JP2003098869A - Fixing apparatus and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing apparatus and an image forming apparatus for easily changing power consumption. SOLUTION: The fixing apparatus 10 has a magnetic flux forming member 12, supplied with power and forming magnetic flux and a fixing roller 11 heated by an induced current generated, by the magnetic flux formed by the magnetic flux forming member 12, and is constituted, so as to fix a toner image to a recording paper P by the heat from the fixing roller 11. The magnetic flux forming member 12 is provided with a plurality of induction coils 12a, 12b and a CPU 21 for independently controlling the power supplied to the induction coils 12a, 12b.

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 an image forming apparatus.

[0002]

2. Description of the Related Art Electrophotographic copying machines, printers, facsimiles and the like are provided with a fixing device for fixing a toner image transferred onto a recording material onto the recording material.

Some fixing devices use a halogen lamp as a heat source. However, since the heat efficiency is low and the energy loss is large, there is a trend to adopt so-called induction heating to save energy.

As a fixing device using this induction heating,
For example, an induction coil is wound around a core made of an iron core for forming a closed magnetic circuit, a conductive fixing roller is provided so as to surround the core around which the induction coil is wound, and fixing is performed by energizing the induction coil. It has been proposed to generate an induced current in a roller to generate heat. In the fixing device using the induction heating, the temperature can be raised with less electric power as compared with the halogen lamp, so that the energy saving efficiency can be improved.

[0005]

However, in the conventional fixing device using induction heating, for example, whether the power supply for energizing the induction coil is 100 V, 200 V or any other voltage, or 50 Hz. The power consumption in the induction coil changes depending on the frequency of 60 Hz. For this reason, it was necessary to prepare induction coils having different specifications for each voltage and frequency of the power supply.

Further, in the conventional image forming apparatus, each of the operating conditions such as warm-up, image formation, and standby is
When it is desired to change the power consumption in the induction coil, the energization to the induction coil is finely turned on / off to change the energization time. However, such control has a problem that the temperature fluctuation of the fixing roller becomes large. In addition, since the electric power must be supplied within the maximum power consumption of the machine, the maximum electric power of the fixing device is limited in accordance with the condition that consumes the most electric power, such as when forming an image. However, more power could not be supplied to the fixing device during warm-up.

An object of the present invention is to provide a fixing device and an image forming apparatus whose power consumption can be easily changed.

[0008]

In order to solve the above problems, the invention according to claim 1 is directed to a magnetic flux forming member which is supplied with electric power to form a magnetic flux, and an induction which is generated by the magnetic flux formed by the magnetic flux forming member. A fixing device for fixing a toner image to a recording material by heat from the heat generating member, wherein the magnetic flux forming member comprises:
It is characterized by comprising a plurality of induction coils, and comprising control means for independently controlling electric power supplied to the plurality of induction coils for each induction coil.

According to the first aspect of the invention, the control means can independently control the induction coil supplying the electric power from the plurality of induction coils, so that the electric power consumed by the magnetic flux forming member can be easily controlled. Can be changed.

According to a second aspect of the present invention, in the fixing device according to the first aspect, the magnetic flux forming member includes a plurality of induction coils each having a different diameter by overlapping the centers of the induction coils. It is characterized in that the induction coils are arranged concentrically.

According to the second aspect of the invention, the same effect as that of the first aspect can be obtained, and the plurality of induction coils are concentrically arranged to save the space. A magnetic flux forming member having a simple structure can be obtained.

According to a third aspect of the present invention, there is provided a magnetic flux forming member which is supplied with electric power to form a magnetic flux, and a heat generating member which generates heat by an induced current generated by the magnetic flux formed by the magnetic flux forming member. A fixing device for fixing a toner image onto a recording material by heat from a magnetic flux forming member, wherein the magnetic flux forming member forms one conducting wire into a plurality of coil shapes each having a different diameter, and these coil-shaped portions are It is arranged in a concentric pattern, and both ends of the conducting wire and at least one place between these ends are provided with a connecting part that serves as a contact point for supplying electric power to the magnetic flux forming member, and the plurality of connecting parts are provided. It is characterized by comprising a control means for independently controlling the electric power supplied between the connection parts selected from among the connection parts.

According to the third aspect of the invention, since the control means supplies the electric power independently between the connecting portions selected from the plurality of connecting portions, the electric power consumed by the magnetic flux forming member can be easily adjusted. Can be changed to

According to a fourth aspect of the present invention, in an image forming apparatus including a fixing device for applying heat to a toner image to fix the toner image on a recording material, the fixing device is according to any one of the first to third aspects. It is a fixing device.

According to the invention described in claim 4, it is possible to obtain the same effect as in any one of claims 1 to 3, and it is possible to easily change the power consumption of the fixing device. Is obtained.

According to a fifth aspect of the present invention, in the image forming apparatus according to the fourth aspect, the image forming apparatus further comprises storage means for storing electric power control data set corresponding to operating conditions, and the control means of the fixing device is the above-mentioned. It is characterized in that the power control data stored in the storage means is acquired corresponding to the operating condition, and the power based on the power control data is supplied to the magnetic flux forming member.

According to the invention of claim 5, it is possible to obtain the same effect as that of claim 4, and it is possible to easily change the power consumption of the fixing device in accordance with the operating conditions of the image forming apparatus. .

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] FIG.
1 to 3, the image forming apparatus 1 according to the first embodiment of the present invention will be described in detail. The image forming apparatus 1 is
This is an apparatus for forming an image on a recording sheet (recording material) R by a so-called electrophotographic method, and as shown in FIG. 1, a photosensitive drum 2, a charging roller 3, an exposure apparatus 4, a developing apparatus 5, A transfer device 6, a cleaner 7, a fixing device 10,
The control unit 30 (see FIG. 3) that controls a series of operations for image formation is roughly configured.

In this image forming apparatus 1, the photosensitive drum 2
Is rotated in the clockwise direction (shown by an arrow) in FIG. 1 to form an image through the process described below. First, the control unit 30 applies a predetermined voltage between the charging roller 3 and the photoconductor drum 2 to uniformly charge the photoconductor drum 2. Next, under the control of the control unit 30, the exposure device 4 scans the laser beam based on the image data to be formed on the recording paper R, and the surface of the photosensitive drum 2 is electrostatically charged corresponding to the image data. Form a latent image. This electrostatic latent image is toner-developed by the developing device 5, and a toner image corresponding to the image data is formed on the surface of the photosensitive drum 2. Next, under the control of the control unit 30, the transfer device 6 charges the recording paper R to a polarity opposite to the charging polarity of the toner, and transfers the toner image on the photosensitive drum 2 to the recording paper R. The recording paper R on which the toner image corresponding to the image data is transferred is conveyed to the fixing device 10.

As shown in FIG. 2, the fixing device 10 includes a fixing roller (heating member) 11, a magnetic flux forming member 12, a pressure roller 13, and a controller 30 (see FIG. 3) of the image forming apparatus 1. The fixing control unit 20 (see FIG. 3) that is provided and controls the electric power supplied from the AC power supply 26 to the magnetic flux forming member 12
With.

The fixing roller 11 is a conductive hollow cylindrical pipe, and is made of, for example, a carbon steel pipe, a stainless alloy pipe, or an aluminum pipe. A heat-resistant release layer (not shown) having good heat resistance and good releasability is formed on the outer peripheral surface of the fixing roller 11. The heat-resistant release layer is formed by coating a fluororesin, for example. Further, a temperature detecting means 11a such as a thermistor is in contact with substantially the center of the fixing roller 11 in the longitudinal direction (see FIG. 2B). The pressure roller 13 is a rubber roller formed by covering a heat-resistant rubber layer 13b around a long cored bar 13a, and has appropriate elasticity. Silicon rubber, for example, is used as the heat-resistant rubber layer 13b. A release layer (not shown) formed by coating a fluororesin is formed on the outer peripheral surface of the pressure roller 13.

The fixing roller 11 and the pressure roller 13
As shown in the sectional view of FIG. 2 (a), the respective outer peripheral surfaces are arranged in pressure contact with each other. As a result, at the portion of the pressure roller 13 that is in pressure contact with the fixing roller 11, a nip portion P that is in close contact with the fixing roller 11 with a certain area is formed due to the elasticity of the pressure roller 13. By giving the nip P a certain area in this way, the amount of heat applied to the toner image transferred to the recording paper R is adjusted.

Inside the fixing roller 11, a magnetic flux forming member 12 is arranged as shown in FIG. 2 (b). As shown in FIG. 3, the magnetic flux forming member 12 is supplied with electric power from the AC power supply 26 under the control of the fixing controller 20 and forms a magnetic flux around the fixing roller 11. Due to this magnetic flux, an induced current is generated in the conductive part of the fixing roller 11, and the induced current causes the fixing roller 11 to generate heat.

The magnetic flux forming member 12 is provided with large and small induction coils 12a and 12b each having a different winding diameter (hereinafter referred to as "winding diameter"). The induction coil 12a having a large winding diameter. By arranging the center of each of the coils on the center of the induction coil 12b having a small winding diameter, the coils are arranged concentrically without making contact with each other. The induction coils 12a and 12b are formed to have substantially the same length as the longitudinal direction of the fixing roller 11. As a result, the fixing roller 11 generates heat almost uniformly over the entire area. The induction coil 12b having a small winding diameter is wound around the coil supporting member 12c (see FIG. 2A). This coil support member 12c
Is formed in a cylindrical shape and extends in the longitudinal direction inside the fixing roller 11.

A core for forming a closed magnetic circuit may be provided inside the magnetic flux forming member 12. In this case, the leakage of the magnetic flux generated by the magnetic flux forming member 12 can be reduced by the core, so that the fixing roller 11 can efficiently generate heat, further contributing to the energy saving of the fixing device 11. The core is preferably formed of a material having a high magnetic permeability in a cylindrical shape. For example, an amorphous core, a permalloy core or a silicon steel plate laminated core is suitable.

FIG. 3 is a block diagram showing a control configuration of the fixing device 10. The fixing controller 20 includes a CPU (Central Processing Unit) 21, a program for controlling the image forming apparatus 1 and a ROM (storage unit) (Read) for storing data used in the program.
Only Memory) 22 and the CPU 2 based on the program
RAM in which various data calculated by 1 are stored
(Random Access Memory) 23 is provided. The CPU 21 includes a semiconductor relay (solid-state relay: “S
(Referred to as "SR") 24 and 25, and a temperature detecting means 11a for detecting the surface temperature of the fixing roller 11 are connected. In addition, the ROM 22 has a
Each SSR2 corresponding to "operating conditions" such as standby and "specifications" such as voltage and frequency of the AC power supply 26
Electric power control data that determines whether to turn on or turn off 4 and 25 is stored. In addition, each induction coil 12
a and 12b are induction coils 12a and 12a so that optimum power can be supplied according to conditions such as "operating conditions" and "specifications".
The number of turns of 12b, the cross-sectional area of the conductive wires to be the induction coils 12a and 12b, the resistance value, and the like are designed. In the above operating conditions, “at the time of image formation” means that the user can form an image on the recording sheet R by the image forming apparatus 1, and “at the time of warm-up” means that the main switch is turned on. From the state until the image formation is possible, the "standby" means a state that the user enters when the image formation is not performed for a period longer than the predetermined time.

The fixing control section 20 includes SSRs 24 and 25.
A power supply switching circuit using is configured as follows. That is, the induction coil 12a is connected to the AC power supply 26 via the SSR 24, and the induction coil 12b is connected to the SSR2.
5 is connected to the AC power supply 26. As a result, CP
Under the control of U21, electric power is independently supplied to the induction coils 12a and 12b. For example, CPU2
Under the control of 1, when both the SSRs 24 and 25 are turned on, both the induction coils 12a and 12b receive the AC power supply 2
Power is supplied from 6. When the SSR 24 is turned on and the SSR 25 is turned off, electric power is supplied only to the induction coil 12a. In addition, the SSR 25 is turned on and SS
When R24 is turned off, electric power is supplied only to the induction coil 12b.

Then, the CPU 21 monitors the operating condition of the image forming apparatus 1 by acquiring the information of "operating condition" from the control unit 30 of the image forming apparatus 1. In addition, the CPU 21 acquires “specification” information from the control unit 30 of the image forming apparatus 1. Based on the information thus obtained, the CPU 21 obtains the power control data corresponding to the “operating condition” and the “specification” from the ROM 22, and based on the power control data, the SSRs 24, 25.
Turn on and off. As a result, the power consumption of the magnetic flux forming member 12 is changed to the optimum power consumption for the condition. In this way, the CPU 21 maintains the surface temperature of the fixing roller 11 at the temperature for heating and fixing the toner image on the recording paper R in "during image formation". Further, in the “warm-up” period, since the surface temperature of the fixing roller 11 rises from a cold state, a larger amount of electric power is supplied to the magnetic flux forming member 1.
Supply to 2. Further, in the “standby” state, the fixing roller 11
The surface temperature of is kept slightly lower than the temperature at which the toner image can be heated and fixed.

For example, when the user turns on the main switch of the image forming apparatus 1 while the image forming apparatus 1 is stopped, the CPU 21 obtains the "operating condition" information from the control unit 30 of the image forming apparatus 1. And "when warming up"
Recognize that Next, the CPU 21 executes the ROM
The power control data corresponding to the "warm-up time" is acquired from S22, and SSR2 is acquired based on this power control data.
Both 4 and 25 are turned on. As a result, the induction coil 12
Both a and 12b are powered.

When the user is in the "standby" state without using the image forming apparatus 1 for longer than a predetermined time, the CPU 21 obtains the power control data corresponding to the "standby" from the ROM 22. Then, the SSRs 24 and 25 are turned on and off based on this power control data.

As described above, in the image forming apparatus 1 of the present embodiment, the power consumption of the magnetic flux forming member 12 can be changed to an optimum value according to the "operating condition" and the "specification". Excessive consumption of electric power can be suppressed, contributing to energy saving. Further, unlike the control in which the power supply is turned on and off to change the energization time, the selected induction coil 12a, 1 is selected.
Since 2b is always energized, the magnetic flux forming member 12 can form a stable magnetic flux. As a result, the rate of temperature rise and the surface temperature of the fixing roller 11 are extremely stable.

In the image forming apparatus 1, the magnetic flux forming member 12
In order to change the power consumption, the simple change of re-storing the power control data stored in the ROM 22 is necessary. As a result, for example, the magnetic flux forming member 12 can be used in common even when configuring the image forming apparatus 1 having different power consumption according to the “operating condition” depending on the destination.

[Second Embodiment] The image forming apparatus according to the second embodiment will be described in detail below with reference to FIG. FIG. 4 is a block diagram showing a control configuration of the fixing device 40. The image forming apparatus according to the second embodiment is a modification of the image forming apparatus 1 according to the first embodiment, and has a different configuration of the magnetic flux forming member 50. Therefore, in the following description, the difference from the first embodiment will be mainly described, and the same components will be denoted by the same reference numerals and the description thereof will be omitted.

The magnetic flux forming member 50 of the second embodiment is
Like the magnetic flux forming member 12 of the first embodiment, the magnetic flux forming member 12 is arranged inside the fixing roller 11. This magnetic flux forming member 5
In No. 0, one conductive wire is formed into two coil shapes having different winding diameters, and these coil-shaped portions are arranged concentrically. As a result, the magnetic flux forming member 50 is formed with two layers, an inner layer and an outer layer. These two layers are formed to have substantially the same length as the longitudinal direction of the fixing roller 11.
In FIG. 4, the magnetic flux forming member 50 formed by winding one conductive wire into two layers is stretched to form a coil of one layer in order to make it easier to understand the wiring that supplies power to the magnetic flux forming member 50. They are shown equivalently.

This one conductor is connected at both ends and at three positions, which are boundaries between the inner layer and the outer layer of the two layers, as connection points for supplying electric power to the magnetic flux forming member 50. Q
1, Q2, Q3 are formed. These connection parts Q1, Q
The wiring drawn from 2, Q3 is connected to the AC power supply 26. Further, the two layers of the magnetic flux forming member 50 are both the fixing roller 1 and the fixing roller 1.
Since it is formed to have substantially the same length as the length of 1 in the longitudinal direction,
Any of the three connection parts Q1, Q2, Q3
Even if power is supplied between 1, Q2, and Q3, the fixing roller 11 uniformly generates heat over the entire area in the longitudinal direction. In FIG. 4, the length in the longitudinal direction of the fixing roller 11 shown in FIG. 2B is indicated by L. Therefore, the connecting portion Q2 is located substantially at the center of the coil, which is equivalently extended and shown as one layer.

The fixing control section 20 has a power supply switching circuit using the SSRs 51 and 52, as in the first embodiment. That is, the connecting portions Q1 and Q3, which are both ends of one conductor forming the magnetic flux forming member 50, are connected to the AC power supply 26 via the SSR 51. Further, a wiring is drawn from the connection portion Q2, and this wiring is connected to the AC power supply 26 via the SSR 52. These SSRs 51 and 52 are connected to a CPU (control means) 21.

Then, under the control of the CPU 21, S
When SR52 is turned on and SSR51 is turned off, power is supplied only to the outer layer of the magnetic flux forming member 50. Also,
When the SSR 51 is turned on and the SSR 52 is turned off, power is supplied over the entire length of the single conductor wire shown in FIG. 4, and power is supplied to both the inner and outer layers of the magnetic flux forming member 50. Therefore, according to the "operating conditions" and "specifications" of the image forming apparatus 1, by selecting between the connection portions Q1, Q2, Q3 from among the three connection portions Q1, Q2, Q3, As in the first embodiment, the power consumption of the magnetic flux forming member 50 can be changed.

The present invention is not limited to the above embodiment. For example, the magnetic flux forming member 12 of the first embodiment is not limited to the case where the magnetic flux forming member 12 is composed of the two induction coils 12a and 12b, but is formed by arranging three or more induction coils having different winding diameters concentrically. You may. In this case, under the control of the fixing control unit 20, there are more choices of induction coils to be supplied with power, so that the power consumption of the magnetic flux forming member 12 can be changed more finely.

In the magnetic flux forming member 50 shown in the second embodiment, if one conductor wire is formed into a coil,
The number of layers is not limited to two, and any number of layers may be formed. In any case, the connecting portion is provided at the position of the end portion of the fixing roller 11 in the longitudinal direction, and the SSR is provided corresponding to each layer. In this case, the more layers the magnetic flux forming member 50 has, the more finely the power consumption can be changed. Further, the magnetic flux forming member 50 may be formed into a multi-layered coil by winding one conductor wire from the outer layer toward the inner layer, or one conductor wire may be formed from the inner layer to the outer layer. It may be formed into a multi-layered coil shape by winding toward.

In the present embodiment, the magnetic flux forming member 1
2 and 50 are applied to the fixing devices 10 and 40 including the fixing roller 11 formed of a cylindrical hollow pipe, but may also be applied to a belt type fixing device in which belts are stretched around rollers provided at a plurality of positions. . In this case, the roller that stretches the belt is heated by the magnetic flux forming members 12 and 50,
It may be applied to a fixing device configured to heat the belt by the heat from the heated roller. Further, the magnetic flux forming members 12 and 50 may be applied to a fixing device configured to heat the belt itself. Of course, other changes can be made without departing from the spirit of the present invention.

[0041]

According to the first aspect of the invention, the control means can independently control the induction coil supplying the electric power from among the plurality of induction coils, so that the electric power consumed by the magnetic flux forming member can be controlled. It can be changed easily.

According to the second aspect of the present invention, the same effect as that of the first aspect can be obtained, and the space for the magnetic flux forming member can be saved. Therefore, the structure is simpler.

According to the third aspect of the invention, since the control means supplies the electric power independently between the connecting portions selected from the plurality of connecting portions, the electric power consumed by the magnetic flux forming member can be easily adjusted. Can be changed to

According to the invention described in claim 4, it is possible to obtain the same effect as any one of claims 1 to 3, and it is possible to easily change the power consumption of the fixing device. Is obtained.

According to the invention of claim 5, it is possible to obtain the same effect as that of claim 4, and it is possible to easily change the power consumption of the fixing device in accordance with the operating conditions of the image forming apparatus. .

[Brief description of drawings]

FIG. 1 is a diagram showing an image forming apparatus 1 according to a first embodiment of the present invention.

2A and 2B are diagrams showing a main configuration of the fixing device 10 of FIG. 1, FIG. 2A is a sectional view showing a fixing roller 11 and a pressure roller 13, and FIG. 2B is a fixing roller 11 and a magnetic flux forming member. It is a figure showing 12 and.

FIG. 3 is a block diagram showing a control configuration of the fixing device 10 in FIG.

FIG. 4 is a block diagram showing a control configuration of a fixing device 40 according to a second embodiment.

[Explanation of symbols]

1 Image forming device 10 Fixing device 11 Fixing roller (heating member) 12 Magnetic flux forming member 12a induction coil 12b induction coil 21 CPU (control means) 22 ROM (storage means) 40 fixing device 50 Magnetic flux forming member Q1 connection part Q2 connection part Q3 connection part R Recording paper (recording material)

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Miho Toyoda             2970 Ishikawa-cho, Hachioji-shi, Tokyo Konica stock             Inside the company F-term (reference) 2H033 AA30 BA24 BA31 BA32 BB01                       BB28 BB33 BE06 CA07 CA20                       CA23 CA28 CA30 CA32 CA48                 3K059 AA08 AB28 AD02 AD13 AD40                       CD19 CD52 CD64 CD66 CD72                       CD73 CD75

Claims (5)

[Claims] 1. A toner image having a magnetic flux forming member which is supplied with electric power to form a magnetic flux and a heat generating member which generates heat by an induced current generated by the magnetic flux formed by the magnetic flux forming member. Is a fixing device for fixing the recording medium to a recording material, wherein the magnetic flux forming member includes a plurality of induction coils, and controls the electric power supplied to the plurality of induction coils independently for each induction coil. A fixing device comprising means. 2. The magnetic flux forming member is configured such that the plurality of induction coils are concentrically arranged by stacking respective centers of the plurality of induction coils having different diameters of one turn. The fixing device according to claim 1, wherein the fixing device is a fixing device. 3. A toner image having a magnetic flux forming member that is supplied with electric power to form a magnetic flux and a heat generating member that generates heat by an induced current generated by the magnetic flux formed by the magnetic flux forming member, and the toner image is generated by the heat from the heat generating member. Is a fixing device for fixing the magnetic flux forming member to a recording material, wherein the magnetic flux forming member is formed by forming one conductive wire into a plurality of coils having different diameters, and arranging the coiled portions in concentric circles. And a connecting part which is a contact point for supplying electric power to the magnetic flux forming member, is provided at both ends of the conducting wire and at least one place between the both ends, and a connection selected from a plurality of the connecting parts. A fixing device comprising control means for independently controlling electric power supplied between the units for each connecting unit. 4. An image forming apparatus comprising a fixing device for applying heat to a toner image to fix the toner image on a recording material, wherein the fixing device is the fixing device according to any one of claims 1 to 3. A characteristic image forming apparatus. 5. A storage unit for storing electric power control data set corresponding to the operating condition, wherein the control unit of the fixing device corresponds the electric power control data stored in the storage unit to the operating condition. And then get
The image forming apparatus according to claim 4, wherein the image forming apparatus is configured to supply electric power based on the electric power control data to the magnetic flux forming member.