Light Sensor Circuit With Single-Window Ambient Compensation
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Solution Overview
Problem
Conventional light sensors require complex control mechanisms and multiple time windows to accurately sense light signals, leading to inefficiencies and limitations in placement and usage, particularly in electronic devices where continuous and flexible light adjustment is needed.
Innovation Solution
A light sensor circuit incorporating a comparator, counter, sample and hold circuit, and reference voltage modulating circuit, which senses photocurrents from both ambient and light-emitting components within a single window time, using a successive-approximation analog-to-digital converter to reduce circuit complexity and enhance accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional light sensors use multiple time windows to sense light signals, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent applies preliminary action by performing ambient light sensing before the main light signal sensing operation. The ambient light level is measured first and stored, then used as a reference during the subsequent proximity detection. This sequencing allows the system to achieve accurate measurements without requiring complex simultaneous control of multiple time windows, as each sensing phase is prepared in advance.
Solution Approach 2:
The patent segments the light sensing process into distinct phases: ambient light sensing phase and proximity light signal sensing phase. Each phase uses dedicated time windows that are sequentially activated rather than simultaneously managed. This segmentation simplifies the control mechanism by breaking down the complex multi-window coordination into manageable, sequential operations with clear state transitions.
2Measurement precision
If conventional light sensors use multiple time windows for sensing, then measurement precision is improved, but area of the device increases
Solution Approach 1:
The patent implements multi-functionality by using a single light receiver component that serves dual purposes: detecting ambient light levels and detecting proximity light signals. The same photodetector, capacitor, and comparator circuitry are reused across different sensing phases rather than dedicating separate components to each function. This universal approach significantly reduces the overall circuit area while maintaining measurement precision through temporal separation of functions.
Solution Approach 2:
The patent merges multiple sensing functions into a unified circuit architecture. The ambient light sensing circuit and proximity sensing circuit share common components including the light receiver, integrating capacitor, comparator, and control logic. By combining these functions that operate at different times into a single integrated system, the patent reduces redundant circuitry and minimizes the total area occupied by the light sensor module.
3Measurement precision
If conventional light sensors use multiple time windows, then measurement precision is improved, but productivity decreases
Solution Approach 1:
The patent maintains continuity of useful action by seamlessly transitioning between ambient light sensing and proximity sensing operations. The control mechanism continuously manages the timing and sequencing of different sensing phases without idle gaps, ensuring that each phase immediately follows the previous one. This continuous operation maximizes the utilization of the light receiver and processing circuits, improving overall sensing productivity while maintaining measurement precision through proper phase sequencing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration allows for continuous and accurate light sensing within a single window time, reducing circuit area requirements, improving accuracy, and enabling flexible placement under electronic device screens while allowing other optical applications to utilize the remaining time.
Implementation Method 1
The light receiver is configured to receive a first photocurrent of both of an ambient light source and a light-emitting component
Data Source
AI summary
A light sensor having a control complexity reducing mechanism is provided. When light is emitted to a photodiode by both of an ambient light source and a light-emitting component, a first coarse count value is counted by a counter and then is sampled and held by a first sample and hold circuit. When light is emitted to the photodiode by only the ambient light source, a second coarse count value is counted by the counter and then is sampled and held by a second sample and hold circuit. After the coarse count values are held, the counter performs a fine counting operation on light intensity of the light emitted by both of the ambient light source and the light-emitting component to generate a first fine count value, and on light intensity of the light emitted by only the ambient light source to generate a second fine count value.