JP2003217793A - Heater control device, fixing device, and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problems in a conventional heater control device that the power source voltage fluctuation which has an electrically bad effect on other electric equipments cannot be reduced, and an inexpensive electronic switch cannot be used. <P>SOLUTION: In this heater control device, when a plurality of heaters 1 and 2 are lighted, a current is carried to the heaters 1 and 2 not simultaneously but with a time lag to independently softly start and light the heaters 1 and 2. When the heaters 1 and 2 are extinguished, the heaters 1 and 2 are softly stopped with a time lag and extinguished. <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 a heater control device, a fixing device, and an image forming apparatus such as a copying machine, a printer and a facsimile.

[0002]

2. Description of the Related Art In electrophotographic image forming apparatuses such as copying machines, printers and facsimiles, a halogen lamp using tungsten as a filament has been used as a fixing heater as a heat source of a heat fixing device.
However, in this image forming apparatus, since the resistance value of the fixing heater changes until the tungsten filament reaches the rated temperature, an inrush current of about 10 times the fixing current flows at the start of energization, and the power supply voltage fluctuates. .

A fixing heater control device which does not worsen the fluctuation of the power supply voltage is described in Japanese Patent Laid-Open No. 2001-109317. This fixing heater control device executes PID control during copying, and energizes the heating heater by hysteresis control during standby.

Japanese Unexamined Patent Publication No. 10-186940 discloses a heater control device for individually controlling the temperatures of a plurality of heaters by performing energization control for repeatedly turning on and off a plurality of heaters. Based on the output of the temperature detecting means for detecting, a delay means for delaying the time from the start of the energization control of the reference heater of the plurality of heaters to the start of the energization control of other heaters, A heater control device is provided, which comprises: a changing unit that changes a delay time of the delay unit.

Japanese Unexamined Patent Publication No. 6-236128 discloses an image forming apparatus that forms an image on a recording medium with a developer such as toner and thermally fixes the image to output an image-formed product. A heater control means for selectively driving the plurality of heaters according to the operating state of the apparatus and a plurality of heaters of the heat fixing means are used at the same time, the start timing of driving each heater is set. An image forming apparatus is described which has a heater control means for shifting.

Japanese Unexamined Patent Publication No. 7-5791 discloses a heating roller which is rotatably arranged in pressure contact with each other and which nips and conveys a recording material, and an energization included in each of the heating rollers or in one of them. A plurality of heating bodies that generate heat by means of a temperature detection means for detecting the temperature of at least one of the heating rollers; and based on the temperature detected by the temperature detection means, control the energization of the plurality of heating bodies to control the heating. In a heating device provided with a temperature control means for maintaining the roller at a predetermined temperature, the temperature control means, when the temperature detected by the temperature detection means is lower than a predetermined reference temperature,
The heating device is characterized in that the start timing of energization to the plurality of heating bodies is set so as to have a predetermined time difference between the start timings of energization of the respective heating bodies so as not to be the same for all the heating bodies. Is listed.

[0007]

In the fixing heater control device, the heat generating heater is energized by the hysteresis control during standby, so that the heat generating heater has a large capacity, that is, in the case of an image forming apparatus using a fixing heater having a large power consumption. However, there is a problem in that the number of lightings of the fixing heater cannot be reduced and the power supply voltage fluctuation cannot be reduced unless the interval between the upper limit value and the lower limit value, which is the temperature range of the hysteresis control during the standby operation, is widened.

If the fluctuation of the power supply voltage cannot be reduced, flicker noise will be given to other electric devices connected to the same branch branch of the commercial power supply. Therefore, especially when the other electric device is a fluorescent lamp, flicker occurs, which causes discomfort to the human body. Also, when using a plurality of heaters that perform the same operation as the fixing heater,
The power supply voltage fluctuation standard could not be met.

Further, in the heater control device, the image forming device, and the heating device, the inrush current of each heater cannot be sufficiently suppressed, and the electronic switch for controlling the energization of each heater is also inexpensive. Cannot be used. Also,
In the above heater control device, there are no measures for fluctuations in the power supply voltage.

The present invention provides a heater control device, a fixing device, and an image forming apparatus which can reduce fluctuations in power supply voltage and have no adverse electrical effect on other electric devices and can be realized at low cost. To aim.

[0011]

To achieve the above object, the invention according to claim 1 has a temperature detecting means for detecting the temperature of a member to be heated which is heated by a plurality of heaters.
In a heater control device for controlling the energization of the plurality of heaters based on the temperature detected by the temperature detecting means, when the plurality of heaters are turned on, the plurality of heaters are energized by shifting the energization instead of energizing them simultaneously. Then, the plurality of heaters are shifted and soft-started to be turned on, and when the plurality of heaters are turned off, the plurality of heaters are shifted and soft-stopped to be turned off.

The invention according to claim 2 has a plurality of heaters for heating the member to be heated, and a temperature detecting means for detecting the temperature of the member to be heated, and from the start of energization from the power source to the heater, In the fixing device that controls the energization of the plurality of heaters by comparing the detected temperature of the temperature detection means with the set temperature at the time of rising until the temperature of the heated member reaches the set temperature, the plurality of the heaters at the time of rising. The heaters are not energized simultaneously but are energized by energizing them to displace the plurality of heaters to light them while soft starting, and when the temperature detected by the temperature detecting means reaches the set temperature, displace the plurality of heaters. The light is turned off while soft-stopping.

The invention according to claim 3 has a plurality of heaters for heating the member to be heated, and temperature detecting means for detecting the temperature of the member to be heated. In a fixing device that controls the energization of the plurality of heaters based on the detected temperature, during the fixing operation, the plurality of heaters are not energized at the same time but are energized by energizing the plurality of heaters to displace the plurality of heaters. The heater is turned on while being started, and the PID control of the plurality of heaters is performed so that the temperature detected by the temperature detecting means is maintained at the set temperature, and the plurality of heaters are shifted and soft-stopped to be turned off. .

The invention according to claim 4 has a plurality of heaters for heating the member to be heated and temperature detecting means for detecting the temperature of the member to be heated, and the temperature detected by the temperature detecting means during the standby operation. In the fixing device that controls the energization of the plurality of heaters based on the above, during the standby operation, the plurality of heaters are not energized at the same time but are energized by being energized to displace the plurality of heaters to be soft-started. The heaters are turned on while performing the hysteresis control of the plurality of heaters so that the temperature detected by the temperature detecting means is maintained at the set temperature, and the plurality of heaters are shifted and soft-stopped to be turned off.

The invention according to a fifth aspect comprises the fixing device according to any one of the second to fourth aspects.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 schematically shows an embodiment of the present invention. In the fixing device of this embodiment, a plurality of fixing heaters 1 and 2, a hollow cylindrical fixing roller 3 as a fixing member in which the fixing heaters 1 and 2 are provided, and the fixing roller 3 are illustrated. A pressure roller as a pressure member pressed by a pressure means, a temperature detector 4 as a temperature detecting means for detecting the surface temperature (fixing temperature) of the fixing roller 3, and a plurality of commercial power sources 5 from the outside. Fixing heater 1,
The electronic switches 6 and 7 for individually controlling the energization to 2 and the detected temperature of the temperature detector 4 are compared with the set temperature, and the energization command signals are individually output to the electronic switches 6 and 7 to output a plurality of electric switches. A control unit 8 as a control unit that controls the energization of the fixing heaters 1 and 2, and a power supply device that outputs a zero-cross signal of a DC input for operating the control unit 8 and an AC input from the commercial power supply 5 to the control unit 8. Have.

Halogen lamps are used as the fixing heaters 1 and 2, and the temperature detector 4, the electronic switches 6 and 7, and the controller 8 are used.
Constitutes a heater control device for controlling energization of the fixing heaters 1 and 2. The fixing roller 3 is heated from inside by the fixing heaters 1 and 2, and the fixing roller 3 and the pressure roller are rotationally driven by a driving unit (not shown). The fixing device of the present embodiment constitutes an image forming apparatus main body and an image forming apparatus, and a sheet as a sheet-like recording medium on which a toner image is formed in the image forming apparatus main body is fixed to the fixing roller 3 and the fixing roller 3 by the fixing device of the present embodiment. The toner image is fixed by being heated and pressed while being nipped and conveyed by the pressure roller.

The fixing heaters 1 and 2 are turned on by being energized from the commercial power source 5 through the electronic switches 6 and 7, respectively, to heat the fixing roller 3, and the temperature detector 4 detects the surface temperature of the fixing roller 3. To do. The control unit 8 includes the temperature detector 4
Output signal is input, the detected temperature of the temperature detector 4 is compared with the set temperature, and the energization command signal is output to the electronic switches 6 and 7 in synchronization with the zero cross signal from the power supply device according to the result. The electronic switches 6 and 7 are controlled by an energization command signal from the control unit 8 to control energization from the commercial power source 5 to the fixing heaters 1 and 2.

FIG. 2 shows a rising time from the start of energization of the power supply 5 to the fixing heaters 1 and 2 until the temperature of the fixing roller 3 reaches a set temperature, an image forming operation (copying operation: fixing). A fixing temperature control state during a standby operation in which the fixing operation is not performed) is performed. First, the temperature control at the time of rising of this embodiment will be described. FIG. 5 shows a control flow when the control unit 8 rises.

When the power of the image forming apparatus is turned on, the temperature detector 4 detects the surface temperature of the fixing roller 3 as needed. In step 11, the control unit 8 checks from the output value of the temperature detector 4 whether the detected temperature of the temperature detector 4 is lower than the set temperature, and if the detected temperature of the temperature detector 4 is not lower than the set temperature. In step 11, it is repeatedly checked whether the temperature detected by the temperature detector 4 is lower than the set temperature.

When the temperature detected by the temperature detector 4 is lower than the set temperature, the controller 8 sends a lighting signal individually to the electronic switches 6 and 7 to control the phase of the power supply from the power source 5 to the fixing heaters 1 and 2. By doing so, the fixing heaters 1 and 2 are turned on while soft-starting. In this case, the control unit 8 operates as shown in FIG.
As shown in FIG. 1, first, a lighting signal is sent to the electronic switch 6 so that the energization phase angle of the fixing heater 1 sequentially increases and the fixing heater 1 is soft-started to be lit. The AC input from the power source 5 to the fixing heater 1 is increased by θ, θ, 2θ, 2θ, 3θ at every 180 ° by increasing the phase angle θ by a predetermined phase angle (for example, 5 °) for each cycle of the AC input from the power source 5. 3θ …… 180 degrees, 180
A lighting signal is sent to the electronic switch 6 so that the fixing heater 1 is lit while soft-starting, and then a lighting signal is sent to the electronic switch 6 so that the energization phase angle of the fixing heater 1 becomes 180 degrees. The fixing heater 1 is sent all the way and is kept lit (all the AC input from the power source 5 is still energized to the fixing heater 1).

Next, the controller 8 turns on all the fixing heaters 1 in step 12 (the energization phase angle of the fixing heater 1 is 18).
If the fixing heater 1 is not all turned on, the process returns to step 11. In addition, the control unit 8
Is a predetermined first delay time from the start of the soft start of the fixing heater 1 so as not to overlap with the soft start of the fixing heater 1 in step 13 when the fixing heater 1 is fully turned on.
For example, after a delay of 500 ms, a lighting signal is sent to the electronic switch 7 so as to sequentially increase the energization phase angle to the fixing heater 2 and the fixing heater 2 is soft-started to be lit. The angle increases by a predetermined phase angle θ for each cycle of the AC input from the power supply 5, and the AC input from the power supply 5 to the fixing heater 2 is θ, θ, 2θ, 2θ, 3θ, 3θ every 180 degrees. 180 degrees, 18
A lighting signal is sent to the electronic switch 7 so that it is energized by 0 degrees, and the fixing heater 2 is lighted while soft-starting. After that, a lighting signal is sent to the electronic switch 7 so that the energization phase angle of the fixing heater 2 becomes 180 degrees. Is sent to keep the fixing heater 2 all lit.

The controller 8 controls the temperature detector 4 in step 14.
It is checked whether the temperature detected by the temperature detector 4 is equal to or higher than the set temperature based on the output value of the. Repeatedly check whether the temperature has exceeded the set temperature. When the detected temperature of the temperature detector 4 becomes equal to or higher than the set temperature, the control unit 8 individually sends an extinguishing signal to the electronic switches 6 and 7 in step 15 to determine the phase of energization from the power source 5 to the fixing heaters 1 and 2. By performing control, the fixing heaters 1 and 2 are turned off while soft-stopping.

In this case, as shown in FIG. 4, the control unit 8 first sends an extinguishing signal to the electronic switch 6 so that the energization phase angle of the fixing heater 1 sequentially decreases, and the fixing heater 1
Is turned off while soft-stopping, and, for example, the energization phase angle of the fixing heater 1 is decreased by a predetermined phase angle θ (for example, 5 degrees) for each cycle of the AC input from the power source 5 to the fixing heater 1 from the power source 5. AC input is 180 degrees for every 180 degrees, 1
80 degrees, 180 degrees-θ, 180 degrees-θ, 180 degrees-2
θ, 180 ° -2θ, 180 ° -3θ, 180 ° -3θ
...... By sending an extinguishing signal to the electronic switch 6 so as to be energized one by one, the fixing heater 1 is extinguished while soft-stopping, the energization of the fixing heater 1 is turned off, and the fixing heater 1 is completely extinguished (from the power supply 5). When the AC input is not applied to the fixing heater 1 at all), it is left as it is.

Next, after the fixing heater 1 is completely turned off, the controller 8 starts a soft stop of the fixing heater 1 so as not to overlap with the soft stop of the fixing heater 1 by a predetermined second time.
After a delay time of, for example, 500 ms, a turn-off signal is sent to the electronic switch 7 so that the energization phase angle to the fixing heater 2 sequentially decreases, and the fixing heater 2 is turned off while soft-stopping. The energization phase angle of 2 decreases by a predetermined phase angle θ for each cycle of the AC input from the power source 5, and the AC input from the power source 5 to the fixing heater 2 is 180 degrees, 180 degrees, 180 degrees every 180 degrees. θ, 1
80 ° -θ, 180 ° -2θ, 180 ° -2θ, 180
Degree −3θ, 180 ° −3θ ... Sending an extinguishing signal to the electronic switch 7 to energize the fixing heater 2 so that the fixing heater 2 is extinguished while being soft-stopped. When the heater 2 is completely extinguished, the fixing heater 2 is kept completely extinguished and the process returns to step 11.

The first delay time, the second delay time, and the optimum values of soft start and soft stop are set according to the capacities of the fixing heaters 1 and 2. When the number of fixing heaters that simultaneously heat the fixing roller 3 is three or more,
Three or more electronic switches are provided to control the power supply from the power source 5 to the three or more fixing heaters, respectively.
One or more electronic switches are controlled to simultaneously energize three or more fixing heaters without simultaneously energizing them so that they do not overlap with each other and energizing them to sequentially turn on the lights while soft-starting. When turning off the heaters, it is sufficient to control three or more electronic switches to shift the three or more heaters so that they do not overlap each other, and to softly stop the heaters. Also in this case, the soft start interval (delay time) of each fixing heater, the soft stop interval (delay time) of each fixing heater, and the optimum values of soft start and soft stop are determined according to the capacities of the fixing heaters 1 and 2. Set.

Next, the temperature control during the image forming operation (fixing operation) of this embodiment will be described. During the image forming operation (fixing operation), the temperature detector 4 detects the surface temperature of the fixing roller 3 as needed. As shown in FIG. 2, the control unit 8 outputs the output value of the temperature detector 4 (currently detected temperature of the temperature detector 4, last detected temperature, previously detected temperature of the temperature detector 4), set temperature, and proportional value at constant time intervals. The fixing heater 1 in the phase control of energization of the fixing heaters 1 and 2 so that the temperature detected by the temperature detector 4 is maintained at the set temperature based on the constant, the integral constant, and the differential constant.
The energization phase angle of 2 is obtained by PID (proportional integral derivative) calculation,
PID control by phase control of the fixing heaters 1 and 2 by individually sending a lighting signal to the electronic switches 6 and 7 so that the AC input from the power source 5 is energized to the fixing heaters 1 and 2 at the obtained energizing phase angle. I do.

In this case, the controller 8 controls the fixing heaters 1, 2
When turning on the light from the off state, first, the fixing heater 1
The lighting signal is sent to the electronic switch 6 to cause the fixing heater 1 to be soft-started so that the energization phase angle of the fixing heater 1 sequentially increases up to the energization phase angle obtained by the PID calculation of the fixing heater 1, and for example, as described above The energization phase angle of the heater 1 is up to the energization phase angle obtained by the PID calculation of the fixing heater 1 by a predetermined phase angle for each cycle of the AC input from the power source 5,
For example, a lighting signal is sent to the electronic switch 6 so as to increase by 5 degrees so that the fixing heater 1 is soft-started and turned on, so that the fixing heater 1 does not overlap with the soft start, and a predetermined number of times are started from the soft start of the fixing heater 1. Three
After a delay time of, for example, 500 ms, a lighting signal is sent to the electronic switch 7 so as to sequentially increase the energization phase angle to the fixing heater 2 to the energization phase angle obtained by the PID calculation of the fixing heater 2. The heater 2 is lit while being soft-started, and for example, as described above, the energization phase angle of the fixing heater 2 reaches the energization phase angle obtained by the PID calculation of the fixing heater 2 at a predetermined phase for each cycle of the AC input from the power source 5. A lighting signal is sent to the electronic switch 7 so that the fixing heater 2 is lit while being soft-started so that the fixing heater 2 is increased by every 5 degrees.

When the fixing heaters 1 and 2 are turned off, the control section 8 first sends an extinguishing signal to the electronic switch 6 so that the energization phase angle of the fixing heater 1 is sequentially decreased. The fixing heater 1 is turned off while soft-stopping, and, for example, the energization phase angle of the fixing heater 1 is decreased by a predetermined phase angle, for example, 5 degrees for each cycle of the AC input from the power source 5, as described above. A light-off signal is sent to the switch 6 to turn off the fixing heater 1 while soft-stopping it, and a predetermined fourth delay time, for example, 500 ms, is delayed from the soft-stop start of the fixing heater 1 so as not to overlap with the soft-stopping of the fixing heater 1. From that point on, a light-off signal is sent to the electronic switch 7 so that the energization phase angle to the fixing heater 2 sequentially decreases, and the fixing heater 2 is not soft-stopped. Al is turned off, for example, conduction phase angle of the fixing heater 2 as described above for the AC input from the power supply 5 1
An extinguishing signal is sent to the electronic switch 7 so as to decrease by a predetermined phase angle, for example, by 5 degrees in each cycle, and the fixing heater 2 is extinguished while soft-stopping.

By thus performing the PID control by the phase control of the fixing heaters 1 and 2, the energization phase angle of the fixing heaters 1 and 2 is changed according to the temperature difference between the temperature detected by the temperature detector 4 and the set temperature. Instead, the energization control of the fixing heaters 1 and 2 is performed so that the temperature detected by the temperature detector 4 is maintained at the set temperature.

The above-mentioned third delay time, fourth delay time, and optimum values for soft start and soft stop are set according to the capacities of the fixing heaters 1 and 2. When the number of fixing heaters that simultaneously heat the fixing roller 3 is three or more,
In the case where three or more electronic switches for respectively controlling the energization of the power source 5 to the three or more fixing heaters are provided, and the controller 8 turns on the three or more heaters during the image forming operation (fixing operation). Controls three or more electronic switches to simultaneously energize three or more fixing heaters without simultaneously energizing them so that they do not overlap with each other, energizing them to sequentially turn on the lights while soft-starting, and during the image forming operation by the control unit 8. 3 (during fixing operation)
To turn off the heaters of three or more, it is sufficient to control three or more electronic switches to shift the heaters of three or more heaters so that they do not overlap with each other and to soft-stop the lights.
Also in this case, the soft start interval (delay time) of each fixing heater, the soft stop interval (delay time) of each fixing heater, and the optimum values of soft start and soft stop are:
It is set according to the capacities of the fixing heaters 1 and 2.

Next, the temperature control during the standby operation of this embodiment will be described. During the standby operation, the temperature detector 4 detects the surface temperature of the fixing roller 3 as needed. As shown in FIG. 2, the control unit 8 determines from the output value of the temperature detector 4 whether the temperature detected by the temperature detector 4 is lower than the set lower limit temperature,
When the detected temperature of the temperature detector 4 is lower than the set lower limit temperature, a lighting signal is individually sent to the electronic switches 6 and 7 so that the AC input from the power source 5 is supplied to the fixing heaters 1 and 2, and the fixing heaters 1 and 2 are supplied. Light up.

In this case, the controller 8 first causes the electronic switch 6 to sequentially increase the energization phase angle of the fixing heater 1.
The fixing heater 1 is soft-started to be lit by sending a lighting signal to the fixing heater 1, and the energization phase angle of the fixing heater 1 is, for example, 5 degrees at a predetermined phase angle for each cycle of the AC input from the power source 5 as described above. The fixing heater 1 is soft-started to be lit by sending a lighting signal to the electronic switch 6 so as to increase in increments, and a predetermined fifth delay from the start of the soft start of the fixing heater 1 so as not to overlap with the soft start of the fixing heater 1. From a time delay of, for example, 500 ms, a lighting signal is sent to the electronic switch 7 so that the energization phase angle to the fixing heater 2 sequentially increases to the energization phase angle obtained by the PID calculation of the fixing heater 2 and the fixing heater 2 is sent. Is turned on while soft-starting, and the energization phase angle of the fixing heater 2 is determined by the PID calculation of the fixing heater 2 as described above, for example. By a predetermined phase angle in each cycle of the AC input from the power supply 5 to the fixing heater 2 is turned while soft-start by sending a lighting signal to the electronic switch 7 to increase by for example 5 °.

Further, the control unit 8 judges from the output value of the temperature detector 4 whether the detected temperature of the temperature detector 4 is higher than the set upper limit temperature, and the detected temperature of the temperature detector 4 is higher than the set upper limit temperature. Occasionally, first, an extinguishing signal is sent to the electronic switch 6 so that the energization phase angle of the fixing heater 1 sequentially decreases, and the fixing heater 1 is extinguished while soft-stopping.
For example, as described above, the energization phase angle of the fixing heater 1 is the power source 5
To a soft stop of the fixing heater 1 by sending an extinguishing signal to the electronic switch 6 so as to decrease by a predetermined phase angle, for example, by 5 degrees for each cycle of the AC input from the fixing heater 1. In order not to overlap with each other, an extinguishing signal is sent to the electronic switch 7 so that the energization phase angle to the fixing heater 2 is sequentially decreased from a time point when a predetermined sixth delay time, for example, 500 ms, is delayed from the soft stop start of the fixing heater 1. The fixing heater 2 is turned off while being soft-stopped, and the energization phase angle of the fixing heater 2 is decreased by a predetermined phase angle, for example, by 5 degrees for each cycle of the AC input from the power source 5, as described above. To the electronic switch 7 to turn off the fixing heater 2 while soft-stopping the fixing heater 2.

By performing the hysteresis control of the energization of the fixing heaters 1 and 2 in this manner, the energization control of the fixing heaters 1 and 2 is performed so that the temperature detected by the temperature detector 4 is maintained at the set temperature.

The above-mentioned fifth delay time, sixth delay time, and optimum values of soft start and soft stop are set according to the capacities of the fixing heaters 1 and 2. When the number of fixing heaters that simultaneously heat the fixing roller 3 is three or more,
Three or more electronic switches are provided to respectively control the energization of the power source 5 to the three or more fixing heaters. When the control unit 8 turns on the three or more heaters during the standby operation, the three or more electronic switches are provided. Is controlled so that three or more fixing heaters are not energized at the same time, so that they do not overlap with each other, and they are energized so that the heaters are sequentially turned on while soft-starting, and the control unit 8 turns off three or more heaters during standby operation. In some cases 3
It suffices to control three or more electronic switches to shift three or more heaters so that they do not overlap each other, and to soft-stop the lights to turn them off. Also in this case, the soft start interval (delay time) of each fixing heater, the soft stop interval (delay time) of each fixing heater, and the optimum values of soft start and soft stop are determined according to the capacities of the fixing heaters 1 and 2. Set.

According to this embodiment, when a plurality of heaters 1 and 2 are turned on, the plurality of heaters 1 and 2 are energized by simultaneously energizing them so that they do not overlap with each other. , 2 are shifted and soft-started to be turned on, and when the plurality of heaters 1 and 2 are turned off, the plurality of heaters 1 and 2 are shifted so as not to overlap with each other and soft-stopped to be turned off. Not only does the inrush current to the heaters 1 and 2 not occur by displacing the heaters 1 and 2 while soft-starting, but also the heaters 1 and 2 are lit while being soft-started by shifting so that they do not overlap. At the same time, the plurality of heaters 1 and 2 are shifted so that they do not overlap each other and are turned off while being soft-stopped to reduce fluctuations in the power supply voltage on the power supply 5 side. It can be, it is not on the electrical adverse effect on other electrical equipment. Further, the energization current per heater can be reduced, the rating of the electronic switch can be reduced, and it can be realized at low cost.

FIG. 6 shows another embodiment of the present invention. This embodiment is one form of the image forming apparatus. A charging unit 102, a cleaning unit 103, and a developing unit that visualizes an electrostatic latent image on the photosensitive member 101 around a drum-shaped photosensitive member 101 as an image bearing member that is rotated in a direction of an arrow by a driving unit (not shown). The developing unit 107 including the developing sleeve 105 and the transfer unit 106 are arranged.

The photoconductor 101 is uniformly charged by the charging means 102 and then exposed by the laser light L from the laser optical system 140 as a writing means (exposure means) to form an electrostatic latent image, and the developing unit is developed. The electrostatic latent image is developed by 107 and becomes a toner image. The toner image on the photoconductor 101 is transferred to the sheet P as a sheet-shaped recording medium by the transfer unit 106 as described later, and the photoconductor 101 is cleaned by the cleaning unit 103 after the toner image is transferred. Therefore, the charging means 102 and the laser optical system 1
40, the developing unit 107, and the transfer unit 106 constitute an image forming unit that forms a toner image on the sheet P.

A paper feeding device having a paper feeding cassette 110 which can be attached and detached in the direction of arrow a is provided at the lower part of the apparatus.
The paper P stored in the paper feed cassette 110 is
1 and is pressed against the sheet feeding roller 113 via the arm 112 by the force of a spring (not shown). The uppermost paper in the paper feed cassette 110 is fed by a command issued from a control unit (not shown) to rotate the paper feed roller 113, and the separation pad 114 prevents double feed, while the downstream registration roller pair 115 is provided. Be transported to.

Further, the paper feed tray 132 is rotatably attached by a pin 133, and the paper as the uppermost sheet-like recording medium in the paper feed tray 132 is fed by a paper feed roller and double-fed by a separation pad. While being prevented, the sheet is conveyed to the registration roller pair 115 on the downstream side. Either one of the sheets in the sheet cassettes 110 and 132 is selectively fed.

The pair of registration rollers 115 sends the conveyed paper P toward the transfer means 106 at a timing so as to be synchronized with the image (toner image) on the photoconductor 101. The transfer unit 106 transfers the image on the photoconductor 101 to the sheet P sent from the registration roller pair 115,
The sheet P on which the image is transferred is conveyed to the fixing device 116. As the fixing device 116, the fixing device of the above-described embodiment shown in FIG. 1 is used, and the toner on the paper P is fixed to the paper P by heating and pressing.

The fixed paper P from the fixing device 116
Are discharged onto the discharge tray 122 from the discharge port 121 with the image surface facing downward by the discharge roller pair 120 and stacked. The paper ejection auxiliary tray 125 is slidable in the direction of arrow b in order to correspond to the size of the paper to be ejected. An operation surface is arranged on the right side of the apparatus, and the operation panel 130 projects from the upper front surface of the exterior part 131 (on the right side of the apparatus in FIG. 10). In a case 134 arranged on the left side in the drawing, electric equipment / control devices such as a power supply circuit 135 and a printed board (engine driver board) 136 are housed, and a controller board 137 is also housed. The cover 138 that constitutes the paper discharge tray 122 has a rotation fulcrum 1
It is possible to release around 39.

According to this embodiment, since the fixing device of the above embodiment shown in FIG. 1 is used as the fixing device 116, no rush current to the heaters 1 and 2 is generated as in the fixing device of the above embodiment. Not only that, fluctuations in the power supply voltage on the power supply 5 side can be reduced, and other electric devices are not adversely affected electrically. Further, the energization current per heater can be reduced, the rating of the electronic switch can be reduced, and it can be realized at low cost.

The present invention is not limited to the above embodiment, but can be applied to the case where a fixing member such as a fixing belt is heated by a plurality of heaters which are turned on / off at the same time. It can also be applied to the case where a heated member such as a fixing member and a pressing member is heated by a plurality of heaters.

[0046]

As described above, according to the present invention, it is possible to reduce the fluctuation of the power supply voltage, to prevent other electric equipment from having an adverse electrical effect, and to realize at low cost.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing a fixing temperature control state at the time of rising, an image forming operation, and a standby operation in the same embodiment.

FIG. 3 is a diagram showing an energization waveform at a soft start of energization of the fixing heater at the time of rising of the embodiment.

FIG. 4 is a diagram showing an energization waveform during soft stop of energization of the fixing heater at the start-up of the same embodiment.

FIG. 5 is a flowchart showing a control flow at the time of rising of a control unit in the same embodiment.

FIG. 6 is a sectional view showing another embodiment of the present invention.

[Explanation of symbols]

1, 2 fixing heater 3 fixing roller 4 Temperature detector 5 Commercial power supply 6,7 electronic switch 8 control unit 116 fixing device

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G05D 23/24 G03G 21/00 372 F term (reference) 2H027 DA12 DE07 DE09 EA12 EA16 ED25 EE02 EF04 EF09 JA20 JC08 2H033 AA41 BA25 BA30 BB17 CA03 CA04 CA05 CA07 CA28 CA30 CA32 CA46 CA48 3K058 AA27 AA29 BA18 CA12 CA22 CB01 CB03 CB04 CB06 DA02 GA06 5H323 AA36 BB20 CA08 CB04 CB42 DA02 DB04 EE01 FF01 HH02 KK20LL11 KK02 LL050211

Claims (5)

[Claims] 1. A heater having temperature detection means for detecting the temperature of a heated member heated by a plurality of heaters, and controlling energization of the plurality of heaters based on the temperature detected by the temperature detection means. In the control device, when the plurality of heaters are turned on, the plurality of heaters are simultaneously energized without being energized to be energized to cause the plurality of heaters to be displaced and soft-started to be turned on. When turning off the heaters, the heater control device is characterized in that the plurality of heaters are turned off while being soft-stopped. 2. A plurality of heaters for heating a member to be heated,
A temperature detecting means for detecting the temperature of the heated member, and the temperature detected by the temperature detecting means at the time of rising from the start of energization of the heater from the power source until the temperature of the heated member reaches a set temperature. In the fixing device that controls the energization of the plurality of heaters by comparing the set temperature with the set temperature, the plurality of heaters are not energized at the same time at the time of start-up, but the energization is performed to displace the plurality of heaters and the soft start is performed. The fixing device is characterized in that the fixing device is turned on while being turned on, and when the temperature detected by the temperature detecting means reaches the set temperature, the plural heaters are shifted to soft stop and turned off. 3. A plurality of heaters for heating a member to be heated,
In a fixing device that has a temperature detection unit that detects the temperature of the heated member, and that controls the energization of the plurality of heaters based on the temperature detected by the temperature detection unit during the fixing operation, Is lit by energizing the plurality of heaters without simultaneously energizing them to energize the plurality of heaters while displacing the plurality of heaters for soft start, so that the temperature detected by the temperature detecting means is maintained at a set temperature. A fixing device, wherein PID control of a plurality of heaters is performed, and the plurality of heaters are turned off while being soft-stopped by shifting. 4. A plurality of heaters for heating a member to be heated,
In a fixing device that has a temperature detection unit that detects the temperature of the heated member, and controls the energization of the plurality of heaters based on the temperature detected by the temperature detection unit during the standby operation, during the standby operation, Instead of simultaneously energizing the plurality of heaters, energize them by energizing them to displace the plurality of heaters and turn them on while soft-starting, so that the temperature detected by the temperature detecting means is maintained at a set temperature. 2. The fixing device is characterized in that hysteresis control of the heater is performed, and the plurality of heaters are shifted to soft stop and turned off. 5. An image forming apparatus comprising the fixing device according to any one of claims 2 to 4.