Certain image forming apparatuses such as copiers, printers, facsimiles and multifunction machines combining several of these features use a pressing and heating fixing device for fixing an image (a toner image) developed with toner as developer on recording media such as paper. The fixing device typically includes a fixing roller heated by a heater, such as a halogen heater, and a pressure roller contacting the fixing roller to form a fixing nip through which the recording medium is conveyed.
When a toner image is fixed on a recording medium, a recording medium bearing a toner image is passed through a fixing nip to be heated and pressed, and the toner image is melted with heat and fixed on the recording medium. However, the melted toner occasionally causes the recording medium to adhere to the surface of the fixing roller and not separate cleanly from the fixing nip.
To solve this problem, a auxiliary separation member such as a separation click contacting its tip to the fixing roller is provided near the exit of the nip area, and has a role of guiding a recording medium separated from the fixing roller in a feed route of the recording medium as well. However, for that reason, an image formed on a recording medium is occasionally scratched by the separation click. Therefore, it is already disclosed that a guide member is disposed near the tip of the separation click such that a recording medium separated from the fixing roller by the separation click is passed to the guide member to guide the recording medium downstream.
Japanese published unexamined application No. 2004-061854 (JP-2004-061854-A) discloses a fixing device including a separation click contacting a fixing roller, a separation click protection member protecting the contact the separation click everywhere except where the click contacts the fixing roller, and a skid projecting beyond the separation click protection member so as prevent the separation click from scratching the images on the recording media.
In JP-2004-061854-A, a recording medium separated from the fixing roller by the separation click is conveyed to a guide member located close to the tip of the separation click. Since the recording medium bearing a toner image is still hot from the passage through the heated fixing nip when guided and discharged by the separation click and the guide member while contacting thereto, i.e., the toner image is not completely fixed, the resultant image has scratches or glossy stripes therein made by the separation click and the guide member.
Further, when a hard recording medium is discharged while pressed by the skid formed on the separation click protection member, although the recording medium is guided by the skid rotatably formed thereon, the skid does not solve the problems of production of defective images such as scratched images because the toner image that emerges from the fixing nip is not yet completely fixed on the recording medium.
USPTO Backgrounds
USPTO Backgrounds