| 摘要 |
PURPOSE:To eliminate an error due to fluctuations of temperature by a device which reads magnetic medium information by a Hall element, by finding the difference between the element output when a medium is not at a read position and that when at the read position. CONSTITUTION:The output signal of a Hall element 10 is applied to a storage part 70 or arithmetic part 90 through an A-D converter. A control part 80 inclues an element which detects a magnetic medium being carried to a read position; before the magnetic medium is before the read position, the output of the Hall element is applied to the storage part 70 to the charactersitic value of the element itself therein and once the medium reaches the read position, the output of the Hall element is applied to the arithmetic part 90 as well as the contents of the storage part 70. This arithmetic part calculates the difference between both inputs. Therefore, errors of the Hall element and an amplifier 30 due to fluctuations of temperature are eliminated and only variation in magnetic flux on the medium is extracted accurately. |
