Image forming apparatus and image forming system with winding detection

1. An image forming apparatus comprising:

(a) a sheet conveyance section having a sheet storing member to store sheets that have been aligned in a prescribed placing direction, which conveys a sheet stored in the sheet storing member;

(b) an image forming section having an image carrier, which forms an image on the image carrier;

(c) an image transfer section which transfers the image formed on the image carrier onto a sheet conveyed by the sheet conveyance section;

(d) a winding detecting section which detects whether or not the sheet conveyed by the sheet conveyance section is wound around the image carrier;

(e) a display section which displays an image to instruct an operator; and

(f) a controller which controls the display section to instruct the operator to conduct a change operation of a placing direction in a front and rear side direction or a leading and trailing edge direction of the sheets stored in the sheet storing member based on a sheet winding detection signal outputted from the winding detection section only after an accumulated number of times that sheets have been wound around the image carrier exceeds a reference number of times for comparison;

wherein the controller receives an input of the sheet winding detection signal outputted from the winding detection section, accumulates a number of times that sheets have been wound around the image carrier by counting the sheet winding detection signal, compares the accumulated number of times with the reference number of times for comparison, and controls the display section to instruct the operator to conduct the change operation of the placing direction in the front and rear side direction or the leading and trailing edge direction of the sheets stored in the sheet storing member when the accumulated number of times exceeds the reference number of times for comparison;

wherein a tray sensor section provided in the sheet storing member detects the change operation of the placing direction in the front and rear side direction or the leading and trailing edge direction of the sheets stored in the sheet storing member that has been conducted by the operator, and the controller resets the accumulated number of times of windings based on the change operation detected; and

wherein when the sheet conveyance section has a plurality of sheet storing members, the controller accumulates the number of times that sheets that have been wound around the image carrier for each of the sheet storing members, the tray sensor section detects the change operation in the front and rear side direction or the leading and trailing edge direction of the placing direction of the sheets stored in the sheet storing member for each of the sheet storing members, and the controller resets the accumulated number of times based on the change operation detected for each of the sheet storing members.

2. The image forming apparatus of claim 1 , further comprising a sheet separation detection section which detects a sheet separated from the image carrier, and outputs a sheet separation detection signal,

wherein the controller controls the display section to instruct the operator to conduct the change operation of the placing direction in the front and rear side direction or the leading and trailing edge direction of the sheets stored in the sheet storing member based on the sheet separation detection signal outputted from the sheet separation detection section.

3. The image forming apparatus of claim 1 , further comprising an operation section which registers establishment for front and back sides of a sheet in which both sides of the sheet indicate characteristics different from each other,

wherein when the establishment of the front and rear sides of the sheet is registered for each of the sheet storing members, and when the accumulated number of times exceeds the reference number of times for comparison, the controller controls the display section to instruct the operator to place the sheets stored in the sheet storing member with the leading and trailing edge direction thereof reversed.

4. The image forming apparatus of claim 3 , wherein the controller detects the change operation of the leading and trailing edge direction of the sheets stored in the sheet storing member, and reverses a position of an image to be formed on the image carrier based on the detected change operation by changing the leading and trailing edge direction of the sheets.

5. The image forming apparatus of claim 1 , wherein the controller controls the display section to display an image which instructs the operator to turn the sheets stored in the sheet storing member upside down or to reverse the leading and trailing edge direction of the sheets stored in the sheet storing member.