Sheet stacker with aligning/conveying rollers and image forming apparatus using the same

A sheet finishing apparatus comprising:

• a sheet passage;
• a conveyor to convey a sheet along the sheet passage;
• an intermediate stacker on which the sheet conveyed along the sheet passage is placed so that a bundle of sheets is formed on the intermediate stacker;
• a finisher to conduct a finishing process for the bundle of sheets formed on the intermediate stacker;
• a sheet delivering section to which the bundle of sheets is delivered;
• and
• a sheet delivering device to true up edges of the bundle of sheets on the intermediate stacker before the finisher conducts the finishing process and to deliver the bundle of sheets from the intermediate stacker to the sheet delivering section after the finisher has conducted the finishing process;
• wherein the sheet delivering device comprises:
• (i) a pair of rollers capable of selectively rotating in one of a regular direction and a reverse direction, and (ii) an arm-shaped actuator to bring the first roller into one of a first position in contact with the second roller and a second position apart from the second roller, (iii) a driving source coupled to the pair of first and second rollers and having a driving shaft rotatable in one of a first rotation direction and a second rotation direction, and (iv) a torque limiter having an input shaft coupled to the driving shaft and an output shaft coupled to the arm-shaped actuator;
• and
• wherein when the input shaft is rotated in the first rotation direction by the driving shaft, the output shaft swings the arm-shaped actuator so as to bring the first roller to the second position apart from the second roller, and when the input shaft is rotated in the second rotation direction by the driving shaft, the output shaft swings the arm-shaped actuator so as to bring the first roller to the first position in contact with the second roller.

An image forming apparatus comprising:

• an image forming device to form an image on a sheet;
• and
• a sheet finishing apparatus comprising:
• a sheet passage;
• a conveyor to convey along the sheet passage the sheet on which the image is formed;
• an intermediate stacker on which the sheet conveyed along the sheet passage is placed so that a bundle of sheets are formed on the intermediate stacker;
• a finisher to conduct a finishing process for the bundle of sheets formed on the intermediate stacker;
• a sheet delivering section to which the bundle of sheets is delivered;
• and
• a sheet delivering device to true up edges of the bundle of sheets on the intermediate stacker before the finisher conducts the finishing process and to deliver the bundle of sheets from the intermediate stacker to the sheet delivering section after the finisher has conducted the finishing process;
• wherein the sheet delivering device comprises:
• (i) a pair of rollers capable of selectively rotating in one of a regular direction and a reverse direction, and (ii) an actuator to bring the pair of rollers in contact with each other or to separate the pair of rollers;
• and
• wherein:
• (i) when the sheet is placed on the intermediate stacker, the pair of rollers rotate in the regular direction and the actuator separates the pair of rollers, (ii) when the edges of the bundle of sheets on the intermediate stacker are trued up, the pair of rollers rotate in the reverse direction and the actuator brings the pair of rollers substantially in contact with each other, and (iii) when the bundle of sheets is delivered from the intermediate stacker to the sheet delivering section after the finisher has conducted the finishing process, the pair of rollers rotate in the regular direction when the pair of rollers are brought substantially in contact with each other.