Paper feeding unit and image forming apparatus having the same

An image forming apparatus comprising:

• a main body;
• a printing unit provided in the main body to form an image on paper;
• a paper feeding unit to supply the paper into the main body, the paper feeding unit including a paper feeding cassette to load paper therein, a knock-up plate to guide the paper loaded in the paper feeding cassette to a pickup device, a pair of elastic members to elastically bias the knock-up plate toward the pickup device, and guide sides provided at both sides of the knock-up plate, the guide sides being adjusted along a distance therebetween according to a width of the paper;
• and
• a pair of force adjusting units to adjust an elastic force of a respective one of the elastic members when the distance between the guide sides is adjusted according to a size of the paper,
• wherein the pair of force adjusting units adjusts a height of a lower end of the respective one of the elastic member.

An image forming apparatus comprising:

• a main body;
• a printing unit provided in the main body to form an image on paper;
• a paper feeding unit to supply the paper into the main body, the paper feeding unit including a paper feeding cassette to load paper therein, a knock-up plate to guide the paper loaded in the paper feeding cassette to a pickup device, a pair of elastic members to elastically bias the knock-up plate toward the pickup device, and guide sides provided at both sides of the knock-up plate, the guide sides being adjusted in a distance therebetween according to a width of the paper;
• and
• a force adjusting unit to adjust an elastic force of each of the elastic members by changing a distance between both ends of each elastic member by interlocking with each of the guide sides when the distance between the guide sides is adjusted according to a size of the paper,
• wherein the force adjusting unit adjusts a height of a lower end of the elastic member.

A recording media feeding unit, comprising:

• a media feeding cassette to load recording media therein;
• a knock-up plate to guide the recording media in the feeding cassette toward a pickup device;
• an elastic device to elastically bias the knock-up plate toward the pickup device;
• guide sides disposed at opposing sides of the knock-up plate to adjustably support side portions of the recording media therebetween along a width direction;
• and
• a force adjusting device to adjust an elastic force of the elastic device according to a type of the recording media loaded in the feeding cassette,
• wherein the force adjusting device adjusts a height of a lower end of the elastic device.