Piezoelectric Resonant Lamp-Ignition Circuit Balancing
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Solution Overview
Problem
Conventional coil-type step-up transformers in CCFL backlight modules have low efficiency and high risk of malfunction or fire due to low breakdown voltage, and traditional capacitor designs suffer from high leakage current and inefficiency in maintaining brightness uniformity and long service life.
Innovation Solution
A piezoelectric parallel or cascade resonant lamp-ignition circuit utilizing a high-power piezoelectric substrate as a capacitor, cooperating with an LC resonance circuit, which automatically protects against overheating and provides high power output, reduces leakage current, and balances lamp currents, replacing traditional transformers with piezoelectric transformers for enhanced reliability and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional coil-type step-up transformer is used in a multi-lamp module, then the device can provide high voltage to the lamps, but the efficiency is low and the breakdown voltage is low, creating a high risk of puncture and fire
Solution Approach 1:
The patent replaces the traditional coil-type electromagnetic transformer with a piezoelectric transformer. The piezoelectric transformer uses piezoelectric ceramic materials that convert electrical energy directly to mechanical vibration, which then generates the high voltage needed for lamp ignition through the inverse piezoelectric effect. This substitution eliminates the electromagnetic induction process that causes energy loss and thermal heating in conventional transformers, thereby improving both efficiency and safety.
Solution Approach 2:
The patent changes the fundamental operating parameters of the transformer by using piezoelectric materials with specific dielectric properties. The piezoelectric ceramic capacitors are designed with high breakdown voltage characteristics, allowing the system to operate at higher voltages without the risk of puncture or fire that plagues conventional transformers. This parameter change in the core material properties directly addresses the safety and efficiency contradictions.
2Reliability
If a traditional capacitor is cascaded to the high-voltage end of the lamp to compensate for current difference, then the current balance can be improved, but the leakage current is great and the capacitor may explode and cause fire
Solution Approach 1:
The patent replaces the traditional electrolytic capacitor with a piezoelectric ceramic capacitor. The piezoelectric capacitor is part of the piezoelectric transformer assembly and uses ceramic material that inherently has very low leakage current characteristics. This substitution eliminates the fire hazard associated with electrolytic capacitors while maintaining the current balancing function through the piezoelectric effect.
Solution Approach 2:
The patent employs piezoelectric ceramic materials that combine the properties of both capacitors and transformers in a single component. The piezoelectric ceramic capacitor integrates the current balancing capability with the safety characteristics of piezoelectric materials, creating a composite solution that addresses both current balance and leakage current issues simultaneously.
3Power
If a piezoelectric capacitor is used to output greater power, then the power output increases, but the device complexity increases due to the need for LC resonance circuit
Solution Approach 1:
The piezoelectric capacitor in the patent serves multiple functions simultaneously: it acts as the primary capacitor for voltage multiplication, provides the resonant inductance through its inherent parasitic inductance, and functions as part of the protection circuitry. This multi-functionality reduces the need for separate discrete components, thereby limiting the increase in device complexity while achieving high power output.
Solution Approach 2:
The patent merges the piezoelectric capacitor with the LC resonance circuit into an integrated assembly where the piezoelectric crystal structure itself forms part of the resonant circuit. This merging of functions allows the system to achieve high power output through resonance while minimizing the number of separate components needed, thus controlling device complexity.
4Reliability
If the piezoelectric capacitor temperature rises under overload, then the capacitance increases and resonance is prevented, but the automatic protection function is activated
Solution Approach 1:
The patent implements a thermal feedback protection mechanism where the piezoelectric capacitor's temperature rise under overload conditions naturally increases its capacitance, which in turn detunes the LC resonance circuit. This feedback mechanism automatically reduces power output and prevents further overheating, creating a self-regulating protection function that responds to temperature changes without external control.
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 achieves reduced power consumption, increased competitiveness, and improved lamp ignition efficiency with automatic protection against overload, balancing lamp currents, and preventing overheating, while ensuring high reliability and safety by minimizing leakage current and breakdown risks.
Implementation Method 1
When voltage is applied to the piezoelectric capacitor, the piezoelectric substrate will deform to generate an inverse-piezoelectric effect and then generate a piezoelectric effect after deformation. Thus, positive charge is generated, and voltage is boosted
Implementation Method 2
The piezoelectric capacitor cooperates with an LC resonance circuit. When the LC resonance circuit resonates, the system has the best output performance.
Data Source
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AI summary
The present invention discloses a piezoelectric resonant lamp-ignition circuit, which uses the intrinsic capacitors of a piezoelectric transformer as piezoelectric capacitors. One lamp is connected to one set of the piezoelectric capacitors. Several sets of the piezoelectric capacitors and a resonant inductor are paralleled or cascaded to form a parallel resonant lamp-ignition circuit or a cascade resonant lamp-ignition circuit. The lamp-ignition circuit of the present invention has advantages of low temperature, small leakage current, high voltage resistance and high lamp ignition efficiency. When applied to drive several lamps, the present invention uses a fixed frequency to attain a fixed inner impedance of the equivalent circuits of the piezoelectric capacitors. Thereby, the currents of the lamps are balanced to have an identical value.