| 摘要 |
PURPOSE:To attain long service life of a resistance change element by connecting a couple of common base transistors (TR) across the resistance change element so as to keep the current density of the resistance change element constant. CONSTITUTION:When a resistance value of a magneto-resistance effect type magnetic head 1 is changed from RMR to (RMR+DELTARMR) because of the magnetization of a medium, a voltage across the magneto-resistance effect type magnetic head 1 is unchanged because emitters of a couple of the common base TRs 4, 5 suppress the change, and only the current changes from IMR to (IMR+ DELTAIMR). Since the terminal voltage of the magneto-resistance effect type magnetic head 1 depends on the difference of the base potentials Vref+ and Vref- of a couple of the common base TRs 4, 5 and is constant always, even if the magneto-resistance effect type magnetic head 1 is worn, the current density is constant. |
