Sheet conveying system, as well as image forming apparatus and sheet conveying apparatus thereof

A sheet conveying system comprising:

• a first sheet conveying device including a first conveying roller pair adapted to nip and convey a sheet, a releasing mechanism adapted to release nipping of the sheet by said first conveying roller pair, a first controller adapted to control said first conveying roller pair and said releasing mechanism, and a detecting device adapted to detect the sheet;
• a second sheet conveying device including a second conveying roller pair adapted to nip and convey the sheet from said first sheet conveying device to be conveyed, and a second controller adapted to control said second conveying roller pair;
• and
• a communicating device adapted to communicate between said first controller and said second controller;
• wherein said first controller is adapted to communicate with said second controller to estimate the time required to nip the sheet by said second conveying roller pair after said detecting device detects the sheet;
• and
• when the estimated time has elapsed after said detecting device detects the sheet, said first controller is adapted to cause said releasing mechanism to release the nipping of the sheet by said first conveying roller pair.

An image forming apparatus including a first roller pair adapted to nip and convey a sheet, a releasing mechanism adapted to release nipping of the sheet by said first conveying roller pair, and a first controller adapted to control said first conveying roller pair and said releasing mechanism, the image forming apparatus comprising:

• a second conveying roller pair adapted to nip and convey the sheet conveyed by said first sheet conveying device;
• a second controller adapted to control said second conveying roller pair;
• and
• a detecting device adapted to detect a sheet;
• wherein in response to the detection by said detecting device, said second controller is adapted to cause said releasing mechanism to release the nipping of the sheet by said first conveying roller pair.

A sheet conveying apparatus including a sheet conveying apparatus connected with an image forming apparatus, a first conveying roller pair adapted to receive a sheet conveyed from said sheet conveying apparatus, a first controller adapted to control said first conveying roller pair, a detecting device adapted to detect a sheet, the sheet conveying apparatus comprising:

• a second conveying roller pair adapted to nip and convey a sheet toward said image forming apparatus;
• a releasing mechanism adapted to release nipping of the sheet by said first conveying roller pair;
• a second controller adapted to control said second conveying roller pair and said releasing mechanism;
• and
• wherein said second controller is adapted to cause said releasing mechanism to release the nipping of the sheet by said second conveying pair based on an instruction from said first controller in response to the detection by said detecting device.