Panasonic KX-FT71LA-B Service Manual page 134

5.4.3. THERMAL HEAD
1. Function
This unit utilizes state of the art thermal printer technology. / The
recording paper (roll paper) is chemically processed. When the
thermal head contacts this paper it emits heat momentarily, and
black dots (appearing like points) are printed on the paper. If this
continues, letters and/or diagrams appear, and the original
document is reproduced.
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