Multicolor image forming apparatus with tension controlled image transfer belt

An image transfer structure for a multicolor image forming apparatus for sequentially transferring developed images of different colors formed one after another on a photoconductive element to an intermediate image transfer body one above another, wherein a non-transfer period exists between periods of the transferring of the images of different colors to the intermediate image transfer body, and then transferring said developed images from said intermediate image transfer body to a recording medium at the same time to thereby form a full-color image, wherein said images are brought into register by either of a skip forward system which during the non-transfer period shifts said intermediate transfer body away from said photoconductive element and moves said intermediate image transfer body at a speed different from a previous speed and a quick return system which during the non-transfer period shifts said intermediate image transfer body away from said photoconductive element and moves said intermediate image transfer body in a direction opposite to a previous direction, said image transfer structure comprising:

• a belt constituting the intermediate image transfer body and passed over a plurality of rollers including a backup roller facing the photoconductive element and a tension roller;
• and
• support means for causing said backup roller and said tension roller to angularly move substantially at the same time such that said belt selectively moves toward or away from said photoconductive element and such that said belt has the same tension when shifted into contact with said photoconductive element and when shifted out of contact with said photoconductive element during the non-transfer period.

An image transfer structure for a multicolor image forming apparatus for sequentially transferring developed images of different colors, comprising:

• a photoconductive element on which the developed images of different colors are formed;
• an intermediate image transfer belt on which said developed images from said photoconductive element are transferred one above another, wherein a non-transfer period exists between periods of the transferring of the images of different colors to the intermediate image transfer belt;
• a recording medium on which said developed images from the intermediate image transfer belt are transferred to thereby form a full-color image, wherein said images are brought into register by either of a skip forward system which during the non-transfer period shifts said intermediate image transfer belt away from said photoconductive element and moves said intermediate image transfer belt at a speed different from a previous speed and a quick return system which during the non-transfer period shifts said intermediate transfer belt away from said photoconductive element and moves said intermediate image transfer belt in a direction opposite to a previous direction;
• belt support means comprising a backup roller supporting the intermediate image transfer belt at a position where said backup roller faces the photoconductive element and a tension roller applying tension to said intermediate image transfer belt;
• and
• roller drive means for shifting said backup roller and said tension roller in conjunction to move said intermediate image transfer belt toward and away from the photoconductive element such that said intermediate image transfer belt has the same tension when shifted into contact with said photoconductive element and when shifted out of contact with said photoconductive element during the non-transfer period.

An image transfer structure for a multicolor image forming apparatus for sequentially transferring developed images of different colors formed one after another on a photoconductive element to an intermediate image transfer belt one above another, wherein a non-transfer period exists between periods of the transferring of the images of different colors to the intermediate image transfer belt, and then transferring said developed images from said intermediate image transfer belt to a recording medium at the same time to thereby form a full-color image, wherein the intermediate image transfer belt is moved while being spaced apart from the photoconductive element during the non-transfer period, thereby bringing the images sequentially transferred from the photoconductive element into register on the intermediate image transfer belt, said image transfer structure comprising:

• belt support means comprising a backup roller supporting the intermediate image transfer belt at a position where said backup roller faces the photoconductive element, and a tension roller applying tension to said intermediate image transfer belt;
• and
• roller drive means for shifting said backup roller and said tension roller to move said intermediate image transfer belt toward and away from the photoconductive element such that said intermediate image transfer belt has the same tension when shifted into contact with said photoconductive element and when shifted out of contact with said photoconductive element during the non-transfer period.

An image transfer structure for a multicolor image forming apparatus for sequentially transferring developed images of different colors formed one after another on a photoconductive element to an intermediate image transfer body one above another, wherein a non-transfer period exists between periods of the transferring of the images of different colors to the intermediate image transfer body, and then transferring said developed images from said intermediate image transfer body to a recording medium at the same time to thereby form a full-color image, wherein the intermediate image transfer body is moved while being spaced apart from the photoconductive element during the non-transfer period, thereby bringing the images sequentially transferred from the photoconductive element into register on the intermediate image transfer body, said image transfer structure comprising:

• a belt constituting the intermediate image transfer body and passed over a plurality of rollers including a backup roller facing the photoconductive element and a tension roller;
• and
• support means for causing said backup roller and said tension roller to angularly move substantially at the same time such that said belt selectively moves toward or away from said photoconductive element and such that said belt has the same tension when shifted into contact with said photoconductive element and when shifted out of contact with said photoconductive element during the non-transfer period.