Spectrophotometer having independently controlled chart scale expansion

Abstract

A variable chart format system for a recorder with a chart print out, the system having a manually selectable switch for simultaneously controlling the abscissa and ordinate formatting independent of scale expansion circuitry normally associated with the abscissa and ordinate. The abscissa formatting is digital and operable in response to a programmable or variable clock, the output of which is selectively passed through a first set of abscissa formatting frequency dividers and then serially through one of a second set of abscissa scale expansion frequency dividers to drive a chart drive stepper motor. The ordinate formatting is analog and includes ordinate scale expansion circuitry in series with the servomotor and ordinate formatting selectable compensating resistors in series with the recording pen potentiometer or slidewire, the selectable compensating resistors being selected simultaneously with the abscissa formatting dividers to thereby preselect a chart format by a single control without affecting the abscissa or ordinate expansion circuitry.