JPH1124487A - Method for driving control for heating element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for the driving control of a heating element capable of controlling time for phase control for restraining a rush current to adequate time in accordance with the driving condition of the heating element. SOLUTION: As to this method for driving control; the on/off driving control of the heating element 2 is performed so that the temperature of the element 2 becomes a specified value, and the phase control for restraining the rush current is performed every time the driving of the element 2 is switched from the off to the on. The time for the phase control for restraining the rush current is controlled based on heating element driving stopping term obtained just before the on/off driving control signal of the element 2 regulates the term.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing heater for an image forming apparatus such as a copying machine, a facsimile machine, and a printer.
The present invention relates to a driving control method for a heating element such as a halogen lamp for exposure.

[0002]

2. Description of the Related Art A fixing heater for heating a fixing roller of a copying machine is controlled on and off based on the temperature of the fixing roller detected by a temperature sensor so that the temperature of the fixing roller always becomes constant. . By the way, in such a fixing heater, when its temperature is low, its resistance value is very small. For this reason, when energization is performed in a state where the temperature of the fixing heater is low, there is a problem that an extremely large current (rush current) flows.

Therefore, conventionally, when the driving of the fixing heater is turned on, the rush current is suppressed by performing phase control so that the electric power supplied to the fixing heater gradually increases. A period in which the power supplied to the fixing heater is limited is referred to as a rush current suppressing phase control period. The inrush current suppression phase control period is about 30 seconds when the main power of the copying machine is turned on, and about 2 seconds when the fixing heater is turned on during the on / off control period based on the temperature sensor.

[0004] If the phase control period is set too short, the inrush current cannot be suppressed low. Conversely, if the phase control period is set too long, the inrush current can be suppressed low, but the driving power of the fixing heater decreases, and the temperature of the fixing roller rises to a predetermined temperature after the fixing roller is turned on. It takes time.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a heating element drive control method capable of controlling the length of time during which the rush current suppressing phase control is performed to an appropriate time length in accordance with the driving state of the heating element. The purpose is to provide.

[0006]

According to the present invention, there is provided a driving control method for a heating element, wherein the heating element is controlled to be turned on and off so that the temperature of the heating element becomes a predetermined value. In the driving control method of the heating element, the rush current suppression phase control is performed, based on the length of the heating element drive stop period immediately before specified by the heating element ON / OFF drive control signal, the rush current suppression phase control. The length of time to be performed is controlled.

The time length for performing the inrush current suppression phase control is controlled such that the longer the heating element drive stop period, the longer the time for performing the inrush current suppression phase control.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a fixing heater for heating a fixing roller of a copying machine will be described below with reference to the drawings.

FIG. 1 shows a drive control circuit of the fixing heater.

In FIG. 1, reference numeral 1 denotes a power source, 2 denotes a fixing heater, and 3 denotes a phase control element such as an SCR and a triac.

FIG. 2 shows an on / off control signal of the fixing heater 2 generated based on a temperature sensor for detecting the temperature of the fixing roller. Generally, when the temperature detected by the temperature sensor becomes equal to or higher than the first predetermined value T1, the on / off control signal becomes H level indicating OFF, and the temperature detected by the temperature sensor becomes the second level.
Is less than or equal to a predetermined value T2 (<T1), the on / off control signal goes to the L level indicating on. ON / OFF control signal is H
The time from when the level is turned off (off) to when the level is turned on to the L level (on) (hereinafter, referred to as a heater drive stop period X) changes due to a change in the external environment or the like.

As shown in FIG. 3, when the ON / OFF control signal becomes L level indicating ON, the fixing heater 2 is controlled for a rush current suppressing phase control time Y determined as described later.
Phase control element 3 so that the power supplied to
Is controlled. In this embodiment, based on the immediately preceding heater drive stop period X, the inrush current suppression phase control time Y
Is determined.

FIG. 4 shows a table storing the relationship between the heater drive stop period X and the rush current suppressing phase control time Y prepared in advance. It is considered that the longer the heater drive stop period X, the lower the temperature of the fixing heater 2 becomes. Therefore, the heater drive stop period X and the rush current The relationship with the suppression phase control time Y is determined. Based on the table of FIG. 4, the inrush current suppression phase control time Y corresponding to the immediately preceding heater drive stop period X is determined.

According to the above embodiment, the inrush current suppressing phase control time Y is controlled such that the longer the heater drive stop period X, the longer the inrush current suppressing phase control time Y. Therefore, the rush current can be suppressed low, and the temperature of the fixing roller can be quickly raised when the fixing heater 2 is turned on.

[0015]

According to the present invention, the time length of the inrush current suppression phase control can be controlled to an appropriate time length according to the driving state of the heating element.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a drive control circuit of a fixing heater.

FIG. 2 is a time chart showing an on / off control signal of a fixing heater.

FIG. 3 is a time chart showing inrush current suppression phase control.

FIG. 4 is a schematic diagram showing a table storing a relationship between a heater drive stop period X and a rush current suppressing phase control time Y.

[Explanation of symbols]

 1 power supply 2 fixing heater 3 phase control element

Claims (2)

[Claims] An on-off drive control of a heating element is performed so that the temperature of the heating element becomes a predetermined value, and a rush current suppressing phase control is performed every time the driving of the heating element is switched from off to on. In the method, the length of time during which the inrush current suppression phase control is performed is controlled based on the length of the heating element drive stop period immediately before specified by the heating element ON / OFF drive control signal. Drive control method. 2. The time period for performing the rush current suppressing phase control is controlled such that the longer the heating element drive stop period, the longer the time for performing the rush current suppressing phase control. Drive control method of heating element.