JP3511336B2 - Fixing device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device, and more particularly, in an electrophotographic recording device such as a copying machine, a fax machine, an electrophotographic printer or the like, by a heat-meltable toner formed on a recording material surface. The present invention relates to a heat-fixing type fixing device that heats an image and fixes a toner image as a permanently fixed image on a recording material surface.

[0002]

2. Description of the Related Art In an electrophotographic recording device, a latent image on a photosensitive drum corresponding to an original image is visualized as a toner image by a developing device, and the visualized toner image is transferred onto a recording material surface such as paper or film by a transfer device. The toner image is transferred onto the recording material surface to form a toner image, and the formed toner image is fixed by a fixing device to form a permanent fixed image. As a fixing method, a heat fixing method in which toner is melted by heat and fixed is generally used. Among the heat fixing methods, the heat roller method is most widely used because of its high thermal efficiency and safety. This is because two rollers are brought into pressure contact with each other and at least one of the rollers is rotated in a heated state, and the unfixed toner is heated at a pressure contact portion (hereinafter referred to as a nip portion) of these two rollers so that the support ( paper,
A recording material such as a resin film) is fixed.

As a method of heating the roller, a halogen lamp is coaxially provided inside a roller made of metal such as A1 (aluminum) or SUS (stainless steel), and heating is performed by heat radiation of the halogen lamp, or the roller is directly heated. There is a surface heating method for generating heat. Further, the surface heating method includes a method in which a heat source composed of a heating resistor such as a ceramics heater is formed on the surface or the inner surface of the roller, or a method in which the roller itself is formed of a heating resistor.

Particularly, the latter surface heating method directly heats the surface of the roller on which the fixing is carried out, so that the heating efficiency is high,
It is an excellent heating method with low power consumption. However, in the case of this surface heating method, since the rotating roller itself has a heat source, it is necessary to supply electric power for heat generation to this heat source. As a power supply method, a method of sliding a fixed electrode such as a conductive brush or a leaf spring on a movable ring electrode formed on a roller is generally used. However, in the case of this power feeding method, it is difficult to always maintain the contact between the electrodes, and when the electrode portion and the fixed electrode are contacted and separated at the time of power feeding, discharge is generated between the electrodes, which causes electromagnetic waves. To do. As a result, there is a problem that the electromagnetic wave noise adversely affects other electronic devices.

As a means for solving this, a technique for sufficiently maintaining the contact state is disclosed in Japanese Patent Laid-Open No. 5-241465. In addition, JP-A-5-297750, JP-A-6-242696, JP-A-6-250548,
The respective publications of JP-A-6-250549 are disclosed.

The fixing device described in Japanese Unexamined Patent Publication No. 5-241465 relates to an electric connection method of a fixing roller in which the inner peripheral surface of the base pipe is formed of a resistance heating element. That is,
An electrode is formed on each of the inner and outer peripheral surfaces of the resistance heating element, an inner sleeve is contacted with the inner peripheral electrode, an outer sleeve is contacted with the outer peripheral electrode, and each electrode is contacted. Each sleeve has a flexible conductive member,
Specifically, by sliding the conductive belt and conductive wire,
Power is supplied through this conductive member, and each conductive member is kept bent and slidably in contact with each sleeve.

The fixing device described in Japanese Unexamined Patent Publication No. 5-297750 is to charge the fixing roller having toner adhered thereto with the same polarity as the toner from the power supply side in order to prevent offset. The electrode structure on the power supply side allows stable power supply without causing defects. That is, with respect to the disc-shaped receiving side electrode part which is attached to the shaft part of the rotating fixing roller and has a surface perpendicular to the shaft part, the two feeding side electrodes have different disc-shaped receiving side electrode parts. When the supply side electrode and the receiving side electrode are rotated relative to each other, the traces of the circular axes drawn by the respective contact parts are made different to eliminate the contact failure.

JP-A-6-242696 and JP-A-6-2
No. 50548 and Japanese Patent Application Laid-Open No. 6-250549 both relate to a heating unit structure of a fixing roller using a self-heating type conductive ceramic material. A method in which conductive coatings are formed on the inner peripheral surface and the outer peripheral surface of a predetermined length section, respectively, an electrode member that comes into contact with each conductive coating by elastic force is provided, and a heating power supply is connected between each electrode member. The fixing roller is heated at.

[0009]

However, the techniques described in these documents are techniques for keeping the contact state stable by reducing the friction of the sliding portion of the electrode and preventing the deterioration of the electrode. However, normally, in a PPC, a laser printer, a PPF, etc., the expected number of sheets to be passed is 10
It is more than 0,000, and the fixing roller also rotates at the corresponding rotation speed. Therefore, the frictional force at the electrode sliding portion and the sliding surface also change over time, and contact stability cannot be maintained. Further, even if the contact stability is increased, when the fixing roller is rapidly changed, for example, when the roller starts to move, the roller vibrates, which causes a problem that the electrodes are separated from each other.

The present invention has been made in view of the above-mentioned drawbacks of the prior art, and when an angular acceleration acts on the fixing roller, such as when the fixing roller starts to rotate, when it stops, or when it accelerates or decelerates to a desired rotation speed. It is an object of the present invention to provide a fixing device in which noise caused by contact failure of electrodes occurs due to vibration of the fixing roller and the like, and which also realizes noise reduction at low cost. . Further, it is an object of the present invention to provide a fixing device that reduces noise caused by vibration of the fixing roller and further prevents the electrode from sliding due to friction when the electrode is slid when not energized.

[0011]

According to a first aspect of the present invention, there is provided a fixing roller, and movable ring electrodes formed at both ends of the fixing roller and electrically connected to a heating element of the fixing roller.
In a fixing device having a fixed electrode for contacting the movable ring electrode and supplying electric power to the heating element, at least when the fixing roller starts rotating from a stopped state, power is temporarily supplied to the heating element. Is to stop.

According to a second aspect of the present invention, a fixing roller, a movable ring electrode formed at both ends of the fixing roller and electrically connected to a heating element of the fixing roller, and contacting the movable ring electrode, In a fixing device having a fixed electrode for supplying electric power to the heating element, power supply to the heating element is temporarily stopped at least when the rotating fixing roller is stopped. .

According to a third aspect of the present invention, a fixing roller, a movable ring electrode formed at both ends of the fixing roller and electrically connected to a heating element of the fixing roller, and contacting the movable ring electrode, In a fixing device having a fixed electrode for supplying electric power to the heating element, power is temporarily supplied to the heating element when the rotation speed of the fixing roller is at least in an accelerating state and / or a decelerating state. Is to stop.

According to a fourth aspect of the invention, in the fixing device according to any one of the first to third aspects, there is provided a contacting / separating means for contacting / separating the fixed electrode with respect to the movable ring electrode.

[0015]

DETAILED DESCRIPTION OF THE INVENTION

(First Embodiment of the Invention) FIG. 1 is a perspective view for explaining a first embodiment of a fixing device according to the present invention, in which 1 is a fixing roller and 2 is a pressure roller. 3 is a base material pipe, 4 is a heating resistor, 5 is a release layer, 6 (6a, 6)
b) is a ring-shaped movable electrode (hereinafter referred to as a movable ring electrode) provided at both ends of the fixing roller 1, 7 (7a, 7a).
b) is a fixed electrode in contact with the ring-shaped movable electrode, 20
Is a power source, 21 is a switch, and 22 is a switch driving means. In addition, in the drawings shown in FIG. 1 and subsequent figures, the same reference numerals as those in FIG.

The first embodiment of the fixing device according to the present invention has a function of temporarily stopping the power supply to the fixing roller 1 when the fixing roller 1 starts to rotate from the stopped state. The fixing device shown in is a diagram for explaining this.

In FIG. 1, the heating roller 1 comprises a base material pipe 3 and a heating element 4 (surface in FIG. 1) formed on the surface or inner surface of the base material pipe 3, and the outermost peripheral surface is A release layer 5 is formed to ensure releasability from the toner. The release layer 5 is made of, for example, a material having excellent releasability such as Teflon. At both ends of the heating element 4,
Ring-shaped movable ring electrodes 6a and 6b for energizing the heating element 4 are formed, and a fixed electrode 7a fixed to the machine body (not shown) side is formed on the movable ring electrode 6a, and similarly, the movable ring electrode. Fixed electrodes 7b fixed to the machine body are in contact with 6b. Fixed electrode 7a, fixed electrode 7
Electric wires are connected to b, respectively, and the heating element 4 is connected to the other end of the electric wires.
A power source 20 for heating the switch is connected in series with a switch 21, and the switch 21 is opened and closed by a switch driving means 22. Further, a pressure roller 2 parallel to the axis is pressed in the fixing roller 1 in the direction of arrow P to form a nip portion n.
It is rotatably supported around a.

FIG. 2 is a diagram for explaining an example of a sectional structure of the fixing roller shown in FIG. In FIG. 2A, a layer of the heating resistor 4 is formed on the surface of the base material pipe 3, and a release layer 5 for ensuring releasability from the toner is formed thereon. In FIG. 2B, a layer of the heating resistor 4 is formed on the inner surface of the base material pipe 3, and a release layer 5 for ensuring releasability from toner is formed on the surface of the base material pipe 3. Is. In FIG. 2C, the base material pipe 3 itself is made of a heat generating resistance material to form a heat generating pipe 8, and a release layer 5 is formed on the surface thereof.

The material of the base material pipe 3 is Al or SU.
Metals such as S, glass, ceramics, heat resistant resins, etc. are used. In particular, glass and heat-resistant resin have poor thermal conductivity, and the surface-heated heat does not escape to the inner surface, so that the surface of the fixing roller 2 on which fixing is performed can be efficiently heated. It is a material. When a metal is used as the base material pipe 3, it is necessary to form an insulating layer (SiO ₂ ) for ensuring electrical insulation between the base material pipe 3 and the layer of the heating resistor 4. The shape of the heating resistor 4 may be formed uniformly over the entire heating area or the entire circumference, or may be formed in a pattern.

As described above, the movable ring electrodes 6 for energizing the heating resistor 4 are provided at both ends of the layered heating resistor 4.
(6a, 6b) are formed. Therefore, the movable ring electrode 6 (6a, 6b) rotates with the rotation of the fixing roller 1. As a method of forming the movable ring electrode 6 (6a, 6b), there are a method of forming a conductive resin by coating and drying, and a method of forming a thin film such as vapor deposition of a metal such as Al. . The fixed electrode 7 (7a, 7b) fixed to the machine body side is in contact with the movable ring electrode 6 (6a, 6b).

FIG. 3 is a view for explaining an example of the fixed electrode shown in FIG. 1, in which 11 is a leaf spring and 12 is a carbon brush. In FIG. 3A, a conductive plate spring 11 having a U-shaped cross section is used for the movable ring electrode 6 of the fixing roller 1.
This is an example where two points are in contact with each other on the diameter. FIG. 3 (B) shows
One conductive leaf spring 1 supported in a cantilever manner at the fulcrum 11a
In this example, 1 touches at one place. In FIG. 3C, a conductive brush such as a carbon brush 12 is added to the contact portion of the conductive plate spring 11 having a U-shaped cross section with the movable ring electrode 6. A conductive material such as phosphor bronze is used as the material of the leaf spring 11 used in FIGS. 3 (A), 3 (B), and 3 (C).

Movable ring electrodes 6a, 6b and fixed electrode 7
A switch 21 that is connected in series with a power source 20 for heating the heating resistor 4 via a and 7b and turns on / off the power supply to the heating resistor 4 is a commonly used switching element such as a relay or a transistor element. Is used. The switch 21 is turned on / off by a switch driving unit 22 driven by a signal from a control unit (not shown) including a CPU or the like, and can control heating and non-heating of the fixing roller 1. The movable ring electrodes 6a and 6b make sliding contact with the fixed electrodes 7a and 7b as the fixing roller 1 rotates.

Next, the operation of the present invention will be described. First, when there is no image information, that is, PPC, laser printer,
When the printer is in a print standby state with PPF or the like, the fixing roller 1
Since there is no need to heat, the power supply to the fixing roller 1 is stopped. When image information is received, that is, when printing is to be started, it is necessary to heat the fixing roller 1 to the fixing possible temperature. Therefore, the switch 21 is turned on to energize the heating resistor 4 from the power source 20.

Generally, as a method of heating the fixing roller 1,
A method is employed in which the rotation of the fixing roller 1 is stopped from the start of heating to a certain temperature lower than the fixing temperature, and the rotation is started when a certain temperature is reached. This is because if the fixing roller 1 and the pressure roller 2 suddenly start rotating in the cold state,
This is because there is a possibility that the surface of the fixing roller 1 and the pressure roller 2 may be damaged because the toner partially stuck to the sheet is stuck to it. Further, as another reason, when the fixing roller 1 is rotated and heated from the beginning, the heat of the fixing roller 1 is taken by the pressure roller 2, and the temperature rising time of the fixing roller 1 is longer than that of the heating without rotation. This is to prevent a long time before printing becomes possible.

In the present invention, when the fixing roller 1 is rotated while the power source 20 is energizing the heating resistor 4, the switch 21 is turned off at least when the rotation is started. The power supply to the heating resistor 4 is turned off. The time for turning off the power may include at least the start of rotation, but even after the start of rotation, there is a certain time (depending on the type of motor, the degree of acceleration at the start of rotation, etc.) 1 vibrates, and the fixed electrodes 7a and 7b move to the respective movable ring electrodes 6a and
Since there is a possibility of being in a non-contact state with 6b, it is preferable to maintain the non-conducting state until the vibration is suppressed to some extent.

However, if it is too long, there is a disadvantage that the temperature of the fixing roller 1 escapes to the pressure roller 2 during that time, and the temperature of the fixing roller drops too much. Optimally, it is desirable to set it to 1 second or less. This is because there is a large difference in the temperature rising time compared to when rotating in the energized state, and there is less time to keep the user waiting.

(Embodiment 1) First of the fixing device according to the present invention
An example of the embodiment will be described. As the fixing roller 1, a glass pipe having a wall thickness of 0.5 mm is used for the base material pipe 3, and a heating resistor 4 is formed on the surface thereof by sintering to have a uniform wall thickness of 2 μm. After the resin containing Ag was applied, it was dried to form the movable ring electrodes 6a and 6b for supplying power to the heating resistor 4. Further, a Teflon layer having a thickness of 30 μm was formed as a release layer 5 on the heating resistor 4 excluding the movable ring electrodes 6a and 6b. The fixing roller 1 was set in the fixing device as shown in FIG. As the fixed electrodes 7a and 7b for supplying power to the fixing roller 1, a plate spring 11 made of phosphor bronze to which a carbon brush 12 is fixed by a conductive adhesive is used.

Further, a relay is provided as the switch 21 between the fixed electrodes 7a and 7b and the power source 20, and the power supply to the fixing roller 1 can be turned on / off by applying a signal to the switch driving means 22. . On the other hand, a pressure roller 2 is in contact with the fixing roller 1, and is pressed against the fixing roller 1 by a leaf spring 11 with a load of 5 kgf. Further, to the pressure roller 2, through a gear provided at one end thereof,
A motor is connected to the fixing roller 1, and the fixing roller 1 is rotated by rotating the pressure roller 2. This fixing device was driven under the following conditions, and the presence or absence of noise at that time was examined. This measurement was performed by placing a radio near the fixing device and examining the presence or absence of noise. For comparison, the same evaluation was performed when the rotation was started while energizing.

[0029]     Drive condition       Resistance of fixing roller 1: 15Ω       Supply voltage: AC voltage 90V       Timing of stopping energization: After starting energizing, the surface of the fixing roller 1 becomes 150 ° C or higher.                             When       Timing of rotation start: 1 second after stopping energization       De-energization interval: From the start of rotation to 1 second later       Fixing temperature: 180 ℃

As a result, in the example, no noise was input to the radio, but in the comparative example, a large amount of noise was generated. Further, comparing the rising times up to the preset fixing temperatures of both, in the case of the comparative example, it was 9 seconds, whereas in the example, it was only 12 seconds, which was a slight delay.

(Second Embodiment of the Present Invention) The second embodiment of the fixing device according to the present invention is the fixing device shown in FIG. 1, in which the heat generation resistance is at least when the rotating fixing roller 1 is stopped. That is, it has a function of stopping the power supply to the body 4.

Next, the operation of the present invention will be described with reference to the fixing device shown in FIG. After printing according to the image information, PP
C, laser printer, PPF, etc. are put in a print standby state. In the print standby state, the rotation of the fixing roller 1 is stopped,
The fixing temperature is lower than the fixing temperature in order to shorten the heating temperature rising time during reprinting, shorten the time until the fixing is restarted, and further reduce the power consumed by the fixing roller 1 at that time. Keep it at (preheat temperature).

During the fixing operation, when the switch 21 is turned on to energize the heating resistor 4 from the power source 20, the fixing roller 1 which is susceptible to vibration is stopped (at least at the moment when the rotation is stopped). Including), the switch 21
Is turned off so that the heating resistor 4 is de-energized.
The time for turning off the power may be at least when the rotation is stopped, but even after the rotation is stopped, there is a certain time (which depends on the type of motor, the degree of deceleration when the rotation is stopped, etc.). Vibrates, and fixed electrodes 7a and 7b
May come into non-contact with the movable ring electrode 6, so it is preferable to maintain the non-energized state until the vibration subsides to some extent.

However, if the non-energized state is too long,
In the meantime, the temperature drops too much and becomes lower than the preheating temperature, and after that, a large amount of electric power is consumed to reach the preheating temperature. Less than a second, optimally 2
It is desirable to set it to less than 2 seconds.

(Second Embodiment) Second fixing device according to the present invention
An example of the embodiment will be described. A glass pipe having a wall thickness of 0.5 mm is used as the base material pipe 3 as the fixing roller 1.
The heating resistor 4 has a uniform thickness of 2 μm on the surface by sintering.
Then, a resin containing Ag was applied to both ends of the heating resistor 4 and dried to form the movable ring electrodes 6a and 6b for supplying power to the heating resistor 4. Further, a Teflon layer having a thickness of 30 μm is formed as a release layer 5 on the heating resistor 4 excluding the movable ring electrodes 6a and 6b.
Was set in the fixing device as shown in FIG. As the fixed electrodes 7a and 7b for supplying electric power to the fixing roller 1,
A phosphor bronze leaf spring 11 to which a carbon brush 12 was fixed with a conductive adhesive was used.

Further, a relay is provided as the switch 21 between the fixed electrodes 7a and 7b and the power source 20, and a signal is applied to the switch driving means 22 of the relay to turn on / off the power supply to the fixing roller 1. I did it. On the other hand, the pressure roller 2 is in contact with the fixing roller 1 and is 5
It is pressed against the fixing roller 1 with a load of kgf. Further, a motor is connected to the pressure roller 2 via a gear provided at one end thereof, and the fixing roller 1 is rotated around by rotating the pressure roller 2. This fixing device was driven under the following conditions, and the presence or absence of noise at that time was examined. This measurement was performed by placing a radio near the fixing device and examining the presence or absence of noise. For comparison, the same evaluation was performed even when stopped while energizing.

[0037]     Drive condition       Resistance of fixing roller: 15Ω       Supply voltage: AC voltage 90V (during fixing operation)                             AC voltage 40V (standby)       Power supply stop timing: 0.5 seconds before the fixing roller stops       Interval of de-energization: From 1 second after rotation stop       Fixing temperature: 180 ℃

As a result, in the example, no noise was input to the radio, but in the comparative example, a large amount of noise was generated.

(Third Embodiment of the Present Invention) The third embodiment of the fixing device according to the present invention is the same as the fixing device shown in FIG. 1, except that the fixing roller 1 rotates at least at an accelerating state. , Or in the deceleration state, the heating resistor 4
It has a function of stopping the power supply to.

Next, the operation of the present invention will be described with reference to the fixing device shown in FIG. When attempting to start printing, the fixing roller 1 first gradually increases the rotation speed from the stopped state and accelerates to the paper conveyance speed. During this period, the energization of the fixing roller 1 is stopped, the paper conveying speed is reached, and the fixing roller 1
After the rotation speed of (1) reaches a constant speed, the switch 21 is turned on to start energizing the heating resistor 4 from the power source 20 to heat the fixing roller 1.

The time for turning off the energization may be at least during acceleration, but even after acceleration is completed and a constant speed is reached, there is a certain time (type of motor, degree of acceleration at the start of rotation, etc.). Fusing roller 1
Vibrates, and the fixed electrodes 7a and 7b are respectively moved to the movable ring electrode 6.
Since there is a possibility of being in a non-contact state with a and 6b, it is preferable to maintain the non-rotating state until the vibration is suppressed to some extent.
However, if it is too long, there is a disadvantage that the temperature raising time becomes too long. Therefore, it is desirable to set it to usually 5 seconds or less, optimally 1 second or less after the constant speed is reached.

(Embodiment 3) Third embodiment of fixing device according to the present invention
An example of the embodiment will be described. As the fixing roller 1,
A glass pipe having a wall thickness of 0.5 mm is used as the base material pipe 3, and a heating resistor 4 is formed on the surface thereof by sintering to have a uniform wall thickness of 2 μm, and a resin containing Ag at both ends of the heating resistor 4. The movable ring electrodes 6a and 6b for supplying power to the heating resistor 4 which has been applied and dried are formed. Movable ring electrode 6
A Teflon layer having a thickness of 30 μm was formed as a release layer 5 on the heating resistor 4 excluding a and 6b. This fixing roller 1
Was set in the fixing device as shown in FIG. As the fixed electrodes 7a and 7b for supplying electric power to the fixing roller 1,
A phosphor bronze leaf spring 11 to which a carbon brush 12 was fixed with a conductive adhesive was used.

Further, a relay is arranged as the switch 21 between the fixed electrodes 7a and 7b and the power source 20, and a signal is applied to the switch driving means 22 of this relay to turn on / off the power supply to the fixing roller 1. I did it. On the other hand, the pressure roller 2 is in contact with the fixing roller 1 and is 5
It is pressed against the fixing roller 1 with a load of kgf. Further, a motor is connected to the pressure roller 2 via a gear provided at one end thereof, and the fixing roller 1 is rotated around by rotating the pressure roller 2. This fixing device was driven under the following conditions, and the presence or absence of noise at that time was examined. This measurement was performed by placing a radio near the fixing device and examining the presence or absence of noise. For comparison, the same evaluation was performed when electricity was applied during acceleration.

[0044]     Drive condition       Resistance of fixing roller: 15Ω       Supply voltage: AC voltage 90V       Timing of de-energization: just before accelerating       Timing of resuming energization: 1 second after the constant speed is reached       Fixing temperature: 180 ℃

As a result, in the example, no noise was introduced into the radio, but in the comparative example, a large amount of noise was generated.

Next, another example of the third embodiment of the fixing device according to the present invention will be described. After printing the image information, the fixing roller 1 is gradually decelerated to a constant speed lower than the fixing speed, or the fixing roller 1 is stopped as it is. During deceleration, the energization of the fixing roller 1 is stopped, and after a constant speed or after stopping, the switch 21 is turned on to energize the heating resistor 4 from the power source 20 to heat the fixing roller 1 to a temperature. Hold.

The time for turning off the power may be at least during deceleration, but even after deceleration ends and reaches a constant speed, or even after stopping, a certain time (degree of deceleration at the start of rotation) The fixing roller 1 vibrates and the fixed electrodes 7a and 7b move the movable ring electrode 6).
Since there is a possibility of being in a non-contact state with a and 6b, it is preferable to maintain the non-conducting state until the vibration is suppressed to some extent.

Example 4 A specific example according to the present invention will be described. As the fixing roller 1, a glass pipe having a thickness of 0.5 mm is used as the pipe base material 3, and a heating resistor 4 is formed on the surface thereof by sintering to have a uniform thickness of 2 μm. A resin containing Ag was applied and dried to form the movable ring electrodes 6a and 6b for supplying power to the heating resistor 4. Further, a Teflon layer having a thickness of 30 μm was formed as a release layer 5 on the heating resistor 4 excluding the movable ring electrodes 6a and 6b. The fixing roller 1 was set in the fixing device as shown in FIG. The fixed electrodes 7a and 7b for supplying power to the fixing roller 1 are made of phosphor bronze leaf spring 1
A carbon brush 12 fixed to the No. 1 with a conductive adhesive was used.

Further, a relay is arranged as the switch 21 between the fixed electrodes 7a and 7b and the power source 20, and the power supply to the fixing roller 1 can be turned on / off by applying a signal to the switch driving means 22. . On the other hand, the pressure roller 2 is in contact with the fixing roller 1, and is pressed against the fixing roller 1 by a spring with a load of 5 kgf. Further, a motor is connected to the pressure roller 2 via a gear provided at one end thereof, and the fixing roller 1 is rotated around by rotating the pressure roller 2. This fixing device was driven under the following conditions, and the presence or absence of noise at that time was examined. This measurement was performed by placing a radio near the fixing device and examining the presence or absence of noise. For comparison, the same evaluation was performed when electricity was applied during acceleration.

Driving condition Resistance of fixing roller: 15Ω Supply voltage: AC voltage 90V Timing of de-energization: just before deceleration Timing of resuming energization: 1 second after reaching a constant speed Fixing temperature: 180 ℃

As a result, in the example, no noise was introduced into the radio, but in the comparative example, a large amount of noise was generated.

(Fourth Embodiment of the Present Invention) FIG. 4 is a view for explaining a fourth embodiment of the fixing device according to the present invention, in which 9 is a solenoid and 10 is an insulator. Is. In FIG. 4, the fixed electrode 7 is provided with an electrode contacting / separating means capable of contacting / separating the fixed electrode 7 and the movable ring electrode 6 in a contact state or a non-contact state. As the electrode contacting / separating means, for example, a solenoid 9 fixed to the frame of the main body as shown in FIG. 4 can be used. In the electrode contacting / separating method, the leaf spring 11 cantilevered by the fixing member 11a is used as the fixed electrode 7, and the shaft 9a of the solenoid 9 is brought into contact with a part of the fixed electrode 7 via the insulator 10.
By turning on / off the solenoid 9, the position of the shaft 9a is changed in the axial direction (the protruding state and the retracted state), whereby the fixed electrode 7 is deformed and the contact state between the fixed electrode 7 and the movable ring electrode 6 is changed. Can be changed.

(Embodiment 5) The fourth fixing device according to the present invention
An example of the embodiment will be described. As the fixing roller 1, a glass pipe having a wall thickness of 0.5 mm is used as the pipe base material 3, and the heating resistor 4 is formed on the surface thereof by sintering to have a uniform wall thickness of 2 μm. A resin containing Ag was applied and dried to form the movable ring electrodes 6a and 6b for supplying power to the heating resistor 4. Movable ring electrode 6
A Teflon layer having a thickness of 30 μm was formed as a release layer 5 on the heating resistor 4 excluding a and 6b. This fixing roller 1
Was set in the fixing device as shown in FIG. As the fixed electrodes 7a and 7b for supplying electric power to the fixing roller 1,
A phosphor bronze leaf spring 11 to which a carbon brush 12 was fixed with a conductive adhesive was used.

Further, a relay is arranged as the switch 21 between the fixed electrodes 7a and 7b and the power source 20, and the power supply to the fixing roller 1 can be turned on / off by applying a signal to the switch driving means 22 of the relay. I chose On the other hand, the pressure roller 2 is in contact with the fixing roller 1, and the spring is 5 kgf.
It is pressed against the fixing roller 1 by the load. Further, a motor is connected to the pressure roller 2 via a gear provided at one end thereof, and the fixing roller 1 is rotated around by rotating the pressure roller 2. This fixing device was driven under the following conditions, and the presence or absence of noise at that time was examined. This measurement was performed by placing a radio near the fixing device and examining the presence or absence of noise. For comparison, the same evaluation was carried out even when the contact was maintained even when the energization was stopped.

Driving conditions: Resistance of fixing roller: 15Ω Supply voltage: AC voltage 90V Timing of stopping energization: When the surface of the fixing roller becomes 150 ° C or higher after starting energization Timing of starting rotation: One second after stopping energizing Stopping energization Interval (restart of energization): 1 second after the start of rotation Solenoid drive timing: Immediately after deenergization Solenoid drive stop timing: Immediately before resuming energization Electrode fixing temperature: 180 ° C Fixing roller rotation speed during fixing: 120 mm / s Solenoid driven From the timing to the timing of stopping the solenoid drive, the electrodes are held in a non-contact state.

As a result, the fixing roller 1 of
Rotating electrode 7a after rotating at a rotational speed equivalent to passing 00 sheets,
The carbon brush 12 of 7b and the carbon brush 12 after the fixing roller 1 of the comparative example was similarly rotated were observed and compared, and the amount of abrasion was smaller in the example.

When the same experiment was carried out in the cases of Examples 2 and 3, the effect of preventing wear was observed by bringing the electrodes into a non-contact state during non-energization. Further, in the present embodiment, an example of acceleration is shown when reaching a constant rotation speed (fixing roller rotation speed at the time of fixing) immediately after the motor starts to rotate, but not limited to this, for example, , When the fixing roller 1 rotating at a low speed is raised to the fixing rotation speed for performing the fixing operation, or vice versa, when the fixing rotation speed is decreased to a rotation speed lower than the fixing rotation speed. It can be applied in all situations such as accelerating and decelerating to shift to different rotational speeds.

[0058]

According to the first aspect of the present invention, there are provided a fixing roller, movable ring electrodes formed at both ends of the fixing roller and electrically connected to a heating element of the fixing roller, and the movable ring electrode. In the fixing device having a fixed electrode for contacting and supplying electric power to the heating element, when the fixing roller starts to rotate from the stopped state, if it is energized, vibration generated at the start of rotation, etc. A contact failure of the electrodes occurs, which causes noise.However, when the fixing roller starts to rotate from a stopped state, power supply to the heating element is temporarily stopped, so that noise is not generated. It was possible to prevent this, and since no special device was added for that purpose, it was possible to realize at low cost.

Effect corresponding to claim 2: A fixing roller,
A movable ring electrode formed on both ends of the fixing roller and electrically connected to a heating element of the fixing roller, and a fixed electrode for contacting the movable ring electrode and supplying electric power to the heating element. In the fixing device, when the fixing roller is stopped, it is energized to cause a contact failure of the electrodes due to vibration or the like generated when the rotation is stopped, which causes noise. When the roller is stopped, the power supply to the heating element is temporarily stopped, so that the generation of noise can be prevented, and since no special device is added for that,
It could be realized at low cost.

Effect corresponding to claim 3: A fixing roller,
A movable ring electrode formed on both ends of the fixing roller and electrically connected to a heating element of the fixing roller, and a fixed electrode for contacting the movable ring electrode and supplying electric power to the heating element. In the fixing device having, when the rotation speed of the fixing roller is in an accelerating state or a decelerating state,
Since the power supply to the heating element is temporarily stopped, it is possible to prevent the occurrence of noise due to contact failure of the electrodes due to vibration and the like, and a special device for that purpose. Since it was not added, it could be realized at low cost.

Effect corresponding to claim 4: In the fixing device according to any one of claims 1 to 3, since there is a contacting / separating means for contacting / separating the fixed electrode with respect to the movable ring electrode, vibration of the fixing roller, etc. In addition, the noise caused by the noise is reduced, and the electrodes are kept in a non-contact state when not energized. Therefore, the electrodes slide when not energized (that is, when it is not necessary to use the electrodes), and the electrodes wear due to friction. Could be prevented.

[Brief description of drawings]

FIG. 1 is a perspective view for explaining a first embodiment of a fixing device according to the present invention.

FIG. 2 is a diagram for explaining a cross-sectional configuration example of the fixing roller shown in FIG.

FIG. 3 is a diagram for explaining an example of the fixed electrode shown in FIG.

FIG. 4 is a diagram for explaining a fourth embodiment of a fixing device according to the present invention.

[Explanation of symbols]

1 ... Fixing roller, 2 ... Pressure roller, 3 ... Base pipe,
Reference numeral 4 denotes a heating resistor, 5 ... release layer, 6, 6a, 6b ... movable ring electrode, 7, 7a, 7b ... fixed electrode, 9 ... solenoid, 10 ... insulator, 11 ... leaf spring, 12 ... carbon brush, 20 ... Power source, 21 ... Switch, 22 ... Switch driving means.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP 62-202481 (JP, A) JP 7-64439 (JP, A) JP 8-76632 (JP, A) JP 9- 62136 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) G03G 13/20 G03G 15/20

Claims (4)

(57) [Claims] 1. A fixing roller, a movable ring electrode formed at both ends of the fixing roller and electrically connected to a heating element of the fixing roller, and a contact with the movable ring electrode for supplying electric power to the heating element. A fixing device having a fixed electrode for supplying the fixing device, wherein when the fixing roller starts to rotate from a stopped state, power supply to the heating element is temporarily stopped. 2. A fixing roller, a movable ring electrode formed at both ends of the fixing roller and electrically connected to a heating element of the fixing roller, and a contact with the movable ring electrode for supplying electric power to the heating element. A fixing device having a fixed electrode for supplying the fixing device, wherein when the rotating fixing roller is stopped, power supply to the heating element is temporarily stopped. 3. A fixing roller, a movable ring electrode formed at both ends of the fixing roller and electrically connected to a heating element of the fixing roller, and a contact with the movable ring electrode for supplying electric power to the heating element. In a fixing device having a fixed electrode for supplying heat, when the rotation speed of the fixing roller is in an accelerating state and / or a decelerating state, power supply to the heating element is temporarily stopped. And fixing device. 4. A contacting / separating means for contacting / separating the fixed electrode with respect to the movable ring electrode is provided.
4. The fixing device according to any one of 3 to 3.