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A fixing device includes a fixing roller and a pressing roller that are in pressure contact with each other. A separating plate is placed opposite to the fixing roller with a certain gap in between them. Positioning portions are installed on the separating plate to be in contact with width-direction

A fixing device includes a fixing roller and a pressing roller that are in pressure contact with each other. A separating plate is placed opposite to the fixing roller with a certain gap in between them. Positioning portions are installed on the separating plate to be in contact with width-direction ends of the fixing roller for determining the gap. The positioning portions are arranged such that edges of contact portions of the positioning portions on the width-direction center side in contact with the fixing unit are positioned outside an image area and inside a paper-passing area for a recording medium of a maximum passing-capable size.

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1. A fixing device comprising: a fixing unit that fixes a toner image onto a recording medium by heating and fusing the toner image;a pressing unit that is in pressure contact with the fixing unit thereby forming a nip with the fixing unit through which a recording medium is carried;a separating uni

1. A fixing device comprising: a fixing unit that fixes a toner image onto a recording medium by heating and fusing the toner image;a pressing unit that is in pressure contact with the fixing unit thereby forming a nip with the fixing unit through which a recording medium is carried;a separating unit that is arranged downstream from the nip in a running direction of the fixing unit, and placed opposite to the fixing unit with a certain gap in between; andpositioning units that are installed on the separating unit to be in contact with width-direction ends of the fixing unit by being pushed directly or indirectly by a pushing unit for determining the gap, wherein the positioning units are arranged such that edges on a width-direction center side of contact portions in contact with the fixing unit are positioned outside an image area and inside a paper-passing area for a recording medium of a maximum passing-capable size. 2. The fixing device according to claim 1, wherein the separating unit is formed such that width-direction ends of tips of the separating unit on which the gap is formed are positioned outside the paper-passing area. 3. The fixing device according to claim 1, wherein each of the positioning units includes a fitting portion with which the positioning unit is to be installed on the separating unit in a detachable manner, andthe fitting portion is arranged outside the paper-passing area. 4. The fixing device according to claim 3, wherein the fitting portion is a snap-fit. 5. The fixing device according to claim 3, wherein the fitting portion is fit to the separating unit with a screw. 6. The fixing device according to claim 3, wherein each of the positioning units includes a stopper that restricts rotation of the contact portion around the fitting portion. 7. The fixing device according to claim 1, wherein the positioning units are formed on the separating unit in an integrated manner. 8. The fixing device according to claim 1, wherein the contact portions of the positioning units are arranged such that edges of the contact portions on width-direction edge sides are positioned inside positions of width-direction ends of the fixing unit. 9. The fixing device according to claim 1, wherein the gap is set to be from 0.1 millimeter to 0.8 millimeter under a state where the fixing unit is heated. 10. The fixing device according to claim 1, wherein the positioning units are made from one of a resin and a metal. 11. An image forming apparatus comprising a fixing device, the fixing device including a fixing unit that fixes a toner image onto a recording medium by heating and fusing the toner image;a pressing unit that is in pressure contact with the fixing unit thereby forming a nip with the fixing unit through which a recording medium is carried;a separating unit that is arranged downstream from the nip in a running direction of the fixing unit, and placed opposite to the fixing unit with a certain gap in between; andpositioning units that are installed on the separating unit to be in contact with width-direction ends of the fixing unit by being pushed directly or indirectly by a pushing unit for determining the gap, wherein the positioning units are arranged such that edges on a width-direction center side of contact portions in contact with the fixing unit are positioned outside an image area and inside a paper-passing area for a recording medium of a maximum passing-capable size. 12. A separating unit configured to be placed opposite to a fixing unit with a certain gap in between, the fixing unit fixing a toner image onto a recording medium by heating and fusing the toner image, wherein the separating unit is configured to be arranged downstream from a nip in a running direction of the fixing unit, the nip being formed between the fixing unit and a pressing unit,positioning units that are pushed by a pushing unit directly or indirectly for determining the gap, and in contact with width-direction ends of the fixing unit are installed on the separating unit, andthe positioning units are arranged such that edges on a width-direction center side of contact portions of the positioning units in contact with the fixing unit are positioned outside an image area and inside a paper-passing area for a recording medium of a maximum passing-capable size. 13. The separating unit according to claim 12, wherein each of the positioning units includes a fitting portion with which the positioning unit is to be installed on the separating unit in a detachable manner, andthe fitting portion is arranged outside the paper-passing area.