| 摘要 |
PROBLEM TO BE SOLVED: To obtain excellent electromagnetic conversion characteristics and low noise by specifying the dry thickness of an upper magnetic layer to a specific value or below and the saturation magnetic flux density thereof to a specific value or above, specifying the dry thickness of a lower magnetic layer to a specific range and specifying the saturation magnetic flux density thereof, the saturation max. magnetization of ferromagnetic powder and the dry thickness so as to satisfy a specific relation and, further, specifying the total thickness to a specific value or below. SOLUTION: The front surface of a base 2 is provided with the lower magnetic layer 3 and the upper magnetic layer 4 and the rear surface thereof is provided with a back-coating layer 5. The saturation magnetic flux density Bs1 (T) of the lower magnetic layer 3 is so determined as to satisfy 40<=Bs1 . (4πσS1 .d1 )<=120 in the relation between the saturation max. magnetizationσS1 (Am<2> /kg) of the ferromagnetic power incorporated into the lower magnetic layer 3 and the dry thickness d1 (m) of the lower magnetic layer 3. At this time, the dry thickness d1 of the lower magnetic layer 3 is specified to 0.1 to 1.5μm the dry thickness d2 of the upper magnetic layer 4 is specified to <=0.2μm and the saturation magnetic flux density BS2 thereof to >=0.25%. As a result, an output characteristic is made high and noise low.
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