mr sensor principle

The below figure shows how the output voltage of MR sensor changes.
It shows the output of MR sensor when magnetic substance is passing horizontally to the surface of MR element.
Fig 1-3 shown in the below figure corresponds with position of MR senor and magnetic substance in the above figures.

The figures below indicate sequence of MR elements operational status.
Figure 1 through Figure 3 shows the status of magnetic substance is passing through the surface of MR sensor.

Contrarily when a strong magnetic field is applied to MR2 the resistance at this element is increasing thus making the output voltage larger than that of median voltage.

For example, at the figure beside when strong magnetic field is applied to MR1, the resistance at this element is increasing more than that of MR2 thus making the output voltage smaller than that of median voltage.

But in case of two different strength of magnetic fields are applied to each MR element, the resistance of element changes thus the output voltage is differ from the previous median voltage.

(Please refer a figure beside)
When voltage V is applied at the two end of MR elements the output voltage V is about half of the applied voltage and this voltage is called median voltage.

Two each of MR elements (MR1 & MR2) whose characteristics are as described at the above are connected in series and apply same level of magnetic field to each element.
The output terminals are installed at the connecting parts of each MR element and the voltage appears at this terminals is called output voltage.

The below graph shows the status of resistance change in MR element according to its applied magnetic field. The resistance is changed according to the strength of the magnetic field applied and it is not related with the direction of magnetic field.

First of all a magnetic resistance effect element (from now on called MR element)'s resistance value is changed according to the applied magnetic field by magnetic resistance effect.

The brief explanation of how a MR sensor detects magnetic substance from magnetic ink and changes it to certain kind of output is as follows: