Printhead Driver Pulse Width Control for Voltage Drop Compensation
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Solution Overview
Problem
In printing apparatuses that use energy generation elements to discharge ink, driving multiple heaters simultaneously leads to increased current flow and voltage drops due to wiring resistance, resulting in inconsistent thermal energy and ink droplet volume, which deteriorates image quality and reduces throughput.
Innovation Solution
A printing apparatus with a control unit that adjusts the pulse width of source follower transistors based on the number of simultaneously driven printing elements, ensuring a fixed voltage across heaters by employing a first control for fewer elements and a second control for more elements, thereby stabilizing ink droplet volume and suppressing heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If as many heaters as possible are driven simultaneously to achieve high printing speed, then productivity is improved, but voltage drop due to parasitic resistance increases causing deterioration of manufacturing precision
Solution Approach 1:
The patent applies dynamics by making the heater driving pulse width variable based on the number of simultaneously driven heaters. When more heaters are driven, the pulse width is reduced to compensate for increased voltage drop, maintaining consistent thermal energy delivery. This dynamic adjustment resolves the contradiction by adapting the driving parameters in real-time based on the printing speed requirements and heater activation patterns.
Solution Approach 2:
The patent changes the parameter of pulse width duration based on the number of heaters driven simultaneously. By adjusting this temporal parameter, the system compensates for voltage drops caused by higher current loads, ensuring that thermal energy delivery remains consistent even when printing speed is increased through simultaneous heater activation.
2Manufacturing precision
If source follower configuration is used to fix voltage across heaters, then manufacturing precision is improved, but heat generation increases reducing productivity
Solution Approach 1:
The patent combines source follower configuration with dynamic pulse width adjustment. The source follower provides a baseline voltage stability, while the dynamic pulse width modification compensates for residual voltage drops under different loading conditions. This hybrid approach maintains manufacturing precision without the excessive heat generation that would occur with fixed high-voltage source follower operation alone.
Solution Approach 2:
Instead of using full-strength source follower configuration that would guarantee voltage stability but cause excessive heat generation, the patent applies partial action by using source follower only when necessary (when voltage drop exceeds thresholds) and adjusting pulse width to provide just enough compensation. This avoids the excessive heat generation while maintaining sufficient voltage stability for manufacturing precision.
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 maintains a consistent voltage across heaters, stabilizes ink droplet volume, and reduces heat generation, thereby improving image quality and throughput.
Implementation Method 1
driving circuits that have at least one source follower transistor and correspond to each of the plurality of printing elements
Implementation Method 2
cause ink to discharge by heating the ink by energy generation elements (hereinafter referred to as heaters)
Implementation Method 3
voltage drop due to parasitic resistance of the wiring increases
Data Source
AI summary
A printing apparatus comprises: a plurality of printing elements; driving circuits that have at least one source follower transistor and correspond to each of the plurality of printing elements; and a control unit configured to, in a case where a number of printing elements driven simultaneously does not exceed a predetermined number, perform a first control for driving the at least one source follower transistor by a fixed pulse width irrespective of the number of printing elements driven simultaneously, and, in a case where the number of printing elements driven simultaneously exceed the predetermined number, perform a second control for changing a pulse width to drive the at least one source follower transistor based on the number of printing elements driven simultaneously.