JP2000098796A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce temperature ripples at a printing time even when a large- capacity heating means is used for a heat roller whose heat capacity is small by executing the supply of electric power to the heating means on full duty at a warm-up time and controlling it in any mode of two kinds of modes being the half-on mode and the off-mode after a warm-up is finished. SOLUTION: Relating to a supply power control means (CPU) 5, the electric power is supplied by making a current flow to the heating means 3 from an AC power source 1 based on the temperature detection information of the surface temperature of the heat roller 2 outputted from a temperature detection means 4. At the warm-up time, the supply of the electric power to the heating means 3 is executed on the full duty that energizing per unit time is 100%. At the printing time, the supply of the electric power is controlled in any model of two kinds of modes being the half-on mode that the proportion of the energizing or non-energizing per minimum unit time with respect to the heating means 3 is 50% duty and the non-energizing off-mode so as to control the temperature of the roller 2.

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 electrophotographic image forming apparatus such as a copying machine, a facsimile or a printer.

[0002]

2. Description of the Related Art In recent years, when various types of OA equipment are used in offices and the like, the power consumption of OA equipment, for example, an electrophotographic image forming apparatus, is reduced by itself when not in use in order to save costs. There is a demand for an energy-saving function to be installed.

Conventionally, as an energy saving function for saving the power consumption of this type of image forming apparatus, an energy saving mode is set so that the power supply to the heating means of the heat roller in the fixing device is turned off when not in use. It is conceivable to set and control the power supply.

[0004] Such power supply control is effective as an energy saving function because the power supply to the fixing heater is turned off when not in use. On the other hand, the surface temperature of the heat roller is set to a predetermined value from the energy saving mode. There is a problem that the warm-up time for starting up and returning to a settable temperature is long.

Therefore, in order to shorten the warm-up time, conventionally, for example, a method of changing the material of the heat roller from aluminum to iron or the like having excellent heat conductivity, a method of reducing the thickness of the roller core, or There is known a method of increasing the heat capacity of a fixing heater as a heating device.

[0006]

However, when the warm-up time is shortened by such a conventional method, even if the fixing heater is turned on for a short time, the temperature of the heat roller rises. Even if it is attempted to control the surface temperature of the roller to a predetermined set temperature via the temperature sensor, there is a problem that the temperature ripple increases.

Accordingly, the present invention solves the above-mentioned problems of the conventional fixing device, and has a short warm-up time.
It is an object of the present invention to provide a fixing device capable of reducing a temperature ripple of a heat roller.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention controls a temperature detecting means for detecting a surface temperature of a heat roller and a supply of electric power to the heating means of the heat roller. In the fixing device having the control unit, the invention according to claim 1 is configured such that at the time of power-on or at the time of warm-up for returning from the energy-saving mode, power is supplied to the heating unit at full duty, and after the warm-up is completed. The control is performed in one of two modes, a half-on mode in which a ratio of energization / non-energization per unit time is 50% duty, and a non-energization off mode.

According to a second aspect of the present invention, in the first aspect of the present invention, energization / non-energization in the half-on mode after warm-up is continuous energization / continuous non-energization, and a unit time of the AC power , Which is an integral multiple of two periods.

[0010] The invention described in claim 3 is the invention according to claim 1 or 2.
In the invention according to any one of the above, the unit time of the half-on mode after the completion of the warm-up is set to an integral multiple of 200 ms AC.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 schematically shows a circuit configuration of a power supply unit according to an embodiment of the present invention. Reference numeral 1 denotes an AC power supply, 2 denotes a heat roller of a fixing device, 3 denotes a heat roller heating unit including a fixing heater,
Reference numeral 4 denotes a temperature detecting means comprising a thermistor for detecting the surface temperature of the heat roller 2, and reference numeral 5 denotes a control means (CPU) for controlling supply of electric power to the heating means 3 by detecting the surface temperature of the heat roller 2 by the temperature detecting means 4. .., 6 are switch means for opening or closing a circuit for energizing or de-energizing the fixing heater 3.

The power supply control means (CP
U) 5 generates a trigger signal to the switch means 6 based on the temperature detection information of the surface temperature of the heat roller 2 from the temperature detection means 4, and when the switch means 6 receives this trigger signal, the switch The means 6 closes the circuit, energizes the heating means 3, and supplies power by passing a current from the AC power supply 1 to the heating means 3.

FIGS. 2 to 4 show the power supply control state in the embodiment. FIG. 2 shows the relationship between the current waveform and the trigger waveform at warm-up when the power is turned on or when returning from the energy saving mode. When the power is turned off or at the time of the energy saving mode, fixing is not performed. Is a high level, and at the time of warm-up at the time of turning on the power or returning from the energy saving mode, the power supply to the heating means 3 is performed at a full duty of 100% per unit time, and the trigger becomes the low level. .

FIG. 3 shows the relationship between the current waveform and the trigger waveform in the printing state after the completion of the warm-up. When the surface temperature of the heat roller 2 reaches a predetermined temperature, the fixing device can print. The state shifts to the printing state. In this printing state, the ratio of energization or non-energization to the heating unit 3 per unit time is a 50% duty "half-on mode" and a non-energization "off mode". The power supply is controlled in one of the two modes, and the temperature of the heat roller 2 is controlled. In this case, even when the fixing is not performed, the power to the heating means 3 is supplied at 50%, so that the heat capacity of the heat roller 2 is reduced, thereby reducing the thermal ripple due to the on / off control. It becomes possible to do.

In the embodiment shown in FIG. 3, an example is shown in which the ON / OFF control of the "half ON mode" is constituted by a cycle of two cycles of AC, one cycle of OFF and one cycle of ON.
As shown in FIG. 4 as another embodiment, the on / off control of the “half-on mode” may be configured with a cycle of three AC cycles including a 1.5 cycle off and a 1.5 cycle on. As described above, in the case of a configuration with an odd cycle, the ON current waveform is asymmetric on the plus side and the minus side, and becomes an even-order high-frequency current component. , An even number of times, that is, the unit time is an integer multiple of two cycles of the AC power supply (1,
2, 3 ...).

FIG. 5 shows another embodiment of the ON / OFF control of the "half-on mode" for the heating means 3, wherein the continuous ON time is 100 ms and the continuous OFF time is 100 ms.
0 ms is set to the “half-on mode”.

According to the on / off control, by setting the continuous on time to 100 ms, the continuous on state can be maintained even in an installation where two types of AC power supply frequencies of 50 Hz and 60 Hz are mixed. 5 cycles for 50Hz and 6 cycles for 60Hz, which are integers at any frequency, suppresses the generation of high-frequency current and enables 50% duty lighting in the minimum unit time, thereby depending on frequency The on / off control can be performed without using the zero-cross detection circuit.

[0018]

The present invention is as described above.
The power supply to the heating means is performed at full duty when the power is turned on or when warming up after returning from the energy saving mode, and the ratio of energization / non-energization per unit time after the warm-up is reduced to 50%. Control is performed in one of two modes, a half-on mode, which is a% duty, and a non-energized off mode. To reduce the warm-up time, a large-capacity heating means is used for a heat roller with a small heat capacity. Also in this case, there is an effect that the temperature ripple at the time of printing can be reduced.

According to a second aspect of the present invention, the energization / de-energization in the half-on mode after the end of the warm-up is continuous energization / continuous non-energization, and the unit time of the AC power source is 2 hours.
Since the period is an integral multiple of the period, the generation of an even-numbered high-frequency current of the high-frequency current of the AC power supply can be suppressed.

According to the third aspect of the present invention, since the unit time of the half-on mode after the warm-up is set to an integral multiple of 200 ms of AC, the frequency of the AC power supply is different even in a mixed area. In addition, it is possible to suppress the generation of the high-frequency current without depending on the power supply, and to control the power supply without using the zero-cross detection circuit.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram schematically showing a circuit configuration of an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an on / off control state of a half-on mode based on a relationship between a current waveform and a trigger waveform at the time of warm-up when the power is turned on or when returning from the energy saving mode.

FIG. 3 is an explanatory diagram showing an on / off control state of a half-on mode based on a relationship between a current waveform and a trigger waveform in a print state after the end of warm-up.

FIG. 4 is an explanatory diagram showing another embodiment of the on / off control state of the half-on mode.

FIG. 5 is an explanatory diagram showing still another embodiment of an on / off control state in a half-on mode.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 AC power supply 2 Heat roller 3 Heating means 4 Temperature detection means 5 Supply power control means (CPU) 6 Switch means

Claims (3)

[Claims] 1. A fixing device having a temperature detecting means for detecting a surface temperature of a heat roller and a control means for controlling supply of electric power to a heating means of the heat roller. During warm-up, power supply to the heating means is performed at full duty, and after warm-up, a half-on mode in which the ratio of energization / de-energization per unit time is 50% duty,
A fixing device which is controlled by one of two types of modes: a non-energized off mode. 2. The method according to claim 1, wherein the energization / non-energization in the half-on mode after the completion of the warm-up is continuous energization / continuous non-energization, and a unit time thereof is an integral multiple of two cycles of the AC power supply. 3. The fixing device according to claim 1. 3. The fixing device according to claim 1, wherein a unit time of the half-on mode after completion of the warm-up is set to an integral multiple of 200 ms AC.