Title: Device for controlling the density of printing characters

Abstract: To adjust the density of alphanumeric to be thermally printed by a thermal printer, a time duration for applying the row or column drive current to the selected dot elements in a thermal head is varied so as to vary a time duration for which the selected dot elements are energized, to thereby change the quantity of heat dissipated therefrom depending upon the environmental temperature, the thermal characteristics and aging of thermally sensitive paper and so forth. The drive current flowing duration may be varied by varying a cycle of the drive current signals to be sequentially applied to the row or column drive lines of a dot element matrix circuit through a character generator. In one embodiment of the present invention, the cycle of the drive current signals may be varied by the frequency division or count down of the clock pulses with a variable pulse repetitive rate used in an electronic computer.

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Inventors: Ito, Matsutoshi (Narashino, JA)
Nishikawa, Tatsuo (Tachikawa, JA)
Takeshita, Kano (Tokyo, JA)

Application Number: 548759
Filing Date: 1975-02-10
Publication_date: 1976-08-17
Assignee: Canon Kabushiki Kaisha (Tokyo, JA)
Primary Class(es): 347/190
Other Classes:
US Patent Ref:

2922688	Jan, 1960	Boyan	346/76.
3139026	Jun, 1964	Meckstroth et al.	346/76.
3577137	May, 1971	Brennan	219/216.

Other Refs:
Primary Examiner: Hartary, Joseph W.
Assistant Examiner:
Attorney: Fitzpatrick, Cella, Harper & Scinto