Temperature Control Method for Fixing Device, and Fixing Device and Image-Forming Apparatus that Use the Same

Abstract

A temperature control method for a fixing device, which includes a heating unit that heats a recording material; a temperature detecting unit that detects a temperature of the heating unit; and a temperature controlling unit that determines an amount of power supplied based on a detected temperature of the temperature detecting unit, and controls the temperature of the heating unit by supplying the determined amount of power supplied, wherein temperature is sampled by the temperature detecting unit at a prescribed cycle, and the amount of power supplied is determined on the basis of this detection result, and when the duty cycle of the determined amount of power supplied is no more than 50%, a first period during which power is intermittently supplied to the heating unit, and a second period during which a power supply to the heating unit is not permitted are set within the prescribed cycle.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view showing the constitution of a fixing device related to this embodiment,

FIG. 2 is a diagram showing temperature fluctuations on a heating roller 1 related to this embodiment;

FIG. 3 is a block diagram showing the constitution of a control device for controlling the temperature of the heating roller 1;

FIG. 4 is a diagram showing an example of a power supply method when the duty cycle is no more than 50%;

FIG. 5 is a diagram showing an example of a power supply method when the duty cycle exceeds 50%;

FIG. 6 is another embodiment of a power supply method when the duty cycle exceeds 50%; and

FIG. 7 is an established example of the invention.

Claims

1. A temperature control method for a fixing device, comprising: a heating unit that heats a recording material;a temperature detecting unit that detects a temperature of the heating unit; anda temperature controlling unit that determines an amount of power supplied based on a detected temperature of the temperature detecting unit, and controls the temperature of the heating unit by supplying the determined amount of power supplied,wherein temperature is sampled by the temperature detecting unit at a prescribed cycle, and the amount of power supplied is determined on the basis of this detection result,when the duty cycle of the determined amount of power supplied is no more than 50%, a first period during which power is intermittently supplied to the heating unit, and a second period during which a power supply to the heating unit is not permitted are set within the prescribed cycle, such that a total amount of power supplied in the first period and second period becomes the amount of power supplied, power being supplied to the heating unit during the first period in a power-supply pattern comprising one unit of energization and one unit of non-energization, and power not being supplied to the heating unit during the subsequent second period, andwhen the duty cycle of the determined amount of power supplied exceeds 50%, a first period during which power is intermittently supplied to the heating unit, and a third period during which power is continuously supplied to the heating unit are set within the prescribed cycle, such that a total amount of power supplied in the first period and third period becomes the amount of power supplied, power being supplied to the heating unit during the first period in a power-supply pattern comprising one unit of energization and one unit of non-energization, and power being supplied continuously to the heating unit during the subsequent third period.

2. A fixing device, which utilizes the fixing device temperature control method of claim 1.

3. An image-forming apparatus, comprising the fixing device of claim 2.