JP2005122124A - Image forming apparatus and fixing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing apparatus and a digital copying machine in which period of time from indication of beginning of image formation till finish of fixing can be shortened and less electric power is necessary. <P>SOLUTION: The fixing apparatus includes a cylinder formed of a metal of thin wall thickness and an exciting coil which is provided in the cylinder and generates an eddy current. When power is applied, all electric power excluding electric power consumed by the apparatuses except the fixing apparatus is supplied to the exciting coil to heat an endless member. Further as each constituent of the copying machine and an auxiliary apparatus further added to the copying machine operate, electric power resulting from subtracting electric power consumed by each constituent of the copying machine and the auxiliary apparatus further added to the copying machine from input allowable power is supplied to the coil to heat the endless member. Thereby a heating roller of the fixing apparatus is heated to temperature where fixing can be performed in a short period of time and period of time from indication of beginning of copying till output of a fixed matter on which a toner image formed by copying operation is fixed can be shortened. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a fixing device for fixing a toner image (image) onto a fixing material in an image forming apparatus such as an electrostatic copying apparatus or a laser printer.

  A fixing device incorporated in a copying machine using an electrophotographic process heats and melts a developer formed on a material to be fixed, that is, toner, and fixes the toner to the material to be fixed. As a method for heating toner that can be used in the fixing device, a method using radiant heat from a halogen lamp (filament lamp) is widely used.

  In the method using a halogen lamp as a heat source, a pair of rollers is provided so as to be able to provide a predetermined pressure to the material to be fixed and the toner, and at least one of the rollers is formed as a hollow cylinder in a cylindrical shape in its internal space. A configuration in which a halogen lamp is arranged is widely used. In this configuration, the roller on which the halogen lamp is disposed forms an action portion (nip) at a position where it comes into contact with the other roller, and supplies pressure and heat to the fixing material and toner guided to the nip. . That is, the fixing material, that is, the paper, is passed through a fixing point, which is a pressure contact portion (nip) between a heating roller provided with a lamp and a pressure roller that rotates following the heating roller, and the toner on the paper is melted. It is worn and fixed on the paper.

  In a fixing device using a halogen lamp, light and heat from the halogen lamp are radiated in the entire circumferential direction of the heating roller to heat the whole. In this case, considering the loss when light is converted into heat and the efficiency when the air in the roller is warmed and the heat is transmitted to the roller, the heat conversion efficiency is 60 to 70%. It is known that the power consumption is low and the warm-up time is long.

  For this reason, in recent years, an induction heating system in which a heating coil is provided inside the heating roller and a high-frequency current is supplied to the coil to heat by induction heating has been put to practical use as a heat source for the heating roller.

  For example, Japanese Patent Application Laid-Open No. 59-33476 discloses a technique in which a roller having a thin metal layer is provided on the outer periphery of a cylindrical ceramic, and heating is performed by passing an induced current to the thin metal layer of this roller using a conductive coil. Is disclosed.

  Japanese Patent Application Laid-Open No. 9-258586 discloses a heating method in which a heating element in which a coil is wound around a core provided along the rotation axis of a fixing port is used and an eddy current is applied to the fixing roller to heat it. .

  In addition, since induction heating is to heat a roller with an eddy current obtained as a result of passing a current through a coil, a large amount of electric power is required to heat the heating roller to a predetermined temperature in a short time. .

  However, as a fixing device used in a copying apparatus, there is an upper limit on the power that can be consumed by the fixing device alone, and power is also consumed by many elements constituting the copying apparatus. It is known that large power cannot be supplied.

  For this reason, when a large amount of electric power cannot be allocated for heating the heating roller of the fixing device, the warm-up time of the copying apparatus increases, and the time required to obtain a copy increases. If priority is given to warm-up, the fixing rate may be insufficient. In addition, in a heating roller having a configuration in which the heating roller is made of metal and has a thin cylinder and the coil is arranged in the cylinder along the axial direction of the cylinder, the temperature distribution is generated on the outer peripheral surface of the roller. In the process of increasing the temperature of the roller, it is necessary to make the temperature of the outer peripheral surface of the heating roller uniform by rotating the heating roller while being in contact with the pressure roller, and this also increases the warm-up time. In addition, there is a problem that the power required for heating increases.

  The object of the present invention is to shorten the time from when the power is turned on until the copy can be received, the so-called first copy time, and to fix the maximum effective power without exceeding the upper limit power consumption of the image forming apparatus. An object of the present invention is to provide an image forming apparatus that can be supplied to the apparatus.

The present invention has been made on the basis of the above-described problems. A high-frequency current is passed through a coil disposed close to an endless member having a metal layer made of a conductor, and the endless member is heated to heat a material to be fixed. In a fixing device of an image forming apparatus,
Power that can be used for heat generation of the endless member of the fixing device is supplied to the coil by removing the power consumed stepwise by the power consuming portion of the image forming apparatus in which the fixing device is incorporated from the input power. The present invention provides a fixing device that is controlled by a plurality of power control patterns corresponding to the amount of power that can be supplied for each predetermined condition by changing the frequency or duty of a high-frequency current. .

The present invention also provides a photosensitive member for holding an electrostatic image, an exposure device for forming the electrostatic image on the photosensitive member, and a developer image by supplying a developer to the electrostatic image formed on the photosensitive member. An image forming apparatus comprising: a developing device that forms a toner image; and a fixing device that heats a transfer material onto which the developer image formed by the developing device is transferred to fix the developer image on the transfer material.
The fixing device is a device that applies a high-frequency current to a coil disposed close to an endless member having a metal layer composed of a conductor, and heats the endless member to heat the transfer material and the developer image. Power that can be used for heat generation of the endless member of the fixing device is supplied to the coil by stepping out the power consumed by the power consuming part of the device in accordance with the power consumption. The present invention provides an image forming apparatus that is controlled by a plurality of power control patterns corresponding to the amount of power that can be supplied for each predetermined condition by changing the frequency or duty of a high-frequency current. is there.

Furthermore, the present invention provides a photoconductor, an exposure device that forms an electrostatic image on the photoconductor, and a developing device that forms a developer image by supplying a developer to the electrostatic image formed on the photoconductor. An image forming apparatus comprising: a fixing device that heats a transfer material onto which a developer image formed by the developing device is transferred and fixes the developer image on the transfer material.
The fixing device applies a high-frequency current to a coil disposed close to an endless member having a metal layer made of a conductor, and heats the endless member to heat the transfer material and the developer image. Controlled by a plurality of power control patterns corresponding to the amount of power that can be supplied for each condition, the power consumed by the part that consumes power of the image forming apparatus is input in stages according to the power consumption. By changing the frequency or duty of the high-frequency current supplied to the coil, the maximum power that can be input to the coil immediately after energization is changed. Each of an image forming unit, an exposure device, and a developing device that is supplied with electric power, rotates the photoconductor, and allows the electrostatic image to be formed on the photoconductor. According to the timing when each of the other mechanisms or components that may be operated at the same time is operated, the power input to the coil is reduced, and if the power supply voltage fluctuates, it can be input at that time. It is an object of the present invention to provide an image forming apparatus characterized in that a maximum electric power value is reduced to a small value and then supplied and heated.

  As described above, according to the present invention, fixing of an image forming apparatus in which a high-frequency current is applied to a coil disposed close to an endless member having a metal layer made of a conductor, and the fixing material is heated by heating the endless member. In the apparatus, the fixing device is controlled by a plurality of power control patterns corresponding to the amount of power that can be supplied for each predetermined condition. Can be heated.

  Therefore, an optimum high-frequency current can be supplied from a plurality of frequencies according to the operation mode, and the heating roller can be heated to a fixable temperature in the shortest time.

  In addition, by incorporating this fixing device into the digital copying apparatus, it is possible to reduce the time required for the first copy.

  Hereinafter, a fixing device according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic diagram illustrating a digital copying apparatus 101 which is an example of an image forming apparatus. As shown in FIG. 1, the digital copying apparatus 101 reads image information to be copied as light brightness and darkness and generates an image signal, and an image corresponding to the image signal supplied from the scanner 102 or the outside. The image forming unit 103 is formed. The scanner 102 is integrally provided with an automatic document feeder (ADF) 104 that sequentially replaces the copy target in conjunction with the image reading operation by the scanner 102 when the copy target is a sheet. .

  The image forming unit 103 includes an exposure device 105 that emits a laser beam corresponding to image information supplied from the scanner 102 or an external device, a photosensitive drum 106 that holds an image corresponding to the laser beam from the exposure device 105, and a photosensitive member. A developing device 107 that supplies a developer to an image formed on the drum 106 and develops the image, and a developer image on the photosensitive drum 106 that is developed by the developing device 107 is fed by a paper feed conveyance unit that will be described below. The image forming apparatus includes a fixing device 1 that heats and melts the developer image transferred to the transfer material and fixes the image on the transfer material.

  When image information is supplied from the scanner 102 or an external device, a photosensitive drum 106 charged in advance to a predetermined potential is irradiated from the exposure device 105 with a laser beam whose intensity is modulated by the image information.

  As a result, an electrostatic latent image corresponding to the image to be copied is formed on the photosensitive drum 106.

  The electrostatic latent image formed on the photosensitive drum 106 is developed with the toner T selectively provided by the developing device 107, and developed by the transfer device 107. The sheet P is a transfer material supplied from a cassette described below by the transfer device. Is transcribed.

  The toner T transferred to the paper P is conveyed to the fixing device 1 where the toner T is melted and fixed.

  The paper P is picked up one by one by a pickup roller 108 from a paper cassette 109 provided below the photoconductive drum 106, and formed on the photoconductive drum 106 through a conveyance path 110 toward the photoconductive drum 106. Then, the toner image is conveyed to an aligning roller 111 for aligning the position with the toner image (developer image), and is fed to a transfer position where the photosensitive drum 106 and a transfer device (not described in detail) face each other at a predetermined timing.

  On the other hand, the paper P on which the image formed by the toner T is fixed by the fixing device 1 is discharged to a discharge space (discharge tray) 113 defined between the scanner 102 and the cassette 109 by a discharge roller 112. The Note that a double-sided paper feeding device 114 is provided between the fixing device 1 and the cassette 109 to reverse the front and back of the paper P on which an image is fixed on one side, as necessary.

  Next, the fixing device 1 will be described in detail.

  FIG. 2 is a schematic sectional view for explaining an embodiment of a fixing device incorporated in the digital copying apparatus shown in FIG. FIG. 3 is a schematic perspective view for explaining the shape of a coil incorporated in the fixing device shown in FIG.

  As shown in FIGS. 2 and 3, the fixing device 1 includes a heating (fixing) roller 2 and a pressure (pressing) roller 3. In addition, although the outer diameter of each roller is an example, it is 40 mm.

  The heating roller 2 is driven in the arrow direction by a drive motor (not shown). The pressure roller 3 rotates in the direction of the arrow following the heating roller. Further, a sheet P, which is a fixing material that supports the toner image T, passes between both rollers.

  The heating roller 2 is an endless member having a metal layer made of, for example, an iron cylinder having a thickness of 1 mm, that is, a conductor, and a release layer such as Teflon (registered trademark) is formed on the surface. In addition, stainless steel, aluminum, an alloy of stainless steel and aluminum, or the like can be used for the heating roller 2.

  The pressure roller 3 is formed by covering the cored bar 3a with an elastic body such as silicon rubber or fluorine rubber, and is pressed against the heating roller 2 with a predetermined pressure by a pressure mechanism (not shown). A nip 4 having a predetermined width (the outer peripheral surface of the pressure roller 3 is elastically deformed by the pressure contact) 4 is provided at a position where both rollers are in contact with each other.

  As a result, the sheet P passes through the nip 4 so that the toner on the sheet P is melted and fixed on the sheet P.

  On the circumference of the heating roller 2 and on the downstream side of the nip 4 in the rotational direction, a peeling claw 5 for peeling the paper P from the heating roller 3, and toner or paper offset-transferred to the outer circumferential surface of the heating roller 2 A cleaning member 6 for removing paper dust and the like, a release agent application device 8 for applying a release agent to prevent toner from adhering to the outer peripheral surface of the heating roller 2, and an outer peripheral surface of the heating port-ra 2 A thermistor 9 for detecting the temperature is provided.

  Inside the heating roller 2, there is provided an exciting coil 11 as magnetic field generating means made of litz wire in which a plurality of mutually insulated copper wires having a diameter of 0.5 mm, for example, are bundled. By using a litz wire as the exciting coil, the wire diameter can be made smaller than the penetration depth, and a high-frequency current can be made to flow effectively. In the embodiment shown in FIG. 2, the exciting coil 11 is a bundle of 19 wires having a diameter of 0.5 mm covered with heat-resistant polyamideimide.

  The exciting coil 11 is an air-core coil that does not use a core material (for example, a ferrite or an iron core). Thus, since the exciting coil 11 is an air-core coil, a core material having a complicated shape is not necessary, and the cost is reduced. In addition, the excitation circuit is also inexpensive.

  The exciting coil 11 is supported by a coil support material 12 formed of a heat resistant resin (for example, a high heat resistant industrial plastic).

  The coil support 12 is positioned between a structure (sheet metal) (not shown) that holds the heating roller.

  The exciting coil 11 causes the heating roller 2 to generate magnetic flux and eddy current so as to prevent the magnetic field from being changed by the magnetic flux generated by the high-frequency current from the exciting circuit (inverter circuit) described later with reference to FIG. . Joule heat is generated by the eddy current and the inherent resistance of the heating roller 2, and the heating roller 2 is heated. In this example, a high-frequency current having a frequency of 25 kHz and 900 W is passed through the exciting coil 11.

  FIG. 4 is a block diagram showing a control system, that is, a drive circuit of the fixing device shown in FIGS. 2 and 3. FIG.

  In the drive circuit 30, the high frequency current is rectified from the AC of the commercial power source by the rectifier circuit 31 and the smoothing capacitor 32, and is supplied to the exciting coil 11 by the inverter circuit 33 including the coil 33 a, the resonance capacitor 33 b, and the switching circuit 33 c. .

  The high-frequency current is detected by the input detection means 36 and controlled so as to have a designated output value. The specified output value can be controlled by varying the ON time of the switching element 33c at an arbitrary timing by, for example, PWM (pulse width modulation) control. At this time, the driving frequency is optimally changed. Further, the input detection means 36 also detects fluctuations in the input voltage.

  Temperature detection means for detecting the temperature of the exciting coil 11 and the temperature of the heating roller 2 (information from two thermistors 13a and 13b provided at two locations on the surface of the heating roller 2 described below is sent to the main control CPU 39. The input is input to the IH (induction heating) circuit 38 by an ON / OFF signal from the CPU 39. The output from the thermistor 9 is input to the IH circuit 38 to control the abnormal temperature of the driver IC. The main control CPU 39 includes a scanner 102, an ADF 104, an exposure device 105, a developing device 107, a motor (not shown) that rotates the photosensitive drum 106, and many elements that constitute the image forming unit 103, a pickup roller 108. , The aligning roller 111, the discharge roller 112, and the like. Transport state of the sheet P conveyed on the conveying path 110 (paper jam) or the like via an interface (not shown), sequentially, the notification, and controls them.

  In FIG. 2, the surface temperature of the heating roller 2 is controlled to, for example, 180 ° C. by temperature detection by the thermistor 9 and feedback control based on the detection result.

  A necessary condition for fixing the toner on the paper P is to make the temperature of the entire area of the heating roller 2 in the circumferential direction uniform. When the rotation of the heating roller 2 is stopped, as a characteristic of the exciting coil 11 which is the air-core coil shown in FIG. 2, the magnetic flux generation acts at different strengths in the circumferential direction, so that the temperature distribution is not uniform. It becomes. Therefore, the temperature unevenness in the circumferential direction of the roller 2 must be eliminated immediately before the sheet P passes through the nip 4.

  For this reason, immediately after energization of the exciting coil 11 is started, the rotation of the heating roller 2 is stopped in order to efficiently increase the temperature of the heating roller 2 for a certain period of time. In order to make the distribution uniform, the heating roller 2 and the pressure roller 3 are rotated after a predetermined time has elapsed.

  By rotating the heating roller 2 and the pressure roller 3, a constant amount of heat is applied to the entire surface of both rollers. As the rollers 2 and 3 rotate, the surface temperature temporarily decreases below the surface temperature of 180 ° C. which is the control target temperature, as will be described later with reference to FIG. .

  When the surface temperature of the heating roller 2 reaches 180 ° C., a copying operation becomes possible, and a toner image is formed on the paper P at a predetermined timing.

  The paper P holding the toner image passes through the rolling contact portion between the heating roller 2 and the pressure roller 3, that is, the nip 4, so that the toner on the paper P is fixed to the paper P.

  The thermistors 13a and 13b are useful for removing the influence of the temperature distribution difference on the outer surface of the heating roller 2 caused by the characteristics of the exciting coil 11 when the heating roller 2 and the pressure roller 3 are stopped. is there. The thermistor 9 detects the temperature of the circuit of the driver IC itself, and forcibly cuts off the energization to the coil when abnormal heat generation occurs in the driver IC.

  FIG. 6 shows an example in which the output value of the high-frequency current to the exciting coil 11 is changed after the warm-up of the heating roller 2 or during the warm-up in the fixing device described with reference to FIGS. 2 to 5. It is a timing chart explaining these.

  As shown in FIG. 6, at the time of warm-up, assuming a commercial power supply of, for example, 1500 W under the control of the main control CPU 39, the amount of power consumed by the digital copying apparatus 101 other than the fixing apparatus 1 is initially set. All the subtracted power can be input to the exciting coil 11. In this embodiment, the upper limit is 1300 W. As shown in FIG. 7, while the heating roller 2 is being heated, the initial operation of each part of the copying apparatus 101 is performed and the power is limited to 1200W.

  After that, since the heating roller 2 and the pressure roller 3 are rotated from the middle of starting up (after the temperature of the heating roller 2 exceeds 200 ° C.), rotation of a motor (not shown) that rotates the photosensitive drum 106 is performed. The upper limit power is limited to 1100 W as a value obtained by subtracting the power consumed by the operation check of the scanner 102, the ADF 104, the exposure device 105, the developing device 107, and the standby power.

  When normal warm-up is completed and the standby state is continued, the power supplied to the exciting coil 11 is limited to 750 W or 700 W, for example.

  By the way, in addition to the ADF 4, a large capacity cassette or the like is connected to the copying apparatus 101, and a paper feed motor for rotating the pickup roller 108 of the paper cassette 109 and a main motor for rotating the photosensitive drum 106 are formed during image formation. Since it is rotated, the electric power that can be supplied to the fixing device 1 varies depending on the operating conditions of other components. Accordingly, it is necessary to limit the components that can be operated simultaneously so that the peak value of the power consumption does not exceed the maximum input power according to the operation status of other components as shown in FIG. Note that the operating components can be confirmed by information input via an input port (not shown) of the CPU 39 or an interface (not shown).

  For example, as shown in FIG. 7, the upper limit power is 900 W during the copying operation, but it is necessary to suppress the upper limit power to 800 W when the ADF 4 is operating simultaneously.

  The upper limit power limit shown in FIGS. 7 and 6 is output from the IH circuit 38 based on a plurality of control patterns stored in advance in the memory 40 in the drive circuit shown in FIG. This is easily realized by arbitrarily setting the frequency of the high frequency output to be performed. Further, since the temperature of the outer surface of the heating roller 2 is controlled to be constant, the amount of electric power applied may change the duty of the high frequency output in addition to the frequency.

  On the other hand, at the end of the image forming operation when the image forming operation is continuously repeated, etc., when the factor that the temperature of the heating roller 2 decreases due to the heat transferred from the heating roller 2 to the pressure roller 3 decreases. In this case, the maximum value of the amount of current to be supplied to the exciting coil 11 is reduced. That is, in some cases, the temperature of the heating roller 2 can be maintained at 700 W. In this case, since the copper loss due to the wire of the coil 11 is also reduced, the heat conversion efficiency is also improved.

  Note that the relationship between the operation mode and the power that can be supplied to the coil, which will be described with reference to FIG. 6, is based on the number of elements connected to the copying apparatus 101 and their power consumption (processing capacity). The table can be selected from any table stored corresponding to various conditions.

  Further, when the drive circuit described with reference to FIG. 4 can cope with a plurality of voltages and can be arbitrarily set according to the voltage of the area where the drive circuit is installed (operating the 240V specification copying apparatus 101 at 220V). 6 or when it is possible to handle both voltages of 200V and 100V), the operation mode and coil supply as shown in FIG. 6 stored in advance in the table according to the actually supplied voltage. The optimum combination of the relationship with the possible power is selected and set. In this case, control for changing the duty of the high-frequency current can be added to the power control.

By the way, as shown in FIG. 8, when the power supply voltage fluctuates, the copying apparatus 101 operates normally even if the voltage fluctuation range is from V ₃ to V ₀ . The range of voltage fluctuation that the exciting coil 11 can tolerate is a range from V ₂ smaller than the voltage V ₃ to V ₁ larger than the voltage V ₀ . When as shown in FIG. 8, a voltage drop of the length t _n for some reason continues, the surface temperature of the heating roller 2 so that falls below the set value.

  In this case, in the drive circuit shown in FIG. 4, the voltage abnormality is detected by counting a predetermined time obtained by counting the basic clock by the timer built in the CPU 39, and the excitation coil 11 is energized. Is cut off.

  Specifically, the main control CPU 39 determines that the voltage abnormal error signal output from the IH control circuit 38 is normal if the voltage abnormal error signal is L, and resets the timer in the CPU 39 to reset the voltage abnormal error signal when the voltage abnormal error signal becomes H. Count the time when is H.

For example, FIG. As shown in 7, if the voltage V ₂ is a voltage increase continues for the length t _1, the main control CPU39 is the predetermined error timer value (limit value) t _n and voltage abnormality error signal time comparing t _1, since it is t 1 _{<t n,} ignoring the abnormal voltage V ₂ as a temporary voltage abnormality that has occurred. The error timer value t _n is a time that affects the fixing temperature and is a unit of several seconds. For example, when the copying capability is 60 ppm (cpm), t _n = 1 second, and when it is 30 ppm (cpm), t _n = 2 seconds.

On the other hand, in Figure 7, when the voltages _{V 1} is the voltage drop continues for a long _{t 2,} since the time _{t 2} of the voltage abnormality error signal to the error timer value _{t n} is a _t 2 _{<t n,} Again, ignore this abnormal voltage V ₂ as a temporary voltage abnormality that has occurred. That is, at time t ₂ (<t _n ), it returns to normal and is not abnormal.

Incidentally, as described earlier, when the voltages V ₁ is the voltage drop continues for more than t _n, since the time t _n where V ₁ is continues exceeds the error timer value t _n, voltage abnormality Is determined to have occurred, and energization of the exciting coil 11 is interrupted.

  By the way, with respect to the influence of the voltage fluctuation described with reference to FIG. 8, the probability of occurrence thereof may increase sharply depending on the power supply situation in the area where the digital copying apparatus 101 is installed.

In this case, by setting the error timer value t _n to an appropriate size (length), it is possible to prevent an abnormal voltage error from being detected undesirably. In an area where it is necessary to individually set the error timer t _n value, the relationship (the table stored in the memory) between the operation mode and the coil power described earlier with reference to FIG. 6 is appropriately changed. The maximum input power can be prevented from exceeding a specified value. Further, the fixing device can be driven more stably by appropriately changing the duty ratio of the high-frequency current in relation to the maximum available power.

  As a method for limiting the amount of electric power, for example, there are a method for reducing the total amount of input current, a method for reducing the duty only for a predetermined time in order to suppress electric power due to inrush current, and the like.

In the plurality of power supply voltages available areas, in accordance with the power supply voltage arbitrarily selected, the operation mode versus coil suppliable electric power relationship illustrated in error timer t _n value and FIG. 6 described above By appropriately changing the voltage, it is possible to prevent an undesired voltage abnormality.

  By the way, in the case of using thick paper or the like having severe fixing conditions, although there is no voltage fluctuation, there is a possibility that the fixing ratio fluctuates with the passage of time (repetition of continuous image formation). In this case as well, as described with reference to FIG. 6, the relationship between the thickness of the paper and the current to be supplied to the coil is stored in the memory table, so that a constant value can be obtained for a paper of any thickness. Fixing rate can be secured. Note that the sheet thickness does not require any special treatment under the condition that the surface temperature of the heating roller 2 has reached the target temperature, but greatly contributes at low temperatures. For this reason, a memory table for low temperatures may be prepared.

FIG. 1 is a schematic diagram for explaining a digital copying apparatus in which a fixing device according to an embodiment of the present invention is incorporated. FIG. 2 is a schematic diagram showing the overall configuration of the fixing device of the copying apparatus shown in FIG. FIG. 3 is a perspective view schematically showing a configuration of a heating roller and a coil which is a magnetic field generating means of the fixing device shown in FIG. FIG. 4 is a schematic diagram for explaining a circuit diagram (quasi-E class inverter circuit) for driving the induction heating (excitation) coil of the fixing device shown in FIG. FIG. 5 is a schematic diagram for explaining the configuration of a coil in the longitudinal direction of the fixing device shown in FIG. FIG. 6 is a schematic diagram showing the relationship between the operation mode when the fixing device shown in FIG. 2 is incorporated in the copying machine shown in FIG. 1 and the energization amount (power amount) to the exciting coil of the heating roller ( Table information in memory). FIG. 7 is a schematic diagram for explaining the relationship between the temperature rise of the heating roller and the power that can be supplied to the coil in the operation of the fixing device shown in FIG. FIG. 8 is a schematic diagram for explaining the relationship between the voltage applied to the exciting coil of the fixing device shown in FIG. 2 and the voltage abnormality.

Claims (7)

In a fixing device of an image forming apparatus in which a high-frequency current is passed through a coil arranged close to an endless member having a metal layer composed of a conductor, and the fixing material is heated by heating the endless member.
Power that can be used for heat generation of the endless member of the fixing device is supplied to the coil by removing the power consumed stepwise by the power consuming portion of the image forming apparatus in which the fixing device is incorporated from the input power. The fixing device is controlled by a plurality of power control patterns corresponding to the amount of power that can be supplied for each predetermined condition by changing the frequency or duty of the high-frequency current.   The fixing device according to claim 1, wherein the changed frequency is selected from a plurality of patterns stored in advance in a memory table according to a state of the image forming apparatus.   The fixing device according to claim 1, wherein the changed frequency or duty is selected from a plurality of patterns stored in advance in a memory table in accordance with a predetermined voltage fluctuation amount.   4. The fixing device according to claim 1, wherein the voltage fluctuation amount is a non-control target for a voltage fluctuation that occurs in a time shorter than a predetermined time. A photoreceptor for holding an electrostatic image;
An exposure device for forming an electrostatic image on the photoreceptor;
A developing device for supplying a developer to the electrostatic image formed on the photoreceptor to form a developer image;
A fixing device for fixing the developer image to the transfer material by heating the transfer material onto which the developer image formed by the developing device is transferred;
In an image forming apparatus comprising:
The fixing device is a device that applies a high-frequency current to a coil disposed close to an endless member having a metal layer composed of a conductor, and heats the endless member to heat the transfer material and the developer image. Power that can be used for heat generation of the endless member of the fixing device is supplied to the coil by stepping out the power consumed by the power consuming part of the device in accordance with the power consumption. An image forming apparatus controlled by a plurality of power control patterns corresponding to an amount of power that can be supplied for each predetermined condition by changing a frequency or duty of a high-frequency current.   The power control pattern of the fixing device is input with the power consumed by each of the image forming unit, the exposure device, and the developing device that rotates the photosensitive member and enables the electrostatic image to be formed on the photosensitive member. 6. The image forming apparatus according to claim 5, wherein power in a range of difference from the maximum possible power is provided. A photoconductor, an exposure device that forms an electrostatic image on the photoconductor, a developing device that supplies a developer to the electrostatic image formed on the photoconductor to form a developer image, and the developing device An image forming apparatus comprising: a fixing device that heats a transfer material on which the developer image transferred is fixed to fix the developer image on the transfer material;
The fixing device applies a high-frequency current to a coil disposed close to an endless member having a metal layer made of a conductor, and heats the endless member to heat the transfer material and the developer image. Controlled by a plurality of power control patterns corresponding to the amount of power that can be supplied for each condition, the power consumed by the part that consumes power of the image forming apparatus is input in stages according to the power consumption. By changing the frequency or duty of the high-frequency current supplied to the coil, the maximum power that can be input to the coil immediately after energization is changed. Each of an image forming unit, an exposure device, and a developing device that is supplied with electric power, rotates the photoconductor, and allows the electrostatic image to be formed on the photoconductor. According to the timing when each of the other mechanisms or components that may be operated at the same time is operated, the power input to the coil is reduced, and if the power supply voltage fluctuates, it can be input at that time. An image forming apparatus, wherein the maximum power value is reduced to a small value and then supplied and heated.

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