Capacitor Discharge Control for Inkjet Printhead Thermal Management
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Solution Overview
Problem
The increasing number of nozzles in inkjet printing apparatuses leads to high power consumption and heat generation in the charging and discharge circuits, particularly during high-density image formation, where the existing solutions fail to shorten the charging and discharge times effectively while controlling heat generation.
Innovation Solution
A control apparatus and method utilizing a large-capacitance electrolyte capacitor as the power supply for the printhead, with a control circuit that manages charging and discharging currents through multiple stages to minimize heat generation and shorten the discharge time, employing a constant-current circuit configuration and switching discharge currents to optimize thermal restrictions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the capacitance of the electrolyte capacitor is increased to supply large instantaneous current to the printhead, then the power supply stability is improved, but the charging time and discharge time are extended
Solution Approach 1:
The patent divides the single large-capacitance capacitor into multiple smaller capacitors connected in parallel. This segmentation maintains the total capacitance value needed for power supply stability while reducing the equivalent series resistance (ESR) and enabling faster charging and discharging operations. Each capacitor can be independently charged and discharged, effectively solving the time delay problem associated with large-capacitance energy storage.
Solution Approach 2:
The patent introduces dynamic control of charging and discharging currents through the control circuit. By dynamically adjusting the current levels based on real-time power supply voltage and current conditions, the system optimizes the charging and discharging speeds, thereby reducing the time required while maintaining power supply stability.
2Productivity
If the charging and discharging currents are increased to shorten the charging time and discharge time, then the processing speed is improved, but the heat generation in the charging circuit and discharge circuit increases
Solution Approach 1:
The patent employs dynamic current control that adjusts charging and discharging current levels based on real-time conditions. The control circuit monitors power supply voltage and current, and dynamically modulates the current to optimize charging/discharging speed while preventing excessive heat generation. This dynamic adjustment allows the system to operate at high speeds when conditions permit and reduce current when thermal limits are approached.
Solution Approach 2:
The patent implements a feedback control mechanism where the control circuit continuously monitors the power supply voltage and current, and uses this information to regulate the charging and discharging currents. This feedback loop ensures that currents are kept within safe thermal limits while still achieving fast charging and discharging, thus resolving the contradiction between processing speed and heat generation.
3Object-generated harmful factors
If a resistor is used to restrict currents in the charging circuit and discharge circuit, then the heat generation is suppressed, but the charging time and discharge time are extended
Solution Approach 1:
The patent segments the current restriction function from a single large resistor into multiple smaller resistors connected in parallel within the control circuit. This segmentation reduces the equivalent resistance value, allowing higher charging and discharging currents to flow without generating excessive heat. The segmented resistor configuration enables faster charging and discharging while maintaining thermal management.
Solution Approach 2:
The patent changes the resistance parameter dynamically through the control circuit, which can switch between different resistance values or adjust the effective resistance based on operating conditions. This allows the system to use lower resistance (faster charging/discharging) when thermal conditions permit and higher resistance (slower but cooler) when needed, optimizing both speed and thermal management.
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
This approach effectively shortens the discharge time of the electrolyte capacitor and suppresses heat generation in the discharge circuit, enhancing the efficiency and stability of the power supply for inkjet printing.
Implementation Method 1
a large-capacitance electrolyte capacitor as the power supply of a printhead
Implementation Method 2
when forming a high-density image by discharging a large amount of ink onto the paper surface by using a thermal method, a large number of heaters arranged near the ink discharge ports of nozzles are instantaneously turned on
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A control apparatus including a power supply means (101) configured to supply electric power, comprises: a capacitor (105) connected to a power supply line extending from the power supply means (101) to a printhead (3); a discharge circuit (107) configured to release charge stored in the capacitor (105); and a control means (102) configured to control a current value during a discharge operation by the discharge circuit (107), such that the current value increases as a voltage value of the capacitor (105) decreases.