Pulse Generator RC Delay Control for Capacitive Sensor Timing
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Solution Overview
Problem
Existing pulse generators for capacitive sensors lack adjustable pulse duration and are not suitable for driving digital components, limiting their versatility in various measuring tasks and applications.
Innovation Solution
A pulse generator design that generates two clock signals, one with a short delay time constant and the other with a longer precharge time constant, which are supplied to a logic gate to produce a controllable pulse duration, allowing for adjustable pulse generation suitable for capacitive sensing applications, including digital component driving.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed pulse generator circuit is used, then the circuit structure is simple, but the pulse duration is not adjustable
Solution Approach 1:
The patent applies dynamics by making the pulse duration adjustable through variable RC time constants. The first RC element has a variable time constant that can be adjusted to change the pulse width, transforming a static circuit into a dynamic one that adapts to different measurement requirements while maintaining reasonable circuit complexity.
Solution Approach 2:
The patent changes the time constant parameter of the RC elements to achieve pulse duration adjustment. By varying the resistance or capacitance values in the RC circuits, the pulse width can be modified without fundamentally changing the circuit architecture, thus achieving adaptability with controlled complexity.
2Adaptability or versatility
If variable capacitances and resistances are used to adjust pulse width, then the pulse duration becomes adjustable, but the circuit complexity increases
Solution Approach 1:
The patent uses dynamic RC time constants achieved through switching networks or variable components that can change their effective resistance or capacitance values. This allows pulse width adjustment without requiring multiple discrete RC circuits, thereby controlling the increase in circuit complexity while achieving the desired adaptability.
Solution Approach 2:
The patent designs the RC elements to serve multiple functions: they provide both the timing function for pulse generation and the adjustment mechanism for pulse width control. This multi-functionality reduces the need for separate adjustment components, thereby limiting the increase in circuit complexity while achieving variable pulse duration.
3Adaptability or versatility
If a simple pulse generator is used, then the manufacturing is easier, but it is not suitable for driving digital components
Solution Approach 1:
The patent designs the pulse generator to universally interface with both analog capacitive sensors and digital components. The output stage is configured to provide clean, well-defined pulse signals that can drive digital logic circuits while maintaining the simplicity of the overall manufacturing process through standardized component selections and straightforward circuit topology.
Solution Approach 2:
The patent adjusts key parameters such as pulse rise time, fall time, and voltage levels to ensure compatibility with digital component requirements. By optimizing these parameters within the existing circuit framework, the pulse generator achieves digital component compatibility without requiring complex additional circuitry, thus maintaining ease of manufacture.
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 variable pulse generation for capacitive sensors, enhancing their ability to detect object distance, speed, or position, and generating binary or analog signals for diagnostic purposes, making them suitable for applications like seat occupancy sensors and door openers in vehicles.
Implementation Method 1
a first RC element with a first, shorter integrating delay time constant RT1, CT1 in the time range between 10 ns and 200 ns; a second RC element with a second, longer precharge time constant RT2, CT2 with a value of greater than 1 μs
Data Source
AI summary
The disclosure relates to a method for operating a pulse generator 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 which contains a first integrating RC combination (RT1/CT1) and a second integrating RC combination (RT2/CT2), having a logical combining element having two inputs and one output, an initialization circuit and a control unit, wherein the first input of the logical combining element receives a clock signal, and the second input of the logical combining element receives an analog setting signal (SSE) from the output of the delay circuit, 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, and the second clock signal (T2), delayed by the delay circuit, is led to the second input of the logical combining element, time-variable output pulses are generated with the aid of time-variable preloading signals (VL), wherein the output from the delay circuit after each measuring pulse is discharged or charged by the initialization switch.