Piezoelectric Dispenser Closed-Loop Control for Dot Consistency
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Solution Overview
Problem
Existing fluid dispensing applicators using piezoelectric devices face challenges in maintaining consistent jetted material dot size and shape due to material wear and environmental changes, leading to undesirable fluid patterns.
Innovation Solution
A system comprising a piezoelectric actuator assembly connected to a needle, a sensor assembly with an emitter and receiver for light occlusion feedback, and a controller to adjust the actuator's operation based on feedback, ensuring constant dot size and shape by dynamically controlling the needle's motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a piezoelectric device is used to actuate the needle for fluid dispensing, then the response speed and control precision are improved, but the consistency of jetted material dot size and shape deteriorates over time due to material wear and environmental changes
Solution Approach 1:
The patent implements a feedback control system using an optical sensor (emitter and receiver) to detect the needle position and a controller to adjust the piezoelectric device operation based on detected position feedback. This closed-loop feedback mechanism compensates for variations caused by material wear and environmental changes, maintaining consistent jetted material dot size and shape over time while preserving the fast response characteristics of the piezoelectric device.
Solution Approach 2:
The patent dynamically adjusts the operation of the piezoelectric device based on real-time feedback from the optical sensor. The controller modifies the voltage supplied to the piezoelectric device to maintain constant needle position and jetted material characteristics despite changes in material properties or environmental conditions, transforming a static system into a dynamically adaptive one.
2Ease of operation
If the needle reciprocates to dispense fluid material, then the fluid dispensing function is achieved, but the jetted material dot size and shape stray from intended values over time
Solution Approach 1:
The optical feedback system continuously monitors the needle position during reciprocation and provides real-time position data to the controller. This feedback enables the controller to make precise adjustments to the piezoelectric device operation, ensuring that the needle maintains the correct position and velocity for producing consistent jetted material dots, thereby preserving manufacturing precision while maintaining the reciprocating dispensing function.
Solution Approach 2:
The patent replaces purely mechanical position control with an optically-based feedback control system. Instead of relying solely on mechanical precision of the piezoelectric device and needle assembly, the system uses optical detection and electronic control to achieve and maintain precise needle positioning, substituting mechanical rigidity with sensor-based measurement and active control.
3Device complexity
If no feedback control is implemented, then the device complexity is reduced, but the jetted material quality becomes unacceptable due to variations from material wear and environmental changes
Solution Approach 1:
The patent introduces a feedback control loop comprising an optical sensor (emitter and receiver), a sensor holder, and a controller that processes sensor signals and adjusts piezoelectric device operation accordingly. This feedback mechanism detects needle position and provides real-time correction signals, maintaining acceptable jetted material quality despite the added complexity of the control system components.
Solution Approach 2:
The optical sensor assembly serves multiple functions: it detects needle position, provides feedback for control adjustments, and enables the system to compensate for various sources of variation including material wear and environmental changes. This multi-functionality justifies the added complexity by providing comprehensive quality assurance through a single integrated sensor system.
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 system provides dynamic, continuous, and automatic correction of needle motion, maintaining consistent jetted material quality over time by adjusting the voltage supplied to the piezoelectric device, thereby ensuring precise and reliable fluid dispensing.
Implementation Method 1
an actuator assembly that contains a piezoelectric device, wherein the actuator assembly is connected to a needle and configured to translate the needle along a vertical direction
Implementation Method 2
a sensor assembly comprising an emitter for emitting light, where a portion of the actuator assembly or a portion of the needle occludes a portion the light. The sensor assembly also includes a receiver for receiving a non-occluded portion of the light
Data Source
AI summary
A system and method for controlling a needle motion of a material applicator are disclosed. The system includes an actuator assembly that contains a piezoelectric device, where the actuator assembly is connected to a needle and translates the needle along a vertical direction, and a sensor assembly that includes an emitter for emitting light, where a portion of the actuator assembly occludes a portion of the light. The sensor assembly also includes a receiver for receiving a non-occluded portion of the light and a sensor holder that secures the emitter and the receiver. The system further includes a controller in electrical communication with the piezoelectric device, emitter, and receiver, where the controller adjusts operation of the actuator assembly based on feedback received from the receiver.