System for printhead pixel heat compensation
AssigneeCodonics, Inc.
InventorChristopher Michael Tainer
Life of this patent
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Abstract
A thermal imaging system for compensating for the temperature dependent changes in thermal elements of a thermal printhead is disclosed. Specifically, the thermal imaging system generates a temperature or energy dependent profile of the resistances of each thermal element which makes up the thermal printhead. Based upon this profile, the imaging system estimates the resistances of thermal elements based upon a pixel density to be transferred to media. Based upon the estimated resistances, the imaging system adjusts the amount of energy to be applied to particular thermal elements for transferring a pixel having a density which more closely approximates the density of a corresponding pixel in a desired image.
Claims28
A method of calibrating a thermal printhead to be incorporated into an imaging system for transferring images to media by applying power to the printhead, the printhead having a thermal element, the thermal element having a resistance and a pixel imaging surface, the method comprising:
- measuring the resistance of the thermal element at a plurality of temperatures or energy levels to provide an associated plurality of resistance measurements;
- and
- establishing or maintaining a temperature or energy dependent profile for the thermal element based upon the associated plurality of resistance measurements,
- wherein the temperature or energy dependent resistance profile varies over at least a portion of an operational temperature or energy range of the thermal element.
A method of transferring an image to media from a thermal printhead, the printhead having a thermal element, the thermal element having a resistance and a pixel imaging surface, the method comprising:
- estimating a level of energy of the thermal element based upon a density of pixels in a desired image;
- estimating the resistance associated with the thermal element based upon the estimated level of energy and a temperature or energy dependent resistance profile associated with the thermal element, the temperature or energy dependent resistance profile varying over at least a portion of an operational temperature or energy range of the thermal element;
- and
- calculating an amount of energy to be applied to the thermal element based upon the estimated resistance.
An imaging system for transferring an image to media from a thermal printhead, the printhead having a thermal element, the thermal element having a resistance and a pixel imaging surface, the imaging system comprising:
- logic for estimating one of an energy level and a temperature to be applied to the thermal element;
- logic for estimating the resistance associated with the thermal element based upon the estimated temperature or energy level and a temperature or energy dependent resistance profile associated with the thermal element, the temperature or energy dependent resistance profile varying over at least a portion of an operational temperature or energy range of the thermal element;
- and
- logic for calculating an amount of energy to be applied to the thermal element based upon the estimated resistance.
A system for calibrating a thermal printhead to be incorporated into an imaging system for transferring images to media by applying power to the printhead, the printhead having a thermal element, the thermal element having a resistance and a pixel imaging surface, the system comprising:
- a measurement circuit configured to measure the resistance of the thermal element at a plurality of temperatures or energy levels to provide an associated plurality of resistance measurements;
- and
- logic establishing or maintaining a temperature or energy dependent resistance profile for the thermal element based upon the associated plurality of resistance measurements,
- wherein the temperature or energy dependent resistance profile varies over at least a portion of an operational temperature or energy range of the thermal element.
Dependencies are inferred from the claim text.