Thermal Printer Pulse Timing for Uniform Optical Density
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing printing control methods using thermal heads fail to maintain uniform optical density across a page, leading to reduced print quality due to variations in print speed.
Innovation Solution
A printer that includes a thermal head with a pulse setting unit to set a first application period of energizing current, an application period correction unit to adjust this period based on the image, and a print speed determination unit to maintain a constant print speed by extending the scanning line time to accommodate the corrected application period, ensuring uniform optical density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If print speed is varied per line to optimize printing efficiency, then productivity is improved, but optical density uniformity deteriorates
Solution Approach 1:
The patent applies parameter changes by adjusting the energizing current application period (duty cycle) based on the print image characteristics. The control unit calculates the duty cycle for each line according to the number of print dots, and varies the application period of energizing current accordingly. This allows maintaining constant print speed while compensating for optical density variations caused by different printing loads, thus resolving the contradiction between productivity and optical density uniformity.
2Manufacturing precision
If application period of energizing current is extended to improve optical density, then print quality is improved, but scanning line time exceeds available period
Solution Approach 1:
The patent applies dynamics by making the application period of energizing current variable rather than fixed. The control unit dynamically adjusts the application period based on the calculated duty cycle for each line, which depends on the number of print dots. This dynamic adjustment allows the system to extend the application period when needed for better optical density while ensuring it never exceeds the scanning line time, thus resolving the contradiction between optical density and scanning line time constraints.
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 improves print quality by maintaining consistent optical density throughout the page, preventing unevenness and enhancing overall print quality.
Implementation Method 1
a thermal head supplies a predetermined current independently to a plurality of heating elements, which are arranged in a line shape, to heat them and form a dot pattern on a print medium having a thermal color developing layer
Implementation Method 2
heat them and form a dot pattern on a print medium having a thermal color developing layer, whereby it prints information
Data Source
AI summary
A printer is configured to print on a print medium having a thermal color developing layer and includes: a thermal head having a plurality of heating elements that are arranged in a line; and a processor configured to: set a first application period of a pulse of energizing current, during a scanning line time for one line, the pulse of energizing current applying thermal energy that causes the thermal color developing layer to develop color, to the plurality of heating elements, correct a length of the first application period, which is set by the processor, based on an image to be printed, and determine print speed to be applied in printing the whole image at a constant speed, by extending the scanning line time so as to contain a maximum length of the first application period that has been corrected by the processor.