Multi-Optical Sensor Circuit Using Signal Modulation Against Crosstalk
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Solution Overview
Problem
Existing touch and proximity-sensitive control devices with optical sensors face issues of incorrect signal evaluation due to ambient light and crosstalk from neighboring sensors, leading to high error rates in signal interpretation.
Innovation Solution
A sensor circuit with multiple optical sensors, each equipped with a transmitter and receiver, utilizes modulation devices with different modulation factors to differentiate measurement signals, reducing the number of active and passive components and allowing for a smaller number of GPIO pins, while maintaining safety standards and enabling the use of an analog multiplexer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple optical sensors are used for touch and proximity detection, then the functionality and reliability of the operating device are improved, but the complexity of the sensor circuit and the number of components increase
Solution Approach 1:
The patent combines multiple optical sensors (first optical sensor with receiver T1 and second optical sensor with receiver T2) into a single sensor circuit that shares common components including a common control signal input Sx, common optical transmitters D1 and D2, and a shared evaluation unit. This merging approach reduces the overall number of components while maintaining the ability to differentiate between sensors through modulation techniques, thereby reducing circuit complexity without compromising reliability
Solution Approach 2:
The patent applies modulation devices M1 and M2 that change the parameter of the measurement signals by applying different modulation factors to the signals from different optical receivers. This parameter change allows the evaluation unit to distinguish between signals from T1 and T2, enabling reliable signal evaluation across multiple sensors while using a reduced number of physical components
2Measurement precision
If multiple optical sensors are used for touch and proximity detection, then the measurement precision is improved, but the number of GPIO pins and processing requirements increase
Solution Approach 1:
The common control signal input Sx serves multiple functions by controlling both the first optical transmitter D1 and the second optical transmitter D2. This multi-functional design allows a single input pin to manage multiple sensors, reducing the number of required GPIO pins while maintaining the ability to precisely differentiate and evaluate signals from each sensor through the modulation scheme
3Ease of manufacture
If conventional sensor circuits are used without modulation differentiation, then the construction is simpler, but incorrect signal evaluation occurs due to ambient light and crosstalk
Solution Approach 1:
The patent introduces modulation devices M1 and M2 that apply different modulation factors to the measurement signals from receivers T1 and T2. This parameter change transforms the signals into distinct, identifiable patterns that allow the evaluation unit to correctly differentiate between sensors even in the presence of ambient light and crosstalk, thereby improving signal evaluation correctness while maintaining relatively simple circuit construction
Solution Approach 2:
The evaluation unit receives modulated measurement signals and uses the modulation information as feedback to identify the source of each signal (T1 or T2). This feedback mechanism enables the system to correctly evaluate signals by referencing the known modulation patterns, preventing incorrect evaluation due to ambient light interference or crosstalk while keeping the overall circuit design straightforward
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
The solution effectively reduces signal evaluation errors, simplifies the circuit construction, and allows for cost-effective implementation with fewer components, while ensuring reliable operation and compliance with safety standards in touch and proximity-sensitive devices.
Implementation Method 1
The first optical transmitter D1 and the second optical transmitter D2 are each connected to a control signal input I1, I2
Implementation Method 2
The first optical receiver T1 and the second optical receiver T2 are connected to a common control signal input Sx
Data Source
Figure 1
AI summary
A sensor circuit with multiple optical sensors comprises a first optical sensor with a first optical transmitter (D1) and a first optical receiver (T1), wherein the first optical transmitter (D1) is connected to a first control signal input (I1) and the first optical receiver (T1) is connected to a first measurement signal output (S1), and a second optical sensor with a second optical transmitter (D2) and a second optical receiver (T2), wherein the second optical transmitter (D2) is connected to a second control signal input (I1) and the second optical receiver (T2) is connected to a second measurement signal output (S2). The first optical receiver (T1) and the second optical receiver (T2) are connected to a common control signal input (Sx).A first modulation device (M1) for modulating a first measurement signal of the first optical receiver (T1) with a first modulation factor is connected between the first optical receiver (T1) and the first measurement signal output (S1), and a second modulation device (M2) for modulating a second measurement signal of the second optical receiver (T2) with a second modulation factor that is different from the first modulation factor is connected between the second optical receiver (T2) and the second measurement signal output (S2).