Image forming apparatus

Abstract

The objective is to provide a new type of fixing device that builds upon conventional technology. [Solution] The guide section is positioned between the transfer roller and the pressure roller in the transport direction in which the transfer roller transports the recording material. The guide section guides the underside of the recording material so that it moves toward the fixing nip after passing through the transfer nip. The moving section moves the guide section to the first or second position. The moving control unit controls the moving section. If the temperature of the pressure roller is below a predetermined threshold, the moving control unit controls the moving section so that the guide section is in the second position. If the temperature of the pressure roller is above a predetermined threshold, the moving control unit controls the moving section so that the guide section is in the first position.

Claims

1. Photosensitive drum and A transfer roller for transferring the developer on the photosensitive drum to a recording material, A heating unit comprising an endless belt and a heater provided on the inner surface side of the belt for heating the belt, A pressure roller having a rubber layer that forms a fixing nip together with the heater via the belt, A guide portion located between the transfer roller and the pressure roller in the transport direction in which the transfer roller transports the recording material, the guide portion guides the lower surface of the recording material so that the recording material, having passed through the transfer nip which is the nip between the photosensitive drum and the transfer roller, is directed toward the fixing nip, A moving part for moving the guide part to a first position or a second position located below the first position, A movement control unit that controls the movement of the aforementioned moving part, Equipped with, If the temperature of the pressure roller is below a predetermined threshold, the movement control unit controls the movement unit so that the guide unit is positioned at the second position. The image forming apparatus is characterized in that, when the temperature of the pressure roller is greater than the predetermined threshold, the movement control unit controls the movement unit so that the guide unit is positioned at the first position.

2. The image forming apparatus according to claim 1, characterized in that, when the temperature of the pressure roller is lower than the predetermined threshold, the movement control unit controls the movement unit to move the guide unit to the second position while the recording material is being guided by the guide unit at the first position.

3. The image forming apparatus according to claim 1, characterized in that when the temperature of the pressure roller is less than a predetermined threshold, the movement control unit controls the movement unit so that the guide unit is positioned at the second position, and then the movement control unit controls the movement unit so that the guide unit moves from the second position to the first position.

4. Photosensitive drum and A transfer roller for transferring the developer on the photosensitive drum to a recording material, A heating unit comprising an endless belt and a heater provided on the inner surface side of the belt for heating the belt, A pressure roller having a rubber layer that forms a fixing nip together with the heater via the belt, A guide portion located between the transfer roller and the pressure roller in the transport direction in which the transfer roller transports the recording material, the guide portion guides the lower surface of the recording material so that the recording material, having passed through the transfer nip which is the nip between the photosensitive drum and the transfer roller, is directed toward the fixing nip, A moving part for moving the guide part to a first position or a second position located below the first position, A movement control unit that controls the movement of the aforementioned moving part, A basis weight detection unit for detecting the basis weight of the recording material being conveyed toward the heating unit, Equipped with, If the basis weight of the recording material detected by the basis weight detection unit exceeds a threshold, the movement control unit controls the movement unit so that the guide unit is positioned at the first position. The image forming apparatus is characterized in that, if the basis weight of the recording material detected by the basis weight detection unit does not exceed the threshold, the movement control unit controls the movement unit so that the guide unit is positioned at the second position.

5. The image forming apparatus according to claim 4, characterized in that, if the basis weight of the recording material detected by the basis weight detection unit does not exceed the threshold, the movement control unit controls the movement unit to move the guide unit to the second position while the recording material is being guided by the guide unit at the first position.

6. The image forming apparatus according to claim 4, characterized in that, if the basis weight of the recording material detected by the basis weight detection unit does not exceed the threshold, the movement control unit controls the movement unit so that the guide unit is positioned at the second position, and then controls the movement unit so that the guide unit moves from the second position to the first position.

7. Photosensitive drum and A transfer roller for transferring the developer on the photosensitive drum to a recording material, A heating unit comprising an endless belt and a heater provided on the inner surface side of the belt for heating the belt, A pressure roller having a rubber layer that forms a fixing nip together with the heater via the belt, A guide portion located between the transfer roller and the pressure roller in the transport direction in which the transfer roller transports the recording material, the guide portion guides the lower surface of the recording material so that the recording material, having passed through the transfer nip which is the nip between the photosensitive drum and the transfer roller, is directed toward the fixing nip, A moving part for moving the guide part to a first position or a second position located below the first position, A movement control unit that controls the movement of the aforementioned moving part, A setting unit for setting the length of the recording material in the transport direction, Equipped with, The transport speed of the recording material by the transfer roller is greater than the transport speed of the recording material by the pressure roller. If the length set by the setting unit is greater than a predetermined threshold, the movement control unit controls the movement unit so that the guide unit is positioned at the second position. The image forming apparatus is characterized in that, when the length set by the setting unit is smaller than the predetermined threshold, the movement control unit controls the movement unit so that the guide unit is positioned at the first position.

8. The image forming apparatus according to claim 7, characterized in that, if the length set by the setting unit is greater than the predetermined threshold, the movement control unit controls the movement unit to move the guide unit to the second position while the recording material is being guided by the guide unit at the first position.

9. The image forming apparatus according to claim 7, characterized in that, when the length set by the setting unit is greater than a predetermined threshold, the movement control unit controls the movement unit so that the guide unit is positioned at the second position, and then controls the movement unit so that the guide unit moves from the second position to the first position.

10. Photosensitive drum and A transfer roller for transferring the developer on the photosensitive drum to a recording material, A heating unit comprising an endless belt and a heater provided on the inner surface side of the belt for heating the belt, A pressure roller having a rubber layer that forms a fixing nip together with the heater via the belt, A guide portion located between the transfer roller and the pressure roller in the transport direction in which the transfer roller transports the recording material, the guide portion guides the lower surface of the recording material so that the recording material, having passed through the transfer nip which is the nip between the photosensitive drum and the transfer roller, is directed toward the fixing nip, A moving part for moving the guide part to a first position or a second position located below the first position, A movement control unit that controls the movement of the aforementioned moving part, Equipped with, The portion of the recording material that is included from the center to one end in the axial direction of the photosensitive drum is defined as the first portion. The portion of the recording material that is included in the axial direction from the center to the other end of the recording material is defined as the second portion. If, in the printed information of the recording material, the absolute value of the difference between the printing rate of the first part and the printing rate of the second part exceeds a predetermined threshold, the movement control unit controls the movement unit so that the guide unit is positioned at the second position. The image forming apparatus is characterized in that, if the absolute value of the difference between the printing rate of the first part and the printing rate of the second part does not exceed the predetermined threshold, the movement control unit controls the movement unit so that the guide unit is positioned at the first position.

11. The image forming apparatus according to claim 10, wherein if the absolute value of the difference between the printing density of the first portion and the printing density of the second portion exceeds the predetermined threshold, the movement control unit controls the movement unit to move the guide unit to the second position while the recording material is being guided by the guide unit at the first position.

12. The image forming apparatus according to claim 10, characterized in that when the absolute value of the difference between the printing rate of the first part and the printing rate of the second part exceeds the predetermined threshold, the movement control unit controls the movement unit so that the guide part is positioned at the second position, and then controls the movement unit so that the guide part moves from the second position to the first position.

Images