Inkjet Recording Head Voltage Pull-Down Circuit
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Solution Overview
Problem
Conventional inkjet recording apparatuses face issues with uncontrollable voltage rise rates during power supply stoppages, leading to unnecessary ink droplet ejection and early degradation of piezoelectric elements due to rapid voltage changes, and are ineffective in preventing ejection during anomalies.
Innovation Solution
An inkjet recording apparatus with a voltage pull-down circuit comprising a switching device and a CR circuit connected to the reference voltage terminal of a D/A converter, which controls the fall rate of the reference voltage during anomalies, preventing unnecessary ink droplet ejection and protecting the piezoelectric element by setting capacitance and resistance values according to load capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If power supply is stopped immediately when anomaly occurs, then circuit protection is achieved, but voltage fall rate becomes uncontrollable causing unnecessary ink droplet ejection
Solution Approach 1:
The patent applies preliminary action by preparing a voltage pull-down circuit with controlled discharge path before the anomaly occurs. When anomaly is detected, the pre-configured pull-down circuit actively controls the voltage fall rate through regulated discharge, preventing the uncontrolled voltage collapse that would otherwise cause unnecessary ink droplet ejection while maintaining circuit protection.
Solution Approach 2:
The voltage pull-down circuit acts as an intermediary between the power supply stop and the piezoelectric element. It mediates the voltage transition by providing a controlled discharge path, ensuring voltage falls at an appropriate rate that prevents both circuit damage and unnecessary ink ejection, thus resolving the contradiction between protection and harmful effects.
2Reliability
If power supply is stopped immediately when anomaly occurs, then circuit protection is achieved, but piezoelectric element degrades early due to rapid voltage changes
Solution Approach 1:
The patent applies preliminary action by pre-configuring a voltage pull-down circuit with controlled discharge characteristics. When anomaly occurs and power supply stops, the pull-down circuit regulates the voltage fall rate to match the piezoelectric element's stress tolerance, preventing rapid voltage changes that would cause early degradation while maintaining circuit protection.
Solution Approach 2:
The patent changes the voltage fall rate parameter through the controlled discharge path provided by the pull-down circuit. By adjusting the discharge characteristics (time constant) of the pull-down circuit, the voltage decreases at an optimized rate that protects both the circuit and the piezoelectric element from stress, extending element lifespan while maintaining protection.
3Speed
If voltage falls rapidly when power supply stops, then power supply response is fast, but piezoelectric element deforms rapidly causing unnecessary ink droplet ejection
Solution Approach 1:
The patent applies preliminary action by pre-establishing a controlled voltage discharge path through the pull-down circuit. This ensures that when power supply stops, voltage falls at a controlled rate determined by the pull-down circuit's time constant, preventing the rapid voltage collapse that would cause unnecessary ink droplet ejection while maintaining acceptable response speed.
Solution Approach 2:
The patent changes the voltage fall rate parameter through the pull-down circuit's controlled discharge characteristics. By adjusting the discharge time constant (through resistor and capacitor values), the system achieves an optimized balance between response speed and preventing harmful rapid voltage changes that would cause unnecessary ink ejection.
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 effectively controls the deformation rate of the piezoelectric element, preventing unnecessary ink droplet ejection and early degradation by managing the voltage fall rate during anomalies, thus enhancing the reliability and longevity of the recording head.
Implementation Method 1
an inkjet recording head configured to eject an ink droplet from a nozzle by utilizing micro vibrations of a piezoelectric element
Implementation Method 2
a voltage pull-down circuit comprising a switching device and a CR circuit connected to the reference voltage terminal of a D/A converter
Implementation Method 3
a voltage pull-down circuit comprising a switching device and a CR circuit connected to the reference voltage terminal of a D/A converter
Data Source
AI summary
An inkjet recording apparatus comprises an inkjet recording head configured to eject an ink droplet from a nozzle by utilizing micro vibrations of a piezoelectric element; and a recording-head driving circuit configured to apply a drive voltage to the piezoelectric element. And, in the apparatus, the recording-head driving circuit includes a D/A converter configured to generate an analog voltage from and corresponding to digital data input to the D/A converter, and a reference-voltage generating circuit configured to generate a reference voltage of the D/A converter, and the reference-voltage generating circuit is configured to be capable of controlling a manner in which the reference voltage falls when an anomaly occurs to the inkjet recording apparatus.