Finnegan, Henderson, Farabow, Garrett and Dunner
Thermal recording apparatus capable of gradation recording
 A thermal recording apparatus includes a comparator for comparing the black density of picture elements to be recorded by thermal recording elements to reference density levels, a counter accumulates a value representing the number of picture elements having density levels in certain ranges as a result of the comparison by the comparator. The counter value is used to adjust the pulse width of pulses used to energize the recording elements to compensate for fluctuations in the levels of the pulses due to the number of recording elements that are energized at one time and the durations of the energizations in order to record visible images of the picture elements with appropriate densities. 
Fuji Xerox Co., Ltd.
B H
B41J H04N
inventional inventional
Nobuhisa
Kato