Capacitive Sensor Pulse Generator With Adjustable RC Pulse Timing
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Solution Overview
Problem
Existing pulse generators for capacitive sensors lack the ability to generate variable pulses with adjustable duration, are not suitable for digital assemblies, and require high complexity with variable resistances and capacitances.
Innovation Solution
A pulse generator design that uses two distinct signal paths, one with a short delay RC element and another with a longer precharging RC element, generating a controllable bias voltage to produce variable pulse durations, suitable for capacitive sensing applications and digital control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If variable resistors and capacitors are used to adjust pulse width, then pulse duration is adjustable, but device complexity and cost increase
Solution Approach 1:
The pulse width adjustment function is segmented into two distinct RC circuits: a first RC circuit for quick charging (short time constant) and a second RC circuit for slow discharging (long time constant). This segmentation allows independent optimization of charging and discharging paths, achieving variable pulse duration without requiring complex variable components.
Solution Approach 2:
The patent uses switchable capacitor configurations to dynamically change the effective capacitance values in the RC circuits. By switching between different capacitor connections (series/parallel combinations), the time constants are dynamically adjusted, enabling variable pulse duration while using fixed, simple components instead of complex variable resistors or capacitors.
2Device complexity
If simple RC circuits are used, then device complexity is reduced, but pulse duration cannot be varied
Solution Approach 1:
The patent introduces dynamic switching capability through capacitor switching arrangements that change the effective capacitance values based on control signals. This allows the same simple RC circuit structure to adapt to different pulse duration requirements by switching between pre-defined capacitance configurations, achieving versatility without increasing fundamental circuit complexity.
Solution Approach 2:
Multiple capacitor configurations are pre-arranged in the circuit, and the desired capacitance value is selected in advance through switching. This preliminary arrangement of multiple fixed capacitor options allows the circuit to achieve variable pulse duration functionality while maintaining the simplicity of fixed-component RC circuits.
3Device complexity
If fixed pulse duration is used, then device complexity is minimized, but adaptability to different measurement tasks is limited
Solution Approach 1:
The patent creates a universal pulse generator that can serve multiple measurement tasks with different pulse duration requirements. By incorporating switchable capacitor configurations, a single circuit design can adapt to various applications (capacitive sensing, digital control, etc.) without requiring multiple dedicated circuits, achieving multi-functionality while keeping the overall device complexity manageable.
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
Enables the generation of variable pulses in the range of 10ns to 200ns, suitable for diverse measurement tasks, including capacitive sensing in automotive applications, with reduced complexity and suitability for digital control systems.
Implementation Method 1
The delay circuit converts the second clock signal into an analog output signal, depending on an integrating delay time constant RT1, CT1, thereby generating a time delay in the range of 10 ns to 200 ns
Implementation Method 2
The delay circuit receives a time-variable pre-charge signal VL at a second input. This pre-charge signal is pre-charged via an integrating pre-charge time constant RT2, CT2 in the time range greater than 1 μs
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a method for operating a pulse generator (1) for generating measuring pulses for a capacitive sensor having an adjustable pulse time in the range from 10 ns to 200 ns, having a controllable delay circuit (2) which contains a first integrating RC combination (RT1/CT1) and a second integrating RC combination (RT2/CT2), having a logical combining element (3) having two inputs and one output, an initialization circuit (5) and a control unit (4), wherein the first input of the logical combining element (3) receives a clock signal, and the second input of the logical combining element (3) receives an analog setting signal (SSE) from the output of the delay circuit (2), wherein two simultaneous clock signals are generated, of which the first clock signal (T) is led without delay to the first input of the logical combining element (3), and the second clock signal (T2), delayed by the delay circuit (2), is led to the second input of the logical combining element (3), time-variable output pulses are generated with the aid of time-variable preloading signals (VL), wherein the output from the delay circuit (2) after each measuring pulse is discharged or charged by the initialization switch (5).