Method and apparatus for controlling a thermal color printer
Thermal printing apparatus with reference gray scale comparator
Tone control for thermal ink-transfer printing apparatus Patent #: 4532523
ApplicationNo. 06/838367 filed on 03/11/1986
US Classes:347/184, Look up table347/183, Gradational recording347/210Including switching means
ExaminersPrimary: Goldberg, E. A.
Assistant: Preston, Gerald E.
Attorney, Agent or Firm
International ClassH04N 1/405 (20060101)
Foreign Application Priority Data1985-03-12 JP
AbstractA gradation control device for a thermal printer, keeps a frequency of a reference clock pulse signal and a data transfer speed to a shift register constant, respectively. A linearity compensation circuit is provided between a data counter and a gate circuit and the gradation level or printing density is controlled by controlling heating times of heating elements within the constant data transfer time, so that a data transfer time for one printing density becomes equal to a maximum heating time of the heating element and a control range described by (maximum printing density)/(minimum printing density) can be set in terms of the period of the reference clock pulse signal to thereby finely control the printing density.