Astro-med, Inc.

Michael J Sullivan

David M Gaskill

Albert W Ondis

A thermal chart recorder which is operative for simultaneously generating a plurality of wave form images on a thermally responsive chart in response to input signals utilizing a stationary thermal print head, includes a sound generation circuit for generating audible sounds which simulate the sounds generated by the styli of a traditional stylus-type recorder. The volume levels of the sound produced by the sound generation circuit correspond to the sum of the approximate absolute values of the rates of change of the input signals and can be utilized for allerting operators to rapid changes in recorded parameters.

Chart recorder with thermal print head and sound generator

A chart recorder includes a chart drive assembly including a drive platen, first and second print heads, a slave controller for energizing the second print head, a master controller for energizing the first print head and for actuating the slave controller and a host computer for controlling the master and slave controllers and for supplying data thereto. The master controller controls the chart drive assembly to coordinate it with the energizations of the print heads, and it actuates the slave controller to synchronize the energizations of the print heads. The print heads are independently mounted in end-to-end relation and independently biased toward the chart and the platen at a printing station to enable them to compensate for deflections in the print head and/or the platen, as well as distortions in the heads due to thermal expansion.

Chart recorded having multiple thermal print heads

An electrical circuit for controlling the energization of thermal print head elements on a thermal print head. The circuit is responsive to the overall temperature of a thermal print head for varying the amounts of energy supplied the print head elements thereof so that markings of substantially uniform darkness can be produced on thermally sensitive sheets regardless of the overall head temperature. The circuit is operative in response to a start signal for producing a predetermined number of sequential pulses of substantially uniform duration during a printing cycle to sequentially energize different groups of print head elements at different times during the cycle. The voltage level of the pulses in the cycles is maintained substantially constant, whereas the duration of the pulses in different cycles is varied to vary the amounts of energy supplied to the print head elements.

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Portsmouth, RI, United States of America

Michael J Sullivan