Fixing device and image forming apparatus having the same

An image forming apparatus comprising:

• a photosensitive medium on which an electrostatic latent image is formed;
• a developing device to develop the electrostatic latent image on the photosensitive medium using developer;
• a transferring device to transfer a developer image to a printing medium;
• and
• a fixing device to fix the developer image transferred onto the printing medium, wherein the fixing device comprises:
• a pressing member,
• a belt member which rotates in contact with the pressing member and forms a nip with the pressing member,
• a first roller member and a second roller member to guide the rotation of the belt member,
• a heating member which is mounted in one of the first roller member and the second roller member to heat the belt member, the heating member comprising at least two heaters to respectively heat at least two areas on the belt member corresponding to at least two width dimensions substantially parallel to a rotational axis of the one of the first roller member and the second roller member, and
• a sensor member to control a temperature of the belt member,
• wherein the heating member comprises a first heater to heat a central portion of the one of the first roller member and the second roller member and a second heater to heat opposite ends of the one of the first roller member and the second roller member,
• wherein the sensor member comprises a first sensor to control an amount of heat generated by the first heater and a second sensor to control an amount of heat generated by the second heater,
• wherein the first sensor is disposed within approximately ±25 mm of a maximum heat-generating point of the first heater along the rotational axis of the one of the first roller member and the second roller member.

A fixing device to fix an image on a printing medium passing through an image forming apparatus, comprising:

• a pressing member;
• a belt member which rotates in contact with the pressing member and forms a nip with the pressing member;
• a first roller member and a second roller member to guide the rotation of the belt member;
• and
• a heating member mounted in one of the first roller member and the second roller member, to generate different amounts of heat along a direction which is substantially parallel to a rotational axis of the one of the first roller member and the second roller member, based on a width of the printing medium,
• a sensor member comprising at least two sensors to control a temperature of the belt member,
• wherein the heating member comprises a first heater and a second heater to respectively heat at least two areas on the belt member corresponding to at least two width dimensions substantially parallel to the rotational axis of the one of the first roller member and the second roller member, and
• wherein a first sensor from among the at least two sensors is disposed within approximately ±25 mm of a maximum heat-generating point of the first heater along the rotational axis of the one of the first roller member and the second roller member.