Image forming apparatus capable of suppressing malfunction of sensor and conveyance control method

An image forming apparatus comprising:

• a transfer portion configured to transfer a toner image to a sheet;
• a fixing portion configured to fix the toner image on the sheet, the toner image being transferred to the sheet by the transfer portion;
• a sensor configured to sense the sheet on a downstream side of the transfer portion in a conveyance direction of the sheet and an upstream side of the fixing portion in the conveyance direction;
• a duct that extends from an air intake port to an air blowing port, the air intake port being open upward on an upper surface of the image forming apparatus, the air blowing port being open toward the sensor;
• an airflow generation portion configured to generate airflow that moves in the duct from the air intake port to the air blowing port;
• a sheet discharge port configured to discharge the sheet on which the fixing portion fixes the toner image, the sheet discharge port being open in a first direction above the fixing portion, the first direction being orthogonal to an up-down direction, wherein
• the transfer portion is provided below the fixing portion, and
• the sensor is provided on a second direction side than a conveyance path of the sheet, the conveyance path extending through the fixing portion, the second direction being opposite to the first direction;
• and
• an inverting conveyance path that extends along the up-down direction on the second direction side than the sensor, wherein the air blowing port is formed on a guide surface of the inverting conveyance path in the second direction
• a stop processing portion configured to stop conveyance of the sheet when a predetermined stop timing arrives while a both-side image forming process of forming images on both sides of the sheet is being executed;
• and
• a reservation processing portion configured to reserve, when the stop timing arrives and the sheet is passing through an opposed portion between the sensor and the air blowing port, a stop of the conveyance of the sheet by the stop processing portion until passage of the sheet through the opposed portion ends.

A conveyance control method that is executed by an image forming apparatus, the image forming apparatus including:

• a transfer portion configured to transfer a toner image to a sheet;
• a fixing portion configured to fix the toner image on the sheet, the toner image being transferred to the sheet by the transfer portion;
• a sensor configured to sense the sheet on a downstream side of the transfer portion in a conveyance direction of the sheet and an upstream side of the fixing portion in the conveyance direction;
• a duct that extends from an air intake port to an air blowing port, the air intake port being open upward on an upper surface of the image forming apparatus, the air blowing port being open toward the sensor;
• an airflow generation portion configured to generate airflow that moves in the duct from the air intake port to the air blowing port;
• a sheet discharge port configured to discharge the sheet on which the fixing portion fixes the toner image, the sheet discharge port being open in a first direction above the fixing portion, the first direction being orthogonal to an up-down direction, wherein
• the transfer portion is provided below the fixing portion, and
• the sensor is provided on a second direction side than a conveyance path of the sheet, the conveyance path extending through the fixing portion, the second direction being opposite to the first direction;
• and
• an inverting conveyance path that extends along the up-down direction on the second direction side than the sensor, the air blowing port being formed on a guide surface of the inverting conveyance path in the second direction, the conveyance control method comprising:
• a stop step of stopping conveyance of the sheet when a predetermined stop timing arrives while a both-side image forming process of forming images on both sides of the sheet is being executed;
• and
• a reservation step of reserving, when the stop timing arrives and the sheet is passing through an opposed portion between the sensor and the air blowing port, a stop of the conveyance of the sheet by the stop step until passage of the sheet through the opposed portion ends.