BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to an image forming apparatus, such as a printer, a copier and a facsimile, utilizing an electrophotographic system. The present invention also relates to an image heating apparatus, such as a gloss applying apparatus that improves a gloss value of a toner image by reheating a fixing unit included in an image forming apparatus and a toner image fixed to a recording material.

Description of the Related Art

Lately the power consumed by an image forming apparatus is increasing as the processing speed of an image forming apparatus increases. In particular, in the case of a high-speed color laser printer which simultaneously forms a plurality of toner image, a drive apparatus, including a motor, consumes a large amount of current. In order to output stable fixed images by such an image forming apparatus, a configuration to change printing productivity (hereafter “throughput”), which is a number of prints per unit time, was proposed in Japanese Patent Application Publication No. 2015-099180. In other words, the apparatus environment, the temperature state of the fixing unit, and the load state of the printer are detected, and when it is determined that the current required for the image forming operation exceeds the maximum current that can be supplied by the AC power supply, a control to increase the transport interval of the recording paper in the initial period of printing is performed.

SUMMARY OF THE INVENTION

However, the configuration of the above mentioned prior art was designed to supply the necessary fixing power to the image forming apparatus, of which the AC power voltage, ambient temperature and load are within a standard range, and did not have sufficient margin to the maximum supply power of the AC power supply to meet the tendency of an increase in the power consumption of the image forming apparatus. Therefore if a replenishing motor or an actuator for a stapling operation are driven during printing, the maximum power may be exceeded. If an operation to drop throughput in general is performed when such an operation as driving a motor or an actuator during printing is performed, usability may be considerably diminished.

It is an object of the present invention to provide an image forming apparatus that can minimize the drop in throughput even if a control to apply power load, such as a driving of a motor and stapling operation, is performed during printing.

To achieve this object, the image forming apparatus of the present invention includes:

an image forming portion which is configured to form an image on a recording material;

a fixing portion which includes a heater constituted of a plurality of heating elements disposed in a direction orthogonal to a transport direction of a recording material, and is configured to fix the image on the recording material using heat of the heater; and

an power control unit which is configured to be capable of controlling power supplied to the plurality of heating elements individually based on image information of an image formed on a recording material,

wherein the image forming apparatus further comprises:

an interval determining unit that is configured to determine a transport interval of a plurality of recording materials in the case of continuous feeding in which images are continuously formed on the plurality of recording materials and the images are continuously heated;

an actuator which is configured to operate during the continuous feeding;

a power predicting unit which is configured to predict power required for controlling the temperature of a plurality of heating regions heated by the plurality of heaters to a predetermined target temperature based on the image information;

a power storing unit which is configured to store power required for operating the actuator; and

an adjusting unit which is configured for adjusting the power supplied to the plurality of heating elements by the power control portion, and the transport interval determined by the interval determining unit,

wherein when an excess period, which is a period in which the total of the power predicted by the power predicting unit and power stored by the power storing unit exceeds a predetermined power, exists during continuous feeding, the adjusting unit: (i) at least during the excess period, adjusts power supplied to the plurality of heating elements by the power control unit, so that the total of the power supplied to the plurality of heating elements and the power stored by the power storing unit does not exceed the predetermined power, and (ii) after the excess period, adjusts the transport interval so that the temperature rising to a target temperature in the plurality of heating regions by supplying power to the plurality of heating regions in which the adjustment of the power supply is cancelled, is completed before the arrival of the recording material to the fixing portion.

According to the present invention, a margin of power is calculated based on the required power predicted from the image information of each heating element, and an optimum print interval is determined based on the newly applied power load even if a control to apply power load, such as a driving of a motor and stapling operation, is performed during printing. Thereby a drop in throughput can be minimized.

Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.

