JP2003228250A - Fixing device and image forming apparatus having the fixing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device capable of improving the maximum power supplied to each heating means from a power source in the case at least one of the heating means is independently conducted and in the case where at least the one heating means is conducted at the same time as another heating means. <P>SOLUTION: In constant voltage output circuits 102a and 102b, predetermined voltage values for voltages which are applied to the heaters 13a and 13b from the power source VCC are set so that the total amounts of power supplied to the heaters 13a and 13b from the heat source VCC are the same in the case where the heater 13a is independently conducted and in the case where the heater 13a is conducted at the same time as the heater 13b. <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 fixing device used in an image forming apparatus such as a copying machine and a laser beam printer adopting an electrophotographic method, and an image forming apparatus including the fixing device.

[0002]

2. Description of the Related Art A laser printer or the like is known as an image forming apparatus adopting an electrophotographic method, and a fixing device used in a conventional general laser printer has a structure as shown in FIG.

In such a fixing device, the fixing roller 10, which is a fixing member, has a core metal 11 made of, for example, aluminum or iron.
A release layer 12 made of a resin such as PFA or PTFE is provided on the heater 1, and the heater 1 is provided inside the fixing roller 10.
It is designed to be heated by 3. Fusing roller 1
The temperature of 0 is detected as a surface temperature of the fixing roller 10 by a temperature detecting element 30 which is a temperature detecting means such as a thermistor which is in contact with the fixing roller 10, and a temperature control circuit which is a controlling means based on the detected temperature (see FIG. The surface temperature is controlled to a predetermined temperature by intermittently operating the heater 13 at one set voltage value by an adjusting means (not shown) by means of not shown.

On the other hand, the pressure roller 20, which is a pressure body, rotates in pressure contact with the fixing roller 10, and has a heat-resistant and low-hardness silicone rubber or a core metal 21 made of metal such as aluminum or iron. Elastic layer 22 such as silicone sponge
And a mold release layer 23 formed by coating a resin having a high mold release property such as PFA or PTFE on the surface thereof.

Then, the recording material carrying the toner image which is an unfixed image is guided to the nip portion between the fixing roller 10 and the pressure roller 20 by the entrance guide 24, and is fixed by being heated and pressed. It This entrance guide 24 is a PBT
Or other resistance control material (10E8 to 10E10Ω) or a guide surface made of metal such as stainless steel,
It is common to use the resistance control material for the contact point with the fixing frame. This is because if the inlet guide is formed of an insulating material or the like, the guide surface is charged by sliding friction with the recording material, which causes adverse effects such as toner scattering. Also, to prevent wrinkles from occurring when the recording material passes through the nip portion,
It is generally practiced that the fixing roller 10 and the pressure roller 20 have proper inverted crown shapes in the longitudinal direction (axial direction), and that the entrance guide 24 optimizes the entry position into the nip portion.

The recording material on which the toner image is fixed by being heated and pressed in the nip portion is separated from either roller by the fixing roller separation claw 25 or the pressure roller separation claw 26, and is discharged by the paper discharge guide 27. Paper ejection roller 2
8 is discharged to the outside of the device.

By the way, in a laser printer having the above-mentioned fixing device, when an attempt is made to increase the printing speed, or when printing is performed on a large size paper (recording material), the electric power supplied to the heater of the fixing device is increased. The print speed can be increased within the range.

However, in the fixing device as described above, the smaller the size of the recording material such as paper to be printed (hereinafter referred to as paper size), the larger the temperature rise in the non-sheet passing area of the fixing roller and the pressure roller. It becomes impossible to increase the print speed.

Therefore, conventionally, the heater 13 shown in FIG. 8 is used.
Instead of a plurality of heating means, heater segment arrangements and heater light distributions as shown in FIGS. 9 and 10 have symmetrical distributions with respect to the sheet passing reference, respectively, and are arranged in the axial direction of the fixing roller. There is known a fixing device including two heaters, a heater 13a having a light distribution mainly in a central portion and a heater 13b having a light distribution mainly in an end portion in the axial direction. The driving of these two heaters is controlled by a lighting method as shown in FIG. That is, the heater 1
3a and the heater 13b are repeatedly turned on and off during a fixed cycle, and the lighting time ratio within the fixed cycle is controlled, so that the temperature distribution of the fixing roller in the axial direction can be kept constant at all times. The lighting ratio of the heater 13a and the heater 13b to the paper size, and the heater 13a is rated 700
Table 1 shows the relationship between W and the maximum power consumption of the heater during the fixing process for each paper size when the heater 13b is rated at 300W.

[0010]

[Table 1]

[0011]

However, even in the fixing device using the above-mentioned two heaters, as shown in Table 1, the maximum usable power to the heater decreases as the paper size decreases, so that the paper cannot be used. If the size is small, the print speed will be limited.

Therefore, according to the present invention, at least one heating means of the plurality of heating means is individually brought into conduction, and when at least one heating means is simultaneously brought into conduction with other heating means. It is an object of the present invention to provide a fixing device capable of improving the maximum electric power that can be supplied from a power source to each heating unit, and an image forming apparatus including the fixing device.

[0013]

According to the present application, the above object is to provide a fixing member and a pressing member that rotate in pressure contact with each other, and at least the fixing member of the fixing member and the pressing member that receives electric power from a power source. A plurality of heating means for heating the body, and fixing and fixing the unfixed image on the recording material by heating and pressing the recording material carrying the unfixed image while being nipped and conveyed by the fixing body and the pressure body. A fixing device for detecting the temperature of the fixing member, and switching the electric power supply from the power source to each heating means to conduction or interruption to set a predetermined voltage to be applied from the power source to each heating means. A fixing device comprising adjusting means for adjusting the voltage value and control means for controlling the driving of the adjusting means so that the fixing body reaches a predetermined temperature based on the temperature detected by the temperature detecting means. , The case where each of the at least one heating means is brought into the conducting state independently and the case where the at least one heating means is brought into the conducting state at the same time as the other heating means, the sum of the electric power supplied from the power source to each heating means is This is achieved by the first invention in which a plurality of set voltage values are set to be the same.

According to the present application, in the first aspect of the present invention, the plurality of heating means are configured to generate heat with different heat distributions in the axial direction of the fixing member.
The control means controls the voltage application time length in the case where at least one heating means is brought into a conductive state independently so that the temperature distribution in the axial direction of the fixing body becomes a predetermined distribution state, the at least one heating means and other The present invention can also be achieved by the second invention in which the driving of the adjusting means is controlled by adjusting the ratio with the voltage application time length when the heating means and the heating means are simultaneously brought into conduction.

Further, according to the present application, in the first or second invention, the above-mentioned object is the number of heating means is n, and one of the n heating means consumes only one heating means. When the electric power is set to d [W], the control means applies D / n to each heating means when the n heating means are simultaneously turned on.
It is also achieved by the third invention in which the driving of the adjusting means is controlled so that the power of [W] is supplied.

Further, according to the present application, the above object is that in any one of the first to third inventions, one of the plurality of heating means heats the pressurizing body. ,
The control means controls the drive of the adjusting means so that the fixing body and the pressure body are heated at the same time when the temperature detected by the temperature detection means is within a predetermined temperature range. It is also achieved by the invention.

Further, according to the present application, the above object is an image forming apparatus for recording a recording material on an image by a series of image forming processes, and the fixing apparatus according to any one of the first to fourth inventions. It is also achieved by the fifth invention of including.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings.

(First Embodiment) First, a first embodiment of the present invention will be described.

First, a schematic structure of the image forming apparatus according to the present embodiment will be briefly described with reference to FIG.

FIG. 1 is a schematic sectional view showing a schematic configuration of a laser printer which is an example of an image forming apparatus adopting an electrophotographic system.

As shown in FIG. 1, such a laser printer includes a photosensitive drum 1, an exposure device 2, a developing device 3, a transfer member 4, a cleaning device 5, a charging member 6, and a fixing device 7. A sheet feeding cassette C for feeding the recording material to the conveyance path P and a sheet feeding device 8 are provided.

In such a laser printer, first,
The photosensitive drum 1 charged to a desired potential by the charging member 6.
The exposure device 2 forms the electrostatic latent image on the photosensitive drum 1 by turning on and off the laser beam L according to the image information and irradiating the surface to remove the electric charge.

Then, the electrostatic latent image is visualized as a toner image on the photosensitive drum 1 by applying toner as a developer by the developing device 3. Here, the developing device 3 includes a developing container (not shown) that stores toner, a developing sleeve 31, and the like, and the developing sleeve 31 supplies toner to the photosensitive drum 1.

After that, the toner image on the photosensitive drum 1 is transferred onto the surface of the recording material by the transfer member 4. The recording material carrying the unfixed toner image is heated and pressed by the fixing device 7 to permanently fix the above-mentioned P-ner image on the recording material and then discharged from the image forming apparatus.

On the other hand, the toner, paper dust and the like remaining on the photosensitive drum 1 during transfer are cleaned by the cleaning device 5.
Removed from above.

Next, the fixing device 7 will be described in detail.

The fixing device 7 of this embodiment includes a fixing roller 10 as a fixing body, a pressure roller 20 as a pressure body, heaters 13a and 13b as a plurality of heating means, and a temperature detecting element (thermistor) as a temperature detecting means. ) 30 and.

This fixing device 7 is an example of a central reference for conveying a recording material having a maximum sheet passing size of A3 (297 mm) width with reference to the sheet passing center of the apparatus.
1000W when inputting 00V, 600 when inputting 71.8V
W output is used, heater 13b is 100V
The one that gives an output of 400 W when input is used.

As shown in FIGS. 9 and 10, the segment arrangement of the heaters 13a and 13b and the heater light distribution have a symmetrical distribution with respect to the sheet passing reference, and the heater 13a is at the center of the fixing roller 10 in the axial direction. The portion (paper passing region) has a heat generation distribution predominantly, and the heater 13b has a heat generation distribution predominantly at the end portion in the axial direction.

The fixing roller 10 is made of aluminum and has a core metal 1.
1 is a roller having a diameter of 50 mm and a thickness of 3.0 mm, and the surface layer thereof is covered with a release layer 12 of PFA.

The pressure roller 20 is made of stainless steel core metal 2.
1 has an elastic layer 22 of silicone rubber and a release layer 23 of PFA on the surface, and has a diameter of 40 mm and a product hardness of 65 ° (As
ker-C), and by applying a pressure of 600 N toward the fixing roller 10, the fixing roller 1
A nip having a nip width of 8.0 mm is formed between the nip and 0.

Since the temperature detecting element 30 is installed at a substantially central portion in the axial direction of the fixing roller 10, the temperature detecting element 30 is provided.
A cleaning means is required for the toner adhesion to the toner. However, by arranging the temperature detecting element at a substantially central portion in the axial direction of the fixing roller, the surface temperature of the fixing roller can be adjusted accurately and stable fixing performance can be secured. In the present embodiment, by performing temperature control control so that the fixing roller 10 reaches 190 ° C., it is possible to print 60 sheets / minute with A4 lateral feed.

The drive control of the heaters 13a and 13b will be described in detail with reference to FIG.

In the fixing device 7 of this embodiment, as shown in FIG. 3, constant voltage output circuits 102a and 102b serving as adjusting means.
And an MPU 113 as a control means.

The constant voltage output circuit 102a is capable of switching the input voltage to the heater 13a at two set voltage values,
The constant voltage output circuit 102b can input a voltage to the heater 13b at a constant set voltage value. Heater 13a
Causes a voltage of 100 V to be applied when it is lit alone to generate an output of 1000 W. When the heater 13a and the heater 13b are turned on at the same time, the heater 13a has a voltage of 71.8V (600
W), by applying 100 V (400 W) to the heater 13b, a total of 1000 W output is generated.

The constant voltage output circuits 102a and 102b include chopping FETs 103a and 103b, inductors 104a and 104b, and snubber diodes 105a and 1b.
It has a step-down type DC-DC converter composed of 05b. The constant voltage output circuits 102a and 102b are control ICs 106a and 106b (U in the present embodiment) for detecting the output voltage and output current to the heaters 13a and 13b and the input effective value voltage and input voltage waveform of the commercial power source.
NUCRODE's UC3854 is used), the output voltage is detected by the voltage detection circuits 107a and 107b, the output current is detected by the current detection resistors 108a and 108b, and the effective input value is measured by the resistors 109a and 109b and the capacitor 110a.
At 110b, the input voltage waveform is converted into resistors 111a, 111b,
The on-duty of the chopping FETs 103a and 103b, which are detected by the resistors 112a and 112b, are turned on / off at about 100 kHz so that the output voltage is constant and the output voltage waveform is similar to the input voltage waveform, is controlled. ing. Here, the constant voltage output circuit 102a
And the constant voltage output circuit 102b perform the same operation except the difference between the voltage detection circuit 107a and the voltage detection circuit 107b.

The MPU 113 is equipped with a ROM, a RAM, input / output ports (none of which are shown), etc., and is adapted to recognize the operating states of the image forming apparatus and the connected equipment. Digital output port P1 provided in MPU113
Is connected to the base of the transistor 115 via the resistor 114, and outputs the signal from the digital output port P1 to H level.
When the voltage is set to IGH, the transistor 115 is turned on, the photodiode 117 connected to the + 5V power source through the resistor 116 is turned on, the phototransistor 118a is turned on, and the transistor 120a is turned off, so that the voltage of the power supply VCC is reached. Is input to the enable terminal ENA of the control IC 106a via the resistor 121a to operate the control IC 106a to control the constant voltage output.

The value of the constant voltage output is that the digital output port P2 of the MPU 113 is connected to the base of the transistor 123 via the resistor 122, and the transistor 123 is turned on by setting the signal from the digital output port P2 to HIGH. When turned on, the photodiode 125 connected to the + 5V power source via the resistor 124 is turned on,
The phototransistor 127 is turned on. When the phototransistor 127 is on, the control IC 106a
V _sense of (resistor 129a + resistor 126) and resistor 12
The divided voltage value of 8a is input, and the constant voltage output circuit 102 outputs a voltage of 71.8V. Phototransistor 12
When 7 is off, the divided voltage value by the resistors 128a and 129a is input to _Vsense via the capacitor 130a, and the constant voltage output circuit 102 outputs a voltage of 100V.

The value of the constant voltage output is that the digital output port P3 of the MPU 113 is connected to the base of the transistor 132 via the resistor 131, and the transistor 132 is turned on by setting the signal from the digital output port P3 to HIGH. When turned on, the photodiode 134 connected to the + 5V power source via the resistor 133 is turned on,
The phototransistor 118b is turned on. When the phototransistor 118b is turned on and the transistor 120b is turned off, the voltage of the power supply VCC is changed to the resistor 121b.
Through the enable terminal E of the control IC 106b
Input to the NA, the control IC 106a is operated to control the constant voltage output. When the phototransistor 118b is on, the constant voltage output circuit 106b
The of V _{sens e} divided value by the resistors 128b and 129b are input to the V _{sen se} via the capacitor 130b, the constant voltage output circuit 102b outputs a voltage of 100 V.

Next, the fixing roller 10 by the MPU 113 is used.
The temperature control method will be described.

FIG. 4 shows the temperature of the fixing roller 10 and the heater 13.
The relation with the power supply state of a and 13b is shown.

In the MPU 113, once every 3 seconds is a lighting cycle of the heater, and the interval is divided into a single conduction time ta1 of the heater 13a and a simultaneous conduction time tb1 of the heaters 13a and 13b. Sampling of the temperature from the temperature detecting element 30 is performed at intervals of 200 msec. If the detected temperature is 190 ° C. or higher, the heater is turned off, and
If the temperature is lower than 0 ° C., the heater is turned on at a predetermined conduction ratio for 3 seconds.

In the present embodiment, by setting ta1 and tb1 to the values shown in Table 2 for the paper size, the maximum power (1000) that can be used for all paper sizes is set.
W) can be added.

[0045]

[Table 2] In the present embodiment, ta1 + ta2 = 3 sec, but the temperature change when the heater is turned on differs depending on the print speed of the image forming apparatus, the heat capacity of the fixing roller, and the thermal conductivity. It can be set. If the heat capacity of the fixing roller is small and the temperature changes rapidly when the heater is on, ta1 + ta2 = 0.5 to 1.0 s
Set to ec.

Table 3 compares the printing speeds for the respective paper sizes in the case of the heater power supply method in the conventional example shown in Table 1 and in the case of the heater power supply method in the present embodiment. As shown in Table 3, in the present embodiment, the portion limited by the maximum usable power of the conventional example can be printed with the maximum throughput.

[0047]

[Table 3] (Second Embodiment) Next, a second embodiment of the present invention will be described. The same components as those of the first embodiment described above are designated by the same reference numerals, and the description thereof will be omitted.

FIG. 5 is a circuit diagram showing a drive control system for the heaters 13a and 13b, which are a plurality of heating means in this embodiment. In the present embodiment, the image forming apparatus, the fixing device, and the heater segment configuration and light distribution are the same as those in the above-described first embodiment. However, the heaters 13a, 13
b is assumed to generate an output of 1000 W when inputting 100 V.

The constant voltage output circuit 102 shown in FIG. 5 outputs a constant voltage only to the heater 13a or the heater 13a.
A constant voltage output is possible with a and the heater 13b connected in series.

The constant voltage output circuit 102 has a step-down DC-DC converter including a chopping FET 103, an inductor 104, and a snubber diode 105. The constant voltage output circuit 102 includes the heaters 13a, 1
Control IC 106 for detecting the output voltage and output current to 3b and the input effective value voltage and the input voltage waveform of the commercial power supply (in this embodiment, UC of UNITRODE, Inc.).
3854), the output voltage is detected by the voltage detection circuit 10
7, the output current is detected by the current detection resistor 108, the input effective value is detected by the resistor 109 and the capacitor 110, the input voltage waveform is detected by the resistor 111 and the resistor 112, respectively, and the output voltage is constant and the output voltage waveform is the input voltage. The on-duty of the chopping FET 103 that is turned on and off at about 100 kHz is controlled so as to have a waveform similar to the waveform.

The MPU 113 has a ROM, a RAM, input / output ports (none of which are shown), etc., and is adapted to recognize the operating states of the image forming apparatus and the connected equipment. Digital output port P1 provided in MPU113
Is connected to the base of the transistor 115 via the resistor 114, and outputs the signal from the digital output port P1 to H level.
When the voltage is set to IGH, the transistor 115 is turned on, the photodiode 117 connected to the + 5V power source via the resistor 116 is turned on, the phototransistor 118 is turned on, and the transistor 120 is turned off, so that the voltage of the power supply VCC. Is input to the enable terminal ENA of the control IC 106 via the resistor 121,
The control IC 106 is operated to control the constant voltage output.

At this time, the digital output port P2 of the MPU 113 is connected to the base of the transistor 123 via the resistor 122. When the signal from the digital output port P2 is LOW, the transistor 123 is off and the resistor 124 is connected. The photodiode 125 connected to the + 5V power supply is turned off, and the phototransistor 127 is turned off. When the phototransistor 127 is off, the resistance 128 and the resistance 1 are added to V _sense of the control IC 106.
The divided voltage value by 29 is V _sense via the capacitor 130.
The constant voltage output circuit 102 outputs a voltage of 100V. Further, the digital output port P2 is connected to the base of the transistor 136 via the resistor 135,
When the signal from the digital output port P2 is LOW, the transistor 136 is turned off, the photodiode 138 connected to the + 5V power source via the resistor 137 is turned off, and the phototransistor 140 is turned off. When the phototransistor 140 is off, the transistor 142 is turned on via the resistor 141 and HIGH is input to the triac 145 via the resistor 143. As a result, the triac 145 becomes conductive and the voltage output of 100 V is output to the heater 13.
It is applied only to a.

Also, the digital output port P of the MPU 113
Transistor by setting the signal from 2 to HIGH
123 is turned on and connected to the + 5V power source via the resistor 124.
The connected photodiode 125 is turned on,
Transistor 127 is turned on. Photo Transis
When the controller 127 is on, V of the control IC 106
_senseTo (resistor 128 + resistor 126) and resistor 129
The divided voltage value is input, and the constant voltage output circuit 102 outputs 12
It outputs a voltage of 7.5V. Also, the digital device of MPU113
By setting the signal from the output port P2 to HIGH
Transistor 136 is turned on, and through resistor 137
The photodiode 138 is turned on and the phototransistor
Switch 140 is turned on. The phototransistor 140 is off
Transistor 142 is turned off and the resistor 144
Input of TRIAC 145 to LOW via
As a result, the triac 145 becomes non-conductive. At this time
The output 127.5V of the constant voltage output circuit is the same as that of the heater 13a.
It is applied with the heater 13b connected in series.
With the heater combined, an output of 1000 W is generated.

Also in this embodiment, the same electric power supply control to the heater as in the first embodiment described above is performed, and the relationship between the temperature of the fixing roller 10 and the electric power supply state of the heaters 13a and 13b is the same as in FIG. Become. 3 for MPU113
The heater lighting cycle is set to once per second, and the individual conduction time ta2 of the heater 13a and the heaters 13a, 13
It is divided into the simultaneous conduction time tb2 of b. Sampling of the temperature from the temperature detecting element 30 is performed at intervals of 200 msec. When the detected temperature is 190 ° C. or higher, the heater is turned off, and when the detected temperature is lower than 190 ° C., the heater is turned on in a predetermined conductive state for 3 seconds.

In the present embodiment, since the two heaters have the same rated power, ta2,
By setting tb2 to the value shown in Table 4, the maximum power that can be used for all paper sizes can be supplied.

[0056]

[Table 4] (Third Embodiment) Next, a third embodiment of the present invention will be described. The same components as those of the first embodiment described above are designated by the same reference numerals, and the description thereof will be omitted.

FIG. 6 shows a fixing device in this embodiment.

The fixing device of this embodiment is A3 (297 m).
m) This is an example of a central reference in which a recording material having a width of the maximum paper passing size is conveyed with the paper passing center of the apparatus as a reference, and the heater 13 as a heating means for heating the fixing roller 10
A heater that outputs 1000 W at V input and 600 W at 71.8 V is used, and the heater 13c as a heating means for heating the pressure roller 20 is 40 W at 100 V input.
Use one that outputs 0W.

As shown in FIG. 7, the light distribution of these heaters has a symmetrical distribution with respect to the sheet passing reference, and the heater 13 is 20 in consideration of heat escape at the end of the fixing roller 10 in the axial direction. % Light distribution characteristics are given from the center. Heater 13c
Has a flat heat generation distribution.

The fixing roller 10 is made of aluminum and has a core metal 1.
1 is a roller having a diameter of 50 mm and a thickness of 3.0 mm, and the surface layer thereof is covered with a release layer 12 of PFA.

The pressure roller 20 is made of stainless steel core metal 2.
1 has an elastic layer 22 of silicone rubber and a release layer 23 of PFA on the surface, and has a diameter of 40 mm and a product hardness of 65 ° (As
ker-C), and by applying a pressure force of 600 N toward the fixing roller 10, the fixing roller 1
A nip having a nip width of 8.0 mm is formed between the nip and 0.

Since the temperature detecting element 30 is installed at a substantially central portion in the axial direction of the fixing roller 10, the temperature detecting element 3
A cleaning means is required for toner adhesion to 0. However, by disposing the temperature detecting element 30 substantially at the center of the fixing roller 10 in the axial direction,
The surface temperature of can be accurately adjusted, and stable fixing property can be secured. Further, a temperature detecting element (thermistor) 30c is provided at a substantially central portion of the pressure roller 20 in the axial direction.
Has been installed.

In the present embodiment, by controlling the temperature of the fixing roller 10 to 190 ° C. and the pressure roller 20 to 140 ° C., it is possible to print 60 sheets / minute by A4 lateral feeding.

Therefore, in this embodiment, a constant voltage output circuit similar to the constant voltage output circuits 102a and 102b of FIG. 3 used in the above-described first embodiment is used as the adjusting means, and the heater 13 has 100V. 1000W at input, 7
Control to output 600W when 1.8V is input,
The heater 13c is controlled to output 400 W when 100 V is input.

Table 5 shows the relationship between the temperatures of the fixing roller 10 and the pressure roller 20 and the power supply states of the heaters 13 and 13c.

[0066]

[Table 5] Here, the detection temperature of the temperature detection element 30 for the fixing roller 10 is T1, and the temperature detection element 3 for the pressure roller 20 is T1.
The detected temperature of 0c is T2. Since the heater 13c is controlled by giving priority to the temperature of the fixing roller 10,
For simultaneous lighting, the temperature of the fixing roller 10 is 190 ° C.> T1 ≧ 1
It was set to be in the range of 87.5 ° C.

The balance of the power supply to the heater 13 and the heater 13c in the present embodiment is not limited to the above value, and can be set arbitrarily according to the specifications of the image forming apparatus and the configuration of the fixing device.

[0068]

As described above, according to the first invention of the present application, the adjusting means includes the case where each of the at least one heating means is brought into a conductive state independently, and the case where the at least one heating means is provided. Since a plurality of set voltage values are set so that the total sum of the electric power supplied from the power source to each heating means is the same when the other heating means is brought into the conductive state at the same time, at least one of the plurality of heating means is set. The maximum electric power that can be supplied from the power source to each heating means is improved depending on whether each heating means is brought into a conducting state independently or when at least one heating means is placed into a conducting state simultaneously with another heating means. be able to.

According to the second invention of the present application,
The adjusting means supplies electric power from the power source to each heating means depending on whether at least one heating means is brought into conduction independently or when at least one heating means is brought into conduction simultaneously with other heating means. A plurality of set voltage values are set so that the total sum of
At least one heating means of a plurality of heating means configured to generate heat with different heat distributions in the axial direction is independently brought into a conductive state so that the temperature distribution in the axial direction of the fixing body becomes a predetermined distribution state. In this case, the ratio of the voltage application time length in the case of performing the voltage application and the voltage application time length in the case where the at least one heating means and the other heating means are simultaneously brought into a conducting state is adjusted to control the drive of the adjusting means. Therefore, each of the plurality of heating means is heated by the power source in a case where at least one heating means is individually brought into conduction, and in a case where the at least one heating means is simultaneously brought into conduction with other heating means. It is possible to improve the maximum power that can be supplied to the means, and it is possible to improve the productivity when fixing a recording material of a small size.

Further, according to the third invention of the present application, the adjusting means includes a case where at least one heating means is brought into a conductive state independently, and a case where the at least one heating means is simultaneously provided with other heating means. Since a plurality of set voltage values are set so that the total sum of the electric power supplied from the power source to each heating means is the same when the conductive state is set, at least one heating means of the plurality of heating means is set. It is possible to improve the maximum electric power that can be supplied from the power supply to each heating means depending on whether each of them is brought into a conducting state independently or when at least one heating means is brought into a conducting state simultaneously with other heating means. it can.

According to the fourth invention of the present application,
The adjusting means supplies electric power from the power source to each heating means depending on whether at least one heating means is brought into conduction independently or when at least one heating means is brought into conduction simultaneously with other heating means. The plurality of set voltage values are set so that the total sum becomes the same, and one of the plurality of heating means heats the pressurizing body, and the control means controls the temperature detected by the temperature detecting means to a predetermined temperature. When the temperature is within the range, the driving of the adjusting means is controlled so that the fixing body and the pressurizing body are heated at the same time. Therefore, at least one heating means of the plurality of heating means is independently in the conductive state. It is possible to improve the maximum electric power that can be supplied from the power source to each heating means depending on the case of the above, and the case where the at least one heating means is brought into conduction simultaneously with the other heating means. The maintained at a predetermined temperature faster fixing process with good fixation can be performed.

Further, according to the fifth invention of the present application, the adjusting means includes a case where at least one heating means is brought into a conductive state independently, and a case where the at least one heating means is simultaneously provided with other heating means. Since a plurality of set voltage values are set so that the total sum of the electric power supplied from the power source to each heating means is the same in the case of the conduction state, at least one heating means among the plurality of heating means is independently used. It is possible to improve the maximum electric power that can be supplied from the power source to each heating means depending on the case where the heating element is brought into the conducting state and the case where the at least one heating means is brought into the conducting state simultaneously with the other heating means.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing a schematic configuration of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view showing a schematic configuration of a fixing device provided in the image forming apparatus of FIG.

FIG. 3 is a circuit diagram showing a drive control system of a heating unit in the fixing device according to the first embodiment of the present invention.

FIG. 4 is a diagram showing a relationship between a power supply state of a heater to a heating unit and a temperature of a fixing body in the first embodiment of the present invention.

FIG. 5 is a circuit diagram showing a drive control system for heating means in a fixing device according to a second embodiment of the present invention.

FIG. 6 is a schematic sectional view showing a schematic configuration of a fixing device according to a third embodiment of the present invention.

FIG. 7 is a diagram for explaining a light distribution of a heater that is a heating unit in a third embodiment of the present invention.

FIG. 8 is a schematic cross-sectional view showing a schematic configuration of a conventional fixing device.

FIG. 9 is a diagram for explaining a segment arrangement of heaters as heating means in a fixing device including a plurality of heating means.

FIG. 10 is a diagram for explaining a light distribution of a heater as a heating unit in a fixing device including a plurality of heating units.

FIG. 11 is a diagram showing the relationship between the power supply state to the heating means and the temperature of the fixing body in the conventional fixing device.

[Explanation of symbols]

7 Fixing device 10 Fixing roller (fixing body) 13 Heater (heating means) 13a heater (heating means) 13b heater (heating means) 13c heater (heating means) 20 Pressure roller (Pressure body) 30 Temperature detection element (temperature detection means) 102 Constant voltage output circuit (adjusting means) 102a Constant voltage output circuit (adjusting means) 102b Constant voltage output circuit (adjusting means) 113 MPU (control means) VCC power supply

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2H033 AA03 BA25 BA26 BA27 BA30                       BB18 CA07 CA23 CA27 CA41                       CA45 CA48                 3K058 AA87 BA18 CA12 CA22 CA61                       CB02 CB09 CB19 CB34 CD01                       DA06 GA06

Claims (5)

[Claims] 1. An unfixed body comprising: a fixing body and a pressure body that rotate in pressure contact with each other; and a plurality of heating means that receives electric power from a power source to heat at least the fixing body of the fixing body and the pressure body. A fixing device for fixing the unfixed image to the recording material by heating and pressurizing the recording material carrying an image by the fixing body and the pressing body while conveying the recording material, and detecting the temperature of the fixing body. Temperature detecting means,
Based on the temperature detected by the temperature detecting means, adjusting means for switching the power supply from the power source to each heating means to conduction or interruption to adjust the voltage applied from the power source to each heating means to a predetermined set voltage value. In the fixing device provided with the control means for controlling the driving of the adjusting means so that the fixing body reaches a predetermined temperature, the adjusting means may be a case where at least one heating means is brought into a conductive state independently, The fixing device is characterized in that a plurality of set voltage values are set so that the total sum of electric power supplied from the power source to each heating means is the same when the heating means is brought into conduction simultaneously with other heating means. 2. A plurality of heating means are configured to generate heat with different heat distributions in the axial direction of the fixing body,
The control means controls the voltage application time length in the case where at least one heating means is brought into a conductive state independently so that the temperature distribution in the axial direction of the fixing body becomes a predetermined distribution state, the at least one heating means and other 2. The driving of the adjusting means is controlled by adjusting the ratio with the voltage application time length when the heating means and the heating means are simultaneously turned on.
The fixing device described in 1. 3. When the number of heating means is n and the power consumption of one of the n heating means alone is d [W], the control means simultaneously controls the n heating means. The fixing device according to claim 1 or 2, wherein the driving of the adjusting means is controlled so that the electric power of D / n [W] is supplied to each heating means when the heating means is brought into the conductive state. apparatus. 4. One of the plurality of heating means is adapted to heat the pressure body, and the control means controls the fixing body when the temperature detected by the temperature detection means is within a predetermined temperature range. And driving of the adjusting means is controlled so that the pressurizing body is heated at the same time.
The fixing device according to claim 3. 5. An image forming apparatus for recording a recording material on an image by a series of image forming processes, comprising the fixing device according to any one of claims 1 to 4. Forming equipment.