To allow correction of gradation density even in the case high-gradation parts can not be adjusted because heating elements have low resistance values and a long energizing period of time is required or in the case low gradation parts exceed the correction limit because the heating elements have high resistance values and the energizing period of time has to be shortened when correction of the gradation density is performed according to the scatter in resistance values of the heating elements.
This gradation heat-sensitive recorder includes a first memory 1, a second memory 2 and an arithmetic circuit 3. The first memory 1 stores head resistance correction values Hm that are gradation values substituted for scatter in resistance values of heating elements of a heat-sensitive recording heat according to differences between the resistance values of the heating elements and a reference resistance value R and an optional gradation number L, and the second memory 2 stores gradation correction width numbers Wn that are shifting values substituted for the gradation value corresponding to the input image data to obtain the same print density within a width between the upper and lower limits of the resistance values of the heating elements. The arithmetic circuit 3 calculates a correction gradation number Zm to correct scatter in the resistance values of the heating elements from the heat resistance correction value Hm, the gradation correction width number Wn and the gradation value (n) corresponding to the input image data.
TOKUMARU SUSUMU
WATANABE SUSUMU
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