| 摘要 |
PURPOSE: To allow a color to develop with a specific density by discriminating a degree of a degradation of a color heat sensitive recording paper with ease and with a simple method, and by regulating a heating energy to be applied to a thermal head, according to this degradation degree. CONSTITUTION: A degradation color sample 4 is divided into 5 grades according to a color to be displayed, from a sample 4a having a green color which is a surface color immediately after production, to a sample 4e having a white color which is a surface color wherein a coloring becomes completely impossible. By executing a comparison between these samples 4a-4e and a color heat sensitive recording paper 2, a degradation of the color heat sensitive recording paper 2 can be known. A color heat sensitive recording paper having a color range (green color-thin brown color) shown in the samples 4a-4e, by regulating a bias heating energy of a thermal head, can be raised to an initial density. The color heat sensitive recording paper 2 having a color range (thin yellow color- white color) shown in the samples 4d, 4e can be known to be in a state wherein a coloring power is almost lost and usage thereof is impossible. |
