Thermal Printer Capacitor Power Management for Consistent Print Quality
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Solution Overview
Problem
Existing battery-operated thermal printers are limited by the number of active resistive elements, leading to undesirable results such as steps in lines and reduced speed due to power source voltage reduction, which also limits the number of devices that can be powered.
Innovation Solution
A thermal printer design incorporating a capacitor to store power and a power converter that steps the voltage from a power source, allowing the capacitor to supply power to the thermal print head, enabling all resistive elements to be active simultaneously and maintaining constant print speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of active resistive elements is limited to avoid overloading the power source, then the power source can be protected from overload, but the print quality deteriorates due to steps in lines and reduced speed
Solution Approach 1:
The capacitor is pre-charged to a voltage higher than the nominal power source voltage before printing operations begin. This preliminary energy storage enables the thermal print head to receive sufficient power for activating all resistive elements simultaneously, eliminating print quality defects caused by power limitations while the power source charges the capacitor during idle periods.
Solution Approach 2:
The capacitor acts as an intermediary energy storage device between the power source and the thermal print head. It decouples the power source from the high-power demands of the print head, allowing the power source to operate within safe limits while the capacitor delivers the necessary power bursts for high-quality printing.
2Productivity
If the power source voltage is reduced due to electrical load, then the battery can power more devices, but the print speed decreases and mark quality becomes inconsistent
Solution Approach 1:
The capacitor is pre-charged to a voltage higher than the nominal power source voltage before printing operations begin. This preliminary energy storage enables the thermal print head to receive sufficient power for activating all resistive elements simultaneously, eliminating print quality defects caused by power limitations while the power source charges the capacitor during idle periods.
Solution Approach 2:
The system changes the voltage parameter by using a capacitor charged to a higher voltage than the power source provides. This voltage parameter change ensures that the thermal print head receives consistent, adequate power for high-speed operation regardless of the power source voltage droop under load, maintaining both print speed and mark quality consistency.
3Illumination intensity
If the strobe time is increased to compensate for reduced power source voltage, then darker marks are produced, but the marks become larger than desired and print speed reduces
Solution Approach 1:
The system changes the voltage parameter by using a capacitor charged to a higher voltage than the power source provides. This voltage parameter change ensures that the thermal print head receives consistent, adequate power for high-speed operation regardless of the power source voltage droop under load, maintaining both print speed and mark quality consistency.
Solution Approach 2:
The system uses short, periodic strobe pulses to activate the resistive elements. Because the capacitor provides sufficient voltage during these brief pulses, the marks are formed quickly with proper size and darkness, eliminating the need for extended strobe times that would cause mark enlargement and speed reduction.
4Reliability
If resistive elements are strobed in separate segments to avoid power overload, then the power source is protected, but steps appear in the printed lines
Solution Approach 1:
The capacitor is pre-charged to a voltage higher than the nominal power source voltage before printing operations begin. This preliminary energy storage enables the thermal print head to receive sufficient power for activating all resistive elements simultaneously, eliminating print quality defects caused by power limitations while the power source charges the capacitor during idle periods.
Solution Approach 2:
The capacitor acts as an intermediary energy storage device between the power source and the thermal print head. It decouples the power source from the high-power demands of the print head, allowing the power source to operate within safe limits while the capacitor delivers the necessary power bursts for high-quality printing.
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 solution ensures consistent print quality and speed by maintaining the charge state of the capacitor above a threshold, allowing all resistive elements to be powered simultaneously, reducing the need for varying print speed and increasing the number of devices that can be powered.
Implementation Method 1
a capacitor selectively coupleable to supply power stored in the capacitor to the thermal print head
Implementation Method 2
a power converter operable to step a voltage from a power source and to supply the stepped voltage to the capacitor and the thermal print head
Implementation Method 3
The marks are produced by a plurality of resistive elements of a thermal print head which heat the thermal paper or thermal ribbon to form successive lines
Data Source
AI summary
A thermal printer includes a capacitor and a power converter operable to step a voltage of a power source, and coupled to charge the capacitor. Printing is controlled based at least in part on a charge state of the capacitor. Delays in charging the capacitor may be avoided where a current line of print data is blank. Operation may be curtailed where the voltage of the power source is below a threshold.