Independent Power Supplies For Color Inkjet Printers

What is this patent about?

'674 is related to the field of thermal inkjet printing, specifically addressing the challenge of supplying appropriate power to the ink ejection elements (firing resistors) within printheads. Traditional inkjet printers often use a single voltage for all print cartridges, which can lead to suboptimal print quality and reduced printhead life, especially when different cartridges or sections within a cartridge require different firing energies.

The underlying idea behind '674 is to use multiple independent power supplies to provide customized firing energy to different groups of ink ejection elements. This allows for precise control over the voltage and current delivered to each group, optimizing ink drop volume and minimizing wasted energy. The key insight is that different color inks, different printhead designs, or even different sections within a single printhead may require different firing voltages to achieve optimal performance.

The claims of '674 focus on an inkjet printing system comprising multiple power sources, each independently settable to a different voltage level, and each connected to a distinct group of ink ejection elements. These groups can be arranged in various ways: different print cartridges for different colors, different arrays within a single cartridge, or different sections of an array for a single color. The core concept is the ability to tailor the firing energy to the specific needs of each group.

In practice, the system achieves this by having separate power supplies (or voltage regulators) for each group of ink ejection elements. The voltage for each supply is set based on factors like the ink's properties, the design of the ejection elements, and any parasitic resistances in the electrical path. This ensures that each group receives the optimal firing energy, leading to consistent drop volumes and improved print quality. The system can also compensate for variations in manufacturing tolerances or changes in operating conditions.

This approach differs significantly from prior solutions that rely on a single voltage for all ink ejection elements. By providing independent control over the firing energy, '674 overcomes the limitations of these earlier designs. It avoids the need to compromise on voltage levels, which can lead to either insufficient firing energy (resulting in poor drop formation) or excessive energy (leading to wasted power, overheating, and premature wear of the printhead). The use of independently settable power supplies allows for a more efficient and reliable inkjet printing system.