Active Clamp Photoelectric Sensing Circuit for Stable Output Recovery
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Solution Overview
Problem
Conventional clamp circuits in photoelectric sensing devices suffer from response delay due to output saturation and clamping voltage offset, which is exacerbated by manufacturing processes and temperature variations, leading to potential misjudgment in determination circuits.
Innovation Solution
An active clamp photoelectric sensing device utilizing operational amplifiers and transistor switches to dynamically control the clamping voltage, ensuring the input and output terminals return to set values during resets, thereby stabilizing the output voltage and reducing misjudgment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a clamp circuit is used to prevent output saturation, then response delay is improved, but clamping voltage offset occurs due to incomplete potential recovery
Solution Approach 1:
The patent implements a feedback mechanism where the reset signal controls the switch to actively restore the input terminal potential to the reference voltage after each clamping operation. This feedback loop ensures complete potential recovery by continuously monitoring and adjusting the terminal voltage, thereby eliminating the voltage offset problem while maintaining the response delay improvement.
Solution Approach 2:
The patent applies preliminary action by proactively resetting the terminal potential to the reference voltage immediately after each clamping event, rather than allowing the potential to drift. The reset switch is designed to automatically activate and restore the potential before the next measurement cycle begins, preventing cumulative offset errors from developing.
2Loss of time
If diodes are used in clamp circuits, then response delay is reduced, but manufacturing process and temperature variations cause incorrect output voltage
Solution Approach 1:
The patent substitutes the passive diode-based clamping mechanism with an active operational amplifier-based circuit. The operational amplifier provides precise voltage control and compensation, replacing the temperature-sensitive diode characteristics with a stable, actively regulated system that maintains accurate output voltage across varying manufacturing processes and temperature conditions.
Solution Approach 2:
The patent changes the operating parameters by using an operational amplifier to actively maintain the reference voltage level, rather than relying on the fixed voltage drop characteristics of diodes. This allows the circuit to compensate for parameter variations due to manufacturing tolerances and temperature changes, ensuring stable output voltage while maintaining fast response characteristics.
3Loss of time
If operational amplifier output is clamped below supply voltage, then response delay is improved, but potential cannot fully return to set value
Solution Approach 1:
The patent uses feedback control through the reset switch mechanism that actively monitors the input terminal potential and restores it to the reference voltage after each clamping event. This feedback ensures that the potential fully returns to the set value, maintaining stability while allowing the clamping function to improve response delay during measurement cycles.
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 device effectively addresses response delay and clamping voltage offset, providing stable output voltages less susceptible to manufacturing and temperature variations, enhancing circuit flexibility and accuracy.
Implementation Method 1
a photoelectric sensor generates a current signal corresponding to incident light
Data Source
AI summary
An active clamp photoelectric sensing device includes an input terminal, a first output terminal, a current-to-voltage conversion circuit, and an active clamp circuit. The input terminal receives an input current. The first output terminal outputs a first output voltage. The current-to-voltage conversion circuit is coupled between the input terminal and the first output terminal, and is used to discharge and lower potentials of the input terminal and the first output terminal to a first set voltage according to the state of a reset signal, or is used to gradually increase the first output voltage to a second set voltage. The active clamping circuit is coupled to the current-to-voltage conversion circuit, and is used to clamp the upper limit of the first output voltage to the second set voltage.