JPH11249485A - Temperature controller for fixing heater of electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the higher harmonic current by holding the conduction of electricity to heater for a fixed time at a designated phase angle, next holding it for a fixed time at a little larger phase angle than the designated phase angle, and repeating such operation several times and then performing soft start on-control when the temperature of the heater is low. SOLUTION: When the temperature of the fixing heater is low, the heater is started up in a state where the 'designated phase angle' being the electricity conduction amount of the fixing heater is set to the 'designated phase angle: a<o> ' near to 0<o> first, and the conduction is held for a fixed time (T). Next, it is started up at the 'designated phase angle: b<o> ' not much larger than the 'designated phase angle: a<o> ', and the conduction is held for a fixed time (T). Then, the designated phase angle is made larger and larger. After such operation is repeated several times, the soft start on- control that voltage equivalent to all the impressed voltage is impressed on the heater is performed. When the temperature of the heater is high, the soft start on-control is performed after making the number of changing times of the designated phase angle smaller than the case that the temperature of the heater is low and shortening the holding time of electricity conduction.

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. FIG. 6 shows the simplest circuit configuration of such a capacitor input type rectifier circuit, and FIG. 7 shows each waveform of each part of the circuit. FIG. 6
As shown in FIG. 2, this circuit has two diodes 13, 13 and an electrolytic capacitor 14 connected in parallel to a load 15, and the load 15 has an alternating current (IAC) from an AC power supply 9.
Is supplied. Only when the instantaneous value of the input voltage (VAC) becomes higher than the voltage (VDC) of the electrolytic capacitor 14 as shown in each waveform of FIG.
Is supplied to the load 15. However, the supplied alternating current (IAC) 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, the harmonic current is regulated by the harmonic current regulation (IEC1000-3-2) which is an international standard. Therefore, it is desired to suppress and reduce such harmonic current.

In order to suppress and reduce the harmonic current, a method is conceivable in which the AC voltage control is turned ON / OFF and then the input current waveform is changed to a sine wave. A large current (rush current) flows to the load, 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. For this reason, when the power switch is turned on, an inrush current flows rapidly to the heater (load), which may cause a failure of the heater and electric parts (switch, relay, etc.) and a power supply trouble.
The fluctuation of the power supply voltage also increases due to the inrush current. Since the power supply voltage fluctuation is regulated by the international standard of power supply voltage fluctuation regulation (IEC1000-3-3), measures to suppress the power supply voltage fluctuation are also desired.

FIG. 8 shows a fixing heater temperature control device described in Japanese Patent Application Laid-Open No. 3-113519, as a countermeasure against this kind of harmonic 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 temperature control device 1 includes triacs 4 and 4 arranged in parallel with a control circuit 2 and a zero-cross circuit 3. In the figure, the fixing heater 5 is connected in series with the triacs 4, 4 and the choke coil 6, and each gate terminal of the triacs 4, 4 is 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 from the control circuit 2
Is output 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.

[0006]

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, to reduce harmonic currents, and to suppress inrush current and power supply voltage fluctuations in an electrophotographic apparatus. It is an object of the present invention to provide a fixing heater temperature control device that can perform the fixing.

[0008]

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 a temperature detecting circuit for detecting a heater temperature. 2. A fixing heater temperature control device for an electrophotographic apparatus, comprising: 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. When power is supplied to the heater, if the temperature of the heater is low, energization of the heater is held at a specified phase angle for a fixed time, and then held at a phase angle slightly larger than the specified phase angle for a fixed time,
After repeating this several times, soft start-on control is performed to turn on all lamps. When the temperature of the heater is high when this power is supplied, the specified phase angle for energizing the heater is set to the specified phase angle compared to when the temperature of the heater is low. It is characterized by suppressing the inrush current, harmonic current and power supply voltage fluctuation at the time of power supply by performing soft start on control to reduce the number of changes in the angle and shorten the holding time and then turn on all lights after turning on. is there.

According to a second aspect of the present invention, in the first aspect of the present invention, when the power supply to the heater is stopped, the power supply to the heater is maintained at a specified phase angle for a certain period of time. Hold for a certain period of time at a phase angle slightly smaller than this, repeat this several times, and then perform soft stop off control to turn off the heater completely, thereby suppressing inrush current, harmonic current and power supply voltage fluctuation at the time of power supply It is characterized by the following. When supplying power to the heater, if the temperature of the heater is low, energize the heater by 30 ° or 60 °.
200 ms in 6 steps of °, 90 °, 120 °, 150 °, 180 °
The power is changed every time, and then the soft start-on control for turning on the heater is performed. If the temperature of the heater is high when the power is supplied, the power supply to the heater is switched to 45 °, 90 °, 135 °, 1 °.
It is characterized by suppressing the rush current, harmonic current and power supply voltage fluctuation at the time of power supply by performing soft start on control that changes the heater every 100 ms in four steps of 80 ° and then turns on the heater all the time. It is.

According to a third aspect of the present invention, in the first aspect of the present invention, when power is supplied to the heater and the temperature of the heater is low, the power supply to the heater is switched to 30 °, 60 °, and 90 °. ,
The temperature is changed every 200 ms in six steps of 120 °, 150 °, and 180 °, and then soft start-on control is performed to turn on all the fixing heaters. 45 °, 90 °, 135 °, 180 °
After changing every 100 ms in four steps, the soft start-on control is performed to turn on the heater all the time, thereby suppressing rush current, harmonic current and power supply voltage fluctuation at the time of power supply. .

According to a fourth aspect of the present invention, in the first aspect of the present invention, when power is supplied to the heater and the temperature of the heater is low, the power supply to the heater is switched to 30 °, 60 °, and 90 °. ,
The temperature is changed every 200 ms in six steps of 120 °, 150 °, and 180 °, and then soft start-on control is performed to turn on all heaters. If the temperature of the heaters is high when this power is supplied, energize the heaters. After changing every 100 ms in four steps of 45 °, 90 °, 135 °, and 180 °, soft start-on control is performed to turn on the heater all the time. When the power supply to the heater is stopped, the heater is energized to 135 ° , 90 °, 45
After changing the temperature every 4 ms in 4 steps of ° and 0 °, the rush current, harmonic current and power supply voltage fluctuation at the time of power supply are suppressed by performing soft stop off control to turn off all heaters. It is assumed that.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the first embodiment of the present invention shown in the drawings, the same parts as those in the conventional example are denoted by the same reference numerals, and different parts will be mainly described. FIG. 1 is a circuit diagram showing an example of 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. The control circuit 2 is connected to a switch 12, and when the switch 12 is turned on, power is supplied to the fixing heater 5 (voltage is supplied). As the switch 12, a semiconductor element capable of high-speed switching such as a transistor or an SCR is used.

The energization (voltage supply) to the fixing heater in the fixing heater temperature control device of the present invention having the above-described configuration is performed as follows. FIG. 2 shows details of the soft start-on control in the first embodiment of the present invention.
A description will be given with reference to the voltage waveforms of FIGS. Here, the horizontal axis X in the figure indicates the voltage application time, and the vertical axis Y indicates the amount of current (applied 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.

FIG. 2A shows an example of a voltage waveform applied to the fixing heater 5 (see FIG. 1) when power is supplied. That is, as described above, when an electrophotographic apparatus such as a copying machine is used (when the power switch is OFF), the temperature of the fixing heater is low (about 0 to 150 ° C.), and the resistance itself of the heater is also low. For this reason, when the power supply is turned on, an inrush current flows rapidly to the heater 5 (load) having a low resistance value, which causes a failure of an electric component or a power supply trouble. Therefore, in the first embodiment, as shown in FIG. 2A, when power is supplied to the fixing heater 5 when the power is turned on (when the temperature of the fixing heater is low), the amount of power supplied to the fixing heater Is almost 0 ° at the beginning of “specified phase angle” (firing angle)
At the designated phase angle: a °, which is close to the above, and the designated phase angle is held for a certain period of time (power-on time: T). In the case of this example, the predetermined time (T) is 10 to 500 m.
It is set to about s.

Next, at the "designated phase angle: b °" which is not much larger than the first "designated phase angle: a °", the power supply is maintained for a predetermined time (T) similarly to the start-up. Then, as shown in FIG. 2A, the designated phase angle (a ° <b ° <
c ° <d ° <e °...) is gradually increased, and after repeating this several times, as shown in the same waveform diagram, a voltage (designated phase) corresponding to the entire applied voltage (100%) is applied to the heater. The soft start-on control for applying (energizing) the angle “180 °”) is performed. At this time, since the heater is fully lit, the heater generates heat almost completely. Specifically, this repetition is about 2 to 20 times, but in this example, the designated phase angle is started from “a °” and “a ° to e”.
° ”five times.

As shown in FIG. 2B, when the fixing heater reaches a predetermined fixing temperature and is in a copy-enabled state (standby state), that is, when the heater temperature is high (150
In the case of (−200 ° C.), the “designated phase angle” (firing angle), which is the amount of power to the fixing heater, is similarly initially low (“f °, g °, h ° in the figure”). And gradually increase this "designated phase angle" for a certain period of time (power-on time:
Hold for T ') and repeat. After the elapse of a certain time, all applied voltages (100
%) To perform soft start-on control to turn on the heater completely (complete heat generation). In this case, however, as shown in FIG. 2 (B), the first startup “designated phase angle: f °” satisfies a ° <f °, and a fixed time (power-on time: T ′) is a fixing heater. The time is set to be shorter (T '<T) than when the temperature is low. The predetermined time (T ') is specifically set to 0 to 400 ms, and the number of repetitions is set to about 1 to 10 times. This is because the influence of the rush current is considered to be low when the temperature of the fixing heater is high.

As described above, by starting the "designated phase angle" (ignition angle) at a low "designated phase angle" and performing the soft start-on control repeatedly while maintaining this for a fixed time, the heater ( Abruptly flowing inrush current (overcurrent) to the load) can be suppressed. In this embodiment, the ON control is performed after the fixing heater is fully turned on, and the OFF control is performed after the fixing heater is completely turned off (ON / OF).
F control) is performed. As a result, the voltage waveform output as shown in FIG. 2 (B) is substantially a sine wave, so that this voltage (current) does not include a harmonic current. Note that this ON / OFF control is actually performed by the temperature sensor 8.
Based on the temperature detected by (see FIG. 1), power is supplied to and stopped from the fixing heater 5 by the temperature detection circuit 10.

FIG. 3 shows a second embodiment of the present invention, in which after performing the above-described soft start on control, soft stop off control which is control when power supply is turned off is performed. This soft stop-off control will be described with reference to an example of a voltage waveform shown in FIG. That is, as shown in FIG. 3, the fixing heater 5 (see FIG. 1)
From the voltage (designated phase angle “180 °”) corresponding to the total applied voltage, the “designated phase angle” that is the amount of current supplied to the power supply is changed from the voltage (designated phase angle “180 °”) to the “designated phase angle” that is not much smaller than the designated phase angle for a certain period of time (T ') Hold (energize). This “designated phase angle” is gradually reduced after a lapse of a predetermined time (T ′), and is repeated (about 1 to 10 times). After a lapse of a predetermined time, the designated phase angle is set to “0 °” to turn off all the heaters (stop heating). Specifically, the designated phase angles (i °, j °, k ° in the figure) are gradually reduced from “180 °” as shown in FIG. Is stopped.

As described above, the soft stop-off control gradually reduces the designated phase angle when the power is turned off, and suppresses the fluctuation of the power supply voltage due to a sudden voltage drop or the like by repeating the phase angle while holding it for a certain period of time. can do. In the second embodiment, the soft start on control and the soft stop off control described above are performed to suppress the rush current and the power supply voltage fluctuation, thereby avoiding the failure of the electric parts and the electric trouble. .

Next, FIGS. 4A and 4B show a third embodiment of the present invention. As shown in FIG. 4A, in the third embodiment, when the temperature of the fixing heater in the first embodiment is low, the “designated phase angle” (a
°, b °, c °, d °, e °...)
It is set to increase in six steps of 60 °, 90 °, 120 °, 150 °, and 180 °. The predetermined time (T) at this time is also set to 200 ms. Then, as shown in FIG. 4B, the “designated phase angle” (f °, g °, h ° in the figure) when the temperature of the fixing heater is high is specifically 45 °,
90 °, 135 ° and the constant time (T ') at this time is also 100ms
Is set to The operation and effect are the same as those of the first embodiment, and thus the description is omitted.

Next, FIG. 5 shows a fourth embodiment of the present invention. As shown in the figure, in the fourth embodiment, the designated phase angles (i °, j °, k ° in the figure) of the soft stop off control when the power supply is turned off are specifically described. It is set at 135 °, 90 °, and 45 °. The predetermined time (T ') at this time is also set to 100 ms. The operation and effect are the same as those of the first embodiment, and thus the description is omitted.

As described above, according to the fixing heater temperature controller 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.

[0023]

As described above, the present invention provides a toner fixing heater, an AC power supply for supplying power to the heater, a temperature detecting circuit for detecting the heater temperature, and an application of the heater temperature to the heater. 2. The heater according to claim 1, further comprising: an arithmetic circuit for determining a voltage; and a control circuit for controlling power supply to the heater. If the temperature is low, the power to the heater is held at the specified phase angle for a certain period of time, then at a phase angle slightly larger than the specified phase angle for a certain period of time, and after repeating this several times, When the temperature of the heater is high at the time of power supply, the designated phase angle for energizing the heater is set to a smaller number of times of changing the designated phase angle than when the temperature of the heater is low. Since the soft start on control even totally turned after a short retention time, suppressing the inrush current, by performing the soft-start on the control, it is possible to suppress the power supply voltage fluctuations. 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.

According to a second aspect of the present invention, in the first aspect of the present invention, when the power supply to the heater is stopped, the power supply to the heater is maintained at a specified phase angle for a certain period of time. It is held for a certain period of time at a phase angle slightly smaller than this, and this is repeated several times.After that, soft stop off control is performed to turn off all heaters.
By performing the soft stop-off control, power supply voltage fluctuation 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 present invention, when power is supplied to the heater and the temperature of the heater is low, the power supply to the heater is switched to 30 °, 60 °, and 90 °. ,
The temperature is changed every 200 ms in six steps of 120 °, 150 °, and 180 °, and then soft start-on control is performed to turn on all heaters. If the temperature of the heaters is high when this power is supplied, energize the heaters. After changing every 100 ms in four steps of 45 °, 90 °, 135 °, and 180 °, the soft start-on control is performed to turn on the heater all the time. Therefore, the rush current is suppressed, and this soft start-on control is performed. ,
Power supply voltage fluctuations 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).
/ OFF control), there is an effect that harmonic current can be suppressed.

According to a fourth aspect of the present invention, in the first aspect of the present invention, when power is supplied to the heater and the temperature of the heater is low, the power supply to the heater is switched to 30 °, 60 °, and 90 °. ,
The temperature is changed every 200 ms in six steps of 120 °, 150 °, and 180 °, and then soft start-on control is performed to turn on all heaters. If the temperature of the heaters is high when this power is supplied, energize the heaters. After changing every 100 ms in four steps of 45 °, 90 °, 135 °, and 180 °, soft start-on control is performed to turn on the heater all the time. When the power supply to the heater is stopped, the heater is energized to 135 ° , 90 °, 45
After changing the temperature every 100 ms in four steps of 0 ° and 0 °, soft stop-off control is performed to turn off all heaters. Therefore, inrush current is suppressed, and power supply voltage fluctuation is suppressed by performing the soft start-on control. be able to. 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.

[Brief description of the drawings]

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

FIGS. 2A and 2B show voltage waveforms of soft start on control according to the first embodiment, wherein FIG. 2A shows a waveform at the time of power-on and FIG.

FIG. 3 is a diagram showing a voltage waveform of soft stop off control according to the second embodiment.

FIG. 4 is a diagram showing a voltage waveform of soft start-on control in the voltage waveform of the third embodiment.

FIG. 5 is a diagram showing a voltage waveform in soft stop off control of the fourth embodiment.

FIG. 6 is a circuit diagram showing a configuration of a first example of a conventional fixing heater temperature control device of the same type as the present invention.

FIG. 7 is a waveform diagram showing waveforms at various points in the circuit diagram.

FIG. 8 is a circuit diagram showing a configuration of a second example of a conventional fixing heater temperature controller.

[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 (4)

[Claims] 1. A toner fixing heater, 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 power supply for the heater In a fixing heater temperature control device of an electrophotographic apparatus having a control circuit for controlling supply, when power is supplied to the heater, if the temperature of the heater is low, energization of the heater is maintained at a specified phase angle for a predetermined time. Then, hold for a certain period of time at a phase angle slightly larger than the designated phase angle, repeat this several times, and then perform soft start on control to turn on all lights. Is a soft start-on system in which the specified phase angle for energizing the heater is set to less than the number of changes in the specified phase angle compared to when the temperature of the heater is low, the holding time is shortened, and then all the lights are turned on. Controlling a rush current, a harmonic current, and a power supply voltage fluctuation at the time of power supply by controlling the fixing heater temperature control device for an electrophotographic apparatus. 2. When power supply to the heater is stopped, energization of the heater is held at a specified phase angle for a certain period of time, and then at a phase angle slightly smaller than the specified phase angle for a certain period of time. 2. A fixing device for an electrophotographic apparatus according to claim 1, wherein a rush current, a harmonic current, and a power supply voltage fluctuation at the time of power supply are suppressed by performing soft stop-off control for turning off the heater all times. Heater temperature control device. 3. When power is supplied to the heater, if the temperature of the heater is low, the power to the heater is turned off by 30 °, 60 °, 90 °, 12 °.
The temperature is changed every 200 ms in six steps of 0 °, 150 °, and 180 °, and then soft start-on control is performed to turn on all heaters. If the temperature of the heaters is high when this power is supplied, energize the heaters. Inrush current, harmonic current, and power supply voltage fluctuation at the time of power supply by performing a soft start-on control that changes the heater every time in four steps of 45 °, 90 °, 135 °, and 180 ° every 100ms, and then turns on the heater. 2. The fixing heater temperature control device for an electrophotographic apparatus according to claim 1, wherein the temperature of the fixing heater is controlled. 4. When power is supplied to the heater, if the temperature of the heater is low, the power supply to the heater is turned off by 30 °, 60 °, 90 °, and 12 °.
The temperature is changed every 200 ms in six steps of 0 °, 150 °, and 180 °, and then soft start-on control is performed to turn on all heaters. If the temperature of the heaters is high when this power is supplied, energize the heaters. After changing every 100 ms in four steps of 45 °, 90 °, 135 °, and 180 °, soft start-on control is performed to turn on the heater all the time. When the power supply to the heater is stopped, the heater is energized to 135 ° , 90 °, 45
After changing the temperature every 4 ms in 4 steps of ° and 0 °, the rush current, harmonic current and power supply voltage fluctuation at the time of power supply are suppressed by performing soft stop off control to turn off all heaters. 2. A fixing heater temperature control device for an electrophotographic apparatus according to claim 1, wherein: