BIO - MEDICAL RECORDING SYSTEM

The strip chart recorder is an electromechanical device  that facilities of Information and data from experiments of the other activities in graphical form many of the voltage generated by the cells of the body are of clinical interest the biomedical signals are the voltage generated by the heart( ECG),  by the brain (EEG), and by the muscle tissue (EMG). The biome electric voltage is picked up by means of electrodes placed on the surface of the body the bioelectric potential of low frequency is of small amplitude of the order of fraction of Mili voltage these signals are being amplified and is applied to the according mechanism to produce a tracing on the strip chat the chart paper is usually heat-sensitive type that turns black where it is in contact with heated stylus functioning as a pen the recording emerges as a long strip of paper solving the tracing aur waveform of the voltage picked up by the electrodes the basic step of recording can be solved with following block diagram.


The main heart of recording system for writing assembly is an permanent magnet moving coil pmmc galvanometer the coil in the pmmc is centred tab so that it can be driven by a push-pull amplifier therefore be + Alpha BCC of power supply is connected to the centre tape the extreme and of soil are connected to collectors of transistor for of the push-pull amplifier if there is no current or equal amount of current flows in opposite direction then the armature is held and center but if one current is larger than the other if will generate this interacts with the magnetic field of permanent magnet adding or subtracting from 8 depending upon current direction a magnetic force is applied to the armature in an attempt two natural eyes that force since the armature is free to move on its bearing this will cause the pan to be deflected alternatively if the other half of the coil has the greater than the armature will reflect in the opposite direction the pain can be going back and forth through and arc by an electrical signal at low currents this mechanism creates a small amount of non linearity this is due to the fact that a certain amount of current must be applied before the magnetic field is able to our come the armature interior and bearing friction this type of that zone and that breathe around the zero input signal can be reduced by various recorder adjustments.

RECORDER MECHANISM

The basic recorder mechanism can be explained with following diagram the paper is stored on either a supply is pole or roller in a z fold packed this is usually located inside a special compartment on the mechanism the end of the paper is there added through or across a paper break then across a writing age paper table and finally between the idler and drive rollers generally the break writing age and table from one assembly which pulls out when paper is loaded into the machine.

The paper break is used to supply a bag tension to the chart paper the break paper and the two roller operate  together to stretch the paper family across the writing edge so that the paper will stay steady under the tip of the stylus or pen.