JPH1074019A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To always obtain a stable fixing temperature by selecting and switching a heating layer connected to a power source in accordance with a value of power source voltage to be used so that fixed power may be consumed. SOLUTION: A heating roll is constituted by laminating plural heating layers 6, two layers in this case, having a different resistance value on the inner peripheral surface of a cylinder 5 consisting of metallic material in a state where they are insulated each other. An insulating layer 7 made of polyimide, etc., is formed on the inner peripheral surface of the metallic cylinder 5 first, and the 1st heating layer 6a constituted of a resistor, the insulating layer 7, and the 2nd heating layer 6b constituted of a different resistor are formed on the layer 7 in order. Voltage is impressed on the terminal parts 8 of the layers 6a and 6b. The voltage is impressed in a state where a ring-like electrode is attached to the terminal parts 8 of the layers 6a and 6b and a metallic sliding member having elasticity is brought into press-contact with the electrode. The connected heating layer is selected and switched by a switch in accordance with the voltage value of the power source to be used so that the fixed power may be consumed on the heating roll.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device for an electrophotographic apparatus incorporated in a copying machine, a facsimile machine, a printer or the like.

[0002]

2. Description of the Related Art In order to maintain a required fixing quality under a single power supply, for example, AC 100 V, a fixing device in an electrophotographic apparatus has a heater rated at 500 V when 100 V is applied.
W. Therefore, when shipping electrophotographic equipment (copiers, facsimile machines, printers, etc.) to various parts of the world, it is necessary to manufacture a fixing device that matches the heater rating for each commercial power supply voltage used in each region. No. Therefore, the manufacturing cost must be increased.

[0003] Also, as in the European region, 220
Where V and 240 V power supplies are used, there are restrictions on moving the device between these different power supplies.

On the other hand, the energizing ratio of the AC voltage applied to the heater is controlled, and when the voltage specification is higher than the rated value of the heater, the energizing ratio is reduced to make the power consumed by the heater equal to the rated voltage value. Accordingly, there has been proposed a heater in which the heater is standardized (JP-A-59-126578).
Reference).

[0005]

SUMMARY OF THE INVENTION The present invention provides a fixing device in which a constant power consumption is generated at different power supply voltages with a simple configuration, not with the above-described method of controlling the energization ratio. The purpose is to do.

[0006]

In order to achieve the above object, the present invention provides (1) a fixing device which heats and fixes a recording paper having a toner image between a heating roll and a pressure roll, The heating roll has a plurality of heating layers having different resistance values that are insulated and laminated on the inner peripheral surface of a cylinder made of metal, glass, or the like, and a value of a power supply voltage to be used so that constant power consumption is generated. The heating layer connected to the power source is selected and switched according to the power.

According to this configuration, the heating layer connected to the power supply is selected and switched according to the value of the power supply voltage used so that constant power consumption is generated, so that a stable fixing temperature can always be obtained, and accordingly, A single fixing device can handle different power supply voltages.

(2) The heating roll is composed of a plurality of linear pattern heat generating layers having different resistance values provided at predetermined intervals on the inner peripheral surface of a cylinder made of metal, glass or the like. The heat generating layer is arranged spirally adjacent to each other, and selects and switches a heat generating layer of a linear pattern connected to the power supply according to a value of a power supply voltage to be used so as to generate a constant power consumption. It was made.

According to the above configuration, the same effect as the configuration (1) can be obtained, and the distance from the heating layer of each linear pattern having a different resistance value to the surface of the heating roll can be made substantially constant. In addition, the time during which the surface of the heating roll is heated can be made constant.

(3) In the above (1) and (2), the apparatus further comprises a temperature detecting means for detecting the temperature of the heating roll, and performs a pre-heating for a few seconds after the power supply to the heating roll is turned on. A configuration is provided in which a heating layer to be energized is selected from the temperature rise width of the heating roll per unit time detected by the detecting means, and a means for automatically switching the heating layer is provided.

According to this configuration, the selection and switching of the heat generating layer are automatically performed, so that an artificial setting error can be eliminated.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. (Embodiment 1) FIG. 1 shows a schematic configuration of a fixing device according to Embodiment 1 of the present invention.
Reference numeral 2 denotes a pressure roll, 3 denotes a bearing, and 4 denotes a thermistor as a temperature detecting element for detecting the surface temperature of the heating roll 1.
The fixing device heats and fixes the recording paper on which a toner image is formed between the heating roll 1 and the pressure roll 2.

The heating roll 1 is mainly made of aluminum,
On the inner peripheral surface of the cylinder 5 made of a metal material such as iron or SUS,
As shown in FIG. 2, a plurality (here, two layers) of heat generating layers 6 having different resistance values are laminated while being insulated from each other. FIG. 2 (b) shows a cross section of the lamination. An insulating layer 7 of polyimide or the like is first formed on the inner peripheral surface of the metal cylinder 5 by coating, baking or vapor deposition, and a resistor is formed thereon. A first heat generating layer 6a, an insulating layer 7, and a second heat generating layer 6b of a different resistor are formed in this order by coating, baking or vapor deposition. On the surface of the heating roll 1, a toner release agent mainly composed of a fluorocarbon-based organic substance such as tetrafluoroethylene or trifluorethylene is formed.

Reference numeral 8 denotes terminals of the heat generating layers 6a and 6b to which a voltage is applied. The method of applying the voltage is, for example, as follows.
A ring-shaped electrode is attached to the terminal portion 6b, and an elastic metal sliding member is pressed on the electrode to apply the pressure.

In the first embodiment, the heating roll 1
Is 20mmφ × 0.6mmt × 270mmL, and the pressure roll 2 is
The surface of a 10 mmφ core is coated with 6 mmt of silicone rubber (JISA hardness 16). Heating roll 1 and pressure roll 2
In order to pressurize, the shafts at both ends of the pressure roll 2 are pressed by a compression spring or the like.

The cylinder 5 is made of a metal material,
Glass, ceramic material, or the like can also be used.

FIG. 3 shows the connection between the power supply 11 and the heat generating layers 6a and 6b formed on the heating roll 1.
In accordance with the voltage value of 11, the heating layer to be connected is selected and switched by the switch 12 so that the heating roll 1 generates a constant power consumption. The switch 12 is a method of switching manually,
Any of the methods of electrically switching by a logic signal may be used.

For example, taking the example of the European region, there are two systems of 220 V system and 240 V system, and when the rating of the heater required for fixing is 500 W, the resistance value of the heating layer is as follows. Becomes Therefore, the above two types of heat generating layers are formed on the inner peripheral surface of the heating roll 1. Then, the heating layer to be energized is selected according to the power supply voltage of the region where the apparatus is used, and the heating layer is switched by the switch 12 to fix the toner image formed by electrophotography.

According to the present embodiment configured as described above, two types of heat generating layers 6a and 6b formed on the inner peripheral surface of the heating roll 1 are required depending on the power supply voltage in the area where the apparatus is used. Is selected and the switch 12 is switched and connected, so that the heating roller 1 can obtain a required fixing temperature with constant power consumption.

(Embodiment 2) FIG. 4 shows a configuration of a main part of a fixing device according to Embodiment 2 of the present invention. In a configuration in which a plurality of heating layers are stacked as in Embodiment 1, the distance from the surface of the heating roll 1 to each heating layer is different. There is a difference in the time required for the surface to heat up.

Accordingly, here, the heating roll 1 has two linear heating layers 9a and 9b having different resistance values on the inner peripheral surface of the cylinder 5 with a predetermined interval between them. Are arranged spirally so as to be adjacent to each other. The surfaces of the heat generating layers 9a and 9b are coated with an insulator such as polyimide to prevent a conductive foreign matter from adhering and causing a short circuit between the heat generating layers 9a and 9b. The interval between the heat generating layers 9a and 9b is set to an optimum value from the surface temperature distribution of the heating roll 1. When selecting the heating layers 9a and 9b according to the power supply voltage to be used, as shown in FIG. 3, the switch 12 is manually operated or the connection is electrically switched.

By adopting such a configuration, the distance from each heating layer to the surface of the cylinder 5 can be made substantially constant, so that the time during which the surface of the heating roll 1 heats up can be made constant. it can.

(Embodiment 3) As in Embodiments 1 and 2, when a switch is manually operated according to the power supply voltage to select and switch a heating layer, an erroneous heating layer is selected due to a setting error. Can be considered. Therefore, in the third embodiment, as shown in FIG. 1, the thermistor 4 is provided as a temperature detecting means for detecting the temperature of the heating roll 1, and the pre-heating is performed for several seconds after the power is supplied to the heating roll. The heating layer to be energized or the heating layer having a linear pattern is selected from the temperature rise width of the heating roll per unit time detected by the thermistor 4 and automatically switched.

For example, in the European region where two power supplies of 220 V system and 240 V system are used, for example, in the heating roll 1 provided with the heat generating layer shown in FIG. 2 or FIG. One heating layer (in this case 240
V, 115.2 Ω) for several seconds with the current supply selected
The pre-heating is performed (for example, 4 to 6 seconds), and the temperature rising width is measured based on the detection value of the thermistor 4.

The temperature rise width when 240 V and 220 V are applied to the heating layer of 240 V and 115.2 Ω is previously stored in a memory or the like, and the detected temperature rise width is 24 as shown in FIG.
Investigate which is closer to the value of the temperature rise of 0V or 220V,
It is determined whether the currently applied voltage is close to 240V or 220V. Thus, based on the determined voltage, the heating layer to be energized is selected and automatically switched. FIG. 6 is a block diagram showing the control system.

It is needless to say that the number of heat generating layers formed on the inner peripheral surface of the heating roll is not limited to two, but may be three or more.

[0027]

As described above, according to the present invention,
By selecting and switching a required heating layer from a plurality of heating layers formed on the heating roll according to the power supply voltage to be used, the heating roll always generates a rated power consumption and can obtain a required fixing temperature. Therefore, stable fixing quality can always be obtained, and it is not necessary to manufacture a fixing device in which the rating of the heater is changed for each power supply voltage as in the related art, and the manufacturing cost can be reduced.

Further, the heat generating layers of a plurality of linear patterns having different resistance values are spirally arranged at predetermined intervals so as to be adjacent to the heat generating layers of the other linear patterns so that each heat generating layer has a different resistance value. Since the distance from to the surface of the heating roll can be made substantially constant, the time during which the temperature of the surface of the heating roll rises can be made constant.

Further, by automatically switching the heat generation layer, it is possible to eliminate an artificial setting error and to reduce the number of work items at the time of setting the apparatus.
This has the effect.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a fixing device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an arrangement of a heating layer of a heating roll according to Embodiment 1 of the present invention.

FIG. 3 is a diagram showing a connection relationship between a heating roll and a power supply according to the first embodiment of the present invention.

FIG. 4 is a diagram showing an arrangement of a heat generating layer of a heating roll according to a second embodiment of the present invention.

FIG. 5 is a diagram illustrating an example of automatic switching of a heating layer according to a third embodiment of the present invention.

FIG. 6 is a block diagram of a control system according to Embodiment 3 of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Heating roll, 2 ... Pressure roll, 4 ... Thermistor, 5 ... Cylinder, 6, 6a, 6b, 9, 9a, 9b ... Heat generation layer, 12 ... Switch.

Claims (3)

[Claims] 1. A fixing device for heating and fixing a recording paper having a toner image between a heating roll and a pressure roll, wherein the heating roll has a different resistance on an inner peripheral surface of a cylinder made of metal, glass or the like. A plurality of heat generating layers having different values are laminated while being insulated from each other, and the heat generating layer connected to the power supply is selected and switched according to a value of a power supply voltage to be used so that constant power consumption is generated. Fixing device. 2. A fixing device for heating and fixing a recording paper having a toner image between a heating roll and a pressure roll, wherein the heating roll has a different resistance on an inner peripheral surface of a cylinder made of metal, glass or the like. The heating layers of a plurality of linear patterns having values are spirally arranged at predetermined intervals and adjacent to the heating layers of other linear patterns, and are used so as to generate a constant power consumption. A fixing device that selects and switches the heating layer of the linear pattern connected to the power supply according to a value of a power supply voltage to be applied. 3. A temperature detecting means for detecting a temperature of the heating roll, wherein a pre-heating is performed for a few seconds after the power supply to the heating roll is turned on, and the heating roll per unit time is detected by the temperature detecting means. 3. The fixing device according to claim 1, further comprising means for selecting a heating layer to be energized from the temperature rise width and automatically switching the heating layer.