![]() ![]() Digital sensors are also extremely compact. Digital light sensors can automatically compensate for various conditions and phenomena. Digital light sensors are more expensive than analog sensors but have advantages.Analog sensors are typically very inexpensive. For example, fluorescent lights vary in intensity with the frequency of the AC power that is supplied to the fixture. Some examples of these phenomena include infrared (IR) light rejection and light frequency compensation. Analog light sensors are connected to an embedded controller with an analog-to-digital (A/D) converter and require firmware that can accurately interpret the light sensor data and compensate for various conditions and phenomena that affect readings.The following are common lighting conditions to reference: Lighting conditionĪmbient light sensors come in two fundamental types: This enables the adaptive brightness algorithm to perform smooth screen brightness transitions. Granularity: To ensure the best experience the ALS should have a granularity of 1 lux when the ambient light is below 25 lux, and a granularity of 4% of the ambient light when it is above 25 lux.Indoor light typically ranges from 0 to 1000 lux. The ALS dynamic range for devices designed to be used indoors can be smaller. Sunlight can range from 0 to 10,000 lux, or more. The ambient light sensors mounted on devices designed to be used outdoors, such as a cell phone, should support outdoor lighting conditions. A low dynamic range light sensor limits the environments in which it can be used. Dynamic range: The dynamic range of a light sensor is the ratio between the largest and smallest values that the sensor can report, and defines range of lighting environments in which the sensor can be effective.A good goal for actual ambient light sensor (ALS) calibrated values is a consistent accuracy of within 4 percent of actual lighting conditions. Generally, the more accurate the sensor, the better the corresponding user experience will be. Accuracy and resolution: To deliver an optimal user experience for adaptive brightness and light-aware UI in applications, accurate sensor data is required as input.The following factors warrant special consideration: The supported bus technology (digital only).Infrared (IR) and ultraviolet (UV) rejection (human eye response).The accuracy, resolution, and field of view of the sensor.The type of sensor, digital light sensors are preferred.These considerations include the following: Several things can greatly affect what can be done with the information that the light sensors provide. Integrating light sensors with device hardware Test light sensors and adaptive brightness using the steps mentioned in Adaptive brightness test cases.Ensure that sensor implementation is optimized mechanically, optically, and from an electrical engineering perspective.Ensure that OEMs, ODMs, and IHVs participate in mechanical design reviews for each major revision of device hardware.Ensure that it runs correctly and passes all test cases. Test the device and third-party drivers with the Windows Hardware Lab Kit (HLK) device requirements and related tests.The meter should measure light incident on the display of the device. Use various types of test lighting (incandescent, fluorescent, LED) at various intensities and compare values reported through the sensor platform with a high-quality light meter. ![]() Test the complete device as a light measurement instrument.Connect the device over USB, SPI, or I2C HID transport. Leverage the inbox HID Sensor class driver.Integrate the sensors on to the device in one of the supported ways.This should be performed using professional, pre-calibrated light meters. Perform per-model calibration taking into account all factors, such as coatings, light pipe, sensor configuration, placement, and so on.Select optimized placement for the light sensor in the device enclosure.The rest of this document describes the process and background information in detail. The following high-level checklist is for developers integrating sensor hardware into devices. Selecting a suitable ambient light sensor (ALS) device is critical. This document provides recommendations for the design and development of devices with integrated ambient light sensors.
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