JPH10105254A - Heater controller and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To satisfactorily perform heater control in accordance with the rectification system of control voltage by detecting that a voltage value of AC power supply becomes close to zero-cross voltage where positive and negative are switched. SOLUTION: A zero-cross detecting circuit 12 informs an engine controller 126 that power voltage of AC power supply 1 which is inputted via an AC filter 2 becomes voltage below a certain threshold as a pulse signal (ZEROX signal). The controller 126 is a voltage controlling means which controls power supply to a ceramic heater 109c, detects an edge of pulse of the ZEROX signal and turns on or off a triac 4 by phase control or wave number control. By this, even though a low voltage power supply part of a printer is a voltage doubler rectification system, a zero-cross detection signal can be supplied as a pulse signal to the controller 126, being similar to zero-cross detection of a system which uses low voltage power supply of a conventional full wave rectification system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heater control device for controlling a heater such as a ceramic heater for fixing a toner image on transfer paper, and an image having an image forming process using an electrophotographic process having the heater control device. The present invention relates to a forming apparatus.

[0002]

2. Description of the Related Art An image forming apparatus such as a laser printer using an electrophotographic process has a heat fixing device for heat fixing an image. This heat fixing device fixes an unfixed image (toner image) formed on a transfer paper by an image forming means such as an electrophotographic process on the transfer paper, and the type thereof is a heat roller using a halogen heater as a heat source. 2. Description of the Related Art There are known a heat fixing device of a film heating type and a heat fixing device of a film heating type using a ceramic surface heater as a heat source.

Generally, the heater of the above-described thermal fixing device is connected to an AC power supply such as a commercial power supply via a switching control element such as a triac, and power is supplied from the AC power supply. Further, the fixing device is provided with a temperature detecting element, for example, a thermistor temperature sensing element. The temperature detecting element detects the temperature of the fixing device, and the engine controller turns on the switching element based on the detected temperature information. By performing the on / off control, the power supply to the heater is turned on / off, and the temperature of the fixing unit is controlled to a target constant temperature. On / off control of the ceramic heater is performed by wave number control or phase control of an AC power supply. This wave number control or phase control includes a point at which the input AC power supply is switched from positive to negative or from negative to positive, and a signal that notifies that the magnitude of the power supply voltage has fallen below a certain threshold (hereinafter, referred to as This is performed with a trigger based on “zero cross signal”).

Next, a case where the phase of a ceramic heater is controlled by a heater driving and control circuit applied to the above-described image forming apparatus will be described with reference to the drawings. FIG. 8 is a circuit diagram showing a configuration of a conventional heater drive and control circuit.

In FIG. 8, an AC power supply 501 supplies electric power to the entire apparatus. Here, a commercial power supply is supplied to the ceramic heater 503 via an AC filter 502 so that the ceramic heater 503 generates heat. It has become. The power supply to the ceramic heater 503 is turned on and off by a triac 504.

The resistors 505 and 506 are connected to the triac 50
The phototriac coupler 507 is a device for securing a creepage distance between the primary and secondary sides. Photo triac coupler 5
The triac 504 is turned on by energizing the light emitting diode 07.

[0007] The resistor 508 is a resistor for limiting the current of the phototriac coupler 507, and is turned on / off by the transistor 509. Transistor 509
Operate according to an ON signal from the engine controller 511 via the resistor 510.

The diodes 512 and 523 perform full-wave rectification of the current of the AC power supply 501 via the AC filter 502. The rectified voltage is input to the minus terminal of the rectifier bridge 524 via the resistor 513, the zener diode 514, the capacitor 515, and the resistor 516, and forms a current loop with respect to the AC power supply 501. Also, A
The current of the AC power supply 501 is full-wave rectified by the rectifier bridge 524 via the C filter 502, and is smoothed by the capacitor 525. The voltage smoothed here is the low voltage power supply 5
26, and a low voltage is output.

The transistor 517 includes an AC power supply 501.
And the voltage determined by the resistor 513, the Zener diode 514, the capacitor 515, the resistor 516, and the transistor 517. When the voltage of the AC power supply 501 is equal to or lower than the slice voltage Vz determined by the resistor 513, the Zener diode 514, the capacitor 515, the resistor 516, and the transistor 517, the transistor 517 is turned off. Become.

The photocoupler 519 is a device for securing a creepage distance between the primary and secondary sides.
520 is a resistor for limiting the current flowing through the photocoupler 519.

When the AC power supply 501 is lower than the slice voltage Vz, the transistor 517 is turned off and the resistor 520 is turned off.
Becomes low and the engine controller 511
"The AC power supply 501 is lower than the slice voltage Vz,
It is a voltage at which the polarity switches (zero cross) or a voltage value near the zero cross. " Hereinafter, this signal transmitted to the engine controller 511 is referred to as “ZEROX”.
Signal ". This ZEROX signal is a pulse signal whose pulse width changes according to the voltage of the AC power supply.

The engine controller 511 controls the ZE
The pulse width of the ROX signal is detected, and the triac 504 is turned on / off by phase control or wave number control based on the pulse width.
Turn off.

The temperature detecting element 521 is for detecting the temperature of the ceramic heater 503, and is composed of, for example, a thermistor thermosensitive element. The temperature detected by the temperature detecting element 521 is detected as a partial pressure between the resistor 522 and the temperature detecting element 521, and is input to the engine controller 511 as an A / D signal as a TH signal.

The temperature of the ceramic heater 503 is monitored by the engine controller 511 as a TH signal, and is compared with the set temperature of the ceramic heater 503 set inside the engine controller 511 to obtain the power to be supplied to the ceramic heater 503. Is calculated and converted into a phase angle (phase control) or a wave number (wave number control) corresponding to the supplied power, and the engine controller 511 sends an ON signal to the transistor 509 according to the control condition.

In the above circuit, phase control or wave number control is performed by the ZER monitoring by the engine controller 511.
Control is performed using the OX signal as a trigger signal.

[0016]

When a heater as a heat source of a heat fixing device is driven and controlled by phase control, the AC power supply voltage is "below a certain threshold value, and a voltage (zero cross) at which positive / negative is switched or zero. It is necessary to detect that the voltage is near zero crossing (hereinafter referred to as zero crossing in general). However, when the rectification method of the low-voltage power supply unit of the image forming apparatus is the full-wave rectification method, zero crossing can be detected by the conventional control circuit of FIG.
When the rectification method is the voltage doubler rectification method, the conventional control circuit cannot detect a zero cross as a pulse signal. Also, in the case of other detection methods, there is a problem that accuracy is difficult and power consumption increases.

Further, the low-voltage power supply of the image forming apparatus is a universal power supply by switching between voltage doubler rectification and full-wave rectification.
When it is necessary to change the control system of the fixing device between the system and the 200 V system, it is necessary to detect which voltage supply system is used, but this has not been conventionally supported.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a heater control apparatus and an image forming apparatus capable of performing good heater control in accordance with a rectification method of a control voltage. Aim.

[0019]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a power supply means for supplying power to the entire apparatus based on an AC power supply, and a predetermined power supply means for supplying power from the power supply means. A heater that generates heat at a set temperature; a temperature detection unit that detects a heat generation temperature of the heater; and a control voltage generator that generates a control voltage required for power control of the heater by rectifying the voltage of the AC power supply by double voltage rectification. Means, a switching control element disposed between the power supply means and the heater, for turning on / off power supply to the heater;
Detecting that the voltage value of the AC power supply is equal to or less than a predetermined threshold value and is near a zero-cross voltage at which positive / negative switches,
Zero-cross detection means for sending the detection result as a pulse signal, and on / off control of the switching control element triggered by the pulse signal sent from the zero-cross detection means, whereby the temperature is detected by the temperature detection means. Power control means for controlling power supply to the heater by the power supply means so that the heat generation temperature of the heater becomes the predetermined set temperature.

According to another aspect of the present invention, there is provided a power supply unit that supports a plurality of voltage supply systems for supplying power to the entire apparatus based on an AC power supply. A heater that generates heat at a predetermined set temperature in response thereto, temperature detecting means for detecting a heat generation temperature of the heater, and voltage doubling rectification or full-wave rectification of the voltage of the AC power supply in accordance with the voltage supply method, Control voltage generation means for generating a control voltage required for power control of the heater, a switching control element disposed between the power supply means and the heater for turning on / off power supply to the heater, and the AC power supply A zero-crossing detecting means for detecting that the voltage value is equal to or less than a predetermined threshold value and near the zero-crossing voltage at which the sign switches, and transmitting the detection result as a pulse signal; A voltage supply method detecting means for detecting a voltage supply method of the AC power supply, and a plurality of control methods according to the voltage supply method detected by the voltage supply method detection means, and a pulse signal transmitted from the zero-cross detection means Is used as a trigger to perform on / off control of the switching control element, so that the electric power supplied to the heater by the electric power supply unit is adjusted so that the heat generation temperature of the heater detected by the temperature detection unit becomes the predetermined set temperature. Power control means for controlling the supply.

[0021]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

(First Embodiment) First, a first embodiment will be described.

FIG. 1 is a schematic configuration diagram showing an example of an image forming apparatus using an electrophotographic process, and shows a configuration example of a laser printer.

The laser printer shown in FIG. 1 has a laser printer main body (hereinafter simply referred to as “main body”) 101 that can be connected to an external device 131.

In the lower part of the main body 101, there is provided a cassette 102 for storing recording paper S as a transfer material. Inside the main body 101, a cassette presence / absence sensor 103 for detecting the presence or absence of the recording paper S in the cassette 102, and a cassette size sensor 104 for detecting the size of the recording paper S in the cassette 102 (comprising a plurality of micro switches) A paper feed roller 105 for feeding out the recording paper S from the cassette 102 is provided.

A pair of registration rollers 106 for synchronously transporting the recording paper S is provided downstream of the paper supply roller 105. On the downstream of the pair of registration rollers 106, the recording paper S based on the laser beam from the laser scanner 107 is used.
An image forming unit 108 for forming a toner image is provided thereon.

Further, downstream of the image forming unit 108, a fixing unit 109 for thermally fixing the toner image formed on the recording paper S is provided.
Is provided downstream of the fixing device 109, a paper discharge sensor 110 for detecting the conveyance state of the paper discharge unit, a paper discharge roller 111 for discharging the recording paper S, and a stack for recording the recording paper S on which recording is completed. A tray 112 is provided.

The laser scanner unit 107 includes a laser unit 113 that emits a laser beam modulated based on an image signal (image signal VDO) sent from an external device 131, which will be described later, and a laser from the laser unit 113. It comprises a polygon motor 114 for scanning light onto a photosensitive drum 117 to be described later, an imaging lens 115, a return mirror 116, and the like.

The image forming section 108 includes a photosensitive drum 117, a primary charging roller 119, a developing device 120, and a transfer charging roller 121 necessary for a known electrophotographic process.
And a cleaner 122 and the like.

Further, the fixing device 109 includes the fixing film 10.
9a, a pressure roller 109b, a ceramic heater 109c provided inside the fixing film, and a temperature detecting element 109 such as a thermistor for detecting the surface temperature of the ceramic heater.
d.

The main motor 123 applies a driving force to the sheet supply roller 105 via a sheet supply roller clutch 124 and a registration roller pair 106 via a registration roller 125, and further includes a photosensitive drum 117. Each unit of the image forming unit 108, the fixing device 109, the paper discharge roller 1
11 is also given a driving force.

Further, the main body 101 serves as a control device,
Engine controller 126 and video controller 1
27. The engine controller 126 and the video controller 127
8 are connected to each other.

The engine controller 126 controls each electrophotographic process in the laser scanner unit 107, the image forming unit 108, and the fixing unit 109, and controls the conveyance of the recording paper S in the main body 101.

The video controller 127 is connected to an external device 131 such as a personal computer by a general-purpose interface (Centronics, RS232C, etc.) 130. The video controller 127 expands image information sent from the general-purpose interface into bit data, and The bit data is sent to the engine controller 126 as a VDO signal.

Next, a heater drive and control circuit for driving and controlling the nine ceramic heaters 109c in the fixing unit 10 will be described.

FIG. 2 shows a ceramic heater 1 according to the present invention.
FIG. 9 is a circuit diagram showing a circuit configuration of a heater drive and control circuit for performing drive and control of the heater 09c.

As shown in FIG. 2, the heater drive and control circuit according to the present invention comprises an AC power supply 1 for supplying power to the entire printer, and a ceramic heater 109c connected to the AC power supply 1 via an AC filter 2. A temperature detecting element 109d for detecting the temperature of the ceramic heater 109c;
A triac 4, resistors 5 and 6 connected between the AC filter 2 and the ceramic heater 109c, a phototriac coupler 7 connected in series between the resistors 5 and 6, a resistor 8 having one end connected to the phototriac coupler 7,
A transistor 9 having a collector terminal connected to the phototriac coupler 7, a resistor 10 connected to a base terminal of the transistor 9, an engine controller (power control means) 126 having one end of the resistor 10 connected to an ON terminal,
A zero-crossing detection circuit 12 connected to the ZEROX terminal of the engine controller 126 and connected between the AC filter 2 and the ceramic heater 109c, diodes 13, 14 connected to the AC power supply 1 via the AC filter 2, and the diodes 13 , 14, a low-voltage power supply 17, and a resistor 22 connected to the TH terminal of the engine controller 126.

An AC power supply 1 such as a commercial power supply supplies electric power to the ceramic heater 109c through the AC filter 2, thereby causing the ceramic heater 109c to generate heat. The power supply to the ceramic heater 109c is turned on and off by the triac 4.

The resistors 5 and 6 are bias resistors for the triac 4, and the photo triac coupler 7
Is a device for ensuring the creepage distance between the primary and secondary. By energizing the light emitting diode of the phototriac coupler 7, the triac 4 is turned on.

The resistor 8 is a resistor for limiting the current of the phototriac coupler 7 and is turned on / off by the transistor 9. The transistor 9 operates according to an ON signal from the engine controller 126 via the resistor 10.

Diodes 13 and 14 and capacitor 1
5 and 16 rectify and smooth the double voltage of the AC power supply 1 via the AC filter 2. The voltage smoothed here is input to the low-voltage power supply 17, and a low voltage (control voltage) is output. The diodes 13 and 14, the capacitors 15 and 16, and the low-voltage power supply 17 constitute a control voltage generation unit that generates a control voltage required for controlling the ceramic heater 109c.

The zero-cross detection circuit 12 has AC
The AC power supply 1 is input via the filter 2 and notifies the engine controller 126 that the power supply voltage is below a certain threshold value as a pulse signal.
Hereinafter, this signal sent to the engine controller 126 is referred to as a ZEROX signal.

The engine controller 126 is power control means for controlling the power supply to the ceramic heater 109c, detects the edge of the pulse of the ZEROX signal, and turns on / off the triac 4 by phase control or wave number control.
F.

The temperature detecting element 109d is a temperature detecting element for detecting the temperature of the ceramic heater 109c, for example, a thermistor thermosensitive element. This temperature detecting element 10
The temperature detected by 9d is detected as a partial pressure between the resistor 22 and the temperature detecting element 109d, and is input to the engine controller 126 as an A / D signal as a TH signal.

The temperature of the ceramic heater 109c is TH
It is monitored by the engine controller 126 as a signal. The engine controller 126 calculates the electric power to be supplied to the ceramic heater 109c so that the temperature of the ceramic heater 109c becomes a predetermined temperature by comparing the temperature with the set temperature of the ceramic heater 109c set internally. Then, the signal is converted into a phase angle (phase control) or a wave number (wave number control) corresponding to the supplied power, and an ON signal is transmitted to the transistor 9 according to the control condition.

In the above circuit, the phase control or the wave number control is performed by the ZER monitoring by the engine controller 126.
Control is performed using the OX signal as a trigger signal.

Next, a detailed circuit configuration of the zero cross detection circuit 12 will be described. FIG. 3 is a circuit diagram showing a detailed circuit configuration of the zero-cross detection circuit 12.

As shown in FIG. 3, the zero-cross detection circuit 12 includes a diode bridge 31 to which the AC power supply 1 is input via the AC filter 2,
1, a protection resistor 32 connected between the protection resistor 32 and the minus terminal of the diode bridge 31, which forms a loop with respect to the AC power supply 1, a zener diode 34, a capacitor 35, and a resistor 36. The transistor 37 and the resistor 38 connected in parallel to the circuit element forming the loop, the transistor 37 and the resistor 3
A Zener diode 39 and a resistor 40 whose output sides are connected between 8, a capacitor 41 having both ends connected to the Zener diode 39 and the resistor 40, a photocoupler 42 connected to the protection resistor 32, and a photocoupler 42 connected to the photocoupler 42. Switching element 43, this switching element 43
, A resistor 45 connected between the Vref terminal of the constant-voltage power supply 17 and the photocoupler 42, a capacitor 46 connected in parallel to the photocoupler 42, and a connection between the engine controller 126 and the photocoupler 42. Is connected to the resistor 47.

The AC power supply 1 is input to the diode bridge 31 via the AC filter 2. The AC signal full-wave rectified by the diode bridge 31 passes through a resistor 33, a Zener diode 34, a capacitor 35, and a resistor 36 via a protection resistor 32, and passes through a diode bridge 3
1 is input to the minus terminal of the AC power supply 1 to form a current loop with respect to the AC power supply 1.

The voltage of the AC power supply 1 and the voltage determined by the resistors 32 and 33, the Zener diode 34, the capacitor 35 and the resistor 36 are input to the transistor 37. Here, when the voltage of the AC power supply 1 is equal to or lower than the slice voltage Vz determined by the resistors 32 and 33, the Zener diode 34, the capacitor 35, the resistor 36, and the transistor 37, the transistor 37 is turned off, and is equal to or higher than the slice voltage Vz. If so, it is turned on.

The output of the transistor 37 is clamped by the Zener voltage of the Zener diode 39. The resistor 38 includes a transistor 37 and a Zener diode 39.
This is a resistor that limits the current supplied to. Transistor 3
7 is output to a switching element 43 (for example, a MOS
FET, bipolar transistor, IGBT). The switching element 43 in the figure is a MOSFET.
And Hereinafter, the switching element 43 is referred to as an FET 43.

The photocoupler 42 is a device for ensuring a creepage distance between the primary and secondary sides.
Reference numerals 4 and 45 denote resistors for limiting the current flowing through the photocoupler 42.

In the above-described zero-crossing detection circuit 12, when the AC power supply 1 is at a zero-crossing that is equal to or lower than the slice voltage Vz, the transistor 37 is turned off and the FET 43 is turned off.
Is turned on, the output of the photocoupler becomes Low, and the engine controller 126 receives the signal "The AC power supply 1 is equal to or lower than the slice voltage Vz and the voltage at which the polarity is switched (zero crossing) or near the zero crossing via the capacitor 46 and the resistor 47. It is a voltage value. "

The switching speed of the transistor 37 is controlled by the resistors 33 and 36 and the capacitor 35, and the switching speed of the FET 43 is controlled by the resistor 3
The switching speed of the output of the photocoupler 42 is controlled by the
Limited by 6.

FIG. 4 is a diagram for explaining the ZEROX signal notified by the zero-cross detection circuit 12 as described above.

The ZEROX signal notified to the engine controller 126 by the zero-cross detection circuit 12 becomes like the ZEROX signal 51 shown in FIG. The engine controller 126 changes the ZEROX signal from High to Low.
Is detected, and it is recognized that the AC power supply voltage is equal to or lower than the slice voltage Vz.

The AC power supply voltage 50 shown in FIG.
At the time of V, the ZEROX signal 51 has an extremely small peak as shown by 51a in FIG. The magnitude of this peak can be controlled by the resistor 45 and the capacitor 46 of the zero-crossing detection circuit 12, and can be sufficiently controlled to a level below which the engine controller 126 can determine Low.

By adopting the configuration of the zero-cross detection circuit 12 as described above, even if the low-voltage power supply unit of the printer is of the double-voltage rectification type, the zero-cross detection of the system using the conventional full-wave rectification type low-voltage power supply can be performed. Similarly, a zero-cross detection signal can be notified to the engine controller 126 as a pulse signal.

Also, by employing the above configuration, the switching element (FET 43) is turned on only when the AC power supply voltage is equal to or lower than a certain threshold, and current is supplied from the AC power supply 1 to the photocoupler 42. The power can be reduced.

(Second Embodiment) Next, a second embodiment will be described.

FIG. 5 is a circuit diagram showing a circuit configuration of a heater drive and control circuit for driving and controlling the ceramic heater 109c in the second embodiment. In the following description, description of the same points as those in the first embodiment will be omitted.

The circuit according to the present embodiment corresponds to a plurality of AC power supply voltage supply systems. As shown in FIG.
A bridge diode 55 is arranged in a portion corresponding to 3, 14, and this bridge diode 55
A changeover switch 56 is arranged between the capacitors 15 and 16. Further, this circuit has a voltage detection circuit 58 for detecting a voltage supply method of the AC power supply 1.

In the circuit shown in FIG. 5, the AC power supply 1 is input to the bridge diode 55 via the AC filter 2. In this circuit, when the changeover switch 56 is on, the voltage doubler rectification is performed, and when the changeover switch 56 is off, full-wave rectification is performed. This changeover switch 56 may be either manual or automatic. When the AC power supply voltage is 100 V, the switch 56 is turned on.
When the changeover switch 56 is turned off, the low-voltage power supply 5
7 can be a universal power supply.

The zero cross detection circuit 12 has the same circuit configuration as that described in the first embodiment. The zero-cross detection circuit 12 sends the ZEROX signal to the engine controller 126 without being affected by the rectification method of the low-voltage power supply unit.

In the control of the ceramic heater 109c, for example, a 100 V system and 2
When it is necessary to switch the control method (phase control / wave number control) in the 00V system, the voltage detection circuit 58 uses the AC power supply 1
Of the voltage supply system is 100 V system or 200 V system, and the result is sent to the engine controller 126 as V
It is sent out as a SENS signal. The engine controller 126 detects the AC power supply voltage based on the VSENS signal and determines a heater control method. For example, 10
In the case of a 0 V system, the phase control is performed, and in the case of a 200 V system, the wave number control or the reverse setting is performed.

FIG. 6 is a circuit diagram showing a detailed circuit configuration of voltage detection circuit 58.

In the voltage detection circuit 58 shown in FIG.
Neu is connected to the diode 61 via the AC filter 2.
The AC signal on the side of the tral terminal, that is, the switch 56 is input and half-wave rectified. The half-wave rectified signal is input to the minus terminal of the diode bridge 55 via the resistor 62, the capacitor 63, and the resistor 64, and forms a loop with respect to the AC power supply 1.

The voltage of the AC power supply 1 and the voltage determined by the resistor 62, the capacitor 63, and the resistor 64 are input to the transistor 67. If the voltage of the AC power supply 1 is equal to or lower than the positive potential or the slice voltage Vr determined by the resistor 62, the capacitor 63, the resistor 64, and the transistor 67, the transistor 67 is turned off. .

The photocoupler 66 is a device for ensuring a creepage distance between the primary and secondary sides.
Is a resistor for limiting the current flowing through the photocoupler 66. Here, the output of the photocoupler 66 is
Is sent to the engine controller 126 as a VSENS signal.

FIG. 7 is a diagram for explaining the VSENS signal transmitted by the voltage detection circuit 58.

When the voltage supply system of the AC power supply 1 is a 100 V system, since the changeover switch 56 is turned on, voltage doubler rectification is performed, the capacitor 16 is charged with the peak voltage of the AC power supply, and the transistor 67 is always turned on. Therefore, VS
The ENS signal is always sent to the engine controller 126 as High.

When the voltage supply system of the AC power supply 1 is a 200 V system, since the changeover switch 56 is off, full-wave rectification is performed, and an AC signal is input to the transistor 67. The transistor 67 is turned off when the AC power supply voltage is equal to or lower than the slice voltage Vr or at a positive potential. Therefore, VSENS
The signal is a pulse signal of an AC power supply cycle as shown in FIG.

As described above, the voltage detection circuit 58 can detect the voltage supply system of the AC power supply 1 by the difference in the rectification system.

The engine controller 126 has a VSEN
If the S signal is High, it is recognized as a 100 V system, and if it is a pulse signal, it is recognized as a 200 V system, and the control method of the heater is determined. For example, phase control is performed for a 100 V system, and wave number control is performed for a 200 V system, or vice versa.

By adopting the above configuration, even if it is necessary to switch the heater control between the 100 V system and the 200 V system in the universal power supply having the double voltage rectification system, the heater control suitable for each voltage supply system is performed. be able to.

The present invention is not limited to the above embodiment, but can be variously modified.

For example, in the universal power supply system shown in FIG. 5 of the second embodiment, if it is known that the circuit board is used exclusively for the 200 V system at the time of shipment of the circuit board or at a timing corresponding thereto, FIG. Voltage detection circuit 5 shown
8 from the diode 61 to the photocoupler 66 are not mounted, the resistor 68 is short-circuited, and the VSENS signal of the engine controller 126 is detected.
In the case of the V system, the cost can be further reduced by setting High as the judgment setting.

[0078]

As described in detail above, according to the present invention,
Even when the double voltage rectification method is used, the fact that the AC power supply is at a zero crossing is reported as a pulse signal every half cycle of the AC power supply, so the same heater control as when using the full-wave rectification method is used. can do.

Even when a universal power supply capable of inputting a plurality of AC power supplies by a plurality of rectification methods is used, for example, each voltage supply method is detected by a difference in the rectification method, and the detection result is reported. This makes it possible to optimally control the heater in each voltage supply method.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a laser printer as an image forming apparatus according to the present invention.

FIG. 2 is a circuit configuration diagram of a heater drive and control circuit according to the present invention.

FIG. 3 is a circuit diagram showing a detailed circuit configuration of a zero-cross detection circuit 12 according to the present invention.

FIG. 4 is a diagram for explaining a ZEROX signal notified by a zero-cross detection circuit 12 according to the present invention.

FIG. 5 illustrates a heater drive according to a second embodiment of the present invention;
FIG. 3 is a circuit configuration diagram of a control circuit.

FIG. 6 is a circuit diagram illustrating a detailed circuit configuration of a voltage detection circuit 58 according to the second embodiment of the present invention.

FIG. 7 shows VSENS sent by the voltage detection circuit 58;
It is a figure explaining a signal.

FIG. 8 is a circuit diagram showing a configuration of a conventional heater drive and control circuit.

[Explanation of symbols]

 Reference Signs List 101 Laser printer main body 109 Thermal fixing device 109c Ceramic heater 109d Temperature detection element 126 Engine controller 12 Zero cross detection circuit 58 Voltage detection circuit

Claims (6)

[Claims] 1. A power supply means for supplying power to the entire apparatus based on an AC power supply, a heater which generates heat at a predetermined temperature in accordance with power supply from the power supply means, and a heat generation temperature of the heater is detected. Temperature detecting means, a control voltage generating means for generating a control voltage required for power control of the heater by doubling voltage rectification of the voltage of the AC power supply, and a control voltage generating means disposed between the power supply means and the heater. A switching control element for turning on / off the power supply to the heater; and detecting that a voltage value of the AC power supply is equal to or less than a predetermined threshold value and is near a zero-cross voltage at which the polarity switches.
A zero-cross detecting means for transmitting the detection result as a pulse signal; and a pulse signal transmitted from the zero-cross detecting means as a trigger to perform on / off control of the switching control element. A heater control unit for controlling power supply to the heater by the power supply unit so that the heat generation temperature of the heater becomes the predetermined set temperature. 2. A power supply means corresponding to a plurality of voltage supply systems for supplying power to the entire apparatus based on an AC power supply, and a heater which generates heat at a predetermined set temperature in accordance with power supply from the power supply means. A temperature detecting means for detecting a heat generation temperature of the heater; and a voltage doubler rectification or full-wave rectification of the voltage of the AC power supply according to a voltage supply method, thereby generating a control voltage required for power control of the heater. A control voltage generation unit that is disposed between the power supply unit and the heater, and a switching control element that turns on / off power supply to the heater; and a voltage value of the AC power supply is equal to or less than a predetermined threshold value; Detects when it is near the zero crossing voltage where the sign switches,
Zero-cross detection means for sending the detection result as a pulse signal; voltage supply method detection means for detecting the voltage supply method of the AC power supply; and a plurality of controls corresponding to the voltage supply method detected by the voltage supply method detection means. And controlling the on / off control of the switching control element by using a pulse signal sent from the zero-cross detecting means as a trigger, so that the heat generation temperature of the heater detected by the temperature detecting means is set to the predetermined setting. A heater control device for controlling power supply to the heater by the power supply unit so that the temperature becomes a temperature. 3. The power control unit controls the power supply by phase control or wave number control as a plurality of control systems according to the voltage supply system detected by the voltage supply system detection unit. The heater control device according to claim 2. 4. The voltage supply method detection means detects the voltage supply method of the AC power supply based on a difference in a rectification method of the control voltage generated by the control voltage generation means. The heater control device according to any one of the preceding claims. 5. An image forming apparatus for heating and fixing an unfixed toner image formed on a transfer material, a power supply means for supplying power to the entire apparatus based on an AC power supply, and a power supply from the power supply means. A heater that generates heat at a predetermined set temperature in accordance with the supply and heats and fixes the unfixed toner image on the transfer paper; a temperature detection unit that detects a heating temperature of the heater; A control voltage generating means for generating a control voltage necessary for power control of the heater; and a switching control element disposed between the power supply means and the heater, for turning on / off power supply to the heater. And detecting that the voltage value of the AC power supply is equal to or less than a predetermined threshold value and is near a zero-cross voltage at which the sign switches.
Zero-cross detection means for transmitting the detection result as a pulse signal; and on / off control of the switching control element triggered by the pulse signal transmitted from the zero-cross detection means. An image forming apparatus comprising: a power control unit configured to control power supply to the heater by the power supply unit so that a heat generation temperature of the heater becomes the predetermined set temperature. 6. An image forming apparatus for heating and fixing an unfixed toner image formed on a transfer material, comprising: a power supply unit corresponding to a plurality of voltage supply systems for supplying power to the entire apparatus based on an AC power supply; A heater that generates heat at a predetermined set temperature in accordance with power supply from the power supply unit and heats and fixes the unfixed toner image on transfer paper; a temperature detection unit that detects a heat generation temperature of the heater; A control voltage generation unit that generates a control voltage necessary for power control of the heater by performing voltage doubler rectification or full-wave rectification on the voltage of the AC power supply according to the voltage supply method, and the power supply unit and the heater A switching control element disposed between the switching control element for turning on / off the power supply to the heater; and a vicinity of a zero-cross voltage at which a voltage value of the AC power supply is equal to or less than a predetermined threshold value and which switches between positive and negative. Is detected,
Zero-cross detection means for sending the detection result as a pulse signal; voltage supply method detection means for detecting the voltage supply method of the AC power supply; and a plurality of controls corresponding to the voltage supply method detected by the voltage supply method detection means. And controlling the on / off control of the switching control element by using a pulse signal sent from the zero-cross detecting means as a trigger, so that the heat generation temperature of the heater detected by the temperature detecting means is set to the predetermined setting. An image forming apparatus comprising: a power control unit configured to control power supply to the heater by the power supply unit so that the temperature becomes equal to the temperature.