Thermal Printer Density Control for Ink Ribbon Wrinkling

Solution Overview

Problem

Thermal printers face issues with ink ribbon wrinkling due to heat from the thermal head, especially at low ambient temperatures, where print density adjustments to prevent wrinkling conflict with maintaining optimal print quality.

Innovation Solution

A thermal printer with a density controller that calculates a density evaluation value based on prior print data to assess the likelihood of wrinkling, allowing for targeted adjustments in print density specifically for high-density areas, reducing the risk of wrinkling without lowering overall print density.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If print density is increased to maintain optimal print quality at low temperatures, then print density is improved, but ink ribbon wrinkling worsens

Engineering Contradiction:

Improveprint densityVSAvoidink ribbon wrinkling

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by differentiating between high-density and low-density regions in the print data. The density evaluation value calculation focuses on high-density regions (e.g., regions with density above a threshold or in the upper percentile), and density adjustment is applied selectively only to these high-density regions. This allows the system to maintain high print density where needed while reducing heat exposure in areas that contribute most to wrinkling, thereby resolving the contradiction between maintaining print quality and preventing wrinkling.

Inventive Principle:

Principle #3Local quality

2Object-affected harmful factors

If energy supplied to thermal head is reduced to suppress wrinkling, then ink ribbon wrinkling is improved, but print density worsens

Engineering Contradiction:

Improveink ribbon wrinklingVSAvoidprint density

Core Design Contradiction:

Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The patent applies local quality by differentiating between high-density and low-density regions in the print data. The density evaluation value calculation focuses on high-density regions (e.g., regions with density above a threshold or in the upper percentile), and density adjustment is applied selectively only to these high-density regions. This allows the system to maintain high print density where needed while reducing heat exposure in areas that contribute most to wrinkling, thereby resolving the contradiction between maintaining print quality and preventing wrinkling.

Inventive Principle:

Principle #3Local quality

3Manufacturing precision

If thermal head temperature is increased to improve ink transfer, then print density is improved, but ink ribbon shrinkage and wrinkling worsen

Engineering Contradiction:

Improveprint densityVSAvoidink ribbon wrinkling

Core Design Contradiction:

Manufacturing precisionVSShape

Solution Approach 1:

The patent applies preliminary action by calculating the density evaluation value based on print data before actual printing occurs. The system analyzes the upcoming print data to identify high-density regions that will generate excessive heat, and pre-adjusts the density for these regions to reduce heat exposure. This proactive approach prevents ink ribbon shrinkage and wrinkling before they occur, while maintaining optimal print density in regions where higher temperature is beneficial.

Inventive Principle:

Principle #10Preliminary action

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

Effectively suppresses ink ribbon wrinkling at low temperatures by reducing heat exposure in high-density areas, maintaining print quality and preventing wrinkles without requiring special patterns in the original image.

Implementation Method 1

A thermal transfer printer performs printing by using a thermal head to heat a predetermined portion of an ink ribbon coated with a molten ink or a sublimation dye, and thermally transferring the ink to printing paper

Methodology Applied

Scientific EffectThermal transfer: Conduction (thermal)

Implementation Method 2

Because this thermal head transfers the ink by generating heat

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS7746367B2Thermal printer

Publication Date: 2010.06.29 CITIZEN WATCH CO LTD

AI summary

The thermal printer of the present invention is a thermal printer for printing on a print medium by thermally transferring an ink ribbon by means of a thermal head, wherein the thermal printer comprises a density controller for keeping the print density of the thermal head low in low-temperature control for raising the print density at low temperatures. The density controller comprises a density calculator for calculating a density evaluation value by finding an average gradation value of print data for each of a plurality of dots included in the predetermined region, a comparator for comparing the calculated density evaluation value with a predetermined value, and an adjuster for adjusting, on the basis of this comparison result, the print density in driving and printing with the thermal head to a low value for print data of high gradation exceeding a predetermined gradation value in print data on a printed line when the density evaluation value exceeds a predetermined value. The printing of each dot by the thermal head is controlled on the basis of the adjusted print density. Even if low temperature control is carried out by the thermal head when the ambient temperature is low, the occurrence of ink ribbon wrinkling due to the effect of print density is suppressed.