| 摘要 |
PURPOSE:To eliminate fluctuation of phases of detecting signals and erroneous code reading, by arranging respectively 4 magnetic detection units of the opposedly located both wheatstone bridge circuits integrally on a substrate of a magnetic head in a proper sequence in the relative displacement direction of magnetic marks. CONSTITUTION:In this position, magnetic detection units 2a, 2c are magnetized most strongly with values of resistances 3a, 3c being (r) throughout, with degrees of magnetization of magnetic detection units 2b and 2d at the lowest and with values of resistances 3b and 3d R throughout. A voltage of a terminal 3g is VS1=V0+R/(R+r)V, and a voltage VS0 of a terminal 3h is VS. Movement of a magnetic head in either direction causes increase of resistances 3a, 3c and decrease of 3b, 3d. When the movement reaches lambda/2, the former takes a value R and the latter r with VS=-(R-r)/(R+r), representing the least value of VS. When a magnetic resistor 2 moves further in the same direction, VS is increased and when the total displacement reaches lambda, the largest value is reached again and consequently, a sinusoidal curve, signal can be obtained in the same way, eliminating function of detecting signals and erroenous reading of code by a phase difference. |
