Image forming apparatus

Abstract

Disclosed is an image forming apparatus that forms an image on one side of a sheet and then forms an image on the other side of the sheet. A single-sided sheet passing path transports a sheet housed in a sheet-feeding tray to the image forming section, and a double-sided sheet passing path reverses a sheet with an image formed on one side and causes the sheet to join the single-sided sheet passing path. The single-sided sheet passing path is formed so as to include a second interval which includes a registration sensor placed near a joining position of the single-sided and double-sided sheet passing paths in the double-sided sheet passing path as one end point and in which a sheet draws a moving trajectory substantially identical to a moving trajectory of a sheet in a first interval extending toward an upstream side in the transport direction of the sheet.

1 . An image forming apparatus that forms an image on one side of a recording medium by an image forming section and then forms an image on another side of the recording medium, the apparatus comprising:
 a first sheet passing path that transports the recording medium housed in a sheet-feeding tray to the image forming section;   a second sheet passing path that reverses the recording medium with an image formed on one side and causes the recording medium to join the first sheet passing path;   a registration sensor that is placed near a joining position of the first sheet passing path and the second sheet passing path and that corrects a leading end position of the recording medium transported; and   a top sensor that is placed at a position away from the registration sensor toward a downstream side of a transport direction of the recording medium by a predetermined distance and that specifies a distance between the recording media transported, wherein:   the second sheet passing path includes:
 a first interval that transports the recording medium with an image formed on one side, in a substantially horizontal direction; and 
 a second interval that transports the recording medium from an end position of the first interval to the position of the registration sensor; and 
   the first sheet passing path includes:
 a third interval that transports the recording medium from a first end point at a position where a virtual line of the first interval virtually extended toward an upstream side of the transport direction of the recording medium intersects the first sheet passing path to a second end point at a position away from the registration sensor toward an upstream side of transport direction of the recording medium by a distance between the end position of the first interval and the first end point; and 
 a fourth interval that transports the recording medium from the second end point of the third interval to the position of the top sensor in a substantially horizontal direction, wherein 
   a moving trajectory of the second interval is identical to a moving trajectory of the third interval.   
     
     
         2 . The image forming apparatus according to  claim 1 , wherein the transport direction of the recording medium in the first interval is a direction opposite to the transport direction of the recording medium in the fourth interval. 
     
     
         3 . The image forming apparatus according to  claim 1 , wherein the image forming section includes:
 a transfer roller;   an organic photo conductor; and   a developing roller, wherein   the image forming section transfers a toner image according to image data to the transported recording medium to form an image on the recording medium.   
     
     
         4 . An image forming apparatus that forms an image on one side of a recording medium by an image forming section and then forms an image on another side of the recording medium, the apparatus comprising:
 a first sheet passing path that transports the recording medium housed in a sheet-feeding tray to the image forming section;   a second sheet passing path that reverses the recording medium with an image formed on one side and causes the recording medium to join the first sheet passing path; and   a top sensor that is placed at a position away from a joining position of the first sheet passing path and the second sheet passing path toward a downstream side of the transport direction of the recording medium by a predetermined distance and that specifies a distance between the recording media transported, wherein:   the second sheet passing path includes:
 a first interval that transports the recording medium with an image formed on one side, in a substantially horizontal direction; and 
 a second interval that transports the recording medium from an end position of the first interval to the joining position; and 
   the first sheet passing path includes:
 a third interval that transports the recording medium from a first end point at a position where a virtual line of the first interval virtually extended toward an upstream side of the transport direction of the recording medium intersects the first sheet passing path to a second end point at a position away from the joining position toward an upstream side of the transport direction of the recording medium by a distance between the end position of the first interval and the first end point; and 
 a fourth interval that transports the recording medium from the second end point of the third interval to the position of the top sensor in a substantially horizontal direction, wherein 
   a moving trajectory of the second interval is identical to a moving trajectory of the third interval.   
     
     
         5 . The image forming apparatus according to  claim 4 , wherein the transport direction of the recording medium in the first interval is a direction opposite to the transport direction of the recording medium in the fourth interval. 
     
     
         6 . The image forming apparatus according to  claim 4 , wherein the image forming section includes:
 a transfer roller;   an organic photo conductor; and   a developing roller, wherein   the image forming section transfers a toner image according to image data to the transported recording medium to form an image on the recording medium.   
     
     
         7 . An image forming apparatus that forms an image on one side of a recording medium by an image forming section and then forms an image on another side of the recording medium, the apparatus comprising:
 a first sheet passing path that transports the recording medium housed in a sheet-feeding tray to the image forming section;   a second sheet passing path that reverses the recording medium with an image formed on one side and causes the recording medium to join the first sheet passing path; and   a top sensor that is placed at a position away from a joining position of the first sheet passing path and the second sheet passing path toward a downstream side of the transport direction of the recording medium by a predetermined distance and that specifies a distance between the recording media transported, wherein:   the top sensor includes a detection arm portion that turns around an axis, while the detection arm portion is provided so as to protrude inward of the first sheet passing path;   the second sheet passing path includes:
 a first interval that transports the recording medium with an image formed on one side, in a substantially horizontal direction; and 
 a second interval that transports the recording medium from an end position of the first interval to the joining position; and 
   the first sheet passing path includes:
 a third interval that transports the recording medium from a first end point at a position where a virtual line of the first interval virtually extended toward an upstream side of the transport direction of the recording medium intersects the first sheet passing path to a second end point at a position away from the joining position toward an upstream side of the transport direction of the recording medium by a distance between the end position of the first interval and the first end point; and 
 a fourth interval that transports the recording medium from the second end point of the third interval to the position of the top sensor in a substantially horizontal direction, wherein 
   a moving trajectory of the second interval is identical to a moving trajectory of the third interval.   
     
     
         8 . The image forming apparatus according to  claim 7 , wherein the transport direction of the recording medium in the first interval is a direction opposite to the transport direction of the recording medium in the fourth interval. 
     
     
         9 . The image forming apparatus according to  claim 7 , wherein the image forming section includes:
 a transfer roller;   an organic photo conductor; and   a developing roller, wherein   the image forming section transfers a toner image according to image data to a transported recording medium to form an image on the recording medium.