JPH11161086A - Fixation heater temp. controlling device for electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixation heater temp. controlling device capable of reducing the high frequency current flow, while preventing from the rush current and the power source voltage fluctuation. SOLUTION: This device 1a is provided with the fixation heater 5, the AC power source 9 applying the power to the heater, the temp. detecting circuit 10 detecting the heater temp., an operating circuit 11 deciding the applying voltage to the above heater based on the heater temp., and the controlling circuit 2 controlling the power supply to the heater. At the time of supplying the power to the heater 5, when the temp. of the heater is low, the device is allowed to perform the soft start on control by which full lighting is permitted after continuing conduction for the specific time at the designated phase angle, and when the temp. of the heater is high, the device is allowed to perform full lighting after holding the conduction to the heater for the time shorter than the specific time at the designated phase angle. In addition, at the time of stopping the power supply to the fixing heater, by performing the soft stop off control that holding the conduction to the heater at the designated phase angle and completely turning off thereafter, the higher harmonic electric current, the rush current and the power source voltage fluctuation is respectively prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing heater temperature control device for an electrophotographic apparatus, and more particularly to a fixing heater temperature control device characterized by controlling the heater temperature when power is turned on.

[0002]

2. Description of the Related Art A rectifier circuit (capacitor input type rectifier circuit) is provided inside electric appliances such as televisions and personal computers which are now widely used. The rectifier circuit converts supplied AC current into DC current. Used. However,
This converted DC current is a pulse wave (distorted wave) different from the input voltage (sine wave), and this pulse wave contains a large amount of harmonic current. In recent years, for harmonic currents,
Harmonic current regulation as international standard (IEC1000-3-2)
Therefore, it is desired to suppress and reduce such harmonic current. In order to suppress and reduce this high-frequency current, the AC voltage control must be turned ON / OFF.
A method is conceivable in which the input current waveform is changed to a sine wave after the OFF control. However, in this case, an excessive current (rush current) flows to the load when the power is turned on, which is not preferable. That is, in an electrophotographic apparatus such as a copying machine, the temperature of the fixing heater is low (about 0 to 150 ° C.) before use (when the power switch is OFF), and therefore, the resistance value of the heater itself also decreases. Therefore, when the power switch is turned on, an inrush current flows rapidly to the heater (load).
This causes failure of the heater and electric parts (switches, relays, etc.) and trouble of the power supply, and furthermore, fluctuations of the power supply voltage due to the rush current increase. This power supply voltage fluctuation is also an international standard of power supply voltage fluctuation regulation (IEC1000-3-3).
Thus, voltage fluctuations of electrical equipment are regulated, and measures to suppress the power supply voltage fluctuations are also desired.

FIG. 4 shows a fixing heater temperature control device disclosed in Japanese Patent Application Laid-Open No. 3-113519, as a countermeasure against such high-frequency current and power supply voltage fluctuation. This conventional fixing heater temperature control device performs phase control during a transition period after power is supplied, thereby reducing inrush current and suppressing power supply voltage fluctuation. As shown in FIG. 1, the fixing heater control device 1 includes a control circuit 2 and a triac 4, 4 arranged in parallel with a zero cross circuit 3. In the figure, the fixing heater 5 is a triac 4,
4 and the choke coil 6 are connected in series, and the respective gate terminals of the triacs 4 and 4 are connected to the output circuit 7. The triac 4 is provided for performing a phase control for suppressing a current to the fixing heater 5 until a certain transition period elapses from the power supply. When the power is turned on, a control pulse (trigger pulse) for controlling the triac 4 is output from the control circuit 2 through the output circuit 7. Since this trigger pulse is output in accordance with the temperature of the fixing heater detected by the temperature sensor 8, power supply to the fixing heater 5 is controlled (phase control) by the trigger pulse.

[0004]

However, the conventional fixing heater temperature control device as described above has the following problems. That is, as described above, in the conventional example, the rush current is reduced by performing the phase control during a transition period (a fixed time after the power is supplied) after the power is turned on. Is not preferable because the AC power supply contains harmonic currents, and after this transition period, this phase control is ON / OFF control. An inrush current flows through the heater, which may cause a failure of the heater and electric components. Further, the power supply voltage fluctuation is increased by such an inrush current, which is not preferable.

Accordingly, an object of the present invention is to solve the above-mentioned problems of the conventional fixing heater temperature control device, reduce harmonic currents, and suppress inrush current and power supply voltage fluctuation in an electrophotographic apparatus. It is an object of the present invention to provide a fixing heater control device that can perform the fixing.

[0006]

In order to achieve the above object, the present invention provides a toner fixing heater, an AC power supply for supplying power to the heater, and an AC power supply for supplying power to the heater. A fixing heater temperature control device for an electrophotographic apparatus, comprising: a temperature detection circuit for detecting a heater temperature; an arithmetic circuit for determining a voltage applied to the heater from the heater temperature; and a control circuit for controlling power supply to the heater. At the time of power supply to the fixing heater, if the temperature of the heater is low, a soft start-on control is performed in which the power supply to the heater is kept turned on at a specified phase angle for a certain period of time and then fully turned on. Sometimes, when the temperature of the fixing heater is high, a soft start-on control is performed in which the energization of the heater is maintained at a specified phase angle for a shorter time than the fixed time and then fully lit. In addition, when the power supply to the fixing heater is stopped, the rush current at the time of power supply, harmonic inrush, It is characterized by suppressing wave current and power supply voltage fluctuation.

According to a second aspect of the present invention, in the first aspect of the invention, when power is supplied to the fixing heater and the temperature of the heater is low, the voltage applied to the fixing heater is reduced. After holding for 800 ms at 20% of the power, soft start-on control to turn on all lights is performed. When the heater temperature is high and the electrophotographic apparatus is in a standby state at the time of power supply, the voltage applied to the heater is reduced to 20% of the whole. Soft start-on control to turn on all lights after holding for 500 ms, and when the power supply to the fixing heater is stopped, the applied voltage is set to 50% of 20% of the whole.
After holding 0 ms, soft stop off control for turning off all lights is performed to suppress inrush current, harmonic current and power supply voltage fluctuation at the time of power supply.

According to a third aspect of the present invention, in the first aspect, when power is supplied to the fixing heater and the temperature of the heater is low, the voltage applied to the fixing heater is reduced. After holding 600 ms at 60% of the time, soft start-on control to turn on all lights is performed, and when the heater temperature is high at the time of power supply and the electrophotographic apparatus is operating, the voltage applied to the heater is reduced to 60% of the whole. Soft start-on control to turn on all lamps after holding for 400 ms. When the power supply to the fixing heater is stopped,
After holding 0 ms, soft stop off control for turning off all lights is performed to suppress inrush current, harmonic current and power supply voltage fluctuation at the time of power supply.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the first embodiment of the present invention shown in the drawings, the same parts as those in the above-mentioned conventional example are denoted by the same reference numerals, and different parts will be mainly described. FIG. 1 is a circuit diagram showing a first embodiment of a fixing heater temperature controller according to the present invention. In this embodiment, reference numeral 1a denotes a fixing heater temperature control device. As shown in the figure, the fixing heater temperature control device 1a uses an AC power supply 9 for supplying a voltage (AC current) to the fixing heater 5 and a heater sensor 8 (thermistor) for controlling the heater temperature of the fixing heater. It comprises a temperature detecting circuit 10 for detecting, a calculating circuit 11 for calculating a resistance value of the heater from the heater temperature detected from the temperature detecting circuit, and a control circuit 2 for controlling energization (supply voltage) to the heater. . The arithmetic circuit 11 selects a supply current based on the calculated resistance value of the heater so that the current supplied to the heater does not exceed a preset current value, and a voltage equal to or higher than a predetermined voltage is supplied to the heater by the control circuit 2. It is controlled not to be supplied. This control circuit 2 is a switch
When the switch 12 is turned on, energization (voltage supply) to the fixing heater 5 is performed. As the switch 12, a semiconductor element capable of high-speed switching such as a transistor or an SCR is used.

In the first embodiment having the above configuration,
The energization (supply of voltage) to the fixing heater is performed as follows. As described above, when an electrophotographic apparatus such as a copying machine is used (when the power switch is turned off), the temperature of the fixing heater is low (about 0 to 150 ° C.), so that the resistance value of the heater itself decreases and the power is turned on. At times, an inrush current suddenly flows to the heater 5 (load), which causes a failure of an electric component or a trouble of a power supply. Therefore, in the present embodiment, when the fixing heater 5 is energized, first, a predetermined energizing amount is held for a predetermined time at “designated phase angle” (total applied voltage amount × α%). After the lapse of time, all applied voltage (100%) is supplied to the heater and this heater is fully lit (complete heat generation)
Soft start-on control is performed. As will be described later, the “designated phase angle” set by the soft start-on control varies depending on the operation state of the electrophotographic apparatus.

When the power supply to the fixing heater 5 is turned off (when the power supply is turned off), the power supply to the heater is maintained at a “specified phase angle” (total applied voltage amount × α%) for a predetermined time. The soft stop off control is performed to stop the applied voltage and turn off the heater (stop heat generation). That is, in the present invention, the full voltage (current) is not applied to the fixing heater immediately after the power is turned on, and the inrush current and the inrush current are set by first setting the applied current amount to “total applied voltage amount × α%”. By suppressing the power supply voltage fluctuation, a failure of an electric component or an electric trouble is avoided.

The details of the soft start on control and the soft stop off control will be described with reference to the voltage waveforms of FIGS. FIG. 2A shows an example of a voltage waveform applied to the fixing heater when power is supplied. Here, the horizontal axis X indicates the voltage application time, and the vertical axis Y indicates the amount of current (voltage) applied to the heater. This waveform diagram shows a voltage waveform applied to the fixing heater. Since the heater is an inductive load, the current waveform is the same, although the current waveform has a different cycle. As shown in FIG. 2A, in the present embodiment, when the temperature of the fixing heater is low (0 to 150 ° C.), such as when the power is turned on, first, the amount of current applied to the fixing heater 5 is reduced. Set to a voltage (designated phase angle) equivalent to 20% of the total voltage, and 800 ms (application time: T) at a predetermined cycle (cycle)
During this period, current is supplied by this applied voltage. At this time, since the voltage applied to the heater is not 100%, the heater is not completely generating heat. After the lapse of 800 ms, a voltage (100%) corresponding to the entire applied voltage is applied to the heater as shown in the waveform diagram. At this time, since the heater is fully turned on, the heater generates heat almost completely.

When the fixing heater reaches a predetermined fixing temperature and enters a copy-enabled state (standby state), that is, when the heater temperature increases (150 to 200 ° C.), FIG. ), The voltage is applied by the applied voltage (voltage corresponding to 20% of the total voltage) for 500 ms (applied time: Ta), which is shorter than the time when the heater temperature is low. After 500 ms, the entire voltage is applied (applied voltage 100%) to completely heat the heater (soft start-on control). The reason for setting the energizing time Ta at this time shorter than the predetermined time T is as follows.
This is because the fixing heater has reached the predetermined fixing temperature, so that the heater temperature is naturally high. As described above, in this soft start-on control, the voltage applied to the heater when the power is turned on is a voltage amount corresponding to 20% of the total voltage amount. Can be suppressed. In this embodiment, ON control is performed after the fixing heater is fully turned on, and OFF control (ON / OFF control) is performed after the fixing heater is completely turned off. As a result, the output voltage waveform is substantially a sine wave as shown in FIG. 3, and this voltage (current) does not include a harmonic current. Actually, this ON
The / OFF control is performed by the temperature detection circuit 10 based on the temperature detected by the temperature sensor 8 (see FIG. 1).

When the power supply to the fixing heater is turned off (when the power supply is turned off), the voltage supply to the heater is not immediately stopped as shown in FIG.
During (Ta), the voltage applied to the heater is held at a voltage (designated phase angle) corresponding to 20% of the total voltage, and after 500 ms, voltage supply (energization) to the heater is performed as shown in the waveform diagram. Stop (soft stop off control). Naturally, at this time, the heater is turned off and the heat generation stops. As described above, when the power supply is turned off by the soft stop-off control, the applied voltage reduced is held for a certain period of time, and then the power supply to the heater is stopped. Can be.

Next, FIGS. 3A to 3C show examples of voltage waveforms according to the second embodiment of the present invention. In this embodiment, since the electrophotographic apparatus indicates an operating state, as shown in FIG.
A voltage (designated phase angle) equivalent to 60% and an application time T of 60
It is set to 0ms. Further, as shown in the figure, the application time Tb when the fixing heater temperature becomes high is set to 400 ms. The reason why the applied voltage amount is set to be larger than that in the standby state of the electrophotographic apparatus in consideration of the fact that the temperature of the fixing heater is consumed by the transferred paper during operation.

As described above, according to the fixing heater temperature control apparatus of the present invention, the rush current is suppressed by performing the soft start on control, and the power supply is controlled by performing the soft start on control and the soft stop off control. Voltage fluctuation can be suppressed. Further, after the heater is completely turned on, the on control is performed, and after the heater is completely turned off, the off control is performed (ON / O).
By performing FF control, harmonic current can be suppressed.
As a result, it is possible to prevent a power supply trouble due to a failure of a heater or an electric component (a switch, a relay, etc.) or a voltage fluctuation. In addition, the present invention is capable of effectively suppressing harmonic current and power supply voltage fluctuation together with reduction of inrush current. Therefore, the international standard of harmonic current regulation (IEC1000-3-2) and power supply voltage fluctuation regulation (IEC1000-3-3). ) And can respond. In the embodiment, the electrophotographic apparatus is described as a copying machine. However, the present invention can be applied to a laser printer, a facsimile, an OA apparatus, and other electrophotographic apparatuses using a fixing heater.

[0017]

The present invention is as described above. According to the first aspect of the present invention, there is provided a toner fixing heater, an AC power supply for supplying power to the heater, and a temperature detecting circuit for detecting a heater temperature. An arithmetic circuit for determining a voltage to be applied to the heater from the heater temperature; and a control circuit for controlling power supply to the heater. At the time of power supply, if the temperature of the heater is low, a soft start-on control is performed in which the power to the heater is kept turned on at a specified phase angle for a certain period of time and then fully lit. If it is high, the power supply to the fixing heater is performed by performing a soft start-on control in which the energization of the heater is maintained at a specified phase angle for a shorter time than the predetermined time and then fully lit. At the time of stop, since the power supply to the heater is kept at the designated phase angle for a time shorter than the predetermined time and then completely turned off, the soft stop off control is performed. By performing the soft start on control and the soft stop off control, it is possible to suppress power supply voltage fluctuation. In addition, there is an effect that harmonic current can be suppressed by performing ON control after the heater is completely turned on and OFF control (ON / OFF control) after the heater is completely turned off.

According to a second aspect of the present invention, in the first aspect of the invention, when power is supplied to the fixing heater and the temperature of the heater is low, the voltage applied to the fixing heater is reduced. After holding for 800 ms at 20% of the power, soft start-on control to turn on all lights is performed. When the heater temperature is high and the electrophotographic apparatus is in a standby state at the time of power supply, the voltage applied to the heater is reduced to 20% of the whole. Soft start-on control to turn on all lights after holding for 500 ms. When the power supply to the fixing heater is stopped, the applied voltage to the heater is reduced to 20% of the total.
After 500ms hold, soft stop off control to turn off all lights is performed, so inrush current is suppressed by performing soft start on control, and power supply voltage fluctuation is performed by performing soft start on control and soft stop off control. Can be suppressed. Further, the ON control is performed after the heater is completely turned on, and the OFF control is performed after the heater is completely turned off (ON / OF).
Performing F control) has the effect of suppressing harmonic current.

According to a third aspect of the present invention, in the first aspect of the invention, when power is supplied to the fixing heater, if the temperature of the heater is low, the voltage applied to the fixing heater is reduced. After holding 600 ms at 60% of the time, soft start-on control to turn on all lights is performed, and when the heater temperature is high at the time of power supply and the electrophotographic apparatus is operating, the voltage applied to the heater is reduced to 60% of the whole. Soft start-on control to turn on all lights after holding for 400 ms, and when power supply to the fixing heater is stopped, perform soft stop off control to turn off all lights after holding the applied voltage to the heater at 60% of the whole for 400 ms. Therefore, inrush current can be suppressed by performing soft start-on control, and power supply voltage fluctuation can be suppressed by performing soft start-on control and soft stop off control. That. Further, after the heater is completely turned on, the on control is performed, and after the heater is completely turned off, the off control is performed (ON / ON).
OFF control) has the effect of suppressing harmonic current.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a configuration of a first embodiment of the present invention.

2A and 2B show voltage waveforms of the above, and FIG.
(b) is a diagram showing a waveform at the time of copying, and (c) is a diagram showing a waveform at the time of power OFF.

FIG. 3 is a waveform diagram showing a voltage waveform according to the second embodiment.

FIG. 4 is a circuit diagram showing a configuration of a conventional fixing heater temperature control device of the same type as the present invention.

[Explanation of symbols]

 1, 1a Fixing heater temperature controller 2 Control circuit 3 Zero cross circuit 4 Triac 5 Fixing heater 7 Output circuit 8 Temperature sensor 9 AC power supply 10 Temperature detection circuit 11 Operation circuit

Claims (3)

[Claims] A heater for toner fixing; an AC power supply for supplying power to the heater; a temperature detection circuit for detecting a heater temperature; an arithmetic circuit for determining a voltage applied to the heater from the heater temperature; And a control circuit for controlling power supply to the heater. In the fixing heater temperature control device for an electrophotographic apparatus, when power is supplied to the fixing heater, if the temperature of the heater is low, power is supplied to the heater. If the temperature of the fixing heater is high at the time of power supply, if the temperature of the fixing heater is high, the power to the heater is turned on at the designated phase angle for a predetermined time from the fixed time. Also performs a soft start-on control that turns on all lights after holding for a short time, and when the power supply to the fixing heater is stopped, the power to the heater is turned on at the specified phase angle for the specified time. A heater temperature control device for a fixing device of an electrophotographic apparatus, characterized by suppressing a rush current, a harmonic current, and a power supply voltage fluctuation at the time of power supply by performing a soft stop-off control for turning off all light after holding for a shorter time. . 2. When power is supplied to the fixing heater, if the temperature of the heater is low, the voltage applied to the fixing heater is maintained at 20% of the whole for 800 ms, and then the soft start on control is performed. If the temperature of the heater is high at the time of power supply and the electrophotographic apparatus is in a standby state, the voltage applied to the heater is reduced to 20% of the whole.
Perform soft start-on control to turn on all lights after holding for 500 ms. When power supply to the fixing heater is stopped, perform soft stop off control to turn off all lights after holding the applied voltage to the heater at 20% of the whole for 500 ms. 2. The fixing heater temperature control device for an electrophotographic apparatus according to claim 1, wherein the inrush current, harmonic current, and power supply voltage fluctuation at the time of power supply are suppressed. 3. When the power supply to the fixing heater is performed, if the temperature of the heater is low, the voltage applied to the fixing heater is maintained at 60% of the total for 600 ms, and then the soft start-on control is performed. When the power is supplied, when the heater temperature is high and the electrophotographic apparatus is in an operating state, the voltage applied to the heater is reduced to 60% of the whole.
Perform soft start-on control to turn on all lights after holding for 400 ms, and perform soft stop off control to turn off all lights after holding the applied voltage to the heater for 400 ms at 60% of the total when power supply to the fixing heater is stopped. 2. The fixing heater temperature control device for an electrophotographic apparatus according to claim 1, wherein the inrush current, harmonic current, and power supply voltage fluctuation at the time of power supply are suppressed.