Patent ID: 7953355

Claim:
A multi-layer endless belt member for use in an image forming apparatus, the multi-layer endless belt member comprising: a base layer; and a surface layer for carrying a toner image thereon disposed on the base layer and having a resistivity higher than the base layer, wherein: the multi-layer endless belt member has a first resistivity of a first surface serving as an outer surface of the multi-layer endless belt member and a second resistivity of a second surface serving as an inner surface of the multi-layer endless belt member opposite the first surface different from the first resistivity, and the second resistivity of the second surface of the multi-layer endless belt member ranges from approximately 9.0 to approximately 12.5 in a common logarithm value (log [Ω/square]) when the second resistivity of the second surface is measured after 500V is applied for 10 seconds, an amount of resistivity change in the first resistivity of the first surface of the multi-layer endless belt member ranges from approximately 0.5 to approximately 1.5 in a common logarithm value (log [Ω/square]) when the first resistivity of the first surface is measured after 100V is applied and the amount of resistivity change of the first resistivity of the first surface of the multi-layer endless belt member is equal to or smaller than 0.2 in a common logarithm value (log [Ω/square]) when the first resistivity of the first surface is measured after 500V is applied, where the amount of resistivity change in the first resistivity of the first surface represents a difference between the first resistivity of the first surface measured after a given voltage is applied for 1 second and the first resistivity of the first surface measured after a given voltage is applied for 100 seconds to the first surface of the multi-layer endless belt member, and an amount of resistivity change in the second resistivity of the second surface of the multi-layer endless belt member is equal to or smaller than 0.1 in a common logarithm value (log [Ω/square]) when the second resistivity of the second surface is measured after 100V is applied and 500V is applied, where the amount of resistivity change in the second resistivity of the second surface represents a difference between the second resistivity of the second surface measured after a given voltage is applied for 1 second and the second resistivity of the second surface measured after a given voltage is applied for 100 seconds to the second surface of the multi-layer endless belt member.