JP2000293059A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device with reduced energy being free from the occurrence of a failure on the operation (such as deterioration of image quality or deviation of sequence operation of a drive system). SOLUTION: This image forming device is, letting power calculated on a controlling part 4 by normally sensing current/voltage of a scanner part and the power source part by a scanner part power sense signal: B and the power source part power sense signal: C. Then, the device is, letting the set value of the maximum power from an IH inverter 23 of the fixing part 2 to an induction heating coil 24 of the fixing part 2 so as to be changed based thereon (according to inverter control signal: A).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile, and more particularly, to an image forming apparatus having an induction heating type fixing device.

[0002]

2. Description of the Related Art As a fixing device in an image forming apparatus such as a copying machine, a printer, a facsimile, etc., there are provided a fixing roller for heating a sheet carrying an unfixed toner image, and a pressure roller pressed against the heating roller. A fixing device of a heat roller type for fixing a non-fixed toner image on a sheet by heat and pressure by nipping and conveying the sheet between a fixing roller and a pressure roller is well known.

Conventionally, in a fixing device of a heat roller type,
A halogen lamp or the like as a heater is provided inside the fixing roller, and the halogen lamp heats the inside of the fixing roller.

However, such a heating method using a heater takes a long time until the fixing roller is heated to a required temperature, and the loss of the heater itself is large. There is a demand for a fixing device with good rise time.

Under such circumstances, the induction heating type fixing device can instantly heat the fixing roller by the eddy current caused by the electromagnetic wave, so that the start-up time can be shortened remarkably. For this reason, the induction heating type fixing device requires the preheating that was required in the conventional halogen lamp method (the temperature of the fixing unit is maintained even during non-image formation because the temperature of the fixing unit quickly rises to a predetermined temperature when reused). Is unnecessary, unnecessary power is not required, and the heating efficiency is excellent.

In an image forming apparatus having an induction heating type fixing device, usually, the temperature of the fixing roller is detected by a thermistor, and an induction heating inverter (so that the fixing roller reaches a target temperature, is operated in accordance with the output voltage thereof). ) Is working. In such fixing control, the maximum power that can be supplied as a device is supplied to the fixing device in order to make the rising time of the fixing roller as short as possible at the start of the image forming operation.

[0007]

Generally, the maximum power of an image forming apparatus is set to be the maximum as a device by combining the power consumption of the fixing device and the power consumption of the other systems. In the case of the image forming apparatus designed in this way, when the power is turned on, the power consumed by the devices other than the fixing device is small, so that the power consumed by the device does not become the maximum power. On the other hand, at the time of image formation, for example, at the time of a copy operation in a copying machine, an exposure lamp for reading a document is turned on, and a drive motor for paper feeding is operated. Is turned on, the power supply to the exposure lamp and the drive system becomes insufficient, and as a result, their operation becomes unstable, affecting the image quality when reading the original and controlling the paper transport sequence control. There were problems such as going crazy.

Further, in the case of an image forming apparatus in which the input power to the induction heating fixing device is set to be large, the rise time can be shortened, but the power consumption other than the fixing device accompanying the image forming operation, such as during a copying operation, greatly increases. However, there is a problem that the maximum power of the device is exceeded.

The present invention solves the above-mentioned problems in a conventional image forming apparatus provided with an induction heating type fixing device, and provides an energy-saving image forming apparatus which does not cause deterioration of image quality or trouble in sequence operation of a drive system. The task is to

[0010]

According to the present invention, there is provided an image forming apparatus including an induction heating type fixing device, wherein the maximum power supplied to the fixing device is continuously varied. .

According to another aspect of the present invention, there is provided an image forming apparatus including an induction heating type fixing device, wherein a maximum power to be supplied to the fixing device is provided as a plurality of different set values and can be switched. It is proposed that

Further, in order to solve the above-mentioned problems, the present invention corresponds to the magnitude of the power supplied to a device other than the fixing device, and when the power supplied to a device other than the fixing device is small, the maximum power to be supplied to the fixing device is provided. The maximum power supplied from the induction heating inverter to the induction heating coil is changed in a direction to increase the power or to increase the maximum power to be supplied to the fixing device when the power supplied to other than the fixing device is large. Suggest.

Further, in order to solve the above-mentioned problem, the present invention proposes that the maximum power is supplied from the induction heating inverter to the induction heating coil at the time of a cold start by turning on the power of the apparatus.

According to another aspect of the present invention, there is provided an exposure lamp having an exposure lamp for exposing a document, the maximum power supplied from an induction heating inverter to an induction heating coil in accordance with the operation of the exposure lamp. To be changed.

Further, in order to solve the above-mentioned problem, the present invention proposes that the maximum electric power supplied from the induction heating inverter to the induction heating coil is changed according to the amount of electric power supplied to the apparatus drive system.

Further, in order to solve the above-mentioned problem, the present invention detects input power of a device, and changes maximum power supplied to an induction heating coil from an induction heating inverter according to the detected input power. Propose that.

Further, in order to solve the above-mentioned problem, the present invention is to change a pulse width or a switching frequency in an inverter drive circuit when changing the maximum supply power from the induction heating inverter to the induction heating coil. Or by changing both the pulse width and the switching frequency to control the maximum supply power.

Further, in order to solve the above-mentioned problem, the present invention proposes to control a power supply amount to an induction heating coil by changing a reference voltage in an inverter drive circuit.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a main part of a copying apparatus which is an example of an image forming apparatus according to the present invention. The copying apparatus shown in FIG. 1 includes an image forming unit 1, an induction heating fixing unit 2, a power supply unit 3, a control unit 4, and the like. Note that, in this figure, the paper feeding unit and the like are omitted.

The image forming section 1 includes a scanner 11, an image carrier 12, and a high-voltage power supply 13. The scanner 11 has an exposure lamp 14, a mirror 15, and a motor 16.
The image carrier 12 is a photosensitive drum in the present embodiment.

The induction heating fixing unit 2 includes an induction heating roller 2
1, pressure roller 22, induction heating (IH) inverter 23
Is included. The IH inverter 23 has a coil 24 for induction heating. This IH inverter 23 is connected to the commercial power supply 5. The induction heating roller 21 is provided with a thermistor 25 as a temperature detecting means.

The power supply unit 3 is a power supply device for stabilizing the electric power from the commercial power supply 5 and supplying it to each unit such as a control unit and a drive system, and usually a switching power supply is often used.

The control section 4 is a control circuit section for controlling the entire copying apparatus, but a detailed description of the configuration will be omitted. In the present embodiment, a control signal: A is sent from the control unit 4 to the IH inverter 23 of the fixing unit 2, and the IH inverter 2
3 is configured to be controlled by the control unit 4. The high-voltage power supply 13 of the image forming unit 1 and the scanner 1
1 is also controlled by the control unit 4.

In the copying apparatus configured as described above,
The scanner 11 irradiates the original with an exposure lamp 14 and exposes the photosensitive drum 12 with light reflected from the original to form an electrostatic latent image. It should be noted that a digital method may be used in which a document image is converted into a laser signal or the like and written on the photosensitive drum 12. The electrostatic latent image formed on the photosensitive drum 12 is visualized as a toner image by applying toner from a developing device (not shown). The toner image is transferred onto a recording medium (transfer paper or the like) supplied from a paper supply unit (not shown), and the recording paper is sent to the fixing unit 2 to fix the toner image on the recording paper.

In the induction heating fixing unit 2, a high frequency magnetic field is generated by driving the induction heating coil 24 at a high frequency by the IH inverter 23, and this magnetic field causes an eddy current to flow through the metal heating roller 21 to raise the roller temperature. I do. Since such an induction heating type fixing device can directly heat the fixing roller (heating roller) by electromagnetic force, it is more efficient than the conventional heating method using a halogen lamp or the like, and the electric power control is performed electrically. It is effective for energy saving.

In an image forming apparatus having a conventional induction heating type fixing device, an IH inverter is used instead of an IH inverter in order to quickly start up a fixing roller (heating roller) to a temperature required for image formation when power is turned on. It operates so that the maximum power that can be supplied by the switching element is supplied. Then, when it is detected that the temperature of the fixing roller has risen and the roller temperature has reached the target temperature, control is performed by changing the frequency or pulse width of the IH inverter so that the temperature of the fixing roller becomes constant. It becomes a steady state.

In the conventional image forming apparatus designed in this way, although the rise time is shorter than in the case where a fixing device using a halogen lamp is provided, on the other hand, the fixing roller of the fixing roller at the time of recording paper conveyance during normal image forming processing is used. When there is a temperature change, a change in the input commercial power supply, a change in the surrounding environmental temperature, and the like, it operates to supply the maximum power from the IH inverter (to the heating coil) in an attempt to follow the change in real time. . FIG. 7 shows an example of the configuration of a conventional image forming apparatus. The IH inverter 23 in the fixing unit 2 is not controlled by the control unit 4, and the IH inverter 23 supplies the heating coil 24 with the maximum power.

In a series of operations in the image forming apparatus, those requiring a large amount of power besides the induction heating fixing device include an exposure lamp, an automatic document feeder (ADF), or power supply to each drive system. If the maximum power is further supplied to the induction heating fixing device while power is being supplied to such a system (as in the conventional device), the commercial power supply line is changed if the total power is large. This adversely affects the image processing operation. In particular, fluctuations in the power supplied to the exposure lamp cause fluctuations in the irradiation intensity of the original,
This may cause a drop in image quality. Further, when the voltage fluctuation affects the image forming apparatus control unit, there is a problem that the operation of the memory and the I / O unit is affected and the operation of the CPU becomes abnormal. Further, when the total power exceeds the input current value allowed by the commercial power supply, there is a problem that the device cannot operate.

In the present invention, in order to avoid these problems, in FIG. 1, a control signal: A is sent from the control unit 4 to set (prescribe) the maximum power output from the IH inverter 23 in FIG. To control the maximum supply power to the heating coil 24. As a mode of the control, in response to a control signal to each drive system output from the control unit 4, power supply (to the heating coil 24) is changed to power supply to each drive system in accordance with the timing of the signal. The software is controlled so as not to overlap. Alternatively, the control unit 4 may be configured to set the maximum power supply time (timing) of the IH inverter 23 in the memory table in advance. In the control of the maximum supply power of the IH inverter 23, the control can be continuously variable, or can be switched stepwise by providing a plurality of set values.

As described above, the maximum power supplied to the fixing device, that is, the maximum power output from the IH inverter 23 to the induction heating coil 24 is variably controlled, so that the power that can be supplied is balanced as required. The image forming apparatus can be distributed, and the power-efficient image forming apparatus can be realized.

When the maximum power to be supplied to the fixing device is changed stepwise by providing a plurality of set values, the control can be performed with a simple configuration, and the cost-effective and power-efficient image can be controlled. A forming apparatus can be realized.

Next, a second embodiment of the present invention will be described. The same parts as those of the above-described embodiment shown in FIG. 1 are denoted by the same reference numerals, and overlapping description will be omitted. In the present embodiment, when the electric power supplied to parts other than the fixing unit 2 is small, the maximum electric power supplied to the fixing device (the maximum electric power from the IH inverter 23 to the induction heating coil 24) is increased, and the electric power is supplied to parts other than the fixing unit 2. When a large amount of power is applied, the maximum power (maximum power from the IH inverter 23 to the induction heating coil 24) supplied to the fixing device is controlled to be reduced.

More specifically, in the embodiment shown in FIG. 2, the sense signal B of the scanner unit 11 is input to the control unit 4, and the sense signal C of the power supply unit 3 is input to the control unit 4. . As a result, the current and voltage of the scanner unit and the power supply unit are constantly sensed, the control unit 4 calculates the power, and based on this, the set value of the maximum power from the IH inverter 23 of the fixing unit 2 to the induction heating coil 24 Is configured to be changed. At this time, the maximum power from the IH inverter 23 to the induction heating coil 24 can be continuously varied, or a plurality of set values can be provided to switch stepwise.

As described above, in the present embodiment, the power consumed in the parts other than the fixing unit is monitored, and the IH
By controlling the maximum supply power of the inverter 23,
It is possible to realize a more efficient image forming apparatus without unnecessary power supply.

Next, a third embodiment of the present invention will be described. The hardware configuration of this embodiment is the same as that of the embodiment shown in FIG. 2, but in this embodiment,
The control section 4 determines whether or not the apparatus is in a cold start.
Supplies the maximum power to the induction heating coil 24, and does not supply the maximum power except during a cold start.
Thereby, the rise of the image forming apparatus at the time of a cold start can be quickened, and the power efficiency can be improved.

Whether the apparatus is in a cold start or not can be determined by, for example, the temperature of the fixing roller 21 of the fixing unit 2. In the present embodiment, as shown in FIG. 2, the fixing roller 21 is provided with a thermistor 25 serving as a temperature detecting means, and the detection output of the thermistor 25 is input to the control unit 4 to determine whether a cold start is performed. Can be determined.

Next, a fourth embodiment of the present invention will be described. The hardware device configuration of this embodiment is the same as that of the above-described embodiment shown in FIG. 2, and a duplicate description will be omitted, and different portions will be mainly described.

In this embodiment, the maximum supply power of the IH inverter 23 is controlled in accordance with the on / off of the exposure lamp 14 during the copying operation. That is,
As shown in the timing chart of FIG. 3, when the exposure lamp is turned on, the maximum power is set to L (low).
When the exposure lamp is turned off, the induction heating coil 24 is supplied from the IH inverter 23 with the maximum power set to H (high).
The maximum power is supplied to

When the current supply limit of the commercial power supply 5 is 15 A, 1500 W is the maximum allowable power in the 100 V system. When the exposure lamp 14 is a halogen lamp, the power of the exposure lamp is usually about 200 to 400 W. Therefore, in the present embodiment, the H level of the maximum power from the IH inverter 23 to the induction heating coil 24 is set to 15
1000 to 12 obtained by subtracting the exposure lamp power from 00W
Set to 00W. Similarly, the L level of the maximum power is set to 800 to 1000 W. Needless to say, the H level and L level of the maximum power to be set can be appropriately changed according to the device configuration such as the exposure lamp and the fixing device.

In the case of an exposure lamp, when the temperature of the heater of the lamp is low, the resistance value of the heater may be low and an inrush current may flow. In such a case, if the maximum power is supplied to the fixing device, the current exceeds the maximum current that can be supplied by the commercial power supply, and the device becomes unusable or the power supply fluctuates and the operation of the device becomes unstable. May affect quality. However, in the present embodiment, since the maximum power to the fixing device is controlled according to the operation of the exposure lamp, such a problem does not occur.

Next, a fifth embodiment of the present invention will be described. The copying apparatus of the present embodiment is an automatic document feeder: A
DF (not shown) is provided. The other configuration of the apparatus is the same as that of the above-described embodiment shown in FIG. 2, and the overlapping description will be omitted, and different parts will be mainly described.

In the document reading section of the image forming apparatus, an ADF motor for conveying a document is used in addition to the exposure lamp of the scanner section as one which consumes a large amount of power. Most of the power supply to the ADF requires about 200 W.
If the maximum power is supplied to the fixing device during DF operation, the current exceeds the maximum current that can be supplied by the commercial power supply, and the equipment becomes unusable or the power supply fluctuates. May be affected.

Therefore, in this embodiment, the maximum power to the fixing device (the maximum power from the IH inverter 23 to the induction heating coil 24) is switched stepwise according to the operation of the exposure lamp and the operation of the ADF motor. To control.

As shown in FIG. 4, in the present embodiment, the maximum power from the IH inverter 23 to the induction heating coil 24 is set in three stages of H, M, and L. Maximum power H level is 1300W, M level is 1100W
And the L level is set to 800W. When the exposure lamp and the ADF motor are not operating, the maximum power from the IH inverter 23 to the induction heating coil 24 is controlled to the H level. AD before exposure lamp lighting
During the operation of the F motor, the maximum power from the IH inverter 23 to the induction heating coil 24 is controlled to the M level. When the exposure lamp 14 is turned on after the ADF motor stops, the maximum power from the IH inverter 23 to the induction heating coil 24 is controlled to L level. As a result, stable document conveyance and operation of the drive system can be performed.

Next, a sixth embodiment of the present invention will be described. As shown in FIG. 5, in the copying apparatus according to the present embodiment, the input voltage and the input current to the fixing unit 2 and the power supply unit 3 are detected, and these signals are calculated by the arithmetic circuit 10 to obtain the respective input powers. And the total input power of the devices are calculated. Other configurations are the same as those of the embodiment shown in FIG.

In this embodiment, the input power data: D from the arithmetic circuit 10 is sent to the control unit 4, and the control unit 4
Always monitor whether the maximum allowable power of the device is exceeded. When the input power to the fixing unit 2 and the power supply unit 3 exceeds the total power of the device, the control signal: A controls the maximum power from the IH inverter 23 to the induction heating coil 24, and the total input power Control not to exceed.

As described above, in the present embodiment, the input power is monitored and the IH
Since the maximum power supply to the induction heating coil 24 is controlled from 3, the operation can be performed more reliably so as not to exceed the maximum value of the commercial input power.

In each of the above embodiments, when controlling the maximum supply power from the IH inverter 23 to the induction heating coil 24, the pulse width or the switching frequency in the inverter drive circuit is changed, or the pulse width and the switching are changed. If the maximum supply power is controlled by changing both the frequencies, the maximum supply power can be controlled with a simple circuit configuration, and the cost can be reduced.

FIG. 6 is a circuit diagram in the case where the IH inverter 23 is configured as a single-type inverter circuit. In this figure, DI is a rectifier circuit for rectifying a commercial power supply ac, and its output voltage is represented by a noise filter FI as a pulsating waveform.
Through L, it is applied to the exciting inductance L1 (induction heating coil) of the fixing roller (heating roller) 21 and the switching element Q1. Here, the switching element Q1 is
High-frequency switching driving is performed by a control circuit including the operational amplifiers OP1 and OP2, an oscillation circuit OSC, a control circuit CONT, a drive circuit DRV, and the like. By this switching operation, the inductance L1 is excited and the fixing roller 2
An eddy current flows through the fixing roller 21 and the fixing roller 21 generates heat.

The temperature of the fixing roller 21 is detected by a thermistor 25. The detected temperature (thermistor output) is compared with the reference voltage Vref by the operational amplifier OP1.
If the roller temperature is different from the target temperature, the drive circuit DRV
By changing the output pulse width or frequency from
The power supply to the inductance L1 is controlled so that the temperature of the fixing roller 21 approaches the target temperature.

In such a circuit, the control circuit CON
Within T, the maximum pulse width is limited. Usually, the maximum pulse width is set so as to supply the maximum power within a range not exceeding the maximum current rating of the switching element in order to start the induction heating fixing device to the target temperature as soon as possible. In the present application, the control circuit CONT is provided with another terminal S1 capable of limiting the pulse width, and the control unit 4 is connected to this terminal.
(See FIGS. 1, 2, and 5), a control signal A according to the control conditions of each of the above embodiments is input, and control is performed so as to change the setting of the maximum pulse width. The setting change of the maximum pulse width may be continuously variable or may be a method of sequentially switching a plurality of set values. Further, a plurality of terminals S1 for limiting the pulse width may be provided. The pulse width can be controlled by controlling the ON pulse width, the OFF pulse width, or both.

Further, the maximum supply power to the inductance L1 can be changed by the drive frequency of the switching element Q1. In FIG. 7, the maximum supply power is changed by changing the reference oscillation circuit OSC of the operational amplifier OP2. It is also possible. Then, both the setting of the maximum pulse width and the driving frequency may be changed.

As described above, by controlling the maximum power supplied to the induction heating coil by the pulse width and / or the driving frequency of the inverter driving circuit, a simple circuit configuration can be realized, and the apparatus can be manufactured at low cost. Can be configured.

Next, another method for limiting the amount of electric power supplied to the induction heating coil 24 will be described. In the configuration for limiting the power supply amount, the set value of the maximum supply power to the induction heating coil 24 is fixed, and the power supply amount is changed by changing the reference voltage. Thereby, the same effect as in the case of controlling the maximum supply power to the induction heating coil 24 described above can be obtained.

Specifically, the reference voltage Vref is changed by applying a signal from the control unit 4 to the S2 terminal of the operational amplifier OP1 in FIG. In this way, when the required power amount in a portion other than the fixing device is large, the reference voltage is changed to a higher value, and the power supply to the induction heating coil 24 is controlled so as not to reach the maximum value. By changing the amount of power supply to the induction heating coil 24 by changing the reference voltage, it is possible to perform time-dependent (time-series) power control of the induction heating inverter.

The method of controlling the maximum supply power to the induction heating coil 24 by the change of the reference voltage in the inverter driving circuit and the method of controlling the induction heating coil by the pulse width and / or the driving frequency in the inverter driving circuit. It is also possible to implement in combination with a method of controlling the maximum supply power to the power supply.

FIG. 6 shows an example in which the IH inverter 23 is configured as a single-type inverter circuit. However, the same applies to other types of inverter drive circuits such as a dual-type inverter circuit and a new type of current transmission type inverter. Control can be realized.

In FIG. 6, the amount of power supplied to the inverter drive circuit is changed from the rectified line to Vin, Li
Although a circuit configuration has been described in which n is input to the arithmetic circuit MUL to calculate the power signal Mo, the configuration for calculating the power supply amount may be used instead of the arithmetic circuit 10 in FIG.

[0059]

As described above, according to the image forming apparatus of the present invention, the maximum power supplied to the fixing device can be continuously varied, so that the power that can be supplied is distributed in a balanced manner as needed. Thus, an image forming apparatus with high power efficiency can be realized.

According to the second aspect of the present invention, since the maximum power to be supplied to the fixing device is provided as a plurality of different set values and is configured to be switchable, an image forming apparatus with a simple circuit configuration and high power efficiency is realized. be able to.

According to the third aspect of the present invention, when the power supplied to other than the fixing device is small, the maximum power to be supplied to the fixing device is increased. The maximum power supplied from the induction heating inverter to the induction heating coil is changed in a direction in which the maximum power supplied to the power supply increases, so that an efficient image forming apparatus without unnecessary power supply can be configured.

According to the fourth aspect of the present invention, the maximum power is supplied to the induction heating coil from the induction heating inverter at the time of a cold start by turning on the power supply of the apparatus, so that the equipment startup at the time of the cold start is quickened and the power efficiency is improved. be able to.

According to the fifth aspect of the present invention, the maximum electric power supplied to the induction heating coil from the induction heating inverter is changed according to the operation of the exposure lamp, so that there is no problem caused by the rush current when the exposure lamp is turned on. In addition, it is possible to prevent unstable operation and adverse effects on image quality.

According to the sixth aspect of the present invention, the maximum electric power supplied to the induction heating coil from the induction heating inverter is changed according to the amount of electric power supplied to the apparatus driving system. It can be carried out.

According to the seventh aspect of the present invention, the input power of the apparatus is detected, and the maximum power supplied to the induction heating coil from the induction heating inverter is changed in accordance with the detected input power. The operation can be performed so as not to exceed the maximum value of the power.

According to the eighth aspect of the present invention, when changing the maximum supply power from the induction heating inverter to the induction heating coil, the pulse width or the switching frequency in the inverter drive circuit is changed, or the pulse width and the switching frequency are changed. By controlling the maximum supply power by changing both of them, the device cost can be reduced with a simple circuit.

According to the ninth aspect of the present invention, the amount of power supplied to the induction heating coil is controlled by changing the reference voltage in the inverter drive circuit, so that time-series power control can be performed.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating a main part of a copying apparatus that is an example of an image forming apparatus according to the present invention.

FIG. 2 is a schematic configuration diagram illustrating a main part of a second embodiment of the present invention.

FIG. 3 is a timing chart of a fixing device maximum supply power control according to a fourth embodiment of the present invention.

FIG. 4 is a timing chart of a fixing device maximum supply power control according to a fifth embodiment of the present invention.

FIG. 5 is a schematic configuration diagram showing a main part of a sixth embodiment of the present invention.

FIG. 6 is a circuit diagram of a single-type inverter drive circuit in each embodiment.

FIG. 7 is a schematic configuration diagram illustrating an example of a conventional copying apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image forming part 2 Induction heating fixing part 3 Power supply part 4 Control part 5 Commercial power supply 21 Fixing roller 22 Pressure roller 23 IH inverter 24 Induction heating coil 25 Thermistor A Inverter control signal B Scanner part power sense signal C Power source part power sense Signal D Input power data signal

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Jiro Ouchi 3-1 Shinmei-do, Nakana, Shimada-cho, Shibata-cho, Shibata-gun, Miyagi F-term in Tohoku Ricoh Co., Ltd. (reference) 2H027 EA12 EA16 ED04 ED06 EE01 EE02 EF01 2H033 AA32 BE06 CA23 CA44 CA48 3K059 AA02 AB00 AC09 AC73 AD03 AD18 AD28 BD02 BD23 CD13 CD18 CD19 9A001 BB06 HH34 JJ35 KK31 KK32 KK54

Claims (9)

[Claims] 1. An image forming apparatus having an induction heating type fixing device, wherein the maximum power supplied to the fixing device is continuously varied. 2. An image forming apparatus having an induction heating type fixing device, wherein the maximum power to be supplied to the fixing device is provided as a plurality of different set values and is switchable. . 3. When the power supplied to a device other than the fixing device is small and the power supplied to the device other than the fixing device is small, the maximum power supplied to the fixing device is increased. The maximum power supplied from the induction heating inverter to the induction heating coil is changed in a direction in which the maximum power supplied to the fixing device increases when the supplied power is large. Image forming apparatus. 4. The image forming apparatus according to claim 1, wherein a maximum power is supplied from an induction heating inverter to an induction heating coil at a cold start when the apparatus is turned on. 5. The apparatus according to claim 1, further comprising an exposure lamp for exposing the document, wherein the maximum power supplied to the induction heating coil from the induction heating inverter is changed according to the operation of the exposure lamp. 3. The image forming apparatus according to 1 or 2. 6. The image forming apparatus according to claim 1, wherein the maximum electric power supplied from the induction heating inverter to the induction heating coil is changed according to the amount of electric power supplied to the apparatus drive system. . 7. The apparatus according to claim 1, wherein input power of the apparatus is detected, and the maximum power supplied from the induction heating inverter to the induction heating coil is changed according to the detected input power.
The image forming apparatus according to claim 1. 8. Changing the maximum supply power from the induction heating inverter to the induction heating coil by changing a pulse width or a switching frequency in the inverter drive circuit, or changing both the pulse width and the switching frequency. The image forming apparatus according to claim 1, wherein the maximum supply power is controlled by causing the image forming apparatus to perform the control. 9. The image forming apparatus according to claim 1, wherein the amount of electric power supplied to the induction heating coil is controlled by changing a reference voltage in the inverter drive circuit.