JPH11316516A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device capable of efficiently heating the whole of a heating roller to a uniform temp., obtaining stable temperature control of the heating roller and preventing the damage to a surface material, etc., caused by the concentration of heat, on the crossing part of longitudinal and lateral heating wires. SOLUTION: The fixing device is provided with a pair of rollers (a fixing roller 5 and a heating roller) and constituted so that at least one of them is the heating roller (fixing roller 5) and a transfer material carrying a toner image is held/carried by the pair of rollers, to fix a toner image on a transfer material. In such a case, the fixing roller 5 has the lateral heating wires 14A to be wired in the axial direction of a heating means and the longitudinal heating wires 12A to be wired in a direction where they cross the lateral heating wires 14A, as the heating means. Voltage is alternately applied to the lateral/ longitudinal heating wires 12A and 14A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner transfer device in which at least one of the rollers has a pair of rollers configured as a heat roller, and the pair of rollers sandwiches and conveys a transfer material carrying a toner image. The present invention relates to a fixing device for fixing an image.

[0002]

2. Description of the Related Art In an image forming apparatus such as an electrophotographic copying machine, a printer, and a facsimile, the above-mentioned fixing device is often used. In this type of fixing device, it is already known to use a heating wire as a heating means as a heat source of a heat roller.
480. The fixing device described in this publication is formed by bending a plurality of heating wires a plurality of times from one end in the axial direction of the heat roller to the other end, and has a higher bending density at the roller end than at a roller central portion. Density is disclosed. Further, the power supply brush is limitedly arranged to partially heat the surface of the heat roller, thereby reducing power consumption.

[0003]

However, in the case of the fixing device described in the above publication, in order to heat the entire heat roller to a uniform temperature, wiring must be performed at high density with a large number of heating wires. There is a problem that efficiency is low in terms of power consumption. Further, depending on the conditions of the partial energization, an object to be fixed arrives before the surface temperature of the fixing roller reaches the set temperature, and there is a danger that fixing defects may occur.

[0004] The present invention solves the above-mentioned conventional problems,
A fixing device that can efficiently heat the entire heat roller to a uniform temperature, achieves stable temperature control of the heat roller, and prevents damage to the surface material due to the concentration of heat at the intersection of vertical and horizontal heating wires. It is intended to provide.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention has a roller pair in which at least one of the rollers is configured as a heat roller, and a transfer material holding a toner image is conveyed by the roller pair. By doing so, in the fixing device for fixing the toner image on the transfer material, the heating roller is heated in the axial direction thereof as a heating means, and the heating wire is bent in a waveform, and in a direction intersecting the heating wire. A vertical heating wire that is wired and bent into a waveform, and voltage applying means for independently applying a voltage to the horizontal heating wire and the vertical heating wire, wherein the voltage applying means includes the horizontal heating wire and the vertical heating wire. Are applied alternately to independently controlled voltage values.

[0006] To achieve the above object, the present invention provides:
A fixing device for fixing a toner image on a transfer material by at least one roller having a roller pair configured as a heat roller, and nipping and conveying the transfer material carrying the toner image by the roller pair; A horizontal heating wire wired in the axial direction as a heating means, a vertical heating wire wired in a direction crossing the horizontal heating wire, and a voltage independently applied to the horizontal heating wire and the vertical heating wire. Voltage applying means for applying, detecting means for detecting the surface temperature of the heat roller, and when it is recognized that the temperature detected by the detecting means has reached a preset temperature, the horizontal heating wire and the vertical heating wire In the normal energized state, a voltage value which is several percent less than the voltage at the time of the normal energization state is applied alternately, and when it is recognized that the temperature detected by the detection means has not reached a preset temperature, It is characterized by comprising a control means for controlling so as to apply heating wire and the vertical heating wire the value of the normal conducting state when a voltage is alternately respectively.

Further, in order to achieve the above object, the present invention provides a method in which at least one of the rollers has a roller pair configured as a heat roller, and the transfer material holding the toner image is nipped and conveyed by the roller pair. In a fixing device for fixing a toner image on a transfer material, a horizontal heating wire wired in the axial direction as heating means on the heat roller, and a vertical heating wire wired in a direction intersecting the horizontal heating wire. Voltage application means for independently applying a voltage to the horizontal heating wire and the vertical heating wire, detection means for detecting the surface temperature of the heat roller, and the temperature detected by the detection means to a preset temperature If it is determined that the voltage is higher than a predetermined percentage, a voltage value which is several percent less than the voltage in the normal energized state is applied alternately to one of the horizontal heating wire and the vertical heating wire. When the temperature detected by the means is found to be lower than a preset temperature by a predetermined percentage or more, control means for controlling so as to alternately apply the voltage value in the normal energized state to the horizontal heating wire and the vertical heating wire, respectively. Are provided.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory diagram illustrating an embodiment of an image forming apparatus including a fixing device according to the present invention.

In FIG. 1, reference numeral 1 denotes a photosensitive member serving as a latent image bearing member, and a toner image is formed on the photosensitive member 1 according to a known electrophotographic process. Transcribed. Then, the transfer material 2 carrying the toner image is sent to the fixing device 4 via the conveying means 3, and the toner image is fixed as a permanent image. The fixing device 4 in the present embodiment includes a fixing roller 5 as a heat roller,
It has a roller pair consisting of a pressure roller 6 pressed against the roller. The fixing roller 5 is provided with a heating means, which will be described in detail later, and a temperature detection sensor 7 is disposed on the surface of the heating means in contact with or close to the roller surface.

FIG. 2 is an explanatory perspective view showing the structure of the fixing roller 5, and FIG. 3 is a sectional view thereof. 2 and 3, the fixing roller 5 has a base metal core 10 made of aluminum, iron or the like as a base thereof, and an insulating layer 11
Vertical heating layer 12 into which vertical heating wire 12A is inserted through
Is coated. The surface of the vertical electric heating layer 12 is covered with a horizontal electric heating layer 14 into which a horizontal electric heating wire 14A is inserted via an insulating layer 13, and the horizontal electric heating layer 14 is formed of a rubber material or the like having good releasability. Is coated.

As shown in FIGS. 2 and 4, each of the horizontal heating wires 14A inserted into the horizontal heating layer 14 has a corrugated shape, and extends from one end of the fixing roller 3 to the other end. And a plurality of them are arranged. Electrodes (hereinafter, referred to as horizontal electrodes) 16 and 17 for horizontal heating wires are provided at both ends of the peripheral surface of the fixing roller 3, and all the horizontal heating wires 14 </ b> A are connected to the horizontal electrodes 16 and 17. I have.
Power supply electrodes 18 and 19 configured as arm-shaped power supply brushes are connected to the horizontal electrodes 16 and 17.
In this case, the power supply electrode 18 is on the plus (+) side,
Is the minus (-) side.

As shown in FIG. 2 and FIG. 5, the vertical heating wire 12A inserted into the vertical heating layer 12 is formed in a corrugated shape similar to the horizontal heating wire 14A. The wiring is arranged so as to be wound around the fixing roller 5 in a direction substantially perpendicular to the heat rays. Arm electrodes 20, 21 for supplying power to the vertical heating wire 12A are provided at both ends of the fixing roller 3, and the arm electrode 20 is positive (+).
Side, the arm-shaped electrode 21 is on the minus (−) side.

FIG. 6 is a detailed view of a connecting portion between the arm electrodes 20, 21 and the vertical heating wire 12A. In FIG. 6, cylindrical electrodes 22 and 23 having a certain thickness and connected to the vertical heating wire 12A are provided at both ends of the fixing roller 5, and circular electrodes are formed on the inner surfaces of the cylindrical electrodes 22 and 23. A groove having a convex cross section in the circumferential direction is formed. In the large diameter part of this groove,
A ring member 24 is rotatably inserted via a bearing 25, and the distal ends of the arm electrodes 20 and 21 are fixed to the ring member 24. With this configuration, the fixing roller 5
Arm electrodes 20 and 21 without hindering the rotation of the arm.
Ring member 24, bearing 25, cylindrical electrode 2
The vertical heating wire 12A is energized via 2 and 23. That is, since the bearing 25 is interposed between the arm electrodes 20 and 21 and the cylindrical electrodes 22 and 23, the cylindrical electrode 2
The arm electrodes 20 and 21 can be in a free state with respect to the rotation on the sides 2 and 23, and power can be supplied without hindering the rotation of the fixing roller 5. The bearing 25 and the ring member 24 are made of a conductive material, and the cylindrical electrodes 22 and 23 are in contact with the metal core 10 and the horizontal electrothermal layer 14 by the insulating layers 11 and 13 similarly to the vertical electrothermal layer 12. Has been prevented.

Next, the temperature control of the fixing device 4 will be described. FIG. 7 is a schematic diagram of the image forming apparatus.
1 is an image forming apparatus main body including an engine, 32 is a main body 31
And 33, 34, 35, and 36, a paper feed unit that feeds the transfer material to the main body.

FIG. 8 is a control block diagram of the image forming apparatus. Reference numeral 40 denotes a main body control circuit, which includes a CPU, a ROM, a RAM, and an input / output for operating the main body. An operation unit control circuit 50 includes an operation input key and a display device such as an LED. 60, 70, 80,
90 is a control circuit for each of the paper feed units 33 to 36,
Sensor inputs such as size and outputs of motors, clutches, solenoids, etc. are connected in parallel with the main unit control circuit. 1
00 is a voltage control circuit for the vertical heating wire 12A, 110 is a voltage control circuit for the horizontal heating wire 14A, and controls the voltage applied to the vertical and horizontal heating wires 12A, 14A by a trigger signal from the main body control circuit 40. .

FIG. 9 is a block diagram of an apparatus for controlling the fixing device 4. The trigger T 1 and the trigger T 2 are input from the main body control circuit 40 to the vertical voltage control circuit 100 through two trigger signal lines T 1 and T 2. The voltage applied to the vertical heating wire 12A is controlled by the two trigger signals. Also,
The trigger T3 and the trigger T4 are transmitted from the main body control circuit 40 to the horizontal voltage control circuit 110 through two trigger signal lines T3 and T4.
To the horizontal heating wire 14 by the two trigger signals.
The voltage applied to A is controlled. In this case, as shown in FIG. 1, the fixing roller 5 is provided with a sensor 7 for detecting the surface temperature, and after the surface temperature value detected by the sensor 7 is read and determined by the main body control circuit 40, It is fed back to the control system.

The vertical voltage control circuit 100 outputs a trigger signal “Trigger T1” ON (1) from the main body control circuit 40 and inputs the signal to the vertical voltage control circuit 100.
The voltage of 2A is not limited, and the voltage value in the normal energized state is applied. On the other hand, when the trigger signal “Trigger T2” is output ON (1) by the main body control circuit 40 and input to the vertical voltage control circuit 100, the voltage applied to the vertical heating wire 12A is different from the value in the normal energized state. In this example, the voltage value is limited to half the normal value. Also, “Trigger T
When both “1” and “trigger T2” are OFF (0) are input to the vertical voltage control circuit 100, the voltage is cut off by the circuit and is not applied to the vertical heating wire 12A.
1 ”When both the trigger T2 and ON (1) are input to the vertical voltage control circuit 100, the CP in the main body control circuit 40
U is determined to be out of control, and the vertical voltage control circuit 100 stops applying voltage to the vertical heating wire 12A.

On the other hand, the horizontal voltage control circuit 110 only changes the trigger signal from "trigger T1" to "trigger T3", "trigger T2" and "trigger T4". Yes, and will not be described to avoid duplication of description. Table 1 shows the vertical voltage control circuit 10
2 illustrates an operation state when each trigger signal is input in the 0 and lateral voltage control circuit 110.

[Table 1]

Next, a description will be given of a method of controlling the fixing device with the above-structured control device. The surface temperature of the fixing roller 5 is controlled so as to maintain a preset temperature. In this temperature control, conventionally, the surface temperature of the fixing roller 5 is detected, and if the detected surface temperature is higher than a set temperature, the heater is turned off, and if the detected surface temperature is lower than the set temperature, on / off control is performed.

On the other hand, in the present invention, the surface temperature is detected, and if the surface temperature detected by the main body control circuit 40 is higher than the set temperature, a trigger signal, "trigger T2" is sent to the vertical voltage control circuit 100. Is turned on (1), a trigger signal is output to the horizontal voltage control circuit 110, and "trigger T4" is turned on (1), and the vertical heating wire 12A and the horizontal heating wire 14A are output.
Is reduced to half the voltage value in the normal energized state. When the surface temperature detected by the main body control circuit 40 is lower than the set temperature, a trigger signal “Trigger T1” is output to the vertical voltage control circuit 100 as ON (1), and the horizontal voltage control circuit 110 is output. Then, the trigger signal “trigger T3” is turned ON (1), and the voltage applied to the vertical heating wire 12A and the horizontal heating wire 14A is returned to the value in the normal energization state. In the present invention, the voltage controlled as described above is applied to the vertical heating wire 12A and the horizontal heating wire 14A. At this time, the application of the voltage to the vertical heating wire 12A and the horizontal heating wire 14A is performed alternately. The voltage is applied to the vertical heating wire 12A and the horizontal heating wire 14A.
By alternately applying A, heat can be prevented from being concentrated at a location where the vertical heating wire 12A and the horizontal heating wire 14A intersect, and damage to the surface material of the portion due to the heat concentration can be prevented.

By performing such control, stable temperature control can be obtained in which the fluctuation width with respect to the set temperature is small as compared with the related art. In addition, the amount of rush current generated when the applied voltage is turned ON / OFF can be reduced, and damage to the filament and the terminal can be reduced.

Further, in the present invention, the surface temperature is detected, and if the surface temperature detected by the main body control circuit 40 is higher than the set temperature by several percent or more, for example, 1 percent or more, the vertical heating wire 12A and the horizontal The voltage applied to only one of the heating wires 14A is reduced to half the voltage value in the normal energizing state, and the other is kept at the voltage value in the normal energizing state. A voltage is alternately applied to the heating wire 14A. When the surface temperature detected by the main body control circuit 40 is lower than the set temperature by several percent or more, for example, 1 percent or more, 1 /
Control may be performed to return the voltage applied to the heating wire reduced to 2 to the value in the normal energized state. Also in this case, control is performed so that a voltage is alternately applied to the vertical heating wire 12A and the horizontal heating wire 14A.

By performing such control, the fluctuation width with respect to the set temperature is further reduced as compared with the conventional case, and stable temperature control can be obtained.
The rush current generated when the switch is turned off can be further reduced.

In the above embodiment, "trigger T2"
When "trigger T4" is input to the vertical and horizontal voltage control circuits, the voltage value is limited to half the normal value. The limited voltage value is a preferable value in the above control, but is not limited to this voltage value and is arbitrary. However, a voltage value of 90% reduction close to OFF or 1 close to ON
The reduced voltage value is not preferable for control. Further, it is obvious that the present invention can be applied to a fixing device in which both roller pairs are configured as heat rollers.

[0025]

According to the first aspect of the present invention, the heat roller has a horizontal heating wire wired in the axial direction as heating means and a vertical heating wire wired in a direction intersecting the horizontal heating wire. Since the voltage applied to the heating wire is alternately applied, it is possible to prevent the surface material and the like from being damaged due to the heating in which the intersections of the vertical and horizontal heating wires are concentrated.

According to the second aspect of the present invention, since the surface temperature of the heat roller can be controlled with a small fluctuation width with respect to the set temperature, stable temperature control can be obtained, and the inrush generated when the applied voltage is turned ON / OFF. The amount of current can be reduced. Furthermore, even if a disconnection or the like occurs in one of the vertical and horizontal heating wires, it is also possible to recover by controlling the other heating wire.

According to the third aspect of the present invention, since the surface temperature of the heat roller can be controlled with a smaller fluctuation width with respect to the set temperature, the surface temperature of the heat roller can be efficiently brought close to the target value with low power consumption. it can.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating an embodiment of an image forming apparatus including a fixing device according to the present invention.

FIG. 2 is a perspective view illustrating a configuration of a fixing roller of the present invention.

FIG. 3 is a sectional view of the fixing roller of FIG. 2;

FIG. 4 is a perspective view illustrating a horizontal electrothermal layer of the fixing roller of FIG. 2;

FIG. 5 is a perspective view illustrating a vertical electrothermal layer of the fixing roller of FIG. 2;

FIG. 6 is a sectional perspective view showing an electrode portion of a vertical heating wire of the fixing roller of FIG. 2;

FIG. 7 is a schematic diagram of an image forming apparatus including a fixing device according to the present invention.

FIG. 8 is a control block diagram of the image forming apparatus.

FIG. 9 is a block diagram of a device that controls the fixing device.

[Explanation of symbols]

 Reference Signs List 4 fixing device 5 fixing roller 7 temperature detection sensor 12 vertical heating layer 12A vertical heating wire 14 horizontal heating layer 14A horizontal heating wire 100 vertical voltage control circuit 110 horizontal voltage control circuit 110

Claims (3)

[Claims] At least one of the rollers has a pair of rollers configured as a heat roller, and the pair of rollers sandwiches and conveys a transfer material carrying a toner image.
In a fixing device for fixing a toner image on a transfer material, a horizontal heating wire wired in the axial direction and bent into a waveform as a heating unit on the heat roller, and a horizontal heating wire wired in a direction crossing the horizontal heating wire to form a waveform. A bent vertical heating wire, and voltage applying means for applying a voltage independently to the horizontal heating wire and the vertical heating wire, wherein the voltage applying means is independent of the horizontal heating wire and the vertical heating wire. A voltage value controlled and applied alternately. 2. A method according to claim 1, wherein at least one of the rollers has a pair of rollers configured as a heat roller, and the pair of rollers sandwiches and conveys a transfer material carrying a toner image.
In a fixing device for fixing a toner image on a transfer material, a horizontal heating wire wired in the axial direction as a heating unit on the heat roller, and a vertical heating wire wired in a direction intersecting the horizontal heating wire, Voltage applying means for independently applying a voltage to the horizontal heating wire and the vertical heating wire, detection means for detecting the surface temperature of the heat roller, and a temperature detected by the detection means reaching a preset temperature If it is recognized that, the voltage value of the horizontal heating wire and the vertical heating wire several times less than the voltage in the normal energized state is applied alternately,
When the temperature detected by the detecting means is not reached the preset temperature, it is controlled to apply the voltage value in the normal energized state to the horizontal heating wire and the vertical heating wire alternately. And a fixing unit. 3. At least one of the rollers has a pair of rollers configured as a heat roller, and the pair of rollers sandwiches and conveys a transfer material carrying a toner image.
In a fixing device for fixing a toner image on a transfer material, a horizontal heating wire wired in the axial direction as a heating unit on the heat roller, and a vertical heating wire wired in a direction intersecting the horizontal heating wire, Voltage applying means for independently applying a voltage to the horizontal heating wire and the vertical heating wire, detection means for detecting a surface temperature of the heat roller, and a temperature detected by the detection means being set to a predetermined temperature. % Or more, it is applied alternately to each of the horizontal heating wire and the vertical heating wire with a voltage value which is several percent less than the voltage in the normal energized state, and the temperature detected by the detection means is applied. And control means for controlling the normal heating state voltage to be alternately applied to the horizontal heating wire and the vertical heating wire, respectively, when it is determined that the predetermined heating temperature is lower than a preset temperature by a predetermined percentage or more. A fixing device characterized by the above-mentioned.