JP2001265162A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device in which the rise time for fixing is not delayed and generated of noise is small. SOLUTION: In the device, substantial consumed power is decreased by providing cut off time within a cycle T, that lasts from 0.3 second to 1.2 second for a signal turning on a heater after the temperature of a fixing roll reaches a reload temperature, and the consumed power is substantially decreased after the reload temperature is reached. The generation of noise is suppressed, by carrying out changing over of on and off of the heater, and setting of the cycle T is set to be not in the halfway peak of AC power voltage wave but is carried out at a position where it reaches 0 V.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for an electrophotographic apparatus such as a facsimile, a printer, and a copying machine, and more particularly to an image forming apparatus in which the temperature of a fixing roller of a fixing device is improved.

[0002]

2. Description of the Related Art In the above-described image forming apparatus using a heater, the temperature of a fixing roller of a fixing device is set to a reload temperature (this specification) when power is turned on or in a power saving mode. The temperature at which the toner image rises to a fixable state in the document, in other words, the temperature at which the toner image can be fixed to the transfer paper.) It is required to reduce the substantial power consumption to prevent the shortening of the service life due to the heater disconnection and the like. Does not exist.

For example, in the image forming apparatus disclosed in Japanese Patent Application Laid-Open No. H10-254306, the power consumption of the fixing heater is made variable in accordance with the power consumption other than that of the fixing heater. In addition, there is a problem that noise is generated because the power supply voltage supplied to the fixing heater is turned on and off in the middle of the peak of the AC waveform.

The present invention has been made in view of such conventional problems, and has as its object to provide an image forming apparatus which does not delay the rise time of fixing and generates less noise.

[0005]

According to a first aspect of the present invention, there is provided an image forming apparatus, wherein the means for controlling the operation of the fixing device is capable of fixing the temperature of the fixing roller to achieve the above object. After reaching the reload temperature indicating the rise to the state, a signal for turning on the fixing heater is set to 0.
In the time period of 3 seconds to 1.2 seconds, a time for partially turning off the heater is provided, and the on time for supplying power obtained by subtracting the off time from the time period is at least 0.
It is characterized in that the control is performed for 2 seconds or more.

According to a second aspect of the present invention, in order to attain the above object, the control means switches a signal for turning on and off the fixing heater after the reload temperature is reached, at a time of switching. The control is performed so that the peak of the waveform of the AC supplied to the fixing heater becomes 0V.

According to a third aspect of the present invention, in order to achieve the above object, the rated wattage AW of the fixing device is
When it is desired to have a substantially different wattage BW, B / A = b / a (a and b are single-digit integers), and a value such that C × 10 / a = d (d is an integer) Is set and controlled.

[0008]

Embodiments and examples of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing an example of a printer as an image forming apparatus of an electrophotographic apparatus such as a printer or a copying machine serving as an image forming apparatus according to the present invention, and FIG. 2 is a cross-sectional view of a fixing device of the apparatus of FIG. is there. As shown in the figure, the apparatus includes a sheet feeding device 1, a registration roller 2, a photoconductor 3, a charging charger 4, a laser optical system 5, a developing device 6, a transfer charger 7, a fixing device 8, a paper discharging unit 9, a discharging lamp 10, , A cleaning device 11, a power supply unit 12, a fan 30, a controller 32, and the like.

The fixing device 8 applies at least heat and pressure to the toner image transferred from the photosensitive member 3 onto the transfer paper fed from the paper feeding device 1 to fix the image. As shown in FIG. 2, the fixing device 8 includes a fixing roller 13 that is heated and driven, a pressure roller 14 that is pressed against and driven by the fixing roller 13, a lever 15 that presses the pressure roller 14 against the fixing roller 13, and a spring 15. 16, a heater 17 for heating the fixing roller 13, and a thermistor 18.

[0010] The fixing roller 13 has a roller length of 320 to 380 mm in an apparatus that passes A3 paper, and has a stainless steel tube (SU).
S304, SUS430, SUS416, or alloys based on them, or carbon steel pipe (STKM1
1, STKM12), the thickness of the paper passing portion is 0.15 to 0.4
mm is provided with a fluororesin coating or a fluororesin tube coated in a range of 300 to 380 mm with an A3 paper passing apparatus. As the kind of the fluororesin, any one of ethylene tetrafluoride resin (PTFE) and perfluoroalkoxy resin (PFA) or a mixed resin thereof is used.

The pressure roller 14 has a diameter of φ10 to φ40 m.
m and the thickness of the rubber is 3 to 8 mm (when the rubber is silicone rubber, the rubber hardness is JISA8 to 40 in solid type,
In the case of the sponge type, the hardness is the same as that of Asuka C40 to 52), the length of the rubber portion is 305 to 340 mm, and a rubber resin tube having a medium resistance of 107Ω to 1012Ω is provided in the rubber. However, the rubber may not be coated with the fluororesin.

As the heater 17, a halogen heater is used, and a single rated voltage of 100V and 1160-1300W is used.

More preferably, it is as follows. In FIG. 3, reference numeral 19 denotes a gear for driving the fixing roller 13 to rotate, and reference numeral 20 denotes a bearing for supporting the fixing roller 13. FIG.
As shown in (A), the fixing roller 13 is made of carbon steel tube STKM11, the roller length L is 375 mm, the outer diameter φ1 of the paper passing range A is 29.8 mm, and the inner diameter φ2 is 29.2.
mm, the thickness t1 is 0.3 mm, and the outer diameter φ3 of the bearing portion is 3
0 mm, and the thickness t2 is 0.1 mm larger than the thickness of the paper passing portion.
It is 0.4 mm thick. Alternatively, as shown in FIG. 3 (B), the outer diameter φ3 of the bearing portion is reduced to 25 mm by drawing,
When the thickness t2 is 0.5 mmmm to 1.5 mm (preferably 1 mm
mm or less). Further, as shown in FIG. 3C, the thickness may be increased inward by cutting or grinding after drawing.

By making the thickness of the paper passing area A thinner as in the above-described example, the rise of fixing is much faster than in the past. The reason why the thickness of the fixing roller 13 is set as described above is that the core metal is thinned in order to minimize the rise time to the fixing-possible temperature of the fixing device. When pressed, the fixing roller 13 is deformed due to crushing or bending, so that a desired nip cannot be formed, resulting in defective fixing or wrinkling of the transfer paper. Therefore, the strength is increased by increasing the thickness of the bearing portion, and the deformation of the roller at the time of pressurization is reduced, thereby preventing the occurrence of defective fixing and the occurrence of wrinkles.

If the thickness of the bearing portion is 1.5 mm or less,
Has almost no effect on fixing rise time. In addition, the reason why STKM or stainless steel pipe is used for the material is that the strength is stronger than that of conventional aluminum. Then, the fixing roller 13 withstands 9N on one side, which is a pressing force of the pressing roller 14 which is known to the fixing roller 13 for forming a nip that can cope with the linear velocity of 115 mm / s to 130 mm / s of the printer. The surface of the fixing roller 13 is coated with a perfluoroalkoxy resin as a main material. The coating length is 355 mm.

The pressure roller 14 has a diameter of 30 mm, a rubber thickness of 5 to 5.5 mm, and a rubber portion length of 316 mm. The heater 17 is a halogen heater rated at 100 V, 1
Use one 200W. The maximum power consumption of the printer is 1450 W. When the power is turned off or in the power saving mode, the heater 17 is turned off and the power consumption of the heater 17 is set to 0.

In this printer, when the fixing temperature is raised from a temperature lower than the temperature at which fixing starts (reload temperature), such as when the power is turned on or in a power saving mode, at least until the reload temperature is reached, The fixing heater 17 is fully turned on to make the power consumption 1200 W,
At least 80% of the maximum power consumption of the image forming apparatus is consumed by the fixing device. In this way, by giving the highest priority to the start of fixing, as shown in FIG.
Fixing rise time from 6 seconds to 40 seconds
It is possible to provide a printer (image forming apparatus) which can be as short as 10 seconds and has a fast startup. Further, since only one halogen heater of 1200 W is required for the heater 17, the cost can be reduced.

By the way, the maximum power consumption of the printer at all times is 1
If the fixing device consumes 80% or more of 1200W with respect to 450W, power cannot be supplied to other units and the function as a printer cannot be sufficiently performed. Therefore, after reaching the reload temperature, the maximum power consumption of the fixing is reduced. 800W or less,
In other words, the power consumption can be reduced to 60% or less of the maximum power consumption, and the cost can be reduced by eliminating the need for a large power supply unit. As means for reducing the maximum power consumption to 60% without increasing the size of the power supply unit, two heaters of 800 W and 400 W may be used, and after reaching the reload temperature, switching to one 800 W heater may be considered. The use of two leads to an increase in the number of components such as triacs, and an increase in cost (see FIG. 5). In FIG. 5, 17a is a heater of 800 W, 17b is 40
0W heaters, 21 is a power supply unit, 22a and 22b are triacs, and 23 is a thermostat.

To reduce the power consumption to 60% of the maximum power consumption without increasing the size of the power supply unit by using one heater, as shown in FIG.
If a transformer having an output of 00 V and an output of 81 V is used and the power supply voltage is switched between 100 V until the reload temperature is reached and 81 V thereafter, the power can be substantially 800 W, one heater 17 is used, and the power supply unit is enlarged. The power consumption can be reduced to 60% of the maximum.

Next, an embodiment of the present invention will be described. In this embodiment, as shown in FIG.
After the temperature of the heater reaches the reload temperature, the halogen heater 1
The signal for turning ON the signal 7 is provided with a cutoff time in a period T of 0.3 to 1.2 seconds to reduce the actual power consumption. Specifically, the cycle is set to 0.3 seconds, power is supplied (ON) to the heater ON signal for 0.3 seconds until the reload temperature is reached, and one cycle is turned on for 0.2 seconds after the reload temperature is reached. (Power supply), OFF (cutoff) for 0.1 second, and power is supplied in that cycle during the heater ON signal. Then, 1200 W × (0.4 seconds / 0.6 seconds) = 800 W, which is a 1200 W halogen heater 17.
However, after reaching reload, the power consumption becomes 800W,
With one heater, the power consumption can be reduced to 60% of the maximum power consumption without increasing the size of the power supply unit, and the cost can be reduced. The above cycle is 0.6 seconds, 0.4 seconds ON, 0.2 seconds OFF
You may sort it out. The order of ON and OFF may be reversed, but the order of ON and OFF is preferable because the fixing temperature can be easily controlled.

As described above, the maximum power consumption can be easily changed with a single heater before and after the reload temperature, but the cycle T
Is controlled so that the power supply time obtained by subtracting the cutoff time from is always 0.2 seconds or more. This is because if the ON time of the halogen heater 17 becomes shorter than 0.2 seconds, the tungsten wire of the halogen heater 17 is broken due to a chemical attack phenomenon. Therefore, shortening the service life such as disconnection of the heater can be prevented by controlling it to 0.2 seconds or longer. From this point of view, the cycle T is set to 0.3 seconds or more, and the cycle is required to be 1.2 seconds or less in order to frequently control the halogen heater 17 and reduce the fixing temperature ripple. The time should be between 3 seconds and 1.2 seconds.

Further, ON / OFF of the halogen heater 17 is performed.
And the setting of the cycle T is the timing from OFF to ON, so the setting of the cycle T is always switched at a position where the peak of the AC power supply voltage waveform is not halfway, but at 0 V, and noise is reduced. It is better to suppress the occurrence.

When it is desired to substantially set the wattage to BW with respect to the rated wattage AW, B / A = b / a (where a and b are single-digit integers), and the cycle C
Is set to a value such that the value of C × 10 / a becomes an integer d. By doing so, even if the supplied AC frequency is 50 Hz, it is 60 Hz.
However, it can be set so that there is no switching between ON and OFF where the waveform is halfway, and it can be switched every cycle. Even when switching on one mountain (0.5 cycle), 0
Since switching is performed with V, generation of noise can be suppressed, but switching in one cycle is more effective in suppressing noise.

Supplementing the above equation, the cycle C = d × a / 10, and the number of peaks in the cycle at 50 Hz is 50 × 2 × C = 5 × 2 × a × d, which is an integer. Also, at 60 Hz, the number of peaks in the cycle (two peaks in one cycle) is 60 × 2 × C = 6 × 2 × a × d, which is an integer and an even number. When it is desired to make the 1200 W heater substantially 800 W, 800/1200 = 2/3, a = 3, and when d = 1, the period T is 0.3 second,
If d = 2, the period is 0.6 seconds, and if d = 3, the period is 0.9 seconds. When d = 2, the number of peaks in the cycle is 60 peaks at 50 Hz,
There are 72 peaks at 60 Hz. Therefore, when the cycle is set as described above, ON and OFF are performed at both 50 Hz and 60 Hz.
Is switched in units of one cycle,
By doing so, as shown in FIG. 8A, it is possible to prevent switching between ON and OFF where the waveform is incomplete (always ON → OFF, OFF → O at the position of 0 V).
N), it is possible to provide an image forming apparatus in which the generation of noise due to the switching is suppressed. In FIG. 8A, the number attached to the peak of the AC waveform is the frequency 50H.
The number of peaks at z, the number in parentheses is the frequency 60H
The number of peaks at z. FIG. 8B shows an example in which ON and OFF are switched at a halfway position of the mountain. In such a waveform, noise occurs.

[0025]

As described above, the image forming apparatus according to the first aspect of the present invention responds to the signal for turning on the fixing halogen heater after reaching the reload temperature by 0.3 seconds to 1.2 seconds. The actual power consumption is reduced by providing a cutoff time in the cycle of, the maximum power consumption can be easily changed even with one heater before and after the reload temperature, and the power supply time obtained by subtracting the cutoff time from the cycle At least 0.2
Since the control is performed so that the time is equal to or longer than seconds, there is an effect that it is possible to easily prevent shortening of the service life such as disconnection of the heater.

According to the second aspect of the present invention, as described above, the heater is turned on after the reload temperature is reached,
At the time of switching off, control is performed so that the peak of the AC waveform supplied to the heater does not switch at a halfway position other than 0 V. In addition to the above-described common effects, the ON / OFF of the heater is controlled in the AC waveform. There is an effect that generation of noise due to switching at a halfway position other than 0 V can be suppressed.

According to the image forming apparatus of the present invention, as described above, when it is desired that the rated wattage AW is substantially BW, B / A = b / a (where a and b are one digit). , And the cycle C is set and controlled so that the cycle C is between 0.3 and 1.2 seconds and the value of C × 10 / a is an integer. In addition to the common effect, there is an effect that there is no ON / OFF switching where the waveform is incomplete even if the frequency of the AC power supply is 50 Hz or 60 Hz, and the generation of noise due to switching at an incomplete position can be suppressed.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a printer shown as an example of an image forming apparatus according to the present invention.

FIG. 2 is a sectional view of a fixing device of the apparatus of FIG.

FIG. 3 is a sectional view of an example of a fixing roller of the apparatus of FIG.

4 is a diagram illustrating a temperature change (A) and a power consumption change (B) when the fixing device of the apparatus in FIG. 1 rises to a reload temperature.

FIG. 5 is a configuration diagram in a case where two heaters are used in the fixing device of the apparatus of FIG. 1;

FIG. 6 is a configuration diagram when one heater is used in the fixing device of the device of FIG. 1;

FIG. 7 is a diagram showing an operation of the embodiment of the present invention, showing an on / off operation (A) of a power supply and a change (B) of power consumption.

FIG. 8 is a diagram showing an on / off switching state (A) and an unfavorable conventional switching state (B) of one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Paper feeder 2 Registration roller 3 Photoreceptor 4 Charger 5 Laser optical system 6 Developing device 7 Transfer charger 8 Fixing device 9 Paper discharge unit 10 Static elimination lamp 11 Cleaning device 12 Power supply unit 13 Fixing roller 14 Pressure roller 15 Lever 16 Spring Reference Signs List 17 heater 17a 800W heater 17b 400W heater 18 thermistor 19 gear 20 bearing 21 power supply unit 22a, 22b triac 23 thermostat 30 fan 32 controller

Claims (3)

[Claims] And a means for controlling the operation of the fixing device, when the temperature of the fixing roller reaches a reload temperature indicating a rise to a fixable state, a signal for turning on the fixing heater from 0.3 seconds. A time period for partially turning off the heater is provided in a 1.2-second time cycle, and an on-time for supplying power obtained by subtracting the off-time from the time cycle is at least 0.2 seconds or more. An image forming apparatus characterized in that: 2. A peak of an AC waveform supplied to the fixing heater becomes 0 V when the control unit switches on and off a signal for turning on the fixing heater after the reload temperature is reached. 2. The image forming apparatus according to claim 1, wherein control is performed so as to be a time point. 3. When it is desired to make the wattage BW substantially different from the rated wattage AW of the fixing device, B / A = b / a (where a and b are single-digit integers). 3. The image forming apparatus according to claim 1, wherein the control is performed by setting the cycle C to a value such that x10 / a = d (d is an integer).