JP3455384B2 - Fixing device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device used in an image forming apparatus such as a copying machine, a facsimile, a printer and the like.

[0002]

2. Description of the Related Art A fixing device used in an image forming apparatus such as a copying machine, a facsimile or a printer has a plurality of heating means for fixing a toner image on a sheet and a plurality of the fixing means. A plurality of temperature detecting means for respectively detecting the temperatures of a plurality of portions corresponding to the heating means, and a control for independently controlling the plurality of heating means based on the temperature detection signals of the plurality of temperature detecting means. Some have means.

Japanese Patent Publication No. 6-73053 discloses that
A fixing roller having a plurality of heating means and a pressure roller are brought into pressure contact with each other, and the recorded transfer paper is passed only between these rollers to fix the toner on the transfer paper by pressure and heating. A plurality of heating means are controlled based on a detection signal of one temperature detecting means for detecting the temperature of the fixing roller, and when the temperature of the fixing roller does not reach a predetermined set temperature, the plurality of heating means are simultaneously driven to fix the fixing roller. A fixing device for maintaining the temperature of the roller at a predetermined set temperature is described.

[0004]

Due to the EU (European Union) market integration since January 1993, uniform safety requirements are applied to products in the EC (Europe) market, and manufacturers are There is an obligation to sell only safe products in the EC market. The safety protection standards for application to the EC market are stipulated in the EC directive, harmonized national standard, and harmonized domestic law for each product. CE marking is mandatory for manufacturers to declare that their products comply with the applicable EC directives, and through CE markings, conformity with the protection standards applied in the directives of products. Proves sex.

EMC (Electr) in the EC command
The electromagnetic compatibility (electromagnetic compatibility) directive includes EMI (Electronic Compatibility)
magnetic interference (electromagnetic interference) standard and EMS (Electromagnetic)
Susceptibility: electromagnetic wave sensitivity) standards, and IEC standards and EN for measurement methods and regulation values.
It is defined by the standard.

[0006] Among the EMC commands, a power supply voltage fluctuation test (peripheral lighting may flicker due to frequently repeated voltage fluctuations, and people may feel uncomfortable. This state is called a flicker state, and the flicker state is measured. The measured values are regulated.) And harmonic current tests (OA equipment that uses an inverter, air conditioners, etc. increase the outflow of harmonic current to the power supply line, which may cause a fire accident or power factor decrease in the power receiving equipment. The harmonic current value is regulated in order to suppress the decrease in the efficiency of power transmission equipment.) Unlike other test items, measures and suppression have not been taken so far, so There is an urgent need to take measures and control.

[0007] Further, these have been determined not only in EC countries but also in Japan, and there is no doubt that they will be legally regulated in countries all over the world. Furthermore, in recent years, due to the complicated control of electrophotographic processes and the use of high-power heating devices, current fluctuations in products have become larger than in the previous year, and noise, power supply voltage fluctuations, and harmonic currents that have occurred are increasing. There is concern about the effects of device malfunction or failure due to the intrusion of other electronic devices in the vicinity. Moreover, safety standards and legal regulations against noise are becoming stricter, and countermeasures and suppressions are also required.

In particular, a fixing device using a heating means having a heating element with a large power consumption consumes a power supply voltage fluctuation test due to the operation of the heating means. This condition is called the flicker condition, and the measured value of the flicker condition is regulated.)
It is difficult to achieve the standard value.

In the fixing device described in Japanese Patent Publication No. 6-73053, a plurality of heating means are controlled on the basis of the detection signal of one temperature detecting means for detecting the temperature of the fixing roller. Driven at the same time often causes a sudden inrush current, resulting in a significant fluctuation in the voltage applied to the power supply. SUMMARY OF THE INVENTION It is an object of the present invention to provide a fixing device capable of attaining a standard value with sufficient reduction / suppression effects on power supply voltage fluctuations.

[0010]

In order to achieve the above object, the invention according to claim 1 has a fixing means for fixing a toner image on a sheet having a plurality of heating means, and the plurality of fixing means in the fixing means. A plurality of temperature detecting means for respectively detecting the temperatures of a plurality of portions corresponding to the respective heating means, and the plurality of heating means are independently controlled based on the temperature detection signals of the plurality of temperature detecting means. A fixing device having a control means for controlling the power consumption of the one heating means except the one heating means other than one of the plurality of heating means. In the standby mode, the temperature of the portion heated by the one heating means is maintained at the target fixing temperature ,
In both cases of fixing and preheating, the one heating means
The power is set so that the time of continuous lighting becomes long , and a sufficient reduction / suppression effect on fluctuations in the power supply voltage can be obtained and the standard value can be achieved.

According to a second aspect of the present invention, the fixing means for fixing the toner image on the sheet having a plurality of heating means, and the temperature of a plurality of portions of the fixing means corresponding to the plurality of heating means are set. A fixing device having a plurality of temperature detecting means for respectively detecting and a control means for independently controlling the plurality of heating means based on the temperature detection signals of the plurality of temperature detecting means. Except at least when the paper passes through the fixing means, the other heating means except at least one heating means among the plurality of heating means are in the non-lighting state, and the power consumption of the one heating means is reduced. , 1 in the fixing means
The temperature of the heating location by the two heating means is maintained at the target fixing temperature to the utmost limit, and the temperature is maintained during standby, during fixing, or during preheating.
Even if the one heating means is continuously lit,
The power is set so that the power supply voltage becomes low, and a sufficient reduction / suppression effect can be obtained for fluctuations in the power supply voltage.

According to a third aspect of the present invention, the fixing means for fixing the toner image on the sheet having a plurality of heating means, and the temperatures of a plurality of portions of the fixing means corresponding to the plurality of heating means are set. A fixing device comprising a plurality of temperature detecting means for detecting the temperature and a control means for independently controlling the plurality of heating means based on the temperature detection signals of the plurality of temperature detecting means. A mode is provided in which one of the heating means other than the one having low power consumption is turned off, and the power consumption of the one heating means is heated by the one heating means in the fixing means. The temperature of the spot is maintained at the target fixing temperature, and it can be used in any of standby, fixing, and preheating.
In the case of the above, the time when the one heating means is continuously lit is long
The electric power is set so that the power supply voltage fluctuation can be sufficiently reduced and suppressed.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a fixing roller and a control system of an embodiment of the invention according to claims 1 and 2. A fixing roller (not shown) is pressed against the fixing roller 1 by pressing means,
The fixing roller 1 and the pressure roller are rotationally driven by a drive source. The fixing roller 1 and the pressure roller constitute a fixing unit, and a sheet (recording sheet) carrying a toner image is a fixing roller 1.
The toner image on the paper is fixed on the paper by heating and pressing at the time of fixing which passes through the nip portion of the pressure roller. The fixing roller 1 includes heating means 2 and 3 including two heaters inside.
The heater 2 is arranged at the center of the fixing roller 1 and the heater 3 is arranged at the end of the fixing roller 1.

One ends of the heaters 2 and 3 are connected to one side of the AC power source 14 via a normally open contact RA1-a of the relay RA1, and between the other ends of the heaters 2 and 3 and the other side of the AC power source 14. Switch elements 4 and 5 each made up of a triac are connected to each. The triacs 4 and 5 are driven by the control drivers 6 and 7, and the control driver 6 and
7 is a CPU (microcomputer) as a control means
On / off control is performed by 8. The coil of the relay RA1 is connected between the DC 24V power source and the ground via the transistor 12, and the driver 11 is controlled by the CPU 8 to turn on / off the transistor 12 to turn on / off the relay RA1.

Therefore, when the relay RA1 is in the ON state and the triacs 4 and 5 are turned on, electric power is supplied from the AC power supply 14 to the heaters 2 and 3 via the triacs 4 and 5 so that the heaters 2 and 3 are turned on ( Then, the central portion and the end portion of the fixing roller 1 are heated by the heaters 2 and 3, respectively.
A sheet carrying a toner image is passed between the fixing roller 1 and the pressure roller, and the fixing roller 1 and the pressure roller fix the toner image on the sheet by heating and pressing.

Temperature detecting elements 9 and 10 formed of thermistors
Are arranged in contact with the outer peripheral surfaces of the central portion and the end portion of the fixing roller 1, and detect the temperatures of the central portion and the end portion heated by the heaters 2 and 3 in the fixing roller 1, respectively. The temperature detection signals from the thermistors 9 and 10 are CP
Input to U8. The CPU 8 converts the analog temperature detection signals from the thermistors 9 and 10 into digital signals and obtains temperature data of the central portion and the end portions of the fixing roller 1 by a program.

The CPU 8 controls the triac 4 via the control driver 6 based on the temperature of the central portion of the fixing roller 1 detected by the thermistor 9 to control the turning on / off of the heater 2, and the thermistor 10 detects it. Based on the end temperature of the fixing roller 1, the triac 5 is controlled via the control driver 7 to control the turning on / off of the heater 3.
Therefore, the heater 2 corresponds to the central temperature of the fixing roller 1.
Is turned on / off, and the heater 3 is turned on / off according to the end temperature of the fixing roller 1.

Further, the CPU 8 receives a detection signal from the cover switch 13 for detecting whether or not the main body cover of the image forming apparatus equipped with the fixing device of the present embodiment, for example, a copying machine is opened, and the main body cover is opened. When opened, the driver 11 is turned off and the transistor 12 is turned off to turn off the relay RA1, and when the body cover is closed, the driver 11 is turned on to turn on the transistor 1.
By turning on 2, the relay RA1 is turned on.
Therefore, the heaters 2 and 3 are not turned on when the main body cover is opened.

Next, the heat generation control of this embodiment will be described. In the present embodiment, when the heaters 2 and 3 are respectively turned on / off, the heater 2 is turned on / off when the main body cover of the copying machine in which the fixing device of the present embodiment is mounted is opened and when the paper is fed. Except when the copying machine is abnormal such as when a jam occurs, when the power is on, the CPU 8 always controls the turning on / off of the heater 2 according to the central temperature of the fixing roller 1 detected by the thermistor 9. .

The CPU 8 controls the turning on / off of the heater 3 according to the end temperature of the fixing roller 1, and controls the turning on / off of the heater 3 at the time of raising the fixing temperature immediately after the power is turned on. The control for turning off the heater 3 is performed in a state other than the copying operation of the copying machine.

The lighting / extinguishing control of the heaters 2 and 3 will be described below with reference to the flow charts shown in FIGS. It should be noted that when the main body cover of the copying machine equipped with the fixing device according to the present embodiment is opened or when the copying machine is abnormal such as when a paper jam occurs, the CPU 8 turns off the driver 11 and turns off the transistor 12 to cause the relay RA1. Is turned off to cut off the energization of the AC power supply 14.

FIG. 2 shows a lighting / extinguishing control flow of the heater 2 in this embodiment. The CPU 8 detects the temperature detection signal from the thermistor 9 so that the center temperature of the fixing roller 1 is (target temperature M-3 ° C) or less (the center temperature of the fixing roller 1 ≤ (target temperature M-3 ° C)). It is determined whether or not the central temperature of the fixing roller 1 is (target temperature M-3 ° C.).
If the following is true, the triac 4 is passed through the control driver 6.
Is turned on to turn on the heater 2. Also, the CPU 8
Is the center temperature of the fixing roller 1 (target temperature M-3 ° C.)
If not, the temperature detection signal from the thermistor 9 determines whether the central temperature of the fixing roller 1 has reached the target temperature M (the central temperature of the fixing roller 1 ≧ the target temperature M), The central temperature of the fixing roller 1 is the target temperature M.
When it reaches, the triac 4 is turned off via the control driver 6 and the heater 2 is turned off.

Therefore, the CPU 8 always keeps the central temperature of the fixing roller 1 at the target temperature (target temperature) when the power is on, except when the copying machine is abnormal such as when the main body cover is opened or when a paper jam occurs. M-3 ℃) or less, heater 2
Is turned on to heat the central portion of the fixing roller 1, and when the central portion temperature of the fixing roller 1 reaches the target temperature M, the heater 2 is turned off.

FIG. 3 shows a lighting / extinguishing control flow of the heater 3 in this embodiment. The CPU 8 has a heater 3 extinguishing mode, which is a feature of this embodiment, in the lighting / extinguishing control of the heater 3. Basically, the turning on / off control of the heater 3 is common to the turning on / off control of the heater 2 except for the judgment and processing as can be seen from FIG.

The judgment and the processing are to control the turning on / off of the heater 3 according to the temperature of the end portion of the fixing roller 1 at the same time as the heater 2 at the time of rising of the fixing temperature and during the image forming operation (copying operation). This is a judgment processing part for forcibly turning off the heater 3 regardless of the end temperature of the fixing roller 1 except after the fixing temperature is raised and during the copying operation.

In the judgment, the CPU 8 checks the copying operation state of the copying machine, and if the copying operation is being performed, the CPU 8 performs the same lighting / lighting-off control of the heater 2 as shown in FIG. The control shifts to "A". CPU8
In the control of "A", the end temperature of the fixing roller 1 is (target temperature S-3 by the temperature detection signal from the thermistor 10).
C.) or less (end portion temperature of fixing roller 1 ≤ target temperature S
-3 ° C.), and if the end temperature of the fixing roller 1 is (target temperature S−3 ° C.) or less, the triac 5 is turned on via the control driver 7 and the heater 3 is turned on. Let

When the end temperature of the fixing roller 1 is not lower than (target temperature S-3 ° C.), the CPU 8 receives the temperature detection signal from the thermistor 10 and the end temperature of the fixing roller 1 reaches the target temperature S. It is determined whether (the end temperature of the fixing roller 1 ≧ the target temperature S), and if the end temperature of the fixing roller 1 reaches the target temperature S, the triac 5 is turned off via the control driver 7. To turn off the heater 3.

If the copying operation is not in progress, the CPU 8 shifts to the control of "B" shown in FIG. 3 in order to forcibly turn off the heater 3. In the control of "B", the CPU 8 checks the heater 3 rising flag to determine whether or not the fixing temperature rising process of the fixing roller 1 by the heater 3 is completed by the judgment, and the heater 3 rising flag is turned off. If so, it is determined that the fixing temperature rising processing of the fixing roller 1 has not been completed, and the control returns to "A".
Therefore, before the fixing temperature of the fixing roller 1 rises, the heater 3 is controlled to be turned on / off like the heater 2 except during the copying operation. The CPU 8 turns off the heater 3 rising flag when the power is turned on.

Therefore, in the process C of turning off the heater 3 in the control of "A", the CPU 8 will reach the target temperature S if the end temperature of the fixing roller 1 reaches (the end temperature of the fixing roller 1 ≧ the target temperature S). If so, since the triac 5 is turned off and the heater 3 is turned off via the control driver 7,
Here, it is considered that the fixing temperature raising process of the fixing roller 1 by the heater 3 is completed, and the heater 3 rising flag is turned on.

When the power is turned on, the heater 3 is controlled as described above. However, when the end temperature of the fixing roller 1 reaches the target temperature S and the heater 3 rising flag is turned on, the CPU 8 turns on. The control for turning off the heater 3 is always performed except during the copying operation.

In this embodiment, at least one heating means 2 is provided without turning on / off the plurality of heating means 2 and 3 at once.
Except for the above, the other heating means 3 is put in a non-lighting mode while the machine is on standby (without fixing operation, the heating means is on standby to control the fixing temperature to the same target temperature as the fixing operation). A) and preheating (when the heating means is controlled so that the fixing temperature becomes a target temperature lower than that during the fixing operation without performing the fixing operation) as the lighting mode of the heating means, a sudden inrush current is generated. By reducing the occurrence of voltage fluctuations applied to the power supply and reducing the voltage fluctuations (physical quantity) to flicker (perceptual quantity), the flicker value Pst (short Time flicker value: standard value 1.0 or less),
A sufficient reduction / suppression effect for Plt (long-term flicker value: standard value of 0.65 or less) can be obtained.

In order to confirm the actual effect, the fluctuation of the power supply voltage was measured. As a result, in the conventional fixing device, Pst was 1.453 and Plt was 1.371 during standby and preheating.
However, in the present embodiment, P
Since st was 0.616 and Plt was 0.603, there was an effect of reducing or suppressing the power supply voltage fluctuation by about 50% or more, and the standard value could be achieved.

Further, it is necessary to supply electric power to a plurality of heating means at the time of copying operation, but at the time of standby and preheating, even if the electric power supplied to the heating means is about several tens W, the fixing roller is sufficient. It is possible to maintain the surface temperature of No. 1 without lowering, and there is no problem even if at least one heating unit 2 other heating unit 3 is in a non-lighting state.

In the present embodiment, at least in the fixing temperature control at the time of standby and preheating except when the recording paper passes through the fixing means composed of the fixing roller and the pressure roller (other than the rising of the fixing temperature and the copying operation). , Heaters 2, 3
By reducing the number of times the power supply is turned on / off, fluctuations in the power supply voltage are suppressed. For example, the target fixing temperature during standby and during copying operation (during fixing) is set to 185
C., the target fixing temperature during preheating is 145.degree. C., and the fixing temperature range sufficient for fixing the toner image on the recording paper by the fixing means is 165.degree. C. to 190.degree. Although a plurality of heaters are independently controlled according to the information from the means to maintain the fixing temperature at 185 ° C., in the present embodiment, all parts heated by the heaters 2 and 3 are 185 ° C. during standby. Even if it is not necessary, the number of heaters 2 which is as small as possible is controlled so that only the heating portion thereof has a temperature of 185 ° C. and the other heaters 3 are turned off.

Therefore, in the conventional fixing device, the number of times each heater is turned on becomes frequent during standby, and the number of times the power supply voltage fluctuates increases. However, in this embodiment, the number of times the heater is turned on / off is reduced during standby. Therefore, the number of times the power supply voltage fluctuates can be suppressed. This can reduce the number of times the heaters are turned on / off as in the case of standby only during the preheating only by the target fixing temperature of 145 ° C., and the number of times the power supply voltage fluctuates can be suppressed. At the time of fixing (during copying operation), the optimum heater of the plurality of heaters for heating the fixing means is turned on in consideration of the size of the recording paper to be used and whether or not continuous fixing is performed. It is also possible to provide a mode in which the other heaters are turned off.

Further, as another countermeasure, a transformer, a filter circuit (LCR circuit) and the like are added to increase the number of countermeasure parts, and the space for mounting the countermeasure parts is increased to increase the size and weight of the product and increase the cost. It was possible to achieve the standard value with respect to fluctuations in the power supply voltage without incurring.

By the way, in a fixing device such as a copying machine, particularly when a halogen heater is used as a plurality of heating means, the current consumption during standby and preheating is low (domestic and North American ones: 0.5 A or less, European ones). The current consumption during the copying operation is higher than that of domestic products (0.2A or less) (domestic and North American products: 12-15A, European products: 6-8).
A is about 30 times).

Further, in the heating means such as a halogen heater, the inrush current flows about 10 to 15 times as much as the normal current, so that when the copying operation state is suddenly switched from the standby state and the preheating state to the copying operation state, the consumption current is increased. However, it goes without saying that the power supply voltage fluctuation will change significantly. However, the electric power is required for the plurality of heating means at the time of copying operation, and the electric power of the heating means at the time of standby and at the time of preheating can be sufficiently coped with until the recording paper passes through the fixing means.

In the present embodiment, the CPU 8 turns off the heater 3 except when the fixing temperature rises and during the copying operation. However, in a copying machine using a fixing device having a heating means having a small heat capacity, the fixing roller and the heating roller are added during the copying operation. The surface temperature of the fixing roller may be remarkably lowered due to the sheet passing through the fixing unit including the pressure roller. In such a copying machine, it is necessary to heat the fixing roller by a plurality of heating means during the standby immediately after the completion of the copying operation.
In another embodiment of the invention according to claim 2, in the embodiment of the invention according to claims 1 and 2, whether or not to forcibly turn off the heater 3 is determined by determining the power consumption during standby of the copying machine. It is judged whether or not it is in the "preheating state" to be reduced (a state in which processing such as turning off the display of the operation section or lowering the target temperature of the fixing temperature of the heating means) is performed.
The heater 3 is forcibly extinguished (heater 3 extinction mode) only during preheating.

As described above, the above-described embodiment is an embodiment of the invention according to claim 1, and has the heaters 2 and 3 as a plurality of heating means and fixes the toner image on the sheet. And fixing means composed of a pressure roller, and temperature detecting means 9 and 10 composed of a plurality of temperature detecting elements for respectively detecting temperatures of a plurality of portions corresponding to the plurality of heating means 2 and 3 in the fixing means. In the fixing device having the CPU 8 as the control means for independently controlling the plurality of heating means 2 and 3 based on the temperature detection signals of the plurality of temperature detection means 9 and 10, the plurality of heating means 2 are provided. Since a mode (heater 3 extinguishing mode) in which the heating means 3 other than at least one of the heating means 2 out of 3 is in the non-lighting state is provided, the effect of sufficient reduction / suppression to the power supply voltage fluctuation can be obtained. It is able to achieve the standard values. In addition, an increase in the number of countermeasure parts due to the addition of transformers, filter circuits (LCR circuits), etc., which are considered as other countermeasures
The standard value can be achieved with respect to power supply voltage fluctuations without increasing the size and weight of the product due to the increase in the space for mounting the countermeasure parts and increasing the cost.

Further, the above-described embodiment is an embodiment of the invention according to claim 2, which has heaters 2 and 3 as a plurality of heating means and has the fixing roller 1 and the fixing roller 1 for fixing the toner image on the sheet. The fixing means including a pressure roller, the temperature detecting means 9 and 10 including a plurality of temperature detecting elements for respectively detecting the temperatures of a plurality of portions of the fixing means corresponding to the plurality of heating means 2 and 3, and the plurality of temperature detecting means 9 and 10. C as a control means for independently controlling the plurality of heating means 2 and 3 based on the temperature detection signals of the individual temperature detection means 9 and 10.
In the fixing device having the PU 8, the control means 8 does not turn on the other heating means 3 except at least one heating means 2 among the plurality of heating means 2 and 3 except at least when the sheet passes through the fixing means. For example, at the time of standby and preheating, the other heating means 3 except at least one heating means 2 are set in the non-lighting state, and at least one sheet is supplied from the start of the copying operation to immediately before the sheet passes the fixing means. The other heating means 3 other than the heating means 2 are turned off, and a plurality of heating means 2, 3 are turned on from the time when the sheet passes through the fixing means, thereby suppressing a rapid change in current consumption. It is possible to reduce Ps
A sufficient reduction / suppression effect on the measured values of t and Plt can be obtained. In addition, the increase in the number of countermeasure components due to the addition of a transformer, a filter circuit (LCR circuit), etc., which is considered as another countermeasure, and the increase in the space for mounting the countermeasure components may lead to an increase in product size, weight, and cost. Without this, it is possible to obtain a sufficient reduction / suppression effect on power supply voltage fluctuations.

An embodiment of the invention according to claim 3 is the same as the embodiment of the invention according to claims 1 and 2, in which at least one of the heating means 2 and 3 comprising a plurality of heaters at the time of standby and preheating is consumed. A mode is provided in which the other heating means (heating means that consumes more power than the heating means 3) 2 excluding the one heating means 3 that consumes less power is set in a non-lighting state, and the CPU 8 waits and preheats. At times, the triac 4 is turned off via the control driver 6 to turn off the heater 2, and the control driver 7 is turned on according to the end temperature of the fixing roller 1 by the temperature detection signal from the thermistor 10.
The triac 5 is turned on / off via the switch to control the heater 3 to be turned on / off.

Here, at least the power consumption of one heating means 3 having a small power consumption is whether the temperature of the heating portion reaches the standby target fixing temperature of 185 ° C. when the heating means 3 is constantly turned on during standby. Determined by Ideally, at least the power consumption of one heating means 3 with low power consumption is such that the fixing temperature during standby and during fixing (during copying operation) is 185 ° C. during standby and during fixing (during copying operation).
Is kept at the target fixing temperature at the time of standby / fixing, or the temperature range is 165 ° C to 1 at the time of fixing (during copying operation).
The electric power is set so that the fixing temperature is kept as close as possible to 90 ° C., or the fixing temperature during preheating is kept as close as possible to the target fixing temperature during preheating at 145 ° C., and the heating means 3 is continuously turned on as much as possible. It As a result, the number of times the heating means 3 is switched on / off is reduced, and fluctuations in the power supply voltage are reduced.

Considering only the target fixing temperature, at least the power consumption of one heating means 3 having a small power consumption is maintained at the preheating target fixing temperature of 145 ° C. at the time of preheating so that the heating means can be used. The power consumption of the heating means 3 can be further reduced by setting the power such that the lighting is continuously performed as much as possible. As a result, the gradient of the fixing temperature when the heating means 3 is turned on becomes smooth during preheating, the time during which the heating means 3 is continuously turned on becomes longer, and the heating means 3 is turned on.
The frequent repetition of lighting, extinguishing, and lighting is reduced, the number of times the heating means 3 is turned on and off is reduced, and fluctuations in the power supply voltage are reduced.

Considering the range of the target fixing temperature, the fixing temperature at which the heating means 3 is turned off at the time of fixing is 19 which is the upper limit value.
The CPU 8 controls the on / off of the heating means 3 so that the fixing temperature is 0 ° C., the fixing temperature is lowered from the upper limit value, and the heating means 3 is turned on again at the lower limit value of 165 ° C. If the electric power of the heating means 3 is determined so as to be maintained within the fixing temperature range of 0 ° C. to 190 ° C., the time during which the heating means 3 is continuously turned on further increases. As a result, the frequent repetition of lighting, extinguishing, and lighting of the heating means 3 is reduced, so that the heating means 3 is turned on / off.
The number of times the light is turned off is reduced, and the fluctuation of the power supply voltage is reduced.

In the most ideal form during standby, at least the power consumption of one heating means 3 with low power consumption is
At the time of standby, even if at least one heating means 3 with low power consumption is constantly turned on, the temperature of the heating point is slightly 1
It is necessary to set it so as not to reach 85 ° C. As a result, at the time of standby, the temperature of the heating point by at least one heating means 3 with low power consumption is 185
The temperature of the heating means 3 does not rise to 0 ° C., and at least one heating means 3 with low power consumption is kept on all the time, and switching on / off does not occur. The temperature of the heating point by the heating means 3 is maintained as close as possible to the target fixing temperature during standby.

Next, as an ideal form during standby, at least the power consumption of one heating means 3 with low power consumption is such that at least one heating means 3 with low power consumption is constantly turned on during standby. The temperature of the part is 185
Although the temperature reaches ℃, it is necessary to set the electric power so that the electric power consumption becomes as small as possible. As a result, since the power consumption of the heating means 3 is small, the rate of change in the temperature detected by the temperature detecting means 10 (temperature gradient) becomes small (smooth), and even if the temperature detected by the temperature detecting means 10 is 185 ° C. or less. Even if the heating means 3 is switched on / off depending on whether or not it exists, the frequency of the switching is reduced, and the temperature of the heating point by the heating means 3 can be maintained at 185 ° C.

Next, as an ideal form during standby, at least the power consumption of one heating means 3 with low power consumption is
The setting is such that, at the time of standby, even if at least one heating means 3 with low power consumption is constantly turned on, the temperature of the heating point does not reach 185 ° C. During the standby, the heating means 3 is constantly turned on so that the temperature of the heating portion is maintained at 185 ° C., but the temperature of the heating portion decreases with time, and as a result, the heating portion 3 The temperature of the heating point becomes the temperature given (heated) by the heating means 3. However, from the viewpoint of switching on / off of the heating means 3, switching on / off of the heating means 3 is not performed, so that the fluctuation of the power supply voltage does not occur. Further, when the temperature given by the heating means 3 is 165 ° C. or higher, the transition from the standby state to the copying operation is smoothly performed.

The setting of the power consumption at the time of preheating of at least one heating means 3 with low power consumption is the same as the setting of the power consumption during standby of at least one heating means 3 with low power consumption as described above. is there. In the present embodiment, the mode in which at least one heating unit 3 with low power consumption is turned on as described above is performed at the time of rising of the fixing temperature and at the time of standby and preheating other than the period during the copying operation, but the recording paper is fixed. The electric power of the heating means 2 and 3 when passing through the means is maintained at the margin of the target fixing temperature at the time of fixing / fixing of 185 ° C., or the temperature range at fixing (during copying operation) is 165 ° C. If the electric power is set so that the heating means 2 and 3 can be continuously turned on as much as possible while being maintained within the fixing temperature range of 190 to 190 ° C., the heating means 2 and 3 can be continuously turned on for a long time. The time during which the heating means 2 and 3 are continuously turned off also becomes long. As a result, the frequent repetition of lighting, extinction, and lighting of the heating means 2 and 3 is reduced, the number of times of lighting / extinguishing of the heating means 2 and 3 is reduced, and fluctuations in the power supply voltage are reduced.

In the embodiment of the invention according to claim 3,
A fixing unit including a fixing roller 1 for fixing a toner image on a sheet and a pressure roller, and a plurality of heating units 2 and 3 in the fixing unit. Temperature detecting means 9 and 10 composed of a plurality of temperature detecting elements respectively detecting the temperatures of a plurality of corresponding parts, and the plurality of heating means based on the temperature detection signals of the plurality of temperature detecting means 9 and 10. A fixing device having a CPU 8 as a control means for independently controlling each of the heating means 2 and 3, and other heating means except at least one heating means 3 having a small power consumption among the plurality of heating means 2 and 3. Since a mode for setting the No. 2 to the non-lighting state is provided, that is, the plurality of heating means are not turned on and off at the same time, and at least one heating means with a small power consumption is used, and the other heating means is defective. Is provided with the mode in which the state as the lighting mode of the heating means during standby and preheating of the machine,
Flicker that is a measurement value by a flicker meter that is a measuring device that converts voltage fluctuation (physical quantity) into flicker (perceptual quantity) by reducing the sudden fluctuation of inrush current and reducing the voltage fluctuation applied to the power supply. Value Pst
(Short-term flicker value: standard value 1.0 or less), Plt
A sufficient reduction / suppression effect for (long-term flicker value: standard value 0.65 or less) can be obtained.

Further, it is necessary to supply electric power to a plurality of heating means at the time of copying operation, but at the time of standby and preheating, even if the electric power supplied to the heating means is several tens of W, the fixing roller is sufficient. It is possible to maintain the surface temperature of the device without lowering it, and there is no problem even if at least one heating device with low power consumption is turned off, the other heating devices are turned off.

The reason why the electric power of the plurality of heating means is required is that the warm-up (rise) time of the machine is shortened. However, the electric power of the plurality of heating means is originally required. Only during the up (rising) period, once the warm-up (rising) state is reached, as described above, the power supplied to the heating means is sufficiently fixed during standby and preheating even if the power is about several tens of W. It is possible to maintain the surface temperature of the roller without lowering it.

When the heating means which consumes a large amount of power is used during standby and preheating, the surface temperature of the fixing means overshoots due to a rapid temperature rise, and unless the heating means is frequently turned on and off, the fixing means It may not be possible to maintain the surface temperature of. Then, since the heating means is frequently turned on and off to cause a large change in the consumed current, a rapid change in the voltage often occurs and the voltage fluctuation applied to the power source increases.

Therefore, even if at least one heating means which consumes a small amount of current is consumed and the other heating means are turned off, there is no problem, and the effect of sufficient reduction / suppression of fluctuations in the power supply voltage can be obtained. As a result, the power consumption of the heating means is reduced, which leads to power saving of the entire machine.

Further, as another measure, a transformer, a filter circuit (LCR circuit) and the like are added to increase the number of countermeasure parts, and the space for mounting the countermeasure parts is increased to increase the size and weight of the product and increase the cost. The effect of sufficiently reducing / suppressing fluctuations in the power supply voltage can be obtained without inducing.

The present invention is not limited to the above-described embodiment, and for example, a fixing device used in an image forming apparatus such as a printer or a facsimile other than a copying machine, and a heating means having three or more fixing means. It can also be applied to a fixing device that has it.

[0057]

As described above, according to the first aspect of the invention, the fixing means having a plurality of heating means for fixing the toner image on the sheet, and the plurality of heating means in the fixing means are provided. A plurality of temperature detecting means for respectively detecting the temperatures of a plurality of corresponding portions; and a control means for independently controlling the plurality of heating means based on the temperature detection signals of the plurality of temperature detecting means. Since the fixing device has a mode in which the heating means other than at least one heating means among the plurality of heating means are in the non-lighting state, the effect of sufficiently reducing / suppressing fluctuations in the power supply voltage is provided. Can be obtained and the standard value can be achieved. further,
Other possible countermeasures are transformers and filter circuits (L
(CR circuit) increases the number of countermeasure components, and the space for mounting the countermeasure components increases the size and weight of the product. can get.

According to the second aspect of the present invention, there are provided a fixing means having a plurality of heating means for fixing the toner image on the sheet, and a plurality of portions of the fixing means corresponding to the plurality of heating means. A fixing device having a plurality of temperature detecting means for respectively detecting temperatures and a control means for independently controlling the plurality of heating means based on temperature detection signals of the plurality of temperature detecting means, The control means sets the other heating means other than at least one heating means among the plurality of heating means to the non-lighting state at least except when the paper passes through the fixing means, so that it is sufficient for the fluctuation of the power supply voltage. The effect of reduction and suppression is obtained.
Further, as another measure, an additional transformer, a filter circuit (LCR circuit), or the like may increase the number of countermeasure components, and an increase in the space for mounting the countermeasure components may lead to an increase in product size, weight, and cost. The effect of sufficient reduction / suppression of fluctuations in power supply voltage can be obtained.

According to the third aspect of the present invention, there are provided a fixing means having a plurality of heating means for fixing the toner image on the sheet and a plurality of portions of the fixing means corresponding to the plurality of heating means. A fixing device having a plurality of temperature detecting means for respectively detecting temperatures and a control means for independently controlling the plurality of heating means based on temperature detection signals of the plurality of temperature detecting means, Since a mode in which at least one heating means, which consumes less power, is turned off among the plurality of heating means is provided in a non-lighting state, a sufficient reduction / suppression effect can be obtained against fluctuations in power supply voltage. Therefore, the power consumption by the heating means is reduced, which leads to power saving. Further, as another measure, an additional transformer, a filter circuit (LCR circuit), or the like may increase the number of countermeasure components, and an increase in the space for mounting the countermeasure components may lead to an increase in product size, weight, and cost. The effect of sufficient reduction / suppression of fluctuations in power supply voltage can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a fixing roller and a control system of an embodiment of the invention according to claims 1 and 2. FIG.

FIG. 2 is a flowchart showing a lighting / extinguishing control flow of the heating means 2 in the same embodiment.

FIG. 3 is a flowchart showing a lighting / extinguishing control flow of the heating means 3 in the same embodiment.

[Explanation of symbols]

1 fixing roller 2-3 heating means 4,5 triac 6, 7 Control driver 8 CPU 9, 10 thermistor 11 drivers 12 transistors 13 cover switch RA1 relay

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-60-87378 (JP, A) JP-A-50-138838 (JP, A) JP-A-6-19363 (JP, A) JP-A-3- 185482 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) G03G 13/20 G03G 15/20

Claims (3)

(57) [Claims] 1. A fixing means having a plurality of heating means for fixing a toner image on a sheet, and a plurality of fixing means for respectively detecting temperatures of a plurality of portions of the fixing means corresponding to the plurality of heating means. A fixing device having temperature detecting means and control means for independently controlling the plurality of heating means based on the temperature detection signals of the plurality of temperature detecting means. A mode is provided in which the other heating means except the one heating means are set to the non-lighting state, and the power consumption of the one heating means is maintained at the target fixing temperature at the temperature of the heating portion of the fixing means heated by the one heating means. And waiting, fixing, preheating
In any case of time, the one heating means is continuously lit
A fixing device characterized in that the electric power is set so as to prolong the staying time . 2. A fixing means having a plurality of heating means for fixing a toner image on a sheet, and a plurality of fixing means for respectively detecting temperatures of a plurality of portions of the fixing means corresponding to the plurality of heating means. In a fixing device having a temperature detecting means and a control means for independently controlling the plurality of heating means based on the temperature detection signals of the plurality of temperature detecting means, the control means includes at least a sheet fixing the paper. Except at the time of passing through the heating means, other heating means except at least one heating means among the plurality of heating means is set to the non-lighting state, and the power consumption of the one heating means is set to the above-mentioned fixing means. temperature of the heating portion by one heating means is barely maintained at the target fixing temperature, wait
In the case of machine, fixing and preheating, the above-mentioned one heating
A fixing device characterized in that the electric power is set so that the means is continuously turned on for a long time . 3. A fixing means having a plurality of heating means for fixing a toner image on a sheet, and a plurality of fixing means for respectively detecting temperatures of a plurality of portions of the fixing means corresponding to the plurality of heating means. A fixing device having temperature detecting means and control means for independently controlling the plurality of heating means based on temperature detection signals of the plurality of temperature detecting means, wherein A mode is provided in which other heating means excluding one heating means that consumes less electric power is in a non-lighting state, and the power consumption of the one heating means is
The temperature of the heating portion of the fixing means heated by the one heating means is maintained at the target fixing temperature just before the standby.
The above-mentioned one heating hand is used at any of the time, fixing, and preheating.
A fixing device characterized in that the electric power is set so that the time during which the steps are continuously lit becomes long .