photodiode array 104 can include an opaque cover or shield that prevents transmission of one or more light frequencies. For example, a metallic layer can be positioned between the dark avalanche photodiode array 104 and the external environment. In some embodiments, the opaque layer can be positioned over the dark avalanche photodiode array 104 during a photolithography process.

[0047] In some embodiments, the number of avalanche photodiodes comprising the dark avalanche photodiode array 104 can be arranged in a pattern across a surface (e.g., in a two-dimensional array). In some embodiments, the number of avalanche photodiodes comprising the dark avalanche photodiode array 104 can be equal to the number of avalanche photodiodes comprising the exposed avalanche photodiode array 102.

[0048] As also depicted Figure 1As depicted, the dark avalanche photodiode array 104 is configured to generate a dark illuminance count 111. The dark illuminance count 111 corresponds to an accumulation of dark count events from the exposure window by the avalanche photodiodes including the dark avalanche photodiode array 104 as the dark avalanche photodiode array 104 becomes obscured due to exposure to ambient light or other light. A dark count event corresponds to an instance of a false positive photon detection by an avalanche photodiode in the absence of light impinging on the avalanche photodiode. For example, due to the nature of an avalanche photodiode, the avalanche photodiode can generate an output voltage pulse even without receiving a photon. In some embodiments, the dark avalanche photodiode array 104 can receive, count, and / or accumulate dark count events generated by the plurality of avalanche photodiodes including the dark avalanche photodiode array 104 during the exposure window. The counted and / or accumulated dark count events can be output by the dark avalanche photodiode array 104 as the dark illuminance count 111.

[0049] Also as depicted Figure 1 As depicted, the example ambient light sensor 100 includes a controller 106. The controller 106 includes circuitry including hardware and / or software configured to generate an ambient light value 114 based on the exposure illuminance count 110 and the dark illuminance count 111. In some embodiments, the controller 106 can include entirely hardware components, such as a combinational logic device. The ambient light value 114 is a value representative of the intensity of ambient light encountered by the ambient light sensor 100. The ambient light value 114 can be expressed as a count corresponding to the number of output voltage pulses generated by the avalanche diodes during the exposure window. For example, a higher count can correspond to a greater intensity of ambient light received at the ambient light sensor 100.

[0050] The ambient light value 114 generated by the controller 106 can be determined based on a combination of the exposure illuminance count 110 and the dark illuminance count 111. For example, the controller 106 can calculate a difference between the exposure illuminance count 110 and the dark illuminance count 111 during a particular exposure window.

[0051] The exposure illuminance count 110 corresponds to a count of exposure photon events. An exposure photon event is an output voltage pulse generated by an avalanche photodiode including the exposure avalanche photodiode array 102. Generally, an exposure photon event includes a positive photon event in which one or more photons encounter an avalanche photodiode triggering an output voltage pulse and a dark count event corresponding to an instance of a false positive photon detection by an avalanche photodiode in the absence of light impinging on the avalanche photodiode.

[0052] The dark illuminance count 111 corresponds to a count of dark photon events. A dark photon event is an output voltage pulse generated by an avalanche photodiode, including the avalanche photodiode array 104, that does not correspond to a true positive photon detection. Generally, a dark photon event includes or at least primarily includes a dark count event corresponding to a false positive photon detection generated by an avalanche photodiode in instances where no light is incident on the avalanche photodiode.

[0053] Assuming that the exposed avalanche photodiode array 102 and the dark avalanche photodiode array 104 experience a related number of dark count events, the number of exposed photon events attributable to dark count events can be approximated as the dark illuminance count 111. Thus, determining the ambient light value 114 based on a difference between the exposed illuminance count 110 and the dark illuminance count 111 removes exposed photon events attributable to dark count events, mitigating the effect of the dark count rate on the ambient light value 114.

[0054] Further, the dark count rate on the exposed avalanche photodiode array 102 and the dark avalanche photodiode array 104 varies similarly based on temperature. Thus, determining the ambient light value 114 based on a difference between the exposed illuminance count 110 and the dark illuminance count 111 improves the accuracy of the ambient light sensor 100 across a range of temperatures. Further, the dark count rate on the exposed avalanche photodiode array 102 and the dark avalanche photodiode array 104 varies similarly over time. Thus, determining the ambient light value 114 based on a difference between the exposed illuminance count 110 and the dark illuminance count 111 improves the resilience of the ambient light sensor 100 to changes due to aging. With respect to Figure 8 Example controller 106 architecture is further described.

[0055] Also as Figure 1 As depicted, the example ambient light sensor 100 includes an avalanche photodiode memory map 108. The avalanche photodiode memory map 108 includes any data structure configured to store one or more associations between a particular avalanche photodiode of the exposed avalanche photodiode array 102 or the dark avalanche photodiode array 104 and an observed dark count rate. An observed dark count rate refers to a number of dark count events triggered by the avalanche photodiode over a given time period. For example, the observed dark count rate can be expressed in counts per second (cps), where a count is the number of dark count events triggered by the avalanche photodiode. The observed dark count rate can be determined during a calibration period, for example, by isolating the avalanche photodiode from a light source and counting the number of dark count events.

[0056] In some embodiments, the observed dark count rate can be associated with a particular avalanche photodiode and stored in an avalanche photodiode memory map 108. The particular avalanche photodiode can be identified based on a location within the avalanche photodiode array (e.g., x position, y position) or other unique identifier. The controller 106 can access the avalanche photodiode memory map 108. In some embodiments, the avalanche photodiode memory map 108 can be within memory associated with the controller 106. In some embodiments, the avalanche photodiode memory map 108 can be stored on a memory device external to the controller 106.

[0057] Referring now to Figure 2 , example embodiments of an ambient light sensor 200 are provided. As Figure 2 depicted, the example ambient light sensor 200 includes an exposed avalanche photodiode array 102 including a plurality of avalanche photodiodes 220 and a dark avalanche photodiode array 104 including a plurality of avalanche photodiodes 221. The dark avalanche photodiode array 104 also includes an opaque layer 104a positioned to block light from interacting with the avalanche photodiodes 221 of the dark avalanche photodiode array.

[0058] Also as Figure 2 depicted, the example ambient light sensor 200 includes adder logic 222 configured to generate an exposed illuminance count 110 based on a total count of exposed photon events at the exposed avalanche photodiode array 102 and adder logic 223 configured to generate a dark illuminance count 111 based on a total count of dark photon events at the dark avalanche photodiode array 104. The example ambient light sensor 200 also includes subtraction logic 224 configured to receive the exposed illuminance count 110 and the dark illuminance count 111 and output an adjusted illuminance count 225 to an accumulator 226. The accumulator 226 generates an accumulated illuminance count 229 based on an accumulation of one or more adjusted illuminance counts 225.

[0059] Also as Figure 2 depicted, the example ambient light sensor 200 includes second subtraction logic 227 configured to generate an ambient light value 114 based on a temperature-compensated residual increment value from a residual increment compensation circuitry 228 and the accumulated illuminance count 229 of the accumulator 226.

[0060] As Figure 2As depicted, the example exposed avalanche photodiode array 102 and the dark avalanche photodiode array 104 each include a plurality of avalanche photodiodes 220, 221. The avalanche photodiodes 220, 221 can include highly reverse-biased photodiodes, single-photon avalanche diodes (SPADs), or other similar photodiodes in avalanche mode. In contrast to integrating photodiodes, in which charge is collected by a photodiode over an integration period, the avalanche photodiodes 220, 221 are designed to cause collisional ionization even upon absorption of a single photon, thereby facilitating development of an avalanche current. The voltage generated by collisional ionization creates a voltage pulse at the output of the avalanche photodiode 220, 221. The output voltage pulse generated by the avalanche photodiodes 220, 221 can be used to determine the intensity of light received at a particular avalanche photodiode array (e.g., the exposed avalanche photodiode array 102, the dark avalanche photodiode array 104).

[0061] Also as Figure 2 As depicted, the adder logic 222, 223 is configured to receive respective photon events (e.g., exposed photon events and dark photon events) generated by the exposed avalanche photodiode array 102 and the dark avalanche photodiode array 104. For example, the adder logic 222 accumulates exposed photon events generated by each of the avalanche photodiodes comprising the exposed avalanche photodiode array 102 and transmits an exposed luxometer count 110 representing the generated exposed photon events. Similarly, the adder logic 223 transmits a dark luxometer count 111 representing dark photon events generated by each of the avalanche photodiodes in the dark avalanche photodiode array 104.

[0062] The subtraction logic 224 is configured to receive the exposed luxometer count 110 and the dark luxometer count 111 and perform a difference to generate an adjusted luxometer count 225. As described herein, by subtracting the dark luxometer count 111 from the exposed luxometer count 110, exposed photon events attributable to dark counting events are effectively removed. Thus, the adjusted luxometer count 225 corresponds to the exposed luxometer count 110 with dark counting events removed. In some embodiments, the subtraction logic 224 and associated logic can be implemented as components of the controller 106.

[0063] Also as Figure 2As depicted, the example ambient light sensor 200 includes an accumulator 226. The accumulator 226 is configured to receive the adjusted photometer count 225 transmitted by the subtraction logic 224 and accumulate the adjusted photometer count 225 over an accumulation period. In some embodiments, the ambient light sensor 200 can be configured to accumulate the adjusted photometer count 225 during one or more exposure windows. For example, the exposure windows can be based on a display pattern of an adjacent digital display. Based on the specifications and / or requirements of the ambient light sensor, the accumulator 226 can be configured to accumulate the adjusted photometer count 225 over multiple exposure windows. Once the accumulation period ends, the accumulated photometer count 229 is output by the accumulator 226. In some embodiments, the accumulator 226 and related logic can be implemented as a component of the controller 106.

[0064] Also as Figure 2 As depicted, the example ambient light sensor 200 can include a residual increment compensation circuitry 228. The residual increment compensation circuitry 228 includes any circuitry, including hardware and / or software, configured to determine a residual increment or difference between the exposed avalanche photodiode array 102 and the dark avalanche photodiode array 104 and adjust the accumulated photometer count 229 based on the residual increment. The dark count rates of the exposed avalanche photodiode array 102 and the dark avalanche photodiode array 104 can not perfectly match, in other words, there can be a residual increment between them. The residual increment can be determined during a calibration period and stored in the ambient light sensor 200. During operation, the residual increment can be used to adjust the accumulated photometer count 229.

[0065] Further, the dark count rate varies with temperature. For example, the dark count rate can double or so every 8 degrees Celsius. With the stored residual increment and corresponding temperature at calibration, the calibrated residual increment can be further adapted to the current operating temperature before being applied to the accumulated photometer count 229.

[0066] Referring now to Figure 3 , an example dark count rate distribution 330 for a plurality of avalanche photodiodes is provided. Figure 3 The dark count rate distribution 330 of depicts the probability that a given avalanche photodiode exhibits a dark count rate equal to or below a particular dark count rate. For example, as Figure 3 depicted, a given avalanche photodiode exhibits a dark count rate of 10 3 (1000) counts per second or lower with a probability close to 0.88 (88%). The dark count rate distribution 330 can be determined based on simulating and / or testing the avalanche photodiodes in a dark environment.

[0067] As Figure 3As depicted, the median dark count rate 332 is equal to or below about 200 counts per second. This means that about half of a given set of avalanche photodiodes can exhibit a dark count rate of 200 counts per second or lower. However, the average dark count rate 336 is equal to or close to 5000 counts per second per avalanche photodiode. This means that, during operation of the avalanche diode array, on average, each avalanche photodiode will generate 5000 dark count events per second. Each dark count event increases the noise of the ambient light sensor. The higher the noise (e.g., average dark count rate 336), the less sensitive the ambient light sensor is to low light levels of ambient light.

[0068] As Figure 3 depicted, the high average dark count rate 336 is attributed to a strong tail 334 on the distribution compared to the median dark count rate 332. The strong tail 334 indicates that a relatively small number of avalanche photodiodes disproportionately contribute to the dark count rate of the avalanche photodiode array of the ambient light sensor. In an example scenario, in an instance with ten avalanche photodiodes, if nine photodiodes exhibit a dark count rate of 100 counts per second, and one photodiode exhibits a dark count rate of 10000 counts per second, the median dark count rate is 100, however, the average dark count rate is 1090. Thus, removing avalanche photodiodes with high dark count rates can reduce the amount of noise in the ambient light value without significantly impacting the sensitivity of the avalanche photodiode array.

[0069] Referring now to Figure 4 , example embodiments of an ambient light sensor 400 are provided. As Figure 4 depicted, the example ambient light sensor 400 includes an exposed avalanche photodiode array 102 including a plurality of avalanche photodiodes 220 and a dark avalanche photodiode array 104 including a plurality of avalanche photodiodes 221. The dark avalanche photodiode array 104 further includes an opaque layer 104a positioned to block light from interacting with the avalanche photodiodes 221 of the dark avalanche photodiode array.

[0070] Also as Figure 4As depicted, the example ambient light sensor 400 includes adder logic 222 configured to generate an exposure lux count 110 based on a total count of exposed photon events at the exposed avalanche photodiode array 102, and adder logic 223 configured to generate a dark lux count 111 based on a total count of dark photon events at the dark avalanche photodiode array 104. The example ambient light sensor 400 also includes subtraction logic 224 configured to receive the exposure lux count 110 and the dark lux count 111, and output an adjusted lux count 225 to an accumulator 226. The accumulator 226 generates an accumulated lux count 229 based on an accumulation of one or more adjusted lux counts 225.

[0071] Also as depicted, the example ambient light sensor 400 includes a second subtraction logic 227 configured to generate an ambient light value 114 based on a temperature-compensated residual increment value from a residual increment compensation circuitry 228 and the accumulated lux count 229 of the accumulator 226. Figure 4

[0072] Also as depicted, the example ambient light sensor includes an avalanche photodiode memory map 108. The avalanche photodiode memory map 108 includes any data structure configured to store one or more associations between a particular avalanche photodiode and an observed dark count rate. For example, in some embodiments, an observed dark count rate for each avalanche photodiode in a plurality of photodiodes including the exposed avalanche photodiode array 102 and the dark avalanche photodiode array 104 can be determined during a calibration period, e.g., by isolating the avalanche photodiode from a light source and counting the number of dark count events. The observed dark count rate can be saved in the avalanche photodiode memory map 108 and associated with the avalanche photodiode by memory location, identifier, or another identification mechanism.

[0073] Storing an observed dark count rate for each avalanche photodiode in a plurality of photodiodes including the exposed avalanche photodiode array 102 and the dark avalanche photodiode array 104 can enable avalanche photodiodes exhibiting a high dark count rate to be disabled and / or ignored during operation of the ambient light sensor 400. For example, based on the observed dark count rates stored in the avalanche photodiode memory map 108, a portion of the avalanche photodiodes 220 of the exposed avalanche photodiode array 102 and a portion of the avalanche photodiodes 221 of the dark avalanche photodiode array 104 can be disabled.

[0074] ​In some embodiments, a maximum dark count threshold can be determined. In such instances, any avalanche photodiode 220, 221 that has a dark count rate that exceeds the maximum dark count threshold can be disabled. For example, if a maximum dark count threshold of 1000 counts per second is determined, any avalanche photodiode 220, 221 that has a dark count rate that exceeds 1000 can be disabled.

[0075] In some embodiments, the portion of disabled avalanche photodiodes can be based on the number of avalanche photodiodes that comprise the corresponding avalanche photodiode array (e.g., exposed avalanche photodiode array 102, dark avalanche photodiode array 104). For example, the portion of disabled avalanche photodiodes can be a percentage of the size of the corresponding avalanche photodiode array. For example, the avalanche photodiodes that exhibit the top 25% of dark rate counts can be selected to be included in the portion of disabled avalanche photodiodes. In some embodiments, the portion of the corresponding avalanche photodiode array can be between 15% and 35%; more preferably between 20% and 30%; most preferably between 24% and 26%.

[0076] In some embodiments, the size of the portion of disabled avalanche photodiodes of exposed avalanche photodiode array 102 and the size of the portion of disabled avalanche photodiodes of dark avalanche photodiode array 104 can be equal. Maintaining the number of illumination counts utilized from both the exposed avalanche photodiode array 102 and the dark avalanche photodiode array 104 when subtracting the dark illumination counts 111 from the exposed illumination counts 110 can be important to mitigate dark count rates.

[0077] Selecting the size of the portion of disabled avalanche photodiodes requires balancing the reduction in noise level due to dark count events and the reduction in ambient light sensor sensitivity. The selection of the size of the portion of disabled avalanche photodiodes can depend on many characteristics, including but not limited to the requirements of the electronic device that houses the ambient light sensor 400, the physical characteristics of the ambient light sensor 400, the application, etc.

[0078] Reference is now made to Figure 5Referring to the example dark count rate distribution 330, a plurality of example disabled avalanche photodiode cutoffs 552, 554, 556 are depicted. The example disabled avalanche photodiode cutoffs 552, 554, 556 depict a portion of the example dark count rate distribution 330 that can be eliminated if the size of the portion of disabled avalanche photodiodes is determined based on the disabled avalanche photodiode cutoffs 552, 554, 556. For example, the disabled avalanche photodiode cutoff 552 corresponds to disabling 25% of the avalanche photodiodes of the particular avalanche photodiode array having the highest observed dark count rate, as recorded in the avalanche photodiode memory map 108. The disabled avalanche photodiode cutoff 554 corresponds to disabling 50% of the avalanche photodiodes of the particular avalanche photodiode array having the highest observed dark count rate, as recorded in the avalanche photodiode memory map 108. The disabled avalanche photodiode cutoff 556 corresponds to disabling 90% of the avalanche photodiodes of the particular avalanche photodiode array having the highest observed dark count rate, as recorded in the avalanche photodiode memory map 108.

[0079] As depicted, increasing the avalanche photodiode cutoffs 552, 554, 556 can have diminishing returns. For example, increasing the avalanche photodiode cutoff from 50% to 90% can significantly reduce the number of enabled avalanche photodiodes in the avalanche photodiode array without significantly reducing the dark count rate. However, setting the avalanche photodiode cutoff 552 to 25% can significantly reduce the dark count rate without adversely affecting the sensitivity and / or resolution of the ambient light sensor. Figure 5 As depicted, increasing the avalanche photodiode cutoffs 552, 554, 556 can have diminishing returns. For example, increasing the avalanche photodiode cutoff from 50% to 90% can significantly reduce the number of enabled avalanche photodiodes in the avalanche photodiode array without significantly reducing the dark count rate. However, setting the avalanche photodiode cutoff 552 to 25% can significantly reduce the dark count rate without adversely affecting the sensitivity and / or resolution of the ambient light sensor.

[0080] Referring now to FIG. 6, Figure 6 An example method 600 for determining an ambient light value (e.g., the ambient light value 114) at a controller (e.g., the controller 106) of an ambient light sensor (e.g., the ambient light sensor 100, 200, 400) is provided. At block 602, in some embodiments, the controller disables a first portion of avalanche photodiodes including an exposed avalanche photodiode array (e.g., the exposed avalanche photodiode array 102). As described herein, the ambient light sensor can store or access an avalanche photodiode memory map (e.g., the avalanche photodiode memory map 108) that associates one or more avalanche photodiodes in the exposed avalanche photodiode array with an observed dark count rate. The observed dark count rate can be determined based on dark count rate measurements of the avalanche photodiodes including the exposed avalanche photodiode array during a calibration period.

[0081] During operation, the controller can select a first portion of the avalanche photodiodes including exposed avalanche photodiodes of the exposed avalanche photodiode array to be disabled based on the observed dark count rates associated with the avalanche photodiodes. In some embodiments, the size of the first portion of the disabled avalanche photodiodes can be determined based on a percentage of a total number of avalanche photodiodes including the exposed avalanche photodiode array. For example, a disabled avalanche photodiode cutoff (e.g., disabled avalanche photodiode cutoffs 552, 554, 556) can be selected. In such examples, the avalanche photodiode with the highest observed dark count rate up to the size of the first portion of the disabled avalanche photodiodes is disabled.

[0082] At block 604, in some embodiments, the controller disables a second portion of the avalanche photodiodes including the dark avalanche photodiode array (e.g., dark avalanche photodiode array 104). As described herein, the avalanche photodiode memory map can associate one or more avalanche photodiodes in the dark avalanche photodiode array with an observed dark count rate. The observed dark count rate can be determined based on the dark count rate measurements of the avalanche photodiodes including the dark avalanche photodiode array during the calibration period.

[0083] During operation, the controller can select a second portion of the avalanche photodiodes including the dark avalanche photodiode array to be disabled based on the observed dark count rates associated with the avalanche photodiodes. In some embodiments, the size of the second portion of the disabled avalanche photodiodes can be determined based on a percentage of a total number of avalanche photodiodes including the dark avalanche photodiode array. For example, a disabled avalanche photodiode cutoff (e.g., disabled avalanche photodiode cutoffs 552, 554, 556) can be selected. In such examples, the avalanche photodiode with the highest observed dark count rate up to the size of the second portion of the disabled avalanche photodiodes is disabled.

[0084] In some embodiments, the size of the first portion of the disabled avalanche photodiodes and the size of the second portion of the disabled avalanche photodiodes can be equal. Disabling the portion of the avalanche photodiodes with the highest observed dark count rate can reduce noise present when determining an ambient light value (e.g., ambient light value 114).

[0085] At block 606, the controller receives an exposed lux count (e.g., exposed lux count 110) corresponding to ambient light received at the exposed avalanche photodiode array (e.g., exposed avalanche photodiode array 102), where the exposed avalanche photodiode array is positioned to receive ambient light from an external environment.

[0086] As described herein, the exposed avalanche photodiode array can include a plurality of avalanche photodiodes positioned in a two-dimensional pattern across a surface exposed to ambient light in an external environment. In instances where one or more photons encounter an avalanche photodiode, each avalanche photodiode can generate an output voltage pulse (e.g., an exposed photon event). Further, in instances where no light is incident on an avalanche photodiode, each avalanche photodiode can generate a dark count event corresponding to an output voltage pulse. The exposed photon events (including positive photon events and dark count events) including each of the avalanche photodiodes of the exposed avalanche photodiode array are summed and transmitted as an exposed illuminance count.

[0087] At block 608, the controller receives a dark illuminance count (e.g., dark illuminance count 111) corresponding to dark counts at a dark avalanche photodiode array (e.g., dark avalanche photodiode array 104), where the dark avalanche photodiode array is shielded from ambient light. As described further herein, the ambient light sensor includes a dark avalanche photodiode array including an avalanche photodiode array that receives light is shielded. For example, in some embodiments, the dark avalanche photodiode array can be covered by a metal plate or layer. The shielded avalanche photodiodes of the dark avalanche photodiode array continue to generate dark photon events. As the dark avalanche photodiode array does not receive light, the dark photon events correspond to dark counts, or in other words, dark count events that generate an output voltage pulse in instances where no light is incident on an avalanche photodiode. The dark photon events (representative of the dark counts of the dark avalanche photodiode array) including each of the avalanche photodiodes of the dark avalanche photodiode array are summed and transmitted as a dark illuminance count.

[0088] At block 610, the controller determines an ambient light value based on a difference between the exposed illuminance count and the dark illuminance count. As described herein, the exposed illuminance count includes exposed photon events including positive photon events and dark count events. The dark illuminance count includes dark photon events that only include dark count events because the dark avalanche photodiode array is shielded from receiving light. By subtracting the dark illuminance count from the exposed illuminance count, the effect of dark count events on the exposed illuminance count is mitigated. Further, as the dark count rate changes with temperature variations and aging, subtracting the dark illuminance count from the exposed illuminance count enables the ambient light sensor to accommodate temperature variations and drift in reliability over time.

[0089] Referring now to Figure 7 An example electronic device 770 including an ambient light sensor 700 is provided. As Figure 7As depicted, the example electronic device 770 includes a housing 771 and a display screen 778, which define an enclosed region in which the ambient light sensor 700 and the controller 106 are disposed. The controller 106 is electrically coupled to the ambient light sensor 700 to receive at least the exposed illuminance count and the dark illuminance count. The controller 106 is also electrically connected to the display screen 778.

[0090] Also as Figure 7 As depicted, the display screen 778 includes a first side 778a and a second side 778b opposite the first side 778a, the first side 778a configured to emit transmissive light 776 into the external environment 772 via a plurality of display pixels 777. Also as Figure 7 As depicted, the ambient light sensor 700 includes an exposed avalanche photodiode array 102 exposed to ambient light 774 from the external environment 772, and a dark avalanche photodiode array 104 shaded from the ambient light 774. During a refresh of the display screen 778, a portion of the display pixels 777 are unlit (e.g., unlit display pixels 779).

[0091] As Figure 7 As depicted, the example electronic device 770 is any electronic device that includes a housing 771, where a portion of the housing 771 includes a display screen 778. Also as Figure 7 As depicted, the electronic device 770 includes an ambient light sensor 700 that includes an exposed avalanche photodiode array 102 and a dark avalanche photodiode array 104 for determining an ambient light value associated with ambient light 774 present in an external environment 772. In some non-limiting examples, the electronic device 770 can include a mobile phone, a laptop computer, a television, a monitor, a computer, a wearable electronic device, or other mobile device.

[0092] Also as Figure 7 As depicted, the example electronic device 770 includes a housing 771. The housing 771 can be any structure, package, enclosure, or similar mechanism designed to provide a protective enclosure for internal components of the electronic device 770 (e.g., including the ambient light sensor 700 and the controller 106). In some embodiments, the housing 771 defines an enclosed region with the display screen 778.

[0093] Also as Figure 7As depicted, the electronic device 770 includes a display screen 778 that includes a plurality of display pixels 777 configured to emit transmissive light 776. The display screen 778 can be any digital display, screen, monitor, or other device configured to output information in visual form via transmissive light 776 based on received electronic signals. The display screen 778 can be transparent or translucent to certain wavelengths of light such that ambient light 774 can be received by the ambient light sensor 700 behind or below the display screen 778. In some non-limiting examples, the display screen 778 can include an organic light-emitting diode (OLED), an active-matrix OLED (AMOLED) display, or other similar variants.

[0094] In some embodiments, the display screen 778 can include a plurality of display pixels 777. The display pixels 777 can be the smallest unit of display in the display screen 778. The display pixels 777 can be configured to output an intensity of light or a combination of intensities of light based on electronic signals indicative of a desired output. For example, in some embodiments, each pixel of the display screen 778 can emit red, green, and blue colors at different intensities to generate a particular color from the display pixels 777.

[0095] The plurality of display pixels 777 can be illuminated in a coordinated manner to generate a display image. For example, in some embodiments, the display pixels 777 can be refreshed one row at a time and sequentially move from one side of the display to the other. Due to the speed of the refresh, the display screen 778 can appear to be fully illuminated. During the refresh process, one or more rows of unlit display pixels 779 can move from a first side of the display screen 778 to a second side of the display screen 778 opposite the first side. In instances where the ambient light sensor 700 is positioned within the housing 771 and below the display screen 778, one or more rows of display pixels 777 directly above the ambient light sensor 700 can be unlit during a refresh of the display screen 778, as shown by the unlit display pixels 779. In some embodiments, the exposure window of the ambient light sensor 700 can be timed such that, in instances where the unlit display pixels 779 of the display screen 778 refresh are directly or partially positioned above the ambient light sensor 700, the exposed illuminometer count 110 and the dark illuminometer count 111 are accumulated and / or aggregated. Timing the exposure window with the refresh of the display screen 778 enables the ambient light sensor 700 to better isolate the ambient light 774 in the external environment 772. Figure 8

[0096] ​In some embodiments, the electronic device 770 is configured to adjust various settings of the electronic device 770 and connected components based on ambient light values determined by the ambient light sensor 700 and the controller 106. For example, capture settings of a digital camera can be adjusted based on an ambient light value indicative of an amount of ambient light 774 in an external environment 772 in which an image is captured. Similarly, display screen 778 settings (e.g., screen brightness) of a mobile device can be adjusted based on ambient light 774 in an external environment 772 in which the display screen 778 is viewed.

[0097] Reference is now made to Figure 8 An example block diagram depicting example components of the controller 106 according to example embodiments of the present disclosure is provided. ​ An example controller 106 according to at least some example embodiments of the present disclosure is illustrated. The controller 106 includes a processor 802, input / output circuitry 804, data storage media 806, and communication circuitry 808. In some embodiments, the controller 106 is configured to perform and execute the operations described herein using one or more of the circuitry groups 802, 804, 806, and / or 808.

[0098] While components are described in terms of functional limitations, it should be understood that particular implementations necessarily include the use of particular computing hardware. It should also be understood that, in some embodiments, certain of the components described herein include similar or common hardware. For example, both circuitry groups can utilize the same processor(s), network interface(s), storage media(s), etc. to perform their associated functions, such that each circuitry group does not require duplicative hardware. Accordingly, use of the term “circuitry” herein with respect to components of the apparatuses described herein should be understood to include the particular hardware configured to perform the functions associated with the particular circuitry described herein.

[0099] In particular, the term “circuitry” should be interpreted broadly to include hardware, and in some embodiments, software for configuring hardware. For example, in some embodiments, “circuitry” includes processing circuitry, storage media, network interfaces, input / output devices, etc. Alternatively or additionally, other elements of the controller 106 provide or supplement the functionality of other particular circuitry groups. For example, in some embodiments, the processor 802 provides processing functionality to any of the circuitry groups, the data storage media 806 provides storage functionality to any of the circuitry groups, the communication circuitry 808 provides network interface functionality to any of the circuitry groups, etc.

[0100] In some embodiments, the processor 802 (and / or co-processors or auxiliary processors or any other processing circuitry associated with the processor) communicates with a data storage medium 806 via a bus for passing information among components of the controller 106. In some embodiments, for example, the data storage medium 806 is non-transitory and can include one or more volatile and / or non-volatile memory devices. In other words, for example, in some embodiments, the data storage medium 806 includes or embodies electronic storage devices (e.g., computer readable storage media). In some embodiments, the data storage medium 806 is configured to store information, data, content, applications, instructions, etc. for enabling the controller 106 to perform various functions in accordance with example embodiments of the present disclosure.

[0101] The processor 802 can be embodied in a number of different ways. For example, in some example embodiments, the processor 802 includes one or more processing devices configured to execute independently. Additionally or alternatively, in some embodiments, the processor 802 includes one or more processors (one or more) configured in tandem via the bus to enable pipelining and / or multithreading of instructions, flow, and / or execution. The use of the terms “processor” and “processing circuitry” should not be construed to limit the embodiments to a single processor or processing circuitry, but rather, the terms “processor” and “processing circuitry” should be understood to encompass a plurality of processors or processing circuitry, either internally or externally connected to the controller 106.

[0102] In example embodiments, the processor 802 is configured to execute instructions stored in the data storage medium 806 or instructions accessible by the processor. Alternatively, or additionally, in some embodiments, the processor 802 is configured to execute hard coded functionality. As such, whether configured by hardware or software methods, or by a combination thereof, the processor 802 represents an entity capable of performing operations according to embodiments of the present disclosure while configured accordingly. Alternatively, or additionally, as another example in some example embodiments, when the processor 802 is embodied as an executor of software instructions, the instructions specifically configure the processor 802 to perform the algorithms described herein in specific operations when the instructions are executed.

[0103] In some embodiments, the controller 106 includes input / output circuitry 804 that provides output to the user, and, in some embodiments, receives an indication of a user input. The input / output circuitry 804, in some embodiments, is in communication with the processor 802 to provide such functionality. The input / output circuitry 804 can comprise one or more user interfaces (e.g., user interface(s)) and, in some embodiments, a display, including interfaces that appear to be web user interfaces, application user interfaces, user devices, backend systems, etc. The processor 802 and / or input / output circuitry 804 comprising a processor can be configured to control one or more functions of one or more user interface elements through computer program instructions (e.g., software and / or firmware) stored on a memory accessible to the processor (e.g., data storage medium 806, etc.). In some embodiments, the input / output circuitry 804 includes or utilizes a user-facing application to provide input / output functionality to a client device and / or other display associated with a user.

[0104] In some embodiments, the controller 106 includes communication circuitry 808. The communication circuitry 808 includes any equipment, such as a device or circuitry embodied in hardware or a combination of hardware and software, configured to receive and / or transmit data from / to a network and / or any other device, circuitry, or module in communication with the controller 106. In this regard, such as in some embodiments, the communication circuitry 808 includes a network interface for enabling communication with a wired or wireless communication network. Additionally or alternatively, in some embodiments, the communication circuitry 808 includes one or more network interface cards, antenna(s), bus(es), switch(es), router(s), modem(s), and supporting hardware, firmware, and / or software, or any other devices suitable for enabling communications via one or more communication networks. Additionally or alternatively, the communication circuitry 808 includes circuitry for interacting with antenna(s) and / or other hardware or software to cause transmission of signals via the antenna(s) or to handle reception of signals received via the antenna(s). In some embodiments, the communication circuitry 808 enables transmission of data to and / or reception of data from a client device in communication with the controller 106.

[0105] Additionally or alternatively, in some embodiments, one or more of the groups of circuit devices 802-914 are combinable. Additionally or alternatively, in some embodiments, one or more of the groups of circuit devices perform some or all of the described functionality associated with another component. For example, in some embodiments, one or more of the groups of circuit devices 802-808 are combined as a single module embodied in hardware, software, firmware, and / or combinations thereof. Similarly, in some embodiments, one or more of the groups of circuit devices are combined such that the processor 802 alone performs one or more of the above-described operations with respect to each of these circuit devices.

[0106] While the present detailed description sets forth embodiments of the application, other embodiments of the present application will be apparent from consideration of the specification and practice of the application disclosed herein. For example, one of ordinary skill in the art will appreciate that the principles can be applied to any electronic device configured to detect ambient light in an environment. For example, mobile communication devices, laptop displays, televisions, monitors, computers, wearable electronic devices, cameras, and the like.

[0107] In the claims, unless two or more aparticular terms are expressly identified as being synonymous, it is intended that those terms not be synonymous. In the claims, unless otherwise indicated, the use of the singular is not intended to impose a limitation on the number of items. For example, it is intended that "a" or "an" to mean "one or more." Unlessexpressly indicated, the use of the singular is not intended to limit the claimed subject matter to a single item unless the context clearly indicates otherwise.

[0108] The use of broad terms such as "comprises," "includes," and "having" should be understood not to exclude, but to include, what follows the term. The use of the negative "not" should be understood not to exclude, but to include, what is stated after the term. The use of the term "or" should be understood as inclusive, meaning either or both. The use of the term "and" should be understood as inclusive, meaning both. The use of the term "if" should be understood as inclusive, meaning "if or when." The use of the term "implies" should be understood as inclusive, meaning "implies or suggests." The use of the term "including" should be understood as inclusive, meaning "including, but not limited to." The use of the term "comprising" should be understood as inclusive, meaning "comprising, but not limited to." The use of the term "consisting essentially of should be understood as inclusive, meaning "consisting essentially of, but not limited to." The use of the term "consisting of should be understood as inclusive, meaning "consisting of, but not limited to." The use of the term "substantially" should be understood as inclusive, meaning "substantially, but not limited to." The use of the term "about" should be understood as inclusive, meaning "about, but not limited to." The use of the term "may" should be understood as inclusive, meaning "may or can not." The use of the term "might" should be understood as inclusive, meaning "might or can." The use of the term "possibly" should be understood as inclusive, meaning "possibly, but not necessarily."

Claims

1. An apparatus comprising: First avalanche photodiode array; The second avalanche photodiode array is blocked by ambient light in the external environment; as well as The controller is configured as follows: Receive a first illuminance count corresponding to the ambient light received at the first avalanche photodiode array; Receive a second illuminance count at the second avalanche photodiode array; and The ambient light value is determined based on the difference between the first illuminance count and the second illuminance count.

2. The apparatus of claim 1, wherein the first avalanche photodiode array is positioned to receive ambient light from the external environment.

3. The apparatus of claim 1, wherein the controller is further configured to: Disable the first portion of the avalanche photodiode, including the first avalanche photodiode array; and Disable the second portion of the avalanche photodiode, which includes the second avalanche photodiode array.

4. The apparatus of claim 3, wherein the size of the first portion corresponding to the first portion of the avalanche photodiode is equal to the size of the second portion corresponding to the second portion of the avalanche photodiode.

5. The apparatus of claim 4, wherein the size of the first portion is based on the size of the first avalanche photodiode array.

6. The apparatus of claim 5, wherein the size of the first portion is based on a percentage of the size of the first avalanche photodiode array, and wherein the percentage is between 15% and 35% of the size of the first avalanche portion.

7. The apparatus of claim 4, wherein the first portion of the avalanche photodiode is based on a dark count rate associated with each first avalanche photodiode comprising the first avalanche photodiode array; and the second portion of the avalanche photodiode is based on the dark count rate associated with each second avalanche photodiode comprising the second avalanche photodiode array.

8. The apparatus of claim 7, wherein the dark count rate associated with each avalanche photodiode corresponds to the number of dark count events generated by the avalanche photodiode.

9. The apparatus according to claim 7, further comprising: An avalanche photodiode memory map is configured to store the dark count rate of one or more avalanche photodiodes, the one or more avalanche photodiodes including a first avalanche photodiode array and a second avalanche photodiode array.

10. The apparatus of claim 9, wherein the controller is further configured to dynamically update the size of the first portion.

11. The apparatus of claim 10, wherein the controller is further configured to dynamically enable and dynamically disable an avalanche photodiode comprising the first portion of the avalanche photodiode and the second portion of the avalanche photodiode based on the first portion size and the second portion size.

12. The apparatus of claim 9, wherein the avalanche photodiode memory map is initialized during the configuration process.

13. The apparatus of claim 1, wherein the first avalanche photodiode array and the second avalanche photodiode array comprise single-photon avalanche photodiodes (SPADs).

14. The apparatus of claim 1, wherein the first illuminance count corresponds to the total number of exposed photon events generated by one or more exposed avalanche photodiodes of the first avalanche photodiode array during the capture period, and wherein the second illuminance count corresponds to the total number of dark photon events generated by one or more second avalanche photodiodes of the second avalanche photodiode array during the capture period.

15. The device of claim 14, wherein the ambient light value for the capture period is determined at least in part based on the difference between the first illuminance count and the second illuminance count.

16. The apparatus of claim 1, further comprising a metal layer that shields the second avalanche photodiode array.

17. A computer-implemented method for determining ambient light values, the computer-implemented method comprising: Receive a first illuminance count corresponding to the ambient light received at the first avalanche photodiode array. The first avalanche photodiode array is positioned to receive ambient light from the external environment; The second illuminance count is received at the second avalanche photodiode array. The second avalanche photodiode array is shielded by the ambient light; and The ambient light value is determined based on the difference between the first illuminance count and the second illuminance count.

18. The computer-implemented method of claim 17, further comprising: Disable the first portion of the avalanche photodiode, which includes the first avalanche photodiode array; as well as Disable the second portion of the avalanche photodiode, which includes the second avalanche photodiode array.

19. The computer-implemented method of claim 18, wherein the first portion of the avalanche photodiode is based on a dark count rate associated with each exposed avalanche photodiode comprising the first avalanche photodiode array; and the second portion of the avalanche photodiode is based on the dark count rate associated with each second avalanche photodiode comprising the second avalanche photodiode array.

20. An electronic device, comprising: shell; A display screen is attached to the housing, the display screen comprising: The first side is configured to emit transmitted light into the external environment via multiple display pixels; and An ambient light sensor is disposed within the housing, opposite to the first side of the display screen, and the ambient light sensor includes: The first avalanche photodiode array is positioned to receive ambient light from the external environment; The second avalanche photodiode array is shielded by the ambient light; and The controller is configured as follows: Receive a first illuminance count corresponding to the ambient light received at the first avalanche photodiode array; Receive a second illuminance count at the avalanche second photodiode array; and The ambient light value is determined based on the difference between the first illuminance count and the second illuminance count.

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