Patent ID: 7113736

Claim:
A fixing apparatus comprising: a coil which, when supplied with a voltage and current of a specific frequency, forms a first area having a magnetic field intensity equal to or higher than a specific intensity on the outside of the coil and a second area having a magnetic field intensity lower than the specific intensity on the outside of the coil, the coil being provided outside a conductive roller which generates heat by a magnetic field supplied from the coil; and a protection cover covering the periphery of the fixing apparatus which is provided near a boundary line between the first area and the second area so that its surface may have the specific magnetic field intensity or less, wherein if the distance between the coil and the protection cover is d and the distance between the protection cover and a specific position with a magnetic flux intensity of Td is D, the following expression holds: d > A ⁢ ( 1 + A ) ( 1 - A ) ⁢ ⁢ where ⁢ ⁢ A = Td 6250 ⁢ ⁢ D ≧ 20