JP2003202769A - Image forming apparatus and method for controlling image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus preventing a shortcoming that current consumption exceeds peak current consumption set in a power restriction rule or the like or the heating time of a fixing means is long, <P>SOLUTION: An AC-DC converter capable of changing output voltage is set as the power source of the heating element of the fixing means. In the case of heating the heating element from low temperature to high temperature, an AC current flowing into the image forming apparatus is detected, and voltage applied to the heating element at the time of warming up is set to the voltage equal to or above that at the copying time and applied so that the detected current may not exceed a specified current value, whereby the fixing means is rapidly heated. <P>COPYRIGHT: (C)2003,JPO

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 and its control method.

[0002]

2. Description of the Related Art Since an image forming apparatus for forming an image by an electrophotographic method consumes a large amount of electric power, when designing an image forming apparatus, the electric power industry law in Japan and other official countries A design that complies with the power restriction rules set by the agency is required.

As a method of adapting an image forming apparatus to such a power limitation, each constituent unit of the image forming apparatus is controlled so that the total power consumption of each constituent unit at each point of the image forming process falls within the limit. A method of setting power consumption and operation timing has been adopted.

Therefore, for example, when the power consumption at a certain point of time exceeds the limit value, a designing method such as shifting the operation timing of the components within a range that does not affect the image formation is also used.

The distribution of such power consumption has been conventionally determined by a designer at the design stage of an image forming apparatus, or corrected through an experiment using a prototype. Therefore,
The manufactured image forming apparatus operates according to the sequence determined in the design stage, and the maximum power consumption value and the power consumption pattern according to the sequence are predetermined in the design stage, and the fixing unit is said to consume 50% of the power consumption. Even if the image is not formed for a long time, the temperature of the heating roller is lowered.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to solve the following problems in an image forming apparatus. The problems to be solved by the invention will be listed below.

(1) The above-mentioned conventional technique is premised on the use of a reference sheet having a predetermined size, thickness, etc. When a sheet other than the reference sheet is used in the copy mode, the load is driven against the sequence set at the time of design. There is a drawback in that there is a possibility that the timing is deviated, sometimes the start timings of the loads are overlapped, and the inrush current at the start is added to exceed the current consumption limit value.

(2) In the image forming apparatus, the heating roller of the fixing means which has a low temperature when the power is turned on and the temperature is low at the time of returning to the copy mode from the low power mode when the copying is suspended for a long time. When heating to a predetermined temperature, it is impossible to apply a voltage higher than the voltage applied in the copy mode to the heating element of the fixing unit in the warm-up mode, so that the heating time is long and the preparation time of the image forming apparatus is long. There was a flaw.

The present invention has been made in view of the above problems, and in a short time during the warm-up mode and during the return from the low power mode to the copy mode without exceeding the limit value of the current consumption. An apparatus capable of increasing the temperature of the heating roller to a predetermined temperature and limiting the current to the heating element of the fixing unit so that the current consumption limit value is not exceeded when the load current of the image forming apparatus increases. The purpose is to provide a control method thereof.

[0010]

The inventor of the present invention cannot directly change the voltage applied to the heating element because the heating element of the fixing means is directly powered by an AC power source in the past. Focusing on the fact that the time required to heat the fixing unit cannot be shortened because it cannot be raised, the voltage is increased to increase the heat generation amount of the heating element by easily increasing or decreasing the applied voltage of the heating element when the current consumption of the image forming apparatus is small. Allows you to
The present invention has been accomplished in view of shortening the time required for heating the fixing unit and suppressing the power consumption of the image forming apparatus within a predetermined value by lowering the voltage and making it possible to reduce the amount of heat generation when the amount is large.

That is, the above object of the present invention is achieved by the following means. An image forming apparatus according to a first aspect of the present invention is an image forming apparatus including a fixing unit having a heating roller heated by a heating element, wherein the output voltage is variable on a DC output side of an AC-DC converter. The temperature of the heating roller is controlled by connecting the heating element, connecting an external AC power source to the AC primary side of the AC-DC converter, and changing the voltage on the DC output side of the AC-DC converter. It is characterized by being configured.

An image forming apparatus according to a sixth aspect of the present invention is a fixing means including a heating roller heated by a carbon heater composed of a halogen heater and a carbon heating element, and the halogen heater. In an image forming apparatus including an AC-DC converter whose voltage on the DC output side is variable to supply electric power to each of the carbon heaters individually via current ON / OFF means, and a control means which controls at least the temperature of the heating roller, The control means connects a current detection means for detecting an alternating current flowing into the image forming apparatus and a fixing temperature sensor for detecting the temperature of the heating roller to an input, and the control means controls the current ON / OFF.
A plurality of ON / OFF command outputs for turning ON / OFF the means are individually connected to the current ON / OFF means, and AC-
An output voltage command output for changing the voltage on the DC output side of the DC converter is connected to the output voltage setting input of the AC-DC converter.

According to a third aspect of the present invention, in a method for controlling an image forming apparatus, a fixing means having a heating roller heated by a heating element is provided, and the heating element is turned on / off.
In an image forming apparatus in which the output of the control unit is connected to the DC output side of an AC-DC converter whose output voltage is variable via the F unit, and the output of the control unit is connected to the input of the AC-DC converter. It is characterized in that the output voltage on the DC output side of the AC-DC converter is changed, and the voltage applied to the heating element is changed to raise or lower the temperature of the heating roller.

According to a fourth aspect of the present invention, in a method for controlling an image forming apparatus, a fixing means having a heating roller heated by a heating element is provided, and the heating element is a current ON / O.
In an image forming apparatus in which an output of a control unit is connected to a DC output side of an AC-DC converter whose output voltage is variable via an FF unit, and an output of the control unit is connected to an input of the AC-DC converter. The output voltage on the direct current output side of the AC-DC converter is changed, the applied voltage of the heating element is changed to control the temperature of the heating roller to rise and fall, and the output is controlled according to another output of the control means. The temperature of the heating roller is controlled by a combination of the voltage applied to the heating element and the ON / OFF of the current ON / OFF means so that the current ON / OFF means is turned ON / OFF to raise or lower the temperature of the heating roller. Characterize.

According to a twelfth aspect of the present invention, there is provided a method of controlling an image forming apparatus, comprising a fixing means having a heating roller heated by a carbon heater composed of a halogen heater and a carbon-based heating element. The heater is connected to the DC output side of the AC-DC converter whose output voltage is individually variable, via the current ON / OFF means,
In the image forming apparatus in which the output of the control means is connected to the input of the AC-DC converter, the AC-
The output voltage on the DC output side of the AC-DC converter corresponding to the halogen heater and the carbon heater is changed according to the output that sets the output voltage on the DC output side of the DC converter, and the applied voltage of the halogen heater and the carbon heater is changed. The temperature of the heating roller is controlled to be raised or lowered by changing the temperature, and the current ON / OF of the control means is controlled.
The current ON / OF corresponding to the halogen heater and the carbon heater according to the output for turning ON / OFF the F means
The voltage applied to the halogen heater and the carbon heater and the current ON / OFF means ON / OFF so that the F means is turned ON / OFF to raise or lower the temperature of the heating roller.
The temperature of the heating roller is controlled by a combination of the above.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited thereto.

First, an outline of the image forming apparatus will be described. FIG. 1 is a schematic configuration diagram of an image forming apparatus showing one embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes an image forming apparatus. Documents are placed on a document feed table 21 of an automatic document feeder 2 with the image surface facing upward, and are fed one by one by the operation of a feed roller 22. The image is read by the image reading means 3 in the process of being stopped by the registration rollers 23 and having its front end adjusted and then being conveyed to the conveying drum 24, and being rotated in the counterclockwise direction integrally with the drum surface. The sheet is branched from the drum surface at a position where it is half-circulated and is ejected to the sheet ejection tray 25.

In the image reading means 3, the light source 31
The first mirror unit 31 including the mirror 1 and the mirror 312 includes a mirror 321 and a mirror 322 arranged at right below the transport drum 24 so as to sequentially illuminate and read the document passing therethrough and to orthogonally intersect the moving direction of the document. The light is reflected by the second mirror unit 32, and forms an image on the linear image sensor 34 via the imaging lens 33.

When a document is placed on the platen glass 35 and image information is read, a first mirror unit having a movable light source 351 and a first mirror 352, and a second mirror having mirrors 353 and 354. Unit 32
And is similarly image-formed on the line-shaped image sensor 34 via the imaging lens 33. The above is the image reading means 3.

The image information of the document read by the image reading means 3 is subjected to image processing by the image processing means 62 of the control means 6, converted into signal as image data, and temporarily stored in the storage means 61.
Stored in.

The image forming means 4 is started by the start of image formation.
Is started and the image data is called from the storage means 61 and input to the image writing means 43, and a laser beam projected from a laser light emitter (not shown) according to the image data rotates a polygon mirror (no reference numeral). The photosensitive drum 4 to which a potential has been applied by the charger 42 in advance by
1 is subjected to scanning exposure in the axial direction of the photoconductor drum 41 and sub-scanning by rotation of the photoconductor drum 41 to form an electrostatic latent image of an original image on the photosensitive layer.

The electrostatic latent image is subjected to reversal development by the developing means 44 to form a toner image, and in parallel with this, a manual sheet feeding means 26 as recording paper feeding means or a paper feeding means 5 for accommodating recording paper. Delivery rollers 52 for each paper cassette,
Either one of 53 and 54 is operated to eject the recording paper, and the recording paper is fed to the conveyance rollers 55 and 56 and the timing roller 51, and is fed to the photosensitive drum 41 in synchronization with the toner image on the photosensitive drum 41. To be done.

The toner image on the photosensitive drum 41 is transferred to the transfer unit 4.
The recording paper on which the toner image has been transferred is transferred to the recording paper side by being applied with a voltage of the opposite polarity by means of No. 5, and the recording paper on which the toner image has been transferred is neutralized by the static eliminator 46 and separated from the photoconductor drum 41. DC converter 64 and control means 6
Then, the toner is conveyed to the fixing means 47 whose temperature is controlled by the heating roller 474 and the pressure roller 475, and the toner is fused and fixed by the pressure heating and then discharged to the tray 57.

Here, the fixing means 47 is a heating element such as a halogen heater 471a and a carbon heater 471b.
And a pressure roller 475 having a heat-resistant elastic layer made of silicon rubber on an aluminum base and a heat-resistant release layer made of fluororesin on an aluminum base. Has been done. Further, a fixing temperature sensor 473 for detecting the temperature of the heating roller 474 is attached so as to be in sliding contact with the heating roller.

On the other hand, the photosensitive drum 41 with the recording paper separated
After removing the residual potential, the cleaning means 48 removes and cleans the residual toner to start the next image forming process.

The outline of the image forming apparatus has been described above. The fixing means will be mainly described below for the image forming apparatus.

FIG. 2 is a block diagram showing the first embodiment. First, the configuration will be described with reference to FIG.

Reference numeral 90 is an AC power source outside the image forming apparatus. Reference numeral 64 denotes an AC-DC converter, an AC power source 90 is connected to the primary AC side, a DC voltage is output to the secondary side, and a fixing heater 471 is connected via the current ON / OFF means 66. The voltage command output of the fixing heater 471 of the control means 6 is connected to the output voltage setting input of 64.

Then, a DC voltage corresponding to the set value input to the output voltage setting input is output to the DC output side.

Reference numeral 65 denotes a current detection means, which is composed of a current detection coil or the like, detects the total alternating current flowing into the image forming apparatus 1, and connects its output to the control means 6.

Reference numeral 6 is a control means, which has a current detection means 65 as an input.
And the fixing temperature sensor 473 are connected, and the output of the current ON / OFF command of the fixing heater 471 is turned ON / OFF.
The voltage command output described above is connected to the AC-DC converter.

Reference numeral 66 is a current ON / OFF means, which is composed of a thyristor, a relay, etc., and is used for the AC-DC converter 6
4 is connected between the DC output side and the fixing heater 471, and ON / OFF of the energization to the fixing heater 471 is performed by the ON / OFF command output output from the control unit 6.

Reference numeral 471 denotes a fixing heater which is a heating element, and is incorporated in a heating roller of fixing means (not shown). The fixing heater 471 is connected to the DC output side of the AC-DC converter 64 via the current ON / OFF means 66 and heats the heating roller 474.

A fixing temperature sensor 473 is composed of a thermistor and a thermocouple and is arranged so as to be in sliding contact with the outer peripheral surface of the heating roller 474. The temperature of the heating roller 474 is detected and the detected value is controlled by the control means 6. Output to.

Reference numeral 70 denotes a control power supply, which is a current detecting means 65 and A
The AC primary side is connected between the C-DC converters 64, and the secondary side DC voltage is connected to the AC-DC converter 64, the control means 6, etc., and supplies electric power for control.

Now that the structure of the first embodiment has been described, the control method thereof will be described below with reference to FIG.

Warm-up mode process When the operator connects the image forming apparatus 1 to the AC power source 90 and turns on a power switch (not shown), the control power source 70 starts to supply power to the control means 6 and the AC-DC converter 64.

The control means 6 determines that it is in the warm-up mode by turning on the power switch.

Then, the control means 6 outputs the maximum output voltage command value to the voltage command output and, at the same time, turns on / off the current.
The ON / OFF command output of the means 66 is turned on to start energizing the fixing heater 471.

Here, the maximum output voltage command value means that the voltage applied to the fixing heater 471 is 1.0 to 2 times, preferably 1.5 to 2 times that in the copy mode in which copying, which will be described later, is performed. It means the output value of the voltage command output of the control means 6.

Here, if the magnification is too small, the heating time cannot be shortened, and if it is too large, the heater may be broken or deteriorated.

As a result, the fixing heater 471 is heated rapidly with the maximum applied voltage, and in the heating roller temperature diagram of FIG. 3, the temperature change of the heating roller 474 is different from the temperature change a at the time of conventional warm-up according to the present invention. The temperature change b during warm-up becomes steep.

Further, the control means 6 checks that the total AC current flowing into the image forming apparatus 1 detected by the current detection means 65 is equal to or less than a preset current value,
When the detected current value is equal to or more than the predetermined current value, the voltage command output value is reduced according to the overcurrent value.

The control means 6 controls the fixing temperature sensor 473.
Output from a preset fixing temperature (for example, approximately 200
C.), the output voltage command value to the AC-DC converter 64 is set as the temperature of the heating roller 474 becomes closer to the fixing temperature so that the temperature of the heating roller 474 does not overshoot greatly or large hunting does not occur. Gradually lowering the heat generation amount of the fixing heater 471 to gradually approach the set value of the copy mode. And the control means 6
After the heating roller 474 reaches the fixing temperature, the fixing temperature sensor 473 always detects the temperature of the heating roller 474, and AC-D is applied so that the temperature of the heating roller 474 becomes constant and reaches the fixing temperature.
The DC output side voltage of the C converter 64 is changed to control the heat generation amount of the fixing heater 471.

Here, as another method of controlling the temperature of the heating roller 474 in the warm-up mode, the control means 6 fixes the voltage on the DC output side of the AC-DC converter 64 to a constant value by turning on the power source, and turns it on / off. OFF command output is O
N to heat the heating roller 474 to heat the heating roller 474.
Current cut-off ON / O as the temperature of the sheet approaches the fixing temperature
The FF command output may be output intermittently and the energization of the fixing heater 471 may be turned ON / OFF to control the OFF period to be gradually extended (PWM control) to prevent a large overshoot or hunting. Both (voltage control by the AC-DC converter 64 and current ON / OFF by the control means 6)
(ON / OFF control of the OFF means 66) may be combined.

The image forming apparatus 1 has a heating roller 474.
The temperature is raised to the fixing temperature, the conditions of the image forming process that are normally performed are set, and the warm-up mode process is completed.

As described above, the present invention is different from the heating roller 474 in the conventional method in which the same voltage is applied to the fixing heater 471 in the warm-up mode as in the copy mode.
It is possible to quickly reach the fixing temperature (about 200 ° C.), and at the same time, prevent large temperature overshoot and hunting that are likely to occur during rapid heating, and quickly complete the warm-up mode. .

When the copy mode process control means 6 finishes heating the temperature of the heating roller 474 to the fixing temperature and completes the preparatory operation for making copies such as setting various developing conditions, the mode is changed from the warm-up mode to the copy mode.

When the mode is changed to the copy mode, the operator can start the copy operation from the operation panel (not shown), and the control means 6 performs the image formation normally performed according to the image forming process by the copy start operation.

In the copy mode, a large number of various loads related to image formation are repeatedly turned on and off, and the current consumption of the entire image forming apparatus increases significantly. Therefore, the control means 6 sets the voltage command output to the copy mode voltage value. The DC output side voltage of the AC-DC converter 64 is lowered to limit the power consumption of the fixing heater 471 for the warm-up process.

Here, the copy mode voltage value refers to a voltage command output value of the control means 6 that causes the temperature of the heating roller to reach the fixing temperature (for example, about 200 ° C.).

The control means 6 sets the total alternating current flowing into the image forming apparatus 1 detected by the current detecting means 65 so that the total alternating current flowing into the image forming apparatus does not exceed a predetermined value. Check that it is less than or equal to the value, and if the detected current value is more than the set current value, decrease the voltage command output value according to the overcurrent value,
Alternatively, the ON / OFF command output is turned off to limit the power consumption of the fixing heater 471.

Then, the control means 6 controls the heating roller 474.
The ON / OFF command output is fixed to ON so that the temperature of the heating roller 474 is controlled to the fixing temperature, the temperature of the heating roller 474 is constantly detected by the fixing temperature sensor 473, and the temperature of the heating roller 474 is set to the fixing temperature (for example, about 200 ° C.). ) AC-D
The DC output side voltage of the C converter 64 is changed to control the heat generation amount of the fixing heater 471.

As another method for controlling the temperature of the heating roller 474 to the fixing temperature, an AC-DC converter 64
Is fixed to the voltage value in the copy mode, the output from the fixing temperature sensor 473 is compared with a preset fixing temperature (for example, about 200 ° C.), and if the fixing temperature sensor output is high, the control means 6 is turned on. / OFF command output is turned OFF, current ON / OFF means 66 is turned OFF, and AC-
Turn on the power from the DC converter 64 to the fixing heater 471.
If FF is performed and the compared output is low, the control means 6 is turned ON / O.
The FF command output is turned ON, the current ON / OFF means 66 is turned ON, the energization from the AC-DC converter 64 to the fixing heater 471 is turned ON, and the ON / OFF of the energization of the fixing heater 471 is repeated in this manner. Fixing heater 4
The heat generation amount of 71 may be controlled.

Both (voltage control by the AC-DC converter 64 and ON / OFF by the current ON / OFF means 66).
OFF control) may be combined to control the heat generation amount of the fixing heater 471.

As described above, the total AC current of the image forming apparatus does not exceed the limit value and the heating roller can be stably maintained at the fixing temperature.

When the copy operation is not performed for a predetermined time (for example, 15 minutes), the low power mode process control means 6 shifts from the copy mode to the low power mode in order to save energy.

In order to save power in the low power mode, the control means 6 sets the voltage command output to the low power mode voltage value and lowers the DC output side voltage of the AC-DC converter 64,
The power consumption of the fixing heater 471 is limited with respect to the copy mode process.

Here, the low power mode voltage value refers to the voltage command output value of the control means such that the temperature of the heating roller becomes 50 to 100 ° C., for example.

Then, the control means 6 fixes the ON / OFF command output to ON, always detects the temperature of the heating roller 474 by the fixing temperature sensor 473, and the temperature of the heating roller 474 becomes a constant temperature (for example, about 100 ° C.). AC-DC to be
The DC output side voltage of the converter 64 is changed to control the fixing heater 471 so as to lower the heat generation amount.

Here, as another control method of the temperature of the heating roller 474 in the low power mode, the control means 6 maintains the voltage command output of the AC-DC converter 64 at the low power mode voltage value, and the fixing temperature sensor 473 operates. Output and a preset low power temperature (for example, about 100
C.) and if the fixing temperature sensor output is high, the ON / OFF command output of the control means 6 is turned OFF and the current ON / O is turned ON.
The FF means 66 is turned off, and the AC-DC converter 64
Power to the fixing heater 471 is turned off.

Further, the output from the fixing temperature sensor 473 is compared with a preset low power temperature (for example, about 100 ° C.), and if the output is low, the current from the control means 6 is turned on / off.
The current cut-off ON / OFF command output of the means 66 is turned on, the current ON / OFF means 66 is turned on, and the energization from the AC-DC converter 64 to the fixing heater 471 is turned on.

The temperature of the heating roller 474 may be kept substantially constant by repeating ON / OFF of the energization of the fixing heater 471 in this manner, or both (voltage control by the AC-DC converter 64 and current ON / OFF). OFF means 6
ON / OFF control by 6) may be combined.

As described above, the power consumption can be saved by lowering the temperature of the fixing heater.

Return Mode Process When the operator performs a copy start operation from the operation panel (not shown) during the low power mode, the control means 6 determines that the mode is the return mode, and returns from the low power mode to the copy mode. The fixing heater is heated to raise the temperature of the heating roller 474 from the low power temperature (for example, about 100 ° C.) to the fixing temperature (for example, 200 ° C.).

Then, the control means 6 outputs the maximum output voltage command value to the voltage command output and simultaneously turns on the ON / OFF command output to start energizing the fixing heater 471.

As a result, the fixing heater 471 is heated rapidly with the maximum applied voltage, and the temperature change of the heating roller 474 becomes steep as in the warm-up mode.

Further, the control means 6 checks that the total AC current flowing into the image forming apparatus 1 detected by the current detection means 65 is less than or equal to a preset predetermined current value,
If the detected current value is greater than or equal to the set current value, the voltage command output value is lowered according to the overcurrent value.

The control means 6 uses the fixing temperature sensor 473.
The temperature of the heating roller 474 is set so that the temperature of the heating roller 474 does not overshoot or hunting significantly. As the temperature gets closer to the temperature, the output voltage command value to the AC-DC converter 64 is gradually reduced to gradually approach the set value of the copy mode while gradually lowering the heat generation amount of the fixing heater 471. After reaching the set temperature, the fixing temperature sensor 473 constantly detects the temperature of the heating roller 474, and the DC output side voltage of the AC-DC converter 64 is changed so that the temperature of the heating roller becomes constant. Control the amount of heat generation.

Here, as another method of controlling the temperature of the heating roller 474 in the return mode, the control means 6 fixes the DC output side voltage of the AC-DC converter 64 to a constant value by turning on the power source, and turns it on / off. When the command output is turned ON and the temperature of the heating roller 474 approaches the set value, the current cutoff ON / OFF command output is intermittently output and gradually turned OFF.
Fixing heater 471 to extend the period (PWM control)
It may be controlled by turning ON / OFF the energization to prevent large overshoot and hunting.
The voltage control by the C converter 64 and the ON / OFF control of the current ON / OFF means 66 by the control means 6) may be combined.

Then, the image forming apparatus 1 raises the temperature of the heating roller to the fixing temperature (for example, about 200 ° C.), completes the return mode process, and can copy again.

As described above, according to the present invention, the temperature of the heating roller 474 reaches the predetermined temperature (about 200 ° C.) earlier than in the conventional method in which the same voltage as in the copy mode is applied to the fixing heater 471 even in the return mode. Then, the return mode can be completed quickly.

Next, the fixing heater, which is a heating element, is composed of a halogen heater and a carbon heater made of a carbon heating element, and both heaters are individually temperature controlled by voltage command output and ON / OFF command output of the control means. A second embodiment will be described with reference to FIG.

FIG. 4 is a block diagram showing a second embodiment of the present invention. The configuration will be described below with reference to FIG.

Reference numeral 64 is an AC-DC converter, which is connected to an AC power source 90 on the primary AC side, outputs two independent DC voltages on the secondary side, and outputs current ON / OFF means 661 and 6
A halogen heater 471a constituting a fixing heater 471 via a carbon heater 47 and a carbon heater 47 composed of a carbon-based heating element.
1b are respectively connected, and the halogen heater 471 of the control means 6 is connected to the output voltage setting input of the AC-DC converter 64.
The voltage command outputs of a and the carbon heater 471b are connected to each other.

Then, the DC voltage according to the set value input to the output voltage setting input of the AC-DC converter is output to the DC output side.

Reference numeral 6 is a control means, and a current detection means 65 is input to it.
And a fixing temperature sensor 473 are connected, and the output of the halogen heater 471a and the carbon heater 471b is turned ON / O.
The FF command output is connected to the corresponding current ON / OFF means, and the voltage command output described above is connected to the AC-DC converter.

Reference numerals 661 and 662 denote current ON / OFF means, which are composed of thyristors and relays, and are individually connected between the DC output side of the AC-DC converter 64 and the halogen heater 471a and the carbon heater 471b as described above. The ON / OFF command output from the control means 6 turns ON / OFF the power supply to the halogen heater 471a and the carbon heater 471b.

A fixing heater 471, which is a heating element, is composed of a halogen heater 471a and a carbon heater 471b which is a carbon heating element, and is incorporated in a heating roller of fixing means (not shown).

The halogen heater 471a and the carbon heater 471b are individually connected to the DC output side of the AC-DC converter 64 via the current ON / OFF means 661 and 662 to heat the heating roller 474.

Since the AC power source 90, the fixing temperature sensor 473, the current detecting means 65, and the control power source 70 are the same as those in the first embodiment, their explanations are omitted.

Now that the configuration of the second embodiment has been described, the control method thereof will be described below with reference to FIG.

When the operator of the warm-up process connects the image forming apparatus 1 to the AC power source 90 and turns on a power switch (not shown), the control power source 70 starts to supply power to the control means 6 and the AC-DC converter 64.

The control means 6 determines that it is in the warm-up mode by turning on the power switch.

The control means 6 outputs the same maximum output voltage command value as the voltage command output of the halogen heater and the carbon heater, and simultaneously turns on the ON / OFF command outputs of both the current ON / OFF means 661 and 662 to turn the halogen heater 4 on.
Energization of 71a and carbon heater 471b is started.

As a result, the halogen heater 471a and the carbon heater 471b are heated rapidly with the maximum applied voltage, and the temperature of the heating roller 474 rises sharply.

Further, the control means 6 checks that the total AC current flowing into the image forming apparatus 1 detected by the current detection means 65 is below a preset current value,
When the detected current value is equal to or more than the predetermined current value, the voltage command output value is reduced according to the overcurrent value.

The control means 6 controls the fixing temperature sensor 473.
The temperature of the heating roller 474 is set so that the temperature of the heating roller 474 does not overshoot or hunting significantly. As the temperature gets closer to the temperature, the output voltage command values of the halogen heater and the carbon heater to the AC-DC converter 64 are gradually decreased, and the heat generation amounts of the halogen heater 471a and the carbon heater 471b are gradually decreased to approach the set value of the copy mode. . After the heating roller 474 reaches the fixing temperature, the control means 6 always uses the fixing temperature sensor 473 to heat the heating roller 4
The temperature of the heating roller 74 is detected, and the secondary DC voltage of the halogen heater and the carbon heater of the AC-DC converter 64 is changed so that the temperature of the heating roller becomes substantially constant and the fixing temperature is reached. Control the amount.

Here, in the temperature control of the heating roller 474 in the warm-up mode, the voltage command output of the halogen heater is kept constant and the voltage command output of the carbon heater is changed.
If it still does not meet the deadline (the fixing temperature does not rise or rises too much), the voltage command output of the halogen heater may be raised or lowered by the excess or deficiency.

As another method for controlling the temperature of the heating roller 474 in the warm-up mode, the control means 6 causes the halogen heater of the AC-DC converter 64 and the voltage on the DC output side of the carbon heater to be constant by turning on the power. Fixed to the ON / O of halogen heater and carbon heater
The FF command output is turned ON, the heating roller 474 is heated, and as the temperature of the heating roller 474 approaches the fixing temperature, the ON / OFF command output of the halogen heater remains ON, and the resistance value is high and the inrush current is small at low temperature. The current ON / OFF command output of the carbon heater is output intermittently, and the energization to the carbon heater 471b is controlled by ON / OFF so as to gradually extend the OFF period (PWM control),
Large overshoot and hunting may be prevented, and the halogen heater 471a and the carbon heater 471b may be prevented.
May be controlled by simultaneously turning on / off the current by means of current ON / OFF means.

Both (voltage control by the AC-DC converter 64 and current ON / OFF means 6 by the control means 6)
6 ON / OFF control) may be combined.

The image forming apparatus 1 has a heating roller 474.
Is raised to the fixing temperature (for example, about 200 ° C.), the conditions of the image forming process that are normally performed are set, and the warm-up mode process is completed.

As described above, the fixing heater 471 applies the same voltage in the warm-up mode as in the copy mode.
(Halogen heater 471a and carbon heater 471b)
In comparison with the conventional method of applying to the heating roller 47,
It becomes possible to quickly reach the fixing temperature (approximately 200 ° C.) of No. 4 and at the same time prevent large temperature overshoot and hunting that tend to occur during rapid heating, and perform normal heater ON / OFF control. Even in such a case, the inrush current can be suppressed low by turning the carbon heater ON / OFF, and the warm-up mode can be completed quickly without exceeding the limit current.

Then, the image forming apparatus completes the warm-up step by performing, for example, condition setting of developing conditions of the process.

When the copy mode process control means 6 finishes heating the temperature of the heating roller 474 to the fixing temperature and completes the preparatory operation for making copies such as setting various developing conditions, the mode is changed from the warm-up mode to the copy mode.

When shifting to the copy mode, the operator can start the copy operation from the operation panel (not shown), and the control means 6 carries out the image formation which is normally performed according to the image forming process by the copy start operation.

In the copy mode, a large number of various loads related to image formation are repeatedly turned ON / OFF and the current consumption of the entire image forming apparatus increases significantly. Therefore, the control means 6 copies the voltage command output of the halogen heater and the carbon heater. The mode output voltage is set to lower the DC output side voltage of the AC-DC converter 64, and the power consumption of the halogen heater 471a and the carbon heater 471b is limited in the warm-up process.

Here, the copy mode voltage value refers to the voltage command output value of the control means 6 that causes the temperature of the heating roller to reach the fixing temperature (for example, about 200 ° C.).

The control means 6 sets the total alternating current flowing into the image forming apparatus 1 detected by the current detecting means 65 so that the total alternating current flowing into the image forming apparatus does not exceed a predetermined value. If the detected current value is greater than the set current value, the voltage command output value of the halogen heater and carbon heater is reduced or turned on / off according to the overcurrent value.
The command output is turned off to limit the power consumption of the halogen heater 471a and the carbon heater 471b.

Then, the control means 6 controls the heating roller 474.
The ON / OFF command output of the halogen heater and the carbon heater is fixed to ON so that the temperature of the heating roller 474 is controlled to the fixing temperature, the temperature of the heating roller 474 is constantly detected by the fixing temperature sensor 473, and the temperature of the heating roller 474 is fixed. AC-DC converter 64 so that the temperature (for example, about 200 ° C.) is reached.
The voltage on the DC output side of the halogen heater and the carbon heater in (a) is kept constant for the halogen heater, the carbon heater is changed, and b) the carbon heater is kept constant and the halogen heater is changed, and c) the halogen heater and the carbon heater are changed. The heaters are simultaneously changed to control the heat generation amounts of the halogen heater 471a and the carbon heater 471b.

As another method of controlling the temperature of the heating roller 474 to the fixing temperature, the voltage command output of the AC-DC converter 64 of the halogen heater and the carbon heater is fixed to the voltage value of the copy mode, and the fixing temperature sensor 473 is always provided.
Detects the temperature of the heating roller 474,
The halogen heater of the current ON / OFF means and the ON / OFF command output of the carbon heater so that the temperature becomes the fixing temperature (eg, about 200 ° C.), a) the halogen heater is turned ON.
Alternatively, the carbon heater may be turned on / off and b) or the halogen heater and the carbon heater may be turned on / off to control the heat generation amounts of the halogen heater 471a and the carbon heater 471b.

Voltage control by the AC-DC converter 64 and ON / OFF by the current ON / OFF means 66.
Controls may be combined. Specifically, for example, the fixing temperature sensor 473 constantly detects the temperature of the heating roller 474,
The temperature of the heating roller 474 is the fixing temperature (for example, about 200).
Temperature of the halogen heater of the AC-DC converter 64 and the voltage on the DC output side of the carbon heater are kept constant, the carbon heater is changed, and at the same time, the halogen heater of the current ON / OFF means and the carbon heater are turned ON. Alternatively, the halogen heater may be turned on and the carbon heater may be turned on / off to control the heat generation amounts of the halogen heater 471a and the carbon heater 471b.

As described above, for example, even if the size of the copy paper is different and the sequence is slightly deviated and the start timing of the motor or the like is deviated, the total inflow current is detected and the heating current of the fixing means is controlled by the value. Therefore, the total AC current flowing into the image forming apparatus does not exceed the limit value set in the power limit rule, etc., and if necessary, a precise temperature control can be performed by combining the heating roller control methods. It is possible to stably maintain the heating roller at the fixing temperature.

The low power mode process control means 6 shifts to the low power mode for energy saving if the copy operation is not performed for a predetermined time (for example, 15 minutes).

When shifting to the low power mode, the control means 6 sets the voltage designation outputs of the halogen heater and the carbon heater to the low power mode voltage value in order to save power, and AC-
The DC output side voltage of the DC converter 64 is lowered to limit the power consumption of the halogen heater 471a and the carbon heater 471b in the copy mode.

Here, the low power mode voltage value refers to the voltage command output value of the control means such that the temperature of the heating roller becomes 50 to 100 ° C., for example.

Then, the control means 6 fixes the ON / OFF command output of the halogen heater and the carbon heater to ON,
The fixing temperature sensor 473 constantly detects the temperature of the heating roller 474, and the DC output side voltages of the halogen heater and the carbon heater of the AC-DC converter 64 are adjusted so that the temperature of the heating roller 474 becomes a constant temperature (for example, about 100 ° C.). Halogen heater 471a and carbon heater 471b
It is controlled to reduce the heat generation amount.

Here, as another control method of the temperature of the heating roller in the low power mode, the control means 6 uses AC-
The voltage command output of the halogen heater and the carbon heater of the DC converter 64 is maintained at the low power mode voltage value, and the output from the fixing temperature sensor 473 is compared with a preset low power temperature (for example, about 100 ° C.). If the output is high, both the halogen heater and the carbon heater or the ON / OFF command output of the carbon heater from the control means 6 are turned OFF and the corresponding current ON / OFF means is turned ON.
FF, AC-DC converter to halogen heater 4
Power to both 71a and the carbon heater 471b or the carbon heater is turned off.

If the output from the fixing temperature sensor 473 is low, both the halogen heater and the carbon heater or the ON / OFF command output of the carbon heater from the control means 6 are turned on.
Set to N and turn ON the corresponding current ON / OFF means,
Power is supplied from the C-DC converter to both the halogen heater 471a and the carbon heater 471b or to the carbon heater.

In this manner, the temperature of the fixing roller may be kept substantially constant by repeating ON / OFF of energization of the halogen heater 471a and the carbon heater 471b.

Further, voltage control by the AC-DC converter 64 and ON / OFF by the current ON / OFF means 66.
Controls may be combined. Specifically, for example, the fixing temperature sensor 473 constantly detects the temperature of the heating roller 474,
The temperature of the heating roller 474 is the fixing temperature (for example, about 100).
Temperature of the halogen heater of the AC-DC converter 64 and the voltage on the DC output side of the carbon heater are kept constant, the carbon heater is changed, and at the same time, the halogen heater of the current ON / OFF means and the carbon heater are turned ON. Alternatively, the halogen heater may be turned on and the carbon heater may be turned on / off to control the heat generation amounts of the halogen heater 471a and the carbon heater 471b.

As described above, the power consumption can be saved by lowering the temperature of the fixing heater.

Return Mode Process When the operator performs a copy start operation from an operation panel (not shown) during the low power mode, the control unit determines that the return mode is set, and the heating is performed to return from the low power mode to the copy mode. The temperature of the roller 474 is changed from a low power temperature (for example, about 100 ° C.) to a fixing temperature (for example, 20
The fixing heater is heated to raise the temperature to 0 ° C.

The control means 6 outputs the same maximum output voltage command value as the voltage command output of the halogen heater and the carbon heater, and simultaneously turns on the ON / OFF command outputs of both the current ON / OFF means 661 and 662 to turn the halogen heater 4 on.
Energization of 71a and carbon heater 471b is started.

As a result, the halogen heater 471a and the carbon heater 471b are rapidly heated with the maximum applied voltage, and the temperature of the heating roller 474 rises sharply.

Further, the control means 6 checks that the total AC current flowing into the image forming apparatus 1 detected by the current detection means 65 is less than or equal to a predetermined current value set in advance,
When the detected current value is equal to or more than the predetermined current value, the voltage command output value is reduced according to the overcurrent value.

The control means 6 uses the fixing temperature sensor 473.
The temperature of the heating roller 474 is set so that the temperature of the heating roller 474 does not overshoot or hunting significantly. As the temperature gets closer to the temperature, the output voltage command values of the halogen heater and the carbon heater to the AC-DC converter 64 are gradually decreased, and the heat generation amounts of the halogen heater 471a and the carbon heater 471b are gradually decreased to approach the set value of the copy mode. . After the heating roller 474 reaches the fixing temperature, the control means 6 always uses the fixing temperature sensor 473 to heat the heating roller 4
The temperature of the heating roller 74 is detected, and the DC output voltage of the halogen heater and the carbon heater of the AC-DC converter 64 is changed so that the temperature of the heating roller is substantially constant and the fixing temperature is reached, so that the halogen heater 471a and the carbon heater 471b generate heat. Control the amount.

Here, in the temperature control of the heating roller 474 in the return mode, the voltage command output of the halogen heater is kept constant,
If the voltage command output of the carbon heater is changed and it is still too late (the fixing temperature does not rise or rises too much), the voltage command output of the halogen heater may be raised or lowered by the excess or deficiency.

Then, as another method for controlling the temperature of the heating roller 474 in the return mode, the control means 6 makes the voltage of the halogen heater of the AC-DC converter 64 and the DC output side of the carbon heater constant by turning on the power. Fixed,
The ON / OFF command output of the halogen heater and the carbon heater is turned ON, the heating roller 474 is heated, and as the temperature of the heating roller 474 becomes closer to the fixing temperature, the ON / OFF command output of the halogen heater remains ON, and when the temperature is low. Carbon heater current O with high resistance and low inrush current
The carbon heater 47 is configured to output the N / OFF command output intermittently and gradually extend the OFF period (PWM control).
The energization to 1b may be controlled to be turned on / off to prevent large overshoot or hunting, and the halogen heater 471a and the carbon heater 471b may be turned on / off.
You may control by turning on / off simultaneously by FF means.

Both (voltage control by the AC-DC converter 64 and current ON / OFF means 6 by the control means 6)
6 ON / OFF control) may be combined.

The image forming apparatus 1 has a heating roller 474.
Is raised to the fixing temperature (for example, about 200 ° C.) to complete the return mode process.

Then, the image forming apparatus completes the restoration process and is ready for copying. As described above, according to the present invention, the temperature of the heating roller 474 is set faster than the conventional method in which the same voltage as in the copy mode is applied to the fixing heater 471 (halogen heater 471a and carbon heater 471b) in the return mode. (About 200 ° C.) can be achieved, and at the same time, large temperature overshoot and hunting that tend to occur during rapid heating can be prevented, and the carbon heater can be turned on / off even when performing normal heater ON / OFF control. By turning off, the inrush current is suppressed low, and the return mode can be completed quickly without exceeding the limit current.

[0124]

According to the present invention, the following effects can be obtained, that is, the total AC current flowing into the image forming apparatus is in accordance with the power restriction rule even if the size of copy paper used is different. The heating current of the fixing means can be heated to a predetermined temperature in a short time without exceeding the predetermined peak current consumption (1.5 kW / 15 A) or more, and the warm-up time and the recovery mode time can be shortened. Precise temperature control is also possible by combining control methods, and the heating roller can be stably maintained at the fixing temperature. For example, stable fixing is possible without the occurrence of an offset phenomenon in which some toner adheres to the roller. Is possible.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an image forming apparatus showing one embodiment of the present invention.

FIG. 2 is a block diagram showing a first embodiment.

FIG. 3 is a heating roller temperature chart.

FIG. 4 is a block diagram showing a second embodiment.

[Explanation of symbols]

6 Control means 47 Fixing means 64 AC-DC converter 65 Current detection means 70 Control power supply 90 AC power supply 471 Fixing heater (heating element) 471a halogen heater 471b carbon heater 473 Fixing temperature sensor 475 pressure roller 661, 662 current ON / OFF means

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H05B 3/00 H05B 3/00 335 335 G03G 21/00 372 (72) Inventor Hiroyuki Watanabe Ishikawa, Hachioji, Tokyo Machi 2970, Konica Stock Company (72) Inventor Watanabe Masayuki Kagawa, 2970 Ishikawa Town, Hachioji, Tokyo Konica Stock Company (72) Inventor Soma Umin, 2970 Ishikawa Town, Hachioji, Tokyo F Term, Konica Stock Company (Reference) 2H027 DA32 DA35 DE04 DE07 EA12 EA15 EC06 EC07 EC18 ED25 EE01 EE07 EF04 ZA07 2H033 AA09 AA30 BA24 BA25 BB18 BB28 CA03 CA04 CA05 CA07 CA23 CA28 CA30 CA45 CA48 CA01 CA22 CA06 CA12 CA02 CA01 CA22 CA04 CA12 CA22 CA04 CA12 CA22 CA04 CA12 CA22 CA04 CA01 CA22 CA04 CA12 CA22 BB04 CA08 CB04 CB42 DA02 DB01 DB06 EE03 EE04 FF01 GG04 HH02 KK05 LL20 MM02 MM06 MM20

Claims (12)

[Claims] 1. An image forming apparatus including a fixing unit having a heating roller heated by a heating element, wherein the heating element is connected to a DC output side of an AC-DC converter having a variable output voltage, and the AC-DC is connected. An image forming apparatus characterized in that an external AC power source is connected to the AC primary side of the converter, and the temperature of the heating roller is controlled by changing the voltage on the DC output side of the AC-DC converter. . 2. A current detection means for detecting an inflowing alternating current and a fixing temperature sensor for detecting a temperature of the heating roller are connected to inputs, and an output voltage command output is output to an output voltage setting input of the AC-DC converter. The image forming apparatus according to claim 1, further comprising a control unit that is connected. 3. An ON / OFF command output which has a current ON / OFF unit between the DC output side of the AC-DC converter and the heating element, and turns ON / OFF the current ON / OFF unit of the control unit. Is connected to current ON / OFF means, and the control means turns ON / O of current to the heating element.
The image forming apparatus according to claim 2, wherein the image forming apparatus is configured to perform FF control. 4. A plurality of heating elements, each of which is individually connected to the direct current output side of the AC-DC converter via the current ON / OFF means, and the control means controls the current ON. And a plurality of ON / OFF command outputs for turning ON / OFF the ON / OFF means, which are individually connected to the plurality of current ON / OFF means, and the control means individually controls the temperature of the plurality of heating elements. The image forming apparatus according to claim 3, wherein: 5. The image forming apparatus according to claim 4, wherein the plurality of heating elements are carbon heaters including a halogen heater and a carbon-based heating element. 6. A fixing unit composed of a heating roller heated by a carbon heater composed of a halogen heater and a carbon-based heating element, and electric power supplied to each of the halogen heater and the carbon heater via a current ON / OFF unit. In an image forming apparatus provided with an AC-DC converter whose voltage on the DC output side supplying the variable voltage is variable and a control means for controlling at least the temperature of the heating roller, the control means controls the alternating current flowing into the image forming apparatus. A current detection unit for detecting and a fixing temperature sensor for detecting the temperature of the heating roller are connected to the inputs, and the control unit controls the ON / OFF of the current.
A plurality of ON / OFF command outputs for turning ON / OFF the OFF means are individually connected to the current ON / OFF means, and an output voltage command output for changing the voltage on the DC output side of the AC-DC converter is used as the AC-DC. An image forming apparatus, which is connected to an output voltage setting input of a converter. 7. A fixing unit having a heating roller heated by a heating element, wherein the heating element is connected to a DC output side of an AC-DC converter whose output voltage is variable through a current ON / OFF unit, In the image forming apparatus in which the output of the control means is connected to the input of the AC-DC converter,
According to the output of the control means, the output voltage on the DC output side of the AC-DC converter is changed, the applied voltage of the heating element is changed, and the temperature of the heating roller is controlled to rise and fall. A method for controlling an image forming apparatus. 8. The control means determines the current operation mode of the image forming apparatus, and when the warm-up mode and when returning from the low power mode to the copy mode, the output is increased from the output in the copy mode. The output voltage on the DC output side of the AC-DC converter is increased from that in the copy mode to increase the amount of heat generated by the heating element, and the heating roller is controlled to reach a predetermined temperature in a short time. The method for controlling an image forming apparatus according to claim 7. 9. The inflowing AC current when the detected current value from the current detection unit for detecting the AC current flowing into the image forming apparatus is larger than the preset current value in each mode set in advance. In order to reduce the output current to less than the set current value in each mode, the output voltage of the DC output side of the AC-DC converter is reduced, and the current consumption of the heating element is controlled to be reduced. A method for controlling an image forming apparatus according to item 1. 10. The controller controls the temperature of the heating roller when the detected temperature value from a fixing temperature sensor for detecting the temperature of the heating roller is higher than the set temperature value in each preset mode. In order to lower the temperature below the set temperature in each mode, the output voltage of the DC output side of the AC-DC converter is reduced to reduce the heat generation amount of the heating element, and the heating is performed when the temperature is lower than the set temperature value in each mode. 8. To raise the temperature of the roller to a temperature not lower than the set temperature in each mode, the output voltage on the DC output side of the AC-DC converter is raised to control the heating amount of the heating element. Alternatively, the image forming apparatus control method according to Item 9. 11. A fixing unit having a heating roller heated by a heating element, wherein the heating element is a current ON / OFF.
In the image forming apparatus, the output of the control means is connected to the DC output side of the AC-DC converter whose output voltage is variable via the means, and the output of the control means is connected to the input of the AC-DC converter. The output voltage on the DC output side of the AC-DC converter is changed, the applied voltage of the heating element is changed to control the temperature of the heating roller to rise and fall, and the current is output according to another output of the control means. The temperature of the heating roller is controlled by a combination of the voltage applied to the heating element and the ON / OFF of the current ON / OFF means so as to raise or lower the temperature of the heating roller by turning ON / OFF the ON / OFF means. And a method for controlling an image forming apparatus. 12. A fixing means having a heating roller heated by a carbon heater composed of a halogen heater and a carbon-based heating element is provided, and the halogen heater and the carbon heater have individually variable output voltages via current ON / OFF means. In an image forming apparatus connected to the DC output side of an AC-DC converter and having the output of the control means connected to the input of the AC-DC converter, the AC-DC of the control means
The output voltage on the DC output side of the converter is changed to change the output voltage on the DC output side of the AC-DC converter corresponding to the halogen heater and the carbon heater, and the applied voltage to the halogen heater and the carbon heater is changed. The temperature of the heating roller is controlled so as to rise and fall, and the current ON / OFF means corresponding to the halogen heater and the carbon heater is controlled in accordance with the output of the control means for turning on / off the current ON / OFF means. The temperature of the heating roller is controlled by a combination of voltage applied to the halogen heater and carbon heater and ON / OFF of the current ON / OFF means so that the temperature of the heating roller is raised or lowered by turning it ON / OFF. Method for controlling an image forming apparatus.