Thermal Print Head Pulsing for Multicolor Direct Thermal Printing
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Solution Overview
Problem
Conventional thermal printing systems face challenges in achieving effective screening techniques for wide format printing, as they cannot vary pulse duty cycles across print head elements, limiting the ability to print multiple colors in a single pass and increasing peak power requirements.
Innovation Solution
The system divides line-printing time into segments with uniform pulses, varying the fraction of subintervals with pulses to select different colors, allowing multiple colors to be printed using a single strobe signal and reducing peak power demands by optimizing pulsing patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional thermal printing systems use uniform pulse duty cycles for all print head elements, then the system operation is simplified, but the ability to print multiple colors in a single pass is limited
Solution Approach 1:
The line-printing time is divided into multiple segments, with each segment assigned to a different color. Within each segment, uniform pulse duty cycles are maintained for simplicity, but different segments can have different duty cycle characteristics. This segmentation allows multicolor printing while preserving operational simplicity within each segment.
Solution Approach 2:
The system uses periodic pulsing patterns within each time segment to print different colors. By organizing the pulsing action into periodic segments corresponding to different colors, the system achieves multicolor capability while maintaining uniform duty cycles within each periodic segment, thus not increasing overall system complexity.
2Adaptability or versatility
If conventional systems print multiple colors using separate donor ribbons or multiple print heads, then color printing capability is achieved, but the system complexity and cost increase
Solution Approach 1:
A single print head is designed to perform multiple functions by printing different colors during different time segments. The same physical print head elements are used universally for all color planes, with color selection achieved through temporal segmentation rather than requiring separate dedicated print heads for each color.
Solution Approach 2:
The system adds a time dimension to color selection rather than requiring spatial separation through multiple print heads. By organizing color printing in the time domain (different segments within a line interval), the system achieves multicolor capability with a single spatial print head configuration.
3Power
If conventional thermal printing systems operate without optimized pulsing patterns, then the printing process is simpler, but peak power requirements increase
Solution Approach 1:
The system employs periodic pulsing patterns within each time segment to reduce peak power requirements. By organizing the energy delivery into periodic pulses rather than continuous operation, and by coordinating these pulses across different print head elements, the system reduces instantaneous power demands while maintaining effective printing.
Solution Approach 2:
The pulsing patterns are dynamically optimized for each time segment and color plane. The system adjusts the timing and distribution of pulses dynamically across different segments, allowing power consumption to be optimized for each specific printing task rather than using a static, conservative power level throughout.
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 enables multicolor thermal imaging in a single pass, improves image stitching tolerance to misregistration, and reduces peak power requirements, making the system more efficient and cost-effective.
Implementation Method 1
The print head elements can be addressed in a first time segment to heat a first color plane of the thermal imaging member to a first temperature to select a first color and to print the first color on the output medium, and can be addressed in a second time segment to heat a second color plane of the thermal imaging member to a second temperature to select a second color
Implementation Method 2
Each of the print head elements, when activated, forms color on the portion of the medium passing underneath the print head element... Providing energy to the print head element increases the temperature of the print head element, causing either the transfer of pigment to the output medium or the formation of color in the output medium
Data Source
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AI summary
A direct thermal printer comprises a thermal print head having a plurality of heating elements, and a controller connected to the thermal print head that applies, during a first portion of a printing time, a first pulse pattern to the heating elements, and that applies, during a second portion of the printing time, a second pulse pattern to the heating elements. The first pulse pattern comprises a first plurality of pulses having a first average power, each of the first plurality of pulses having a common energy, wherein the first portion of the printing time comprises a first plurality of subintervals, and wherein the first plurality of pulses is provided in a plurality of consecutive subintervals. The second pulse pattern comprises a second plurality of pulses having a second average power that differs from the first average power, wherein each of the second plurality of pulses has the common energy, wherein the second portion of the printing time comprises a second plurality of subintervals, and wherein the second plurality of pulses is provided in a plurality of nonconsecutive subintervals.