A strip chart recorder is a type of analog-graphical recorder which records the variation of one or more variables with respect to time on a chart (graph paper) moving at a constant speed.
Working of Strip Chart Recorder
The block diagram of a strip chart recorder is shown in figure 1.
Figure 1: Strip Chart Recorder
The functional elements of a strip chart recorder are a stylus (recording pen) for tracing the signal on the graph paper, a system which drives the stylus, a long roll of graph paper, a mechanism which drives the paper in vertical direction. The speed of a movement of graph paper (chart) is selected through a speed selector which is connected to the chart drive mechanism. The strip chart recorder also consists of a range selector switch and a signal conditioning circuit at its input section so that the level of the input signal is within the limits acceptable by stylus drive system.
When the input signal to be recorded is fed to the strip chart recorder the input signal is processed through a range selector and signal conditioner and then it is applied to the stylus drive system. The input to the stylus drive mechanism is a voltage or cun ent signal corresponding to the signal to be recorded. The stylus drive mechanism is driven by a servo motor. The stylus drive mechanism moves the stylus horizontally by an amount proportional to the magnitude of the input signal. Simultaneously the chart driving mechanism moves the graph paper vertically at a certain speed selected through the chart speed selector. The graph paper is usually moved at speeds of 1-100 mm/s.
The simultaneous movement of the stylus and chart in horizontal and vertical directions respectively traces (records) the input signal with respect to time on the graph paper. The strip chart recorder also uses a pointer connected to the stylus. This pointer moves over a uniformly marked scale thus displaying the instantaneous values of recorded quantity.