JPH1124488A - Method for driving control for heating element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for driving control for a heating element capable of controlling time for restraining and controlling a rush current by load resistance 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 rush current is restrained and controlled by the load resistance 3 every time the on/off driving control signal of the element 2 is switched from off to on. The time for restraining and controlling the rush current by the load resistance 3 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 a constant temperature. . 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, every time the fixing heater is turned on, the rush current is suppressed by performing the rush current suppression control by the load resistance for a predetermined time (for example, 0.5 [sec]). However, if the time for performing the inrush current suppression control by the load resistance is set too short,
Inrush current cannot be kept low. Conversely, if the time for performing the rush current suppression control by the load resistance is set too long, the rush current can be suppressed low, but the driving power of the fixing heater is reduced and the temperature of the fixing roller is reduced after the fixing roller is turned on. Takes a long time to rise to a predetermined temperature. In addition, the load resistance generates heat, and the temperature inside the device increases.

[0004]

SUMMARY OF THE INVENTION The present invention provides a heating element drive control method that can control the time for performing the rush current suppression control by the load resistance to an appropriate time according to the driving state of the heating element. The purpose is to:

[0005]

According to the driving control method of a heating element according to the present invention, the heating element is controlled to be turned on and off so that the temperature of the heating element becomes a predetermined value, and the on / off driving control signal of the heating element is changed from off to on. In the heating element drive control method in which the rush current suppression control by the load resistance is performed every time the switching is performed, the load resistance is determined based on the length of the immediately preceding heating element drive stop period defined by the ON / OFF drive control signal of the heating element. It is characterized in that the length of time during which the inrush current suppression control is performed is controlled.

The length of time during which the inrush current suppression control by the load resistance is performed is controlled such that the longer the heating element drive suspension period, the longer the inrush current suppression control time by the load resistance.

[0007]

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 driving circuit for the fixing heater. In FIG. 1, 1 is a power supply, 2 is a fixing heater, 3 is a load resistor, and 4 is a first solid state relay (SSR).
1) and 5 are second solid state relays (SSR2)
It is.

FIG. 2 shows a fixing heater ON / OFF control signal a generated based on a temperature sensor for detecting the temperature of the fixing roller, the ON / OFF timing of the first solid state relay 4, and the ON / OFF of the second solid state relay 5. The timing is shown.

Generally, when the temperature detected by the temperature sensor becomes equal to or higher than a first predetermined value T1, the on / off control signal becomes H level indicating OFF, and the temperature detected by the temperature sensor becomes lower than a second predetermined value T2 (<T1). Then, the on / off control signal becomes L level indicating ON. The time from when the on / off control signal goes high (off) to when it goes low (on) (hereinafter referred to as a heater drive stop period X) varies depending on changes in the external environment and the like.

When the on / off control signal of the fixing heater is at H level indicating off, the first solid state relay 4 and the second solid state relay 5 are off.

When the ON / OFF control signal a of the fixing heater 2 becomes L level indicating ON, the first solid state relay (SSR1) 4 is first turned ON. Therefore,
The power supply 1, the fixing heater 2, the load resistor 3, and the first solid state relay 4 form a closed circuit. Since the voltage from the power supply 1 is applied to the series circuit of the fixing heater 2 and the load resistor 3 as described above, the current flowing through the circuit is reduced, and the resistance value is stabilized by the self-heating of the heater. That is, the inrush current can be kept low. Suppressing the inrush current by applying the voltage from the power supply 1 to the series circuit of the fixing heater 2 and the load resistor 3 in this manner is referred to as inrush current suppression control by the load resistor 3.

When the inrush current suppression control time Y, which will be described later, elapses after the on / off control signal a becomes L level indicating on, the second solid state relay (SSR2) 5 is turned on. . Therefore, the power supply 1, the fixing heater 2, the second solid state relay 5, and the first solid state relay 4 form a closed circuit. Thus, the voltage of the power supply 1 is applied only to the fixing heater 2.

When the on / off control signal a becomes H level indicating off, the first solid state relay (S
SR1) 4 and the second solid state relay (SS)
R2) 5 are both turned off. Thereby, the driving of the fixing heater 2 is stopped.

In this embodiment, the rush current suppression control time Y is controlled based on the heater drive stop period X.
That is, each heater drive stop period X is measured, and the rush current suppression control period Y is controlled based on the measured heater drive stop period X immediately before.

FIG. 3 shows a table storing the relationship between the heater drive stop period X and the inrush current suppression control period Y prepared in advance. Since the temperature of the fixing heater 2 is considered to be lower as the heater drive stop period X becomes longer, the heater drive stop period X and the rush current suppression control are performed so that the rush current suppression control period Y becomes longer as the heater drive stop period X becomes longer. The relationship with the period Y is determined. Based on the table of FIG. 3, the rush current suppression control period Y corresponding to the immediately preceding heater drive stop period X is determined.

According to the above embodiment, the rush current suppression control time Y is controlled such that the longer the heater drive stop period X, the longer the rush current suppression control time Y. Therefore, the rush current when the fixing heater is turned on can be suppressed low, and the temperature rise by the fixing heater when the fixing heater is turned on can be quickly increased.

[0018]

According to the present invention, the length of time during which the rush current suppression control by the load resistance is performed can be controlled to an appropriate time according to the driving state of the heating element.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a driving circuit of a fixing heater.

FIG. 2 is a time chart showing an on / off control signal of a fixing heater, an on / off timing of a first solid state relay, and an on / off timing of a second solid state relay.

FIG. 3 is a schematic diagram showing a table storing a relationship between a heater drive stop period X and an inrush current suppression control time Y.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 power supply 2 fixing heater 3 load resistance 4 first solid state relay 5 second solid state relay

Claims (2)

[Claims] The heating element is controlled so that the temperature of the heating element becomes a predetermined value, and inrush current suppression control by a load resistor is performed each time the on / off driving control signal of the heating element is switched from off to on. In the body drive control method, based on a length of a heating element drive stop period immediately before specified by an ON / OFF drive control signal of the heating element, a time length for performing inrush current suppression control by a load resistance is controlled. Drive control method of the heating element. 2. The time length for performing the inrush current suppression control by the load resistance is controlled such that the longer the heating element drive stop period, the longer the inrush current suppression control time by the load resistance. Drive control method of heating element.