Paper feeding device and image forming apparatus having the same and control method thereof

Abstract

A paper feeding device to sense various sizes of paper according to a sensing voltage output from a sensor and an image forming apparatus having the same includes a body to receive paper in which an image is printed thereon. The image forming apparatus further includes a paper feeding device to feed paper into the body. The paper feeding device includes a paper tray in which paper is loaded, and paper guides that are slidably installed to the paper tray to guide left and right ends of paper loaded in the paper tray in a paper feeding direction. A light reflector is installed to be moved in linkage with the paper guides and includes a stepped reflection surface. A sensor emits light to the light reflector and receives the light reflected by the light reflector to determine the sizes of paper.

1 . A paper feeding device comprising:
 a paper tray in which paper is loaded;   at least one paper guide adjustable in a plurality of positions according to a width of the paper to guide a left or right end of the paper loaded in the paper tray in a paper feeding direction;   a light reflector installed to be moved in linkage with the paper guide and having a stepped reflection surface; and   a sensor that emits light to the light reflector and receives the light reflected by the light reflector and outputs a sensing voltage corresponding to the received light, to enable calculation of a size of the paper.   
     
     
         2 . The paper feeding device according to  claim 1 , wherein:
 the at least one paper guide includes a pair of paper guides to guide the left and right ends of the paper in the paper feeding direction; and   the paper feeding device further comprises first and second racks connected respectively to the pair of paper guides to allow the pair of paper guides to be moved in linkage with each other, and a pinion gear-engaged with the first and second racks.   
     
     
         3 . The paper feeding device according to  claim 2 , wherein the light reflector is coupled to at least one of the first rack and the second rack and is moved in linkage with the paper guides. 
     
     
         4 . The paper feeding device according to  claim 3 , wherein the light reflector is one of injection-molded or assembled to one of the first rack and the second rack. 
     
     
         5 . The paper feeding device according to  claim 1 , wherein:
 the sensor includes a light emitting element to emit light and a light receiving element to receive the light; and   the light emitting element and the light receiving element are one of integrally formed with each other or are separated from each other.   
     
     
         6 . An image forming apparatus comprising:
 a body in which an image is printed on paper;   at least one paper tray to support paper i; and   a paper feeding device comprising:
 at least one paper guide that guides a left or right end of the paper loaded in the paper tray in a paper feeding direction, wherein a position of the paper guide being adjusted according to a width of the paper; and 
 a light reflector installed to be moved in linkage with the paper guide and having a stepped reflection surface; a sensor that emits light to the light reflector and receives the light reflected by the light reflector; and 
   a controller that calculates a size of the paper according to a sensing voltage output from the sensor.   
     
     
         7 . The image forming apparatus according to  claim 6 , wherein:
 the at least one paper guide includes a pair of paper guides to guide the left and right ends of the paper in the paper feeding direction; and   the paper feeding device further includes first and second racks connected respectively to the pair of paper guides to allow the pair of paper guides to be moved in linkage with each other, and a pinion gear-engaged with the first and second racks.   
     
     
         8 . The image forming apparatus according to  claim 7 , wherein the light reflector is coupled to one of the first rack and the second rack and is moved in linkage with the paper guides. 
     
     
         9 . The image forming apparatus according to  claim 8 , wherein the light reflector is one of injection-molded or assembled to one of the first rack and the second rack. 
     
     
         10 . The image forming apparatus according to  claim 6 , wherein:
 the sensor includes a light emitting element to emit light and a light receiving element to receive the light; and   the light emitting element and the light receiving element are one of integrally formed with each other or are separated from each other.   
     
     
         11 . The image forming apparatus according to  claim 6 , wherein the at least one paper tray includes at least one first paper tray pivotally rotatably coupled to the body and at least one second paper tray inserted into the body in a drawer manner. 
     
     
         12 . A method of determining a paper size of paper in an image forming apparatus comprising:
 confirming whether or not paper is loaded in at least one paper tray;   emitting light to a light reflector if the paper is loaded in the paper tray, the light reflector being moved in linkage with a paper guide installed to the paper tray and having a stepped reflection surface;   detecting a size of the paper according to a magnitude of a sensing voltage if a sensor installed at a side of the paper tray outputs the sensing voltage corresponding to the quantity of light reflected by the reflection surface; and   performing a printing operation according to the detected paper size.   
     
     
         13 . The control method according to  claim 12 , wherein:
 the at least one paper tray includes at least one first paper tray pivotally rotatably coupled to the body and at least one second tray inserted into the body in a drawer manner; and   the confirming whether or not paper is loaded further comprises confirming that paper is newly loaded into the at least one first paper tray when paper inside the at least one first paper tray is detected subsequent to confirming paper was not loaded and confirming that paper is newly loaded into the at least one second paper tray when the second paper tray is separated and thereafter is reinstalled.   
     
     
         14 . A paper tray to receive paper, comprising;
 at least one paper guide that is adjustable according to a width of the paper;   a light reflector having a reflective portion to reflect light and coupled to the at least one paper guide to be moved in linkage with the paper guide; and   a sensor that emits light to the light reflector and receives the light reflected by the light reflector and outputs a sensing voltage corresponding to the received light.   
     
     
         15 . The paper tray of  claim 14 , wherein the reflective portion is formed to reflect light at a plurality of distances different from one another based on an area of the reflective portion that reflects the light. 
     
     
         16 . The paper tray of  claim 15  wherein the reflective surface includes a plurality of reflective surface disposed in a step-like manner from one end of the light reflector to an opposite end of the light reflector such that distance between each reflective surface and the sensor defines a reflective distance between the light reflector and the sensor. 
     
     
         17 . The paper tray of  claim 14  further comprising a rack unit connected to the paper guide to move in a width direction of the paper wherein the light reflector moves together with the rack unit in the width direction. 
     
     
         18 . The paper tray of  claim 14  wherein the reflector is disposed in a width direction of the paper and the sensor emits light in a direction horizontal to the width direction. 
     
     
         19 . The paper tray of  claim 14 , wherein the reflector has a pattern representing paper sizes and the sensor and the reflector are arranged in a length direction of the paper direction. 
     
     
         20 . A paper tray to receive paper, comprising;
 first and second paper guides that are adjustable according to a width of the paper to center the paper along a center axis of the paper tray extending in a paper feed direction;   a light emitting element that emits light along a light path following the center axis of the paper tray;   a light reflector moveable into the light path in response to adjusting the first and second paper guides to reflect emitted light; and   a light receiving element that receives the reflected emitted light from the light reflector and outputs a sensing voltage corresponding to the received light.