JP2007079293A - Image forming apparatus and control method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which is capable of achieving on demand fixing with quicker temperature rise by more effectively using an upper limit current of a commercial power source, and a control method thereof. <P>SOLUTION: In the image forming apparatus including a fixing means which incorporates a heating element which generates heat using power supplied from the commercial power source and applies the heat of the heating element to a transfer material having had a toner image formed thereon to fix the toner image onto the transfer material, a chargeable/dischargeable capacitor means is charged, and a limit level of the power supplied from the commercial power source to the fixing means is increased by an amount corresponding to power supply while the power supply from the capacitor means to loads other than the fixing means is indicated. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus and a control method thereof, and more particularly to an image forming apparatus using an electrophotographic process or the like and a control method thereof.

  2. Description of the Related Art Image forming apparatuses using an electrophotographic process such as a laser beam printer are provided with a fixing device that heats and fixes a toner image formed on a recording medium (recording paper, OHP sheet, etc.). There are several types of heating systems in this fixing device. In particular, an electromagnetic induction heating method in which a current is induced in the fixing roller by magnetic flux and heat is generated by the Joule heat can directly heat the fixing roller by using generation of induced current. Therefore, it is advantageous in that a higher-efficiency fixing process can be achieved than a heat roller type fixing device using a halogen lamp as a heat source (see, for example, Patent Document 1).

  By the way, in a color image forming apparatus (A4 machine) capable of printing A4 size standard paper at a speed of 16 sheets / minute, in recent years, a fixing device with a small heat capacity of the electromagnetic induction heating method as described above is used. I use it. Therefore, there is no need for fixing temperature adjustment during standby (hereinafter, “temperature adjustment” may be abbreviated as “temperature adjustment”), and so-called “on-demand fixing” in which heating is performed only during printing can be realized. It has become.

  On the other hand, in a color image forming apparatus (A3 machine) capable of printing up to A3 size standard paper, the heat capacity required for the fixing device is generally larger than that of the A4 machine, although it depends on the printing speed. Therefore, so-called “standby temperature control” is performed in which preheating is performed by supplying power to the fixing device at predetermined time intervals even during standby (see, for example, Patent Document 2). The reason for performing standby temperature control is as follows.

  FIG. 22 shows the rise time until the temperature of the fixing device reaches a printable state (for example, 180 ° C.) in the color image forming apparatus (A3 machine) using the conventional electromagnetic induction heating type fixing device. The relationship with the electric power (fixing electric power) supplied to the heater of the fixing device at that time is shown. In FIG. 22, assuming that the fixing power that can be supplied is about 900 W, the rise time until the temperature reaches the printable state (print temperature) is 30 sec (point Wa). This time is extremely short compared with a fixing device using a generally used halogen heater.

  However, considering the paper transport time and the like, the time from the start of printing until the first image-formed paper is discharged to the paper discharge unit (first printout time) is later than 30 sec. It makes me wait. For this reason, in order to shorten the first printout time, as is generally done in an image forming apparatus using a halogen heater type fixing device, the power is fixed at predetermined time intervals even during standby. Preheating is performed by supplying to By performing this standby temperature control, a predetermined fixing temperature at which an image can be formed is quickly reached after a print job is started.

  The power consumption during standby temperature adjustment in the electromagnetic induction heating method can be set to a lower temperature compared to the fixing method using a halogen heater, so the power consumption during the standby temperature adjustment can be reduced. It is. However, when compared with the on-demand fixing method, extra power (power during standby temperature control) is still required.

  By the way, in this image forming apparatus, if the power supplied to the heater of the fixing device can be increased by about 200 W, 1100 W can be supplied to the fixing device, and the time to reach the printing temperature is about 15 seconds (FIG. 22 is point Wb). For this reason, if the target first printout time of this image forming apparatus is about 20 seconds, it depends on the configuration of the image forming apparatus, the paper transport path, the transport speed, etc., but on-demand that does not require standby temperature control. It is also possible to realize fixing.

  However, recently, with the improvement of the technology of image forming apparatuses, the image forming apparatuses in the category of medium speed machines (intermediate machines) have been speeded up while being reduced in size and price, and the speed of high speed machines a decade ago Has reached. Along with this, added value such as energy saving and shortening the first printout time has been demanded from the market more than ever.

  Considering such a background, even if a high-efficiency electromagnetic induction heating type fixing device is used, it has become difficult to meet market demands with on-demand fixing that could be realized with the conventional A4 machine.

  Further, as described above, the standby temperature control that has been conventionally performed in the A3 machine means that the electric power is supplied to the fixing device even in the standby state although it is the minimum necessary electric power. For this reason, this standby temperature control is also one of the factors that make it difficult to reduce power consumption during standby of the image forming apparatus.

  However, if the standby temperature adjustment control is not performed with emphasis on energy saving at the time of standby, it takes a long time to reach a predetermined fixing temperature at which image formation is possible from the start of printing. As a result, you face the problem of slow first printout time. In other words, there is a trade-off between energy saving during standby and shortening of the first printout time.

  Therefore, it is necessary to develop an on-demand fixing system that can be accepted in the market and has a rapid rise in temperature while balancing both energy saving during standby and shortening the first printout time.

  On the other hand, in large-sized and high-value-added image forming apparatuses such as monochrome high-speed printing machines and color printing high-quality machines, so-called high-speed machines (high-grade machines), efforts are made to save energy. However, there is a demand for further added value such as enhancement of functions and enhancement of optional devices, and power consumption is increasing. One guideline for the upper limit of power consumed by these devices is the maximum current that can be supplied by commercial power. For example, if a maximum supply current of 15 A is specified for a commercial power supply with a voltage of 100 V, the upper limit of the power is 1500 W (= 100 V × 15 A). The image forming apparatus main body is usually designed so that the maximum current of the apparatus does not exceed the maximum current of the commercial power source.

  Further, in this high-speed machine class fixing device, in general, a fixing device having a large heat capacity is often used so as to withstand high-speed continuous fixing. The disadvantage of such a fixing device is that it takes a long time (for example, several minutes) to reach the standby state temperature (warm-up time) from the cold state of the fixing device, and this warm-up time is shortened. This was one of the improvement issues.

  On the other hand, simply trying to reduce the warm-up time of the fuser by simply turning on a large amount of power would limit the maximum power of the commercial power supply that can be used as a device. Unless done, it was difficult to further reduce the warm-up time.

  As one method for solving such a problem, for example, in Patent Document 3, in order to effectively use the power to the fixing device, a power storage unit is provided in an image forming apparatus including a main heater and a sub heater in the fixing device. Has proposed. The power storage unit is selectively connected to a DC power source or a DC motor control unit. While power is being supplied from the power storage unit to the DC motor, the power that is supposed to be supplied to the DC motor can be supplied to the sub-heater. It can be copied.

Further, in Patent Document 4, a power storage device is provided in the image forming apparatus, and when the fixing device is started up, the power from the commercial power source and the power from the power storage device are used together, thereby saving energy and shortening the print start time. A method has been proposed.
Japanese Utility Model Publication No. 51-109739 JP 2002-056960 A Japanese Utility Model Publication No. 7-41023 JP 2002-174988 A

  However, in an image forming apparatus having a configuration in which the fixing device includes a main heater and a sub heater, if an attempt is made to start up the fixing device in a state where sufficient electric power is not stored in the power storage device, the auxiliary heater and the fixing device are connected from the power storage device. There is a possibility that power cannot be supplied to the load of the image forming apparatus other than the apparatus. Further, if power cannot be supplied to the sub-heater, the sub-heater section is also warmed by the main heater, and there is a possibility that the startup time is longer than that of the conventional fixing device not provided with the power storage device. Furthermore, if the power necessary for the load of the image forming apparatus other than the fixing device cannot be supplied, the image forming apparatus may not operate normally. In this case, processing such as stopping the image forming apparatus for a predetermined period. In some cases, inconvenience occurs in use.

  Further, in the configurations such as Patent Document 3 and Patent Document 4, since the power supply from the power storage unit to the sub heater and the predetermined load is simply turned on / off, the voltage of the commercial power supply to which the image forming apparatus is connected Depending on the load condition of the image forming apparatus and the maximum power that can be supplied by the commercial power source cannot be used effectively. Further, since the configuration requires a plurality of heaters, the configuration of the fixing device is complicated.

  The present invention has been made in view of such problems, and more effectively utilizes the upper limit current of a commercial power supply, and an image forming apparatus capable of realizing on-demand fixing with a faster temperature rise than before, and the image forming apparatus An object is to provide a control method.

  In order to solve the above-described problems, an image forming apparatus according to the present invention includes a heating element that generates heat using electric power supplied from a commercial power supply, and heat of the heating element is formed on a transfer material on which a toner image is formed. An image forming apparatus having fixing means for fixing the toner image to the transfer material by adding a power limiting means for limiting power supplied from a commercial power source to the fixing means to a predetermined restriction level; It is characterized by comprising: a dischargeable power storage means; a control means for controlling power supply from the power storage means; and an adjustment means for adjusting the limit level in accordance with a control state by the control means.

  Here, the control unit controls power supply from the power storage unit to a load excluding the fixing unit, and the adjustment unit controls power supply from the power storage unit to the load excluding the fixing unit. While instructed, the limit level of power supplied to the fixing means is increased by an amount corresponding to the power supply. The control unit supplies power from the power storage unit when the heating of the fixing unit is started. Further, it further comprises a print request presence / absence detection means for detecting the presence / absence of a print request, and the control means is at least when the power is turned on or when returning from the energy saving mode according to the detection result by the print request presence / absence detection means. The power supplied to the chargeable / dischargeable power storage means is controlled. In addition, when the print request presence / absence detection unit detects that there is no print request when the power is turned on or when returning from the energy saving mode, the control unit executes power supply to the chargeable / dischargeable power storage unit. In addition, when the print request is detected by the print request presence / absence detecting means during the power supply to the chargeable / dischargeable power storage means, the control means stops the power supply to the chargeable / dischargeable power storage means.

  The power storage means further comprises a power storage amount detection means for detecting the power storage amount of the power storage means, and a temperature detection means for detecting the temperature of the fixing means, wherein the control means is configured to detect the power storage means detected by the power storage amount detection means. When the storage amount is equal to or greater than a predetermined amount, and when the temperature of the fixing unit detected by the temperature detection unit is lower than a predetermined temperature, power from the storage unit is supplied to the load, While supplying electric power to the load, the amount of electricity stored in the electricity storage unit and the temperature of the fixing unit are monitored by repeating detection by the electricity storage amount detection unit and the temperature detection unit, and the amount of electricity stored in the electricity storage unit Is less than the predetermined amount, or when the temperature of the fixing unit is equal to or higher than the predetermined temperature, power supply from the power storage unit to the load is cut off.

  The fixing means is an electromagnetic induction heating type fixing device. The fixing means is a ceramic sheet heater type fixing device.

  The image forming apparatus control method of the present invention includes a heating element that generates heat using electric power supplied from a commercial power source, and applies the heat of the heating element to a transfer material on which a toner image is formed. A control method of an image forming apparatus having a fixing unit for fixing the toner image to the transfer material, a power limiting step for limiting power supplied from a commercial power source to the fixing unit to a predetermined limit level, and charge / discharge A charging step of charging a possible power storage unit, a control step of controlling power supply from the power storage unit to a load excluding the fixing unit, and a power supply from the power storage unit to the load excluding the fixing unit in the control step And an adjustment step of increasing the limit level of the power supplied to the fixing unit by an amount corresponding to the power supply.

  Furthermore, a computer-executable program for realizing the control method of the image forming apparatus is provided.

  According to the present invention, it is possible to provide an image forming apparatus and a control method therefor capable of realizing on-demand fixing with a temperature rising faster than ever by making more effective use of the upper limit current of a commercial power source.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the following, a laser beam printer will be described as an example of an embodiment of the present invention. However, the present invention is not limited to the laser beam printer, and can be applied to all image forming apparatuses using an electrophotographic process.

<Example of schematic configuration of laser beam printer of this embodiment>
FIG. 1 is a diagram showing a schematic configuration of a laser beam printer 100 according to an embodiment of the present invention. The laser beam printer 100 is a so-called tandem type printer in which an image forming unit is provided for each color of a black image (Bk), a yellow image (Y), a magenta image (M), and a cyan (C) image.

  Each image forming unit includes a photosensitive drum 18, a primary charger 16 for uniformly charging the photosensitive drum, a scanner unit 11 for forming a latent image on the photosensitive drum, and developing the latent image into a visible image. The developing unit 14, a transfer unit 19 that transfers a visible image onto transfer paper, a cleaning device 15 that removes residual toner on the photosensitive member, and the like. Note that the last reference number represents components of a: yellow, b: magenta, c: cyan, and d: black.

(Scanner unit: Fig. 2)
Here, the configuration of the scanner unit 11 will be described. FIG. 2 is a diagram illustrating a configuration of the scanner unit 11.

  When there is an image formation instruction from an external device (not shown) such as a personal computer, a controller (not shown) in the laser beam printer 100 outputs an image signal (image signal for turning on / off a laser beam as exposure means). VDO signal) 101. This image signal (VDO signal) 101 is input to the laser unit 102 in the scanner unit 11. Reference numeral 103 denotes a laser beam that is on / off modulated by the laser unit 102. Reference numeral 104 denotes a scanner motor that regularly rotates a rotary polygon mirror (polygon mirror) 105. Reference numeral 106 denotes an imaging lens that focuses the laser beam 107 changed by the polygon mirror on the photosensitive drum 108 that is the surface to be scanned.

  With this configuration, the laser beam 103 modulated by the image signal 101 performs horizontal scanning (scanning in the main scanning direction) on the photosensitive drum 108, and a latent image is formed on the photosensitive drum 108.

  Reference numeral 109 denotes a beam detection port, which takes in a beam from a slit-shaped entrance port. The laser beam entering from the entrance is guided to the photoelectric conversion element 111 through the optical fiber 110. The laser beam converted into an electric signal by the photoelectric conversion element 111 is amplified by an amplifier circuit (not shown) and then becomes a horizontal synchronization signal.

  Returning to FIG. The transfer sheet as a recording medium fed from the cassette 22 stands by at the registration roller 21 in order to take timing with the image forming unit.

  A registration sensor 24 for detecting the leading edge of the fed transfer paper is provided in the vicinity of the registration roller 21. An image formation control unit (corresponding to an image formation control circuit below) that controls the image formation unit detects the timing at which the leading edge of the paper reaches the registration roller 21 based on the detection result of the registration sensor 24. When the top end is detected, an image of the first color (yellow in the example in the figure) is formed on the photosensitive drum 18a as an image carrier, and the heater of the fixing device 23 (in this example, the following fixing belt 501). ) The temperature is controlled to be a predetermined temperature.

  Reference numeral 29 denotes a suction roller, which applies a suction bias to the shaft of the roller to electrostatically attract the transfer paper onto the transport belt 20.

  The transfer paper waiting on the registration roller 21 is conveyed on the transfer belt 20 arranged so as to penetrate each color image forming portion, taking the timing of the detection result of the registration sensor 24 and the image forming process, and the transfer device. The first color image is transferred onto the transfer paper by 19a.

  Similarly, the image of the second color (magenta in the example in the figure) is obtained by taking the timing of the detection result of the registration sensor 24 and the process of forming the second color image on the transfer sheet conveyed on the transfer belt 20. It is superimposed and transferred onto the image. Similarly, the image of the third color (cyan in the example in the figure) and the image of the fourth color (black in the example in the figure) are sequentially superimposed and transferred onto the transfer paper at the timing of each image forming process.

  Then, the transfer paper on which the toner image is transferred is conveyed to the fixing device 23, and the transfer paper passes through a nip portion N (details will be described later) in the fixing device 23, whereby the toner is pressurized and heated. It is fused and fixed on transfer paper. The transfer paper that has passed through the fixing device 23 is discharged out of the apparatus, and full-color image formation is completed.

(Configuration example of fixing unit: FIGS. 3 to 5)
The fixing device 23 in this embodiment employs an electromagnetic induction heating method that is more efficient than a heat roller method using a halogen lamp as a heat source. Here, a structural example of the fixing device 23 will be described with reference to FIGS. 3 to 5. 3 is a block diagram showing the cross-sectional structure of the main part of the fixing unit 23, FIG. 4 is a block diagram showing the front structure of the main part of the fixing unit 23, and FIG. 5 is a fixing belt guide member constituting the fixing unit 23. FIG.

  Reference numeral 501 denotes a cylindrical fixing belt as an electromagnetic induction heat generating rotating body having an electromagnetic induction heat generating layer (conductor layer, magnetic layer, resistor layer). A specific structural example of the fixing belt 501 will be described later.

Reference numeral 516a denotes a saddle-shaped belt guide member having a substantially semicircular arc shape in cross section, and a cylindrical fixing belt 501 is loosely fitted outside the belt guide member 516a. The belt guide member 516a basically performs the following functions.
(1) Pressurization to a fixing nip N formed by pressure contact with a pressure roller 530 described later,
(2) Support of exciting coil 506 and magnetic core 505 as magnetic field generating means,
(3) Support of the fixing belt 501
(4) Ensuring the conveyance stability when the fixing belt 501 rotates.
In order to fulfill these roles, it is desirable to use a belt guide member 516a made of a material that can withstand a high load and has excellent insulation and heat resistance. For example, a phenol resin, a fluorine resin, a polyimide resin, a polyamide resin, a polyamideimide resin, a PEEK resin, a PES resin, a PPS resin, a PFA resin, a PTFE resin, an FEP resin, an LCP resin, or the like may be selected.

  The belt guide member 516a holds a magnetic core (configured in a T shape by the core members 505a, 505b, and 505c) and an exciting coil 506 as magnetic field generating means. Further, as shown in FIG. 3, the belt guide member 516a has a heat conductive member (for example, an aluminum material) 540 that is long in the direction perpendicular to the paper surface on the side facing the pressure roller 530 of the nip portion N, and the fixing belt 501. Is disposed inside. The good heat conducting member 540 has an effect of making the temperature distribution in the longitudinal direction uniform.

  The flange members 523a and 523b shown in FIG. 4 are fitted on both left and right ends of the assembly of the belt guide member 516a. Then, the belt guide member 516a is rotatably attached while fixing the left and right positions thereof, and when the fixing belt 501 rotates, the end of the fixing belt 501 is received to restrict the shifting of the fixing belt 501 along the longitudinal direction of the belt guide member. To play a role.

  Reference numeral 530 denotes an elastic pressure roller as a pressure member, and a fixing nip portion N having a predetermined width is formed on the lower surface of the belt guide member 516a with a predetermined pressing force with the fixing belt 501 sandwiched therebetween, thereby being pressed against each other. Here, the magnetic core 505 is disposed so as to correspond to the fixing nip portion N. The pressure roller 530 includes a cored bar 530a and a heat-resistant / elastic material layer 530b such as silicon rubber, fluorine, or fluororesin that is concentrically formed and covered around the cored bar 530a. The pressure roller 530 is disposed such that both end portions of the core metal 530a are rotatably supported by bearings between chassis side metal plates (not shown) of the apparatus. By pressing the pressure springs 525a and 525b between the both ends of the pressure rigid stay 510 and the spring receiving members 529a and 529b on the apparatus chassis side, a pressing force is applied to the pressure rigid stay 510, respectively. . As a result, the lower surface of the belt guide member 516a and the upper surface of the pressure roller 530 are pressed against each other with the fixing belt 501 interposed therebetween, so that a fixing nip portion N having a predetermined width is formed.

  The pressure roller 530 is rotationally driven by the drive motor M in the counterclockwise direction indicated by the arrow. A rotational force acts on the fixing belt 501 by the frictional force between the pressure roller 530 and the outer surface of the fixing belt 501 by this rotational driving. As a result, the fixing belt 501 has a circumferential surface substantially corresponding to the rotational peripheral speed of the pressure roller 530 in the clockwise direction indicated by the arrow while the inner surface of the fixing belt 501 slides in close contact with the lower surface of the belt guide member 516a in the fixing nip portion N. The belt guide member 516a is rotated around the outer periphery of the belt guide member 516a at a speed (pressure roller driving method). Further, as shown in FIG. 5, convex rib portions 516e are formed on the peripheral surface of the belt guide member 516a at a predetermined interval along the length thereof. Thereby, the contact sliding resistance between the peripheral surface of the belt guide member 516a and the inner surface of the fixing belt 501 is reduced, and the rotational load of the fixing belt 501 is reduced.

  The exciting coil 506 is a conductive wire (electric wire) that constitutes a coil (wire ring) using a bundle of a plurality of thin copper wires each coated with an insulation coating (bundled wire). An exciting coil is formed. As the insulating coating, it is preferable to use a coating having heat resistance in consideration of heat conduction due to heat generated by the fixing belt 501. For example, a coating such as amideimide or polyimide may be used. The excitation coil 506 may be externally pressurized to improve the density.

  As shown in FIG. 3, the exciting coil 506 has a shape along the curved surface of the heat generating layer. In this embodiment, the distance between the heat generation layer of the fixing belt 501 and the exciting coil 506 is set to be approximately 2 mm.

  The magnetic flux absorption efficiency is higher when the distances between the magnetic cores 505a, 505b, and 505c and the exciting coil 506 and the heat generating layer of the fixing belt 501 are as close as possible. If this distance exceeds 5 mm, the efficiency is significantly reduced. If the distance is within 5 mm, the distance between the heat generating layer of the fixing belt 501 and the exciting coil 506 does not have to be constant. With respect to the lead wires from the belt guide member 516a as the exciting coil holding member of the exciting coil 506, that is, 506a and 506b (FIG. 5), an insulation coating is applied to the outside of the bundled wire.

  The excitation coil 506 generates an alternating magnetic flux by an alternating current supplied from a fixing control circuit (excitation circuit) described later with reference to FIGS. FIG. 6 is a diagram schematically showing how the alternating magnetic flux is generated.

  A magnetic flux C represents a part of the generated alternating magnetic flux. The alternating magnetic flux C guided to the magnetic cores 505a, 505b, and 505c is intensively distributed in the areas of Sa and Sb in FIG. 3 by the magnetic cores 505a and 505c and the magnetic cores 505a and 505b. An eddy current is generated in the induction heating layer 1. This eddy current causes Joule heat (eddy current loss) to be generated in the electromagnetic induction heat generating layer 1 by the specific resistance of the electromagnetic induction heat generating layer 1.

  The calorific value Q here is determined by the density of the magnetic flux passing through the electromagnetic induction heat generating layer 1, and shows a distribution like the graph on the right side of FIG. The graph on the right side of FIG. 6 shows the position in the circumferential direction of the fixing belt 501 with the vertical axis represented by an angle θ with the center of the magnetic core 505 a being 0, and the horizontal axis is the electromagnetic induction heating layer 1 of the fixing belt 501. The calorific value Q is shown. Here, the heat generation area H (corresponding to the areas Sa and Sb in FIG. 3) is defined as an area where the heat generation amount is Q / e or more, where Q is the maximum heat generation amount. This is an amount by which a heat generation amount necessary for fixing can be obtained.

  The temperature of the fixing nip N is controlled so that a predetermined temperature is maintained by controlling the current supply to the exciting coil 506 by a temperature control system including the temperature sensors 405 and 406. The temperature sensor 405 shown in FIG. 3 and FIG. 4 is composed of, for example, a thermistor that detects the temperature of the fixing belt 501. In this embodiment, the temperature sensor 405 is based on the temperature information of the fixing belt 501 measured by the temperature sensor 405. The temperature of the fixing nip portion N is controlled.

(Example of fixing belt configuration)
FIG. 7 is a diagram illustrating a configuration example of layers of the fixing belt 501.

  As shown in FIG. 7, the fixing belt 501 includes a heat generation layer 501A composed of an electromagnetic induction heat generating metal belt or the like as a base layer, an elastic layer 501B laminated on the outer surface, and a release layer laminated on the outer surface. It has a composite structure with 501C. For adhesion between the heat generation layer 501A and the elastic layer 501B and adhesion between the elastic layer 501B and the release layer 501C, a primer layer may be provided between the layers. In the fixing belt 501 having a substantially cylindrical shape, the heat generating layer 501A is on the inner surface side, and the release layer 501C is on the outer surface side.

  As described above, an alternating magnetic flux acts on the heat generating layer 501A, so that an eddy current is generated in the heat generating layer 501A and the heat generating layer 501A generates heat. The heat heats the fixing belt 501 via the elastic layer 501B and the release layer 501C, and heats the recording material P as the material to be heated that is passed through the fixing nip portion N, thereby heating and fixing the toner image. Made.

(Fixer operation example)
The structure of the fixing device 23 in the present embodiment is generally as described above, but the outline of the operation is as follows.

  The pressure roller 530 is driven to rotate, and accordingly, the cylindrical fixing belt 501 rotates around the belt guide member 516a. Then, the electromagnetic induction heat generation of the fixing belt 501 is performed as described above by supplying power from the excitation circuit to the excitation coil 506, and the fixing nip portion N rises to a predetermined temperature and is in a temperature-controlled state. In this state, the transfer sheet on which the unfixed toner image t formed on the transfer belt 20 of FIG. 1 is formed has an image surface facing upward between the fixing belt 501 and the pressure roller 530 in the fixing nip N. That is, it is introduced to face the fixing belt surface. Next, the image surface is in close contact with the outer surface of the fixing belt 501 at the fixing nip portion N, and the fixing nip portion N is nipped and conveyed together with the fixing belt 501. In the process where the transfer paper is nipped and conveyed together with the fixing belt 501 through the fixing nip N, the unfixed toner image t on the transfer paper is heated and fixed by the fixing belt 501 heated by electromagnetic induction heat generation. When the transfer paper passes through the fixing nip portion N, it is separated from the outer surface of the rotating fixing belt 501 and discharged and conveyed.

  In this embodiment, since the toner containing a low softening substance is used in the toner, the fixing device 23 is not provided with an oil application mechanism for preventing offset, but a toner containing no low softening substance is used. In some cases, an oil application mechanism may be provided. In addition, when a toner containing a low softening substance is used, oil application or cooling separation may be performed.

<Configuration example of power supply control system of this embodiment>
FIG. 8 is a diagram showing the configuration of the power supply control system of the laser beam printer 100 according to this embodiment.

  The AC voltage from the commercial power supply 301 is supplied to the fixing control circuit 330 that functions as an excitation circuit (induction heating control unit) that supplies an alternating current to the fixing device 23 and the switching power supply circuit 470. Yes. The switching power supply circuit 470 steps down and supplies the AC voltage of the commercial power supply to a DC voltage such as 24V used in the image forming unit or the like. The output voltage Ve from the switching power supply circuit 470 is a voltage for operating the image formation control circuit 316 that controls image formation, and the output voltage Va supplies a voltage to the load 460.

  Here, the load 460 is a load in the image forming unit other than the exciting coil 506 serving as a heating element. For example, four DC brushless motors (not shown) that individually drive the four photosensitive drums 18a to 18d, respectively. 1) including one DC brushless motor (not shown) for driving the conveyor belt 20. These five DC brushless motors are simultaneously rotationally driven / stopped by the image forming control circuit 316 so that the surface of the belt 20 in contact with the photosensitive drum 18 is not rubbed. Further, it has been found that the photosensitive drums 18a to 18d and the like to which these motors supply driving force vary in torque between the start of use of the laser beam printer 100 and after durability. Therefore, it is necessary to design the torque of the DC brushless motor and the power to be supplied in anticipation of torque increase after endurance.

  A charging circuit 456 receives the voltage Va supplied from the switching power supply circuit 470 and supplies a predetermined voltage Vb (here, Vb≈Va) to the battery 455 in accordance with a charging command from the image forming control circuit 316. The battery 455 is composed of, for example, a plurality of electric double layer capacitor elements, and the charging circuit charges the battery 455 to a predetermined voltage Vc (≈Vb). An electric double layer capacitor is a device that has attracted attention in many fields in recent years because it has a large capacity of several F or more and has a charging efficiency and a long life as compared with a secondary battery.

  The charging voltage Vc of the battery 455 is detected by the battery voltage detection circuit 457, and the detection result is transmitted, for example, as an analog signal to the A / D port of the CPU (see FIG. 13A described later) in the image formation control circuit 316. The The image formation control circuit 316 determines whether or not the charging circuit 456 needs to be charged according to the detection result of the battery voltage detection circuit 457.

  The constant voltage control circuit 458 is, for example, a switching type boost converter, and the charging voltage Vc of the battery 455 is changed to a voltage Vd (Vd≈Va−Vf required for driving the load 460, where Vd> Vc, Vf = diode 453 The voltage is boosted to a forward voltage (approximately 0.6V). The voltage Vd is supplied to the load 460 through the switch 463 and used for driving the motor. The switch 463 functions as a selection unit that selects either the commercial power supply 301 or the battery 455 as a power supply source to the load 460. That is, when the switch 463 is turned off, the commercial power supply 301 becomes a power supply source to the load 460, and conversely, when the switch 463 is turned on, the battery 455 becomes a power supply source to the load 460. Although it is preferable to use a semiconductor switch such as an FET for the on / off durability reason for the switch 463, a mechanical switch such as a relay may be used if there is no problem with the life such as the number of on / off times. The diode 453 prevents the output Va from the switching power supply circuit 470 from being supplied to the load 460 when the voltage Vd is supplied from the battery 455 via the constant voltage control circuit 458.

<Configuration of Fixing Control Circuit 330>
First, refer to the block diagram of the fixing device 23 in FIG. In this embodiment, as shown in FIG. 3, a thermo switch 502 as a temperature detection element is disposed in a non-contact manner at a position facing the heat generation area Sa (corresponding to the heat generation area H in FIG. 6) of the fixing belt 501. ing.

  The fixing control circuit 330 controls the power supply to the excitation coil 506 in accordance with the operation of the thermo switch 502 in order to cut off the power supply to the excitation coil 506 during, for example, runaway. Here, the off-operation temperature of the thermo switch 502 was set to 220 ° C. The distance between the thermo switch 502 and the fixing belt 501 was about 2 mm. Thereby, the fixing belt 501 is not damaged by the contact of the thermo switch 502, and the deterioration of the fixed image due to durability can be prevented.

  As this temperature detection element, a temperature fuse or the like may be used instead of the thermo switch 502.

  FIG. 9 is a block diagram showing a configuration of the fixing control circuit 330 in the present embodiment. In the fixing control circuit 330, a thermo switch 502 is connected in series to a +24 VDC power source and a relay switch 303. When the thermo switch 502 is cut off, the power supply to the relay switch 303 is cut off, and the relay switch 303 is opened to cut off the power supply to the fixing control circuit 330, thereby cutting off the power supply to the excitation coil 506. ing.

  The configuration of the fixing control circuit 330 shown in FIG. 9 will be described in detail along with its operation. The rectifier circuit 304 includes a bridge rectifier circuit that performs both-wave rectification from an AC input and a capacitor that performs a high-frequency filter. The first and second switch elements 308 and 307 perform current switching, respectively. A current transformer (CT) 311 is a transformer that detects a switching current switched by the first and second switch elements 308 and 307.

  As described above, the fixing device 23 is provided with the exciting coil 506, the temperature detection thermistors 405 and 406, and the thermo switch 502 that detects excessive temperature rise.

  The driver circuit 315 drives the first and second switch elements 308 and 307 through the gate transformers 306 and 305, respectively. The driver circuit 315 includes a filter 325 that filters the output voltage of the current transformer 311, an oscillation circuit 328, a comparator 327 such as a comparator, a reference voltage Vs supply unit 326, and a clock generation unit 329. The clock generation unit 329 generates a clock for performing temperature control. At the same time, when the detected temperature at the mutual pressure contact portion between the fixing belt 501 and the pressure roller 530 exceeds the specified temperature, the drive pulse to the excitation coil 506 is stopped by a signal from the image formation control unit 316, and the fixing device 23. Control to stop power supply to

  The image formation control circuit 316 controls the control amount while comparing with the target temperature based on the temperature detection values of the thermistors 405 and 406 provided in the fixing device 23. The driver circuit 315 receives a control signal from the image formation control circuit 316, generates a switching clock to the gate transformers 305 and 306, and performs control suitable for the control mode of the high-frequency inverter device.

  As the first and second switch elements 308 and 307, a power switch element for power is optimal, and is configured by an FET or IGBT (+ reverse conducting diode). Since the first and second switch elements 308 and 307 control the resonance current, the first and second switch elements 308 and 307 are preferably small in steady-state loss and switch loss, and high breakdown voltage and large current type.

  When AC input power is received from the power line input terminal 301 and AC power is applied to the rectifier circuit 304 via the relay 303, a pulsating DC voltage is generated by the double-wave rectifier diode of the rectifier circuit 304. Thereafter, by driving the gate control transformer 305 so that the second switch element 307 performs switching, an AC pulse voltage is applied to the resonance circuit constituted by the excitation coil 506 and the resonance capacitor 309. As a result, a pulsating DC voltage is applied to the exciting coil 506 when the first switch element 308 is conductive, and a current determined by the inductance and resistance of the exciting coil 506 starts to flow. When the first switch element 308 is turned off according to the gate signal, the exciting coil 506 continues to pass a current. Therefore, a high voltage called a flyback voltage is generated due to the sharpness Q of the resonance circuit determined by the resonance capacitor 309 and the excitation coil 506 at both ends of the excitation coil 506. This voltage oscillates around the power supply voltage and converges to the power supply voltage if it is kept off as it is.

  During a period in which the ringback of the flyback voltage is large and the voltage at the coil side terminal of the first switch element 308 is negative, the reverse conducting diode is turned off and current flows into the exciting coil 506. During this period, the contact point between the exciting coil 506 and the first switch element 308 is clamped at 0V. It is generally known that if the first switch element 308 is turned on during such a period, the first switch element 308 can be turned on without bearing a voltage, which is called ZVS (Zero Voltage Switching). . With such a driving method, loss associated with switching of the first switch element 308 can be minimized, and efficient and low-noise switching can be performed.

  Next, detection of the current of the exciting coil 506 using the current transformer 311 in FIG. 9 will be described. An example of the detected waveform is shown in FIG.

  The current transformer 311 is configured to detect a current flowing from the emitter (drain in the case of FET) of the first switch element 308 to the negative terminal of the rectifier circuit 304 and a filter capacitor (not shown) at the subsequent stage of the rectifier circuit 304. Yes. A current on the power side is passed through one turn side of a current transformer 311 having a 1: n winding, and is detected as voltage information by a detection resistor provided on the n turn side. As shown in FIG. 10, the switching current waveform shows a sawtooth wave corresponding to the switching frequency (20 k to 500 kHz). The envelope of the current peak value is a full-wave rectification of a sine wave of a commercial frequency (for example, 50 Hz). It has become a shape.

  The detected current detected by the current transformer 311 is peak-hold rectified by the filter 325. The current detection (voltage) value filtered by the filter 325 is transmitted to the (−) input terminal of the comparator 327, and the predetermined reference voltage Vs 326 is transmitted to the (+) input terminal of the comparator 327. Compare values. When the detected current value is larger than the reference voltage Vs 326, the comparator 327 outputs a low level to the clock generation unit 329 so that a switching (peak) current larger than the current corresponding to the reference voltage Vs 326 does not flow. . Therefore, the on time of the clock transmitted from the clock generator 329 to the gate transformers 305 and 306 is limited by pulse-by-pulse, and the switching (peak) current is limited.

  FIG. 11 is an enlarged view of the time range A shown in FIG.

  In this example, when the on-time of the pulse for driving the first switching element 308 is tona, the peak value of the detection voltage of the flowing switching current does not reach the predetermined voltage Vs. On the other hand, when the on-time becomes tonb when the input power to the fixing device 23 increases, in this example, the peak value of the detected voltage of the flowing switching current reaches the predetermined voltage Vs. For this reason, the clock generator 329 limits the on-time so as not to be longer than tonb by the output from the comparator 327. That is, the limiter operation for limiting the maximum power of the power supplied to the fixing device 23 is performed by suppressing the peak value of the switching current to a predetermined value. Such protection is provided when an abnormal current is detected, such as when a large current flows.

  Next, the voltage dependence of the maximum power (initial power) input to the fixing device 23 will be described. In a system in which current control is not performed at all, the output power varies with the square of the AC line voltage with respect to the AC line voltage. On the other hand, according to the present configuration in which the limit is set by current detection, the output power can be linearly dependent on the input voltage.

  FIG. 12 shows the result of an experiment conducted with such a circuit.

  The “non-control region” in FIG. 12 is an experimental result when current control is not performed, and a power change is observed with the square of the input voltage, and power dependency due to the power supply voltage is large. On the other hand, the “constant peak control region” is an experimental result when the detected peak current is controlled to be constant within the input voltage range including the voltage used in the laser beam printer 100. FIG. 12 shows that the power fluctuation due to the power supply voltage is small. That is, by controlling the maximum output value of the power control circuit based on the detected peak current, the maximum value of the power control width (maximum input power) is controlled based on the AC line current detection result, and the maximum power that can be supplied is Control is made so as not to depend on the AC line voltage.

  Since the current is detected and the electric power is controlled, the maximum value of the time during which the current flows through the exciting coil 506 of the fixing unit 23, that is, the time during which the first switch element 308 is on is the current flowing through the AC line Determined by possible power. The control signal from the image formation control circuit 316 is in a range not exceeding the maximum value of the time. Moreover, you may take the structure which prescribes | regulates also about minimum time.

<Example of power control operation of this embodiment>
(Outline of power control)
Below, the power control in this embodiment is demonstrated.

  An image forming apparatus generally consumes a large amount of power. Much of its power consumption is due to the fuser. Therefore, as an operation mode, when the standby state for a print request continues for a certain time or more, power control is generally performed such that the power supply to the fixing device is reduced to shift to a so-called energy saving mode or sleep mode. Is. The laser beam printer 100 in this embodiment also has this energy saving mode as an operation mode. Naturally, in the energy saving mode, the temperature of the fixing device is lowered. Then, it is considered that the fixing device is cooled not only when the power switch is turned on but also when returning from the energy saving mode (when shifting to the normal mode). As described above, it is an issue to reduce the time (warm-up time) until the temperature of the fixing device from the cold state to the standby state temperature. This issue is described below in the present embodiment. It is solved by power control.

  First, the image formation control circuit 316 turns off the switch 463 and operates the charging circuit 456 to charge the battery 455 in the energy saving mode or when power supply from the battery 455 is unnecessary.

  On the other hand, when the fixing device 23 is used when a print request is received upon power-on or return from the energy saving mode or when the image forming operation is started, the image forming control circuit 316 turns on the switch 463 to turn on the capacitor. The load 460 is driven by the electric power from 455. Therefore, the amount of power consumed by the load 460 due to the power supply from the battery 455 is not consumed from the commercial power supply, so that there is a surplus with respect to the maximum power defined from the maximum current of the commercial power supply.

  For example, when the temperature of the fixing device 23 is raised, a current of 11 A flows on the primary side (AC side) of the fixing control circuit 330, and a current of 3 A flows on the primary side (AC side) of the switching power supply circuit 470. Suppose that Assuming that the variation of the power depending on the input voltage in the fixing control circuit 330 is about 1 A, the total power is assumed (assuming that the power factor cos θ of the fixing control circuit 330 and the switching power supply circuit 470 is 1). 15A (= 11A + 3A + 1A), which is within the maximum current 15A of the commercial power supply, that is, within the allowable power 1500W (= 100V × 15A).

  Under such conditions, if the current value on the primary side (AC side) of the switching power supply circuit 470 is reduced by 2 A due to power supply from the capacitor 455 to the load 460, the load 460 is driven by the power from the capacitor 455. During this time, the power for 2 A (200 W = 100 V × 2 A) is not consumed from the commercial power source, so that there is a surplus for the maximum supply current of the commercial power source.

  Therefore, the image forming control circuit 316 increases the reference voltage Vs 326 in the driver 315 of the fixing control circuit 330 by an amount corresponding to 2A, and increases the input power limit value to the fixing device 23. Therefore, the primary side (AC side) of the fixing control circuit 330 is 13A, the primary side (AC side) of the switching power supply circuit 470 is 1A, and the variation is about 1A. The total current is similarly 15A (= 13A + 1A + 1A). Therefore, it is within the maximum allowable power of the commercial power supply. Of course, in actual design, it is necessary to take into account design variations so as not to exceed the maximum current that can be supplied by the commercial power supply.

  In this way, by adjusting the reference voltage Vs 326 according to the power supply state from the battery 455 to the load 460, that is, the state of the switch 463 as the selection means, the input power limit level to the fixing device 23 is adjusted. Can do.

  In addition, when the battery 455 is used as described above, when it is possible to supply about 200 W (= 100 V × 2 A) to the fixing device 23 when the temperature of the fixing device 23 is raised, the fixing on demand is performed. There is a possibility that can be realized. That is, in FIG. 22, by using the battery 455 in the same manner as described above, by further supplying 200 W of power to the fixing device 23, the time to reach the print temperature in the figure is 30 sec (point Wa) is 15 sec (point Wb). Become. In this way, it is possible to shorten the temperature rise time of the fixing device 23.

(Details of power control)
The power control operation in the present embodiment is generally as described above. Hereinafter, power control that further considers the presence / absence of a print request and / or the state of charge of the battery 455 and / or the temperature of the fixing device 23 will be described.

  FIG. 13A is a diagram illustrating a configuration example of the image formation control circuit 316. Although FIG. 13A shows an example realized by a program-controlled computer, the procedure shown in the flowchart of FIG. 13B below may be realized by a hardware logic circuit.

  In FIG. 13A, 131 is a CPU for arithmetic control, 132 is a ROM for storing fixed programs and parameters, and 133 is a RAM for temporarily storing data while the CPU 131 is operating.

  The ROM 132 has a power control program storage area 132a shown in FIG. 13B as a program storage area. As a data storage area, a storage area 132b of TL, which is a lower limit temperature at which the fixing device 23 is operable, and a lower limit of the battery 455 that can be boosted to the voltage Vd necessary for driving the load 460 via the constant voltage control circuit 458. It has a storage area 132c of voltage VL. In addition, in this embodiment, the storage area 132d of the WF / Vs table that stores the reference voltage Vs326 of the (+) input terminal of the comparator 327 in association with each other and realizes the increase value WF of the fixing power consumption, and the maximum of the commercial power supply 301. It has a current consumption value storage area 132e. In this example, the maximum current consumption value of the commercial power supply 301 is 14A (= 15A-1A: 1A is a variation in power depending on the input voltage).

  The RAM 133 stores, as a temporary data storage area, a storage area 133a of THb (THa), which is a measured temperature of the fixing device 23 measured by the thermistor 496 (405), and a storage voltage of the battery 455 detected by the battery voltage detection circuit 457. It has a Vc storage area 133b. Further, the storage region 133c of the temporary current value of the fixing control circuit 330 corresponding to the power currently consumed by the fixing device 23, and the temporary current value of the switching power supply circuit 470 corresponding to the power currently consumed by the load 460. Storage area 133d. Furthermore, the storage area 133e of the power consumption value that can be increased to the fixing device 23 when the power of the battery 455 is supplied to the load 460 in this embodiment.

  Note that the configurations of the ROM 132 and the RAM 133 are only those deeply related to the operation of the present embodiment.

  Reference numeral 134 denotes an input signal interface required when the CPU 131 executes the power control program, and 135 denotes a control signal interface for the CPU 131 to execute the power control program and perform power control.

  The input signal includes a temperature signal THa from the thermistor 405, a temperature signal THb from the thermistor 406, and a storage voltage signal of the capacitor 455 from the capacitor voltage detection circuit 457. Also included are a primary current value from the commercial power supply 301 consumed by the fixing control circuit 330 or the switching power supply circuit 470, a signal indicating power ON (or return from the energy saving mode), and a signal indicating a print request. In FIG. 13A, the power ON signal and the print request signal are shown via the input signal interface, but may be directly input to the CPU 131 as an interrupt signal.

  The output control signal includes a relay control signal for controlling the relay 303, a clock generation control signal for controlling the clock generation unit 329, and a control signal for controlling the reference voltage Vs326. In addition, a storage battery connection control signal for controlling the switch 463 to control connection / disconnection of power from the storage battery to the load and a charging circuit control signal for controlling the charging circuit 456 for charging the storage battery 455 are included.

  The input and output signals are only those that are deeply related to the operation of the present embodiment.

(Procedure example 1 of power control of this embodiment)
FIG. 13B is a flowchart showing an operation procedure example 1 of power control in consideration of the presence / absence of a print request and / or the charge state of the battery 455 by the image forming control circuit 316 having the above configuration. This processing starts when a print request is received upon power-on or return from the energy saving mode.

  First, in step S401, it is determined whether the printer is turned on or returned from the energy saving mode. If the printer power is turned on or the printer returns from the energy saving mode, the battery 455 is connected to the charging circuit 456 in step S402.

  Here, the image forming apparatus detects the presence or absence of a print request in step S403. If it is detected that there is no print request, it is not necessary to supply power from the battery 455 to quickly start up the fixing device 23, and the process proceeds to step S411. Step S411 is a process of disconnecting the battery 455 from the load 460 by turning off the switch 463. In this case, the switch 463 is originally maintained in the off state. In step S412, it is determined whether there is an instruction to turn off the power or there is no print request for a predetermined time, and in the meantime, the process returns to step S403 to wait for a print request. If there is no instruction to turn off the power or there is no print request for a predetermined time, in step S413, the power-off process or the energy saving mode is entered, and this process ends.

  On the other hand, if it is detected in step S403 that there is a print request to the image forming apparatus, the process proceeds to step S404, and the image formation control circuit 316 determines the temperature detection value THb of the thermistor 406 provided in the fixing device 23. It is input (see FIG. 9), and it is determined whether or not the temperature detection value THb is equal to or higher than the lower limit temperature TL at which fixing is possible. When the temperature of the fixing device 23 is already equal to or higher than the lower limit temperature TL at which fixing is possible, it is not necessary to supply the electric power from the battery 455 to quickly start up the fixing device 23 in the first place. In that case, the process proceeds to step S410, and normal power WL is supplied from the commercial power supply 301 to the fixing unit 23 by maintaining the switch 463 in the OFF state. The subsequent step S411 is a process of disconnecting the battery 455 from the load 460 by turning off the switch 463. In this case, the switch 463 is originally maintained in the off state.

  In step S404, if the temperature detection value THb is lower than the lower limit temperature TL at which fixing is possible, the process proceeds to step S405. In step S405, whether or not the charging voltage Vc of the battery 455 detected by the battery voltage detection circuit 457 is equal to or higher than the lower limit voltage VL that the constant voltage control circuit 458 can boost to the voltage Vd necessary for driving the load 460. Determine whether. Here, when the charging voltage Vc of the battery 455 is less than VL, it is considered that the charging is insufficient and the process proceeds to step S410. Even if the switch 463 is turned on and the electric power from the battery 455 is supplied while the charging is insufficient, it does not contribute to the rapid start-up of the fixing device 23, but may also hinder the start-up. is there.

  In step S405, if the charging voltage Vc is equal to or higher than VL, the process proceeds to step S406, and the switch 463 is turned on to connect the battery 455 to the load 460. Therefore, the load 460 is driven by the electric power from the battery 455. Thus, as described above, it is possible to make a surplus with respect to the maximum power defined from the maximum current of the commercial power source and to pass the surplus power to the fixing device 23.

  Therefore, in this embodiment, in step S407, the power supplied to the fixing device 23 is increased by the remaining power WF with respect to the maximum power of the commercial power supply. Specifically, for example, the reference voltage Vs 326 (see FIG. 9) in the driver 315 of the fixing control circuit 330 is increased by an amount corresponding to the power WF to increase the input power limit value to the fixing device 23. An increase in power supply can be realized. As a result, the power supplied to the fixing device 23 becomes the normal power WL from the commercial power supply 301 + the increased power WF. At this time, the power (WL + WF) supplied to the fixing unit 23 is adjusted to the lowest voltage within the voltage range of the commercial power supply 301 (for example, when the voltage range is 100 to 127 V, the lower limit voltage is 100 V). It is desirable to set.

  While the electric power from the battery 455 is supplied to the load 460 by the above steps S406 and S407, the charging voltage Vc of the battery 455 detected by the battery voltage detection circuit 457 is changed by the constant voltage control circuit 458 in step S408. It is monitored whether or not the voltage VL is maintained at or above the lower limit voltage VL that can be boosted to the voltage Vd required for driving the load 460. Further, in step S409, it is monitored whether the temperature detection value THb of the thermistor 406 is equal to or higher than a lower limit temperature TL at which the fixing device 23 can fix.

  Here, when the charging voltage Vc of the battery 455 falls below VL (NO in step S408), or when the temperature detection value THb of the thermistor 406 (that is, the temperature of the fixing device 23) becomes equal to or higher than TL (step S409). In step S410, the process proceeds to step S410. In step S410, the power supplied to the fixing device 23 is returned to the normal power WL. Specifically, for example, the reference voltage Vs 326 (see FIG. 9) in the driver 315 of the fixing control circuit 330 is lowered by an amount corresponding to the power WF increased in step S407, and the input power limit value to the fixing device 23 is decreased. By lowering, it is possible to realize a drop to the normal power WL.

  In step S411, the switch 463 is turned off to disconnect the battery 455 from the load 460.

(Effect of power control by this procedure example 1)
The effects of power control taking into account the presence / absence of a print request and / or the state of charge of the battery 455 and / or the temperature of the fixing device 23 described above will be described.

  FIG. 14 shows the time transition of the power supply amount to the fixing device for each of the present embodiment and the conventional example that does not use the capacitor. In FIG. 14, a solid line a in (B) indicates the amount of power supplied to the fixing device 23 in the present embodiment, and a broken line b in (C) indicates power supply to the fixing device in a conventional example that does not use a capacitor. Indicates the amount. Also, a solid line c and a broken line d in (A) indicate the time transition of the temperature of the fixing device of the present embodiment and the time transition of the temperature of the conventional fixing device accompanying the power supply to the fixing device, respectively.

  As shown in FIG. 14, when starting up from a temperature lower than the lower limit temperature TL at which the fixing device can fix, the conventional image forming apparatus supplies only the normal power WL of the commercial power source to the fixing device. In the laser beam printer 100 of the present embodiment, since the amount of power supplied to the fixing unit 23 is increased by WF, it takes time t2 until the temperature reaches TL. It takes only t1 shorter than t2 to reach TL.

  In the power control that takes into account the charging state and / or the temperature of the fixing device as described above, the condition for disconnecting the battery 455 from the load 460 is set as the lower limit temperature at which the fixing device 23 can be fixed as in step S407. If the relationship between the power supplied to the fixing device 23, the rising temperature and the falling temperature, and the time is known in advance, instead of the condition as in step S407, the elapsed time or the total power supply amount It is also possible to set with.

  As described above, the battery 455 is provided in the laser beam printer 100, and power is supplied from the battery 455 to the load 460 such as a motor other than the fixing device 23 when the fixing is started. Therefore, while power is being supplied from the battery 455 to the load 460, the power limit value to the fixing device 23 can be increased by an amount corresponding to surplus power. By effectively utilizing the surplus power as the startup power of the fixing unit 23, the startup time of the fixing unit 23 can be shortened. In addition, since the fixing device 23 does not require a plurality of heat sources such as a main heater and a sub-heater, the configuration of the fixing device can be simplified, and it can be turned on depending on the configuration of the image forming apparatus and the performance such as the printing speed. Demand fixing can be realized.

  Further, in addition to the above effects, when the printer is turned on or returned from the energy saving mode, the state of charge of the battery 455 is confirmed and the presence or absence of a print request is also confirmed. At this time, the power supply for starting up the laser beam printer 100 is prioritized over the charging of the battery 455, so that the power supply for starting up the laser beam printer 100 is hindered by the charging of the battery 455. Can be prevented. Also, when it is determined that there is no print request when confirming whether or not there is a print request, if the charging state of the battery 455 is insufficient, the charging process of the battery 455 is immediately started. The battery 455 can be put into a usable state.

  The first embodiment of the present invention has been described above. In the following, several other embodiments will be described. The configuration and operation of each part including the schematic configuration of the image forming apparatus are substantially the same as those of the first embodiment described above, but the characteristic differences in the configuration of the power supply control system are exhibited. Therefore, in the following embodiment, the drawings used in the first embodiment are used, and for the newly used drawings, the same reference numerals are assigned to the same components as those in the first embodiment, and the descriptions thereof are made. Is omitted, and a configuration or operation different from that of the other embodiments will be described.

(Procedure 2 of power control of this embodiment)
FIG. 15 is a flowchart illustrating an operation example 2 of power control when the printer is turned on or returned from the energy saving mode by the image formation control circuit 316 in the present embodiment.

  The difference from the first procedure example (FIG. 13B) is that the presence / absence of a print request is continuously detected at a predetermined timing until the charging voltage Vc of the battery 455 becomes substantially full (≈VH). This process starts when a print request is received when the printer is turned on or returned from the energy saving mode.

  First, in step S701, it is determined whether the printer power is turned on or returned from the energy saving mode. If the printer power is turned on or the printer returns from the energy saving mode, the battery 455 is connected to the charging circuit 456 in step S702.

  In step S703, the presence or absence of a print request in the image forming apparatus is detected. If it is detected that there is no print request, it is not necessary to supply power from the battery 455 to quickly start up the fixing device 23, so the process proceeds to step S713. Step S713 is a process of disconnecting the battery 455 from the load 460 by turning off the switch 463. In this case, since the switch 463 is originally maintained in the OFF state, the process proceeds to step S714, and the capacitor voltage detection circuit 457 detects whether or not the capacitor 455 is substantially full (≈VH). If the battery 455 is substantially full, the process proceeds to step S715 to end the charging. In step S716, it is determined whether there is an instruction to turn off the power or there is no print request for a predetermined time, and in the meantime, the process returns to step S703 to wait for a print request. If there is no instruction to turn off the power or there is no print request for a predetermined time, in step S713, the process proceeds to the power off or energy saving mode, and this process ends.

  If the battery 455 is not almost full, the process returns to step S703 to detect the presence or absence of a print request. If there is no print request, the process similarly proceeds to step S713, and steps S703-S713-S714 are repeated.

  On the other hand, if it is detected in step S703 that there is a print request, the process proceeds to step S704 as in the procedure example 1, and the image formation control circuit 316 detects the temperature detection value THb of the thermistor 406 provided in the fixing device 23. (See FIG. 9), and it is determined whether or not the temperature detection value THb is equal to or higher than the lower limit temperature TL at which fixing is possible. When the temperature of the fixing device 23 is already equal to or higher than the lower limit temperature TL at which fixing is possible, it is not necessary to supply the electric power from the battery 455 to quickly start up the fixing device 23. Accordingly, the process proceeds to step S711, and the normal power WL is supplied from the commercial power supply 301 to the fixing unit 23 by maintaining the switch 463 in the OFF state. The subsequent step S712 is a process of disconnecting the battery 455 from the load 460 by turning off the switch 463. In this case, the switch 463 is originally maintained in the off state.

  In step S704, if the temperature detection value THb is lower than the lower limit temperature TL at which fixing is possible, the process proceeds to step S705. In step S705, whether or not the charging voltage Vc of the battery 455 detected by the battery voltage detection circuit 457 is equal to or higher than the lower limit voltage VL that the constant voltage control circuit 458 can boost to the voltage Vd necessary for driving the load 460. Determine whether. Here, when the charging voltage Vc of the battery 455 is less than VL, it is considered that the charging is insufficient, and in the above-described step S704, the temperature of the fixing device 23 is already equal to or higher than the lower limit temperature TL that can be fixed. Then, the process proceeds to step S711. Even if the switch 463 is turned on and the electric power from the battery 455 is supplied while the charging is insufficient, not only does it not contribute to the rapid start-up of the fixing unit 23, but also the start-up may be hindered. is there.

  If the charging voltage Vc is greater than or equal to VL in step S705, the process proceeds to step S706, the battery 455 is disconnected from the charging circuit 456, and the process proceeds to step S707. In step S707, the switch 463 is turned on to connect the battery 455 to the load 460. Therefore, the load 460 is driven by the electric power from the battery 455. As a result, as in the first procedure example, a surplus power is generated with respect to the maximum power defined from the maximum current of the commercial power supply 301, and the surplus power can be sent to the fixing device 23.

  Therefore, as in the first procedure example, in this procedure example 2, in step S708, the power supplied to the fixing device 23 is increased by the surplus power WF with respect to the maximum power of the commercial power supply. Specifically, for example, the reference voltage Vs 326 (see FIG. 9) in the driver 315 of the fixing control circuit 330 is increased by an amount corresponding to the power WF to increase the input power limit value to the fixing device 23. realizable. As a result, the power supplied to the fixing device 23 becomes the normal power WL + WF from the commercial power supply 301. At this time, the power (WL + WF) supplied to the fixing unit 23 is adjusted to the lowest voltage within the voltage range of the commercial power supply 301 (for example, when the voltage range is 100 to 127 V, the lower limit voltage is 100 V). It is desirable to set.

  While the electric power from the battery 455 is being supplied to the load 460 by the above steps S707 and S708, the charging voltage Vc of the battery 455 detected by the battery voltage detection circuit 457 is changed by the constant voltage control circuit 458 in step S709. It is monitored whether or not the voltage VL is maintained at or above the lower limit voltage VL that can be boosted to the voltage Vd required for driving the load 460. Further, in step S710, it is monitored whether or not the temperature detection value THb of the thermistor 406 has become equal to or higher than the lower limit temperature TL at which the fixing device 23 can be fixed.

  Here, when the charging voltage Vc of the battery 455 falls below VL (NO in step S709), or when the temperature detection value THb of the thermistor 406 (that is, the temperature of the fixing device 23) becomes equal to or higher than TL (step S710). In step S711, the power supplied to the fixing device 23 is returned to the normal power WL. Specifically, for example, the reference voltage Vs 326 (see FIG. 9) in the driver 315 of the fixing control circuit 330 is lowered by an amount corresponding to the power WF increased in step S708, and the input power limit value to the fixing device 23 is decreased. It can be realized by lowering.

  In step S712, the switch 463 is turned off to disconnect the battery 455 from the load 460.

(Effect of power control by this procedure example 2)
In this procedure example 2, overcharge of the battery 455 can be prevented by detecting at an arbitrary interval until the charge voltage Vc of the battery 455 becomes almost full. Further, by continuously checking the presence or absence of a print request at an arbitrary interval until the battery 455 is in a usable charge state, the battery 455 can be charged quickly, and at the time of starting up the laser beam printer 100, By giving priority to the power supply for starting up the laser beam printer 100 over the charging of the battery 455, charging of the battery 455 can prevent the power supply for starting up the laser beam printer 100 from being hindered.

(Procedure example 3 of power control of this embodiment)
FIG. 16 is a flowchart showing an operation procedure example 3 of power control when the printer is turned on or returned from the energy saving mode by the image formation control circuit 316 in the present embodiment.

  In the first procedure example (FIG. 13B), whether to use the battery 455 is determined based on whether the temperature THb of the fixing device 23 has reached the lower limit temperature TL at which fixing is possible. However, in the procedure example 3, it is determined whether or not to use the battery 455 depending on whether or not the battery 455 is used and the temperature TL1 of the fixing device 23 that has a warm-up time of 15 seconds or less has been reached. Incidentally, in this procedure example 3, the temperature TL1 of the fixing device 23 is 120 ° C. when the warm-up time is within 15 sec without using the battery 455. This process starts when a print request is received when the printer is turned on or returned from the energy saving mode.

  First, in step S801, it is determined whether the printer is turned on or returned from the energy saving mode. If the printer power is turned on or the printer returns from the energy saving mode, the battery 455 is connected to the charging circuit 456 in step S802.

  In step S803, the image forming apparatus detects whether there is a print request. If it is detected that there is no print request, it is not necessary to supply the electric power from the battery 455 to quickly start up the fixing device 23, so the process proceeds to step S813. Step S813 is processing for disconnecting the battery 455 from the load 460 by turning off the switch 463. In this case, the switch 463 is originally maintained in the off state. Accordingly, the process proceeds to step S814, and the capacitor voltage detection circuit 457 detects whether the capacitor 455 is substantially full. If the battery 455 is substantially full, the process proceeds to step S815 and charging is terminated. In step S816, it is determined whether there is an instruction to turn off the power or there is no print request for a predetermined time. During this time, the process returns to step S803 to wait for a print request. If there is no power-off instruction or there is no print request for a predetermined time, in step S813 the power-off process or the energy-saving mode is entered, and this process ends.

  If the battery 455 is not almost full, the process advances to step S803 to detect the presence or absence of a print request. If there is no print request, the process similarly proceeds to step S813.

  On the other hand, if it is detected in step S803 that there is a print request, the process proceeds to step S804 as in procedure example 2, and the image formation control circuit 316 detects the temperature detection value Hb of the thermistor 406 provided in the fixing device 23. (See FIG. 9), and it is determined whether or not the detected temperature value VHb is equal to or higher than the lower limit temperature TL1 at which fixing is possible. When the temperature of the fixing device 23 is already equal to or higher than the lower limit temperature TL1 at which fixing is possible, it is not necessary to start up the fixing device 23 by supplying power from the battery 455 in the first place. Accordingly, the process proceeds to step S811, and normal power WL is supplied from the commercial power supply 301 to the fixing unit 23 by maintaining the switch 463 in the OFF state. The subsequent step S812 is a process of disconnecting the battery 455 from the load 460 by turning off the switch 463. In this case, the switch 463 is originally maintained in the off state.

  If it is determined in step S804 that the temperature detection value is less than the lower limit temperature TL1 at which fixing is possible, the process proceeds to step S805. In step S805, whether or not the charging voltage Vc of the battery 455 detected by the battery voltage detection circuit 457 is equal to or higher than the lower limit voltage VL that the constant voltage control circuit 458 can boost to the voltage Vd necessary for driving the load 460. Determine whether. Here, when the charging voltage Vc of the battery 455 is less than VL, it is considered that the charging is insufficient, and in the step S804, the temperature of the fixing device 23 is already equal to or higher than the lower limit temperature TL1 at which fixing is possible. Then, the process proceeds to step S811. Even if the switch 463 is turned on and the electric power from the battery 455 is supplied while the charging is insufficient, it does not contribute to the rapid start-up of the fixing device 23, but may also hinder the start-up. is there.

  In step S805, if the charging voltage Vc is greater than or equal to VL, the process proceeds to step S806, the battery 455 is disconnected from the charging circuit 456, and the process proceeds to step S807. In step S807, the switch 463 is turned on to connect the battery 455 to the load 460. Therefore, the load 460 is driven by the electric power from the battery 455. As a result, as in Procedure Examples 1 and 2, there is a surplus with respect to the maximum power defined from the maximum current of the commercial power supply 301, and the surplus power can be passed to the fixing device 23.

  Therefore, as in the first and second procedure examples, in this procedure example 3, in step S808, the power supplied to the fixing device 23 is increased by the surplus power WF with respect to the maximum power of the commercial power supply. Specifically, for example, the reference voltage Vs 326 (see FIG. 9) in the driver 315 of the fixing control circuit 330 is increased by an amount corresponding to the power WF to increase the input power limit value to the fixing device 23. realizable. As a result, the power supplied to the fixing device 23 becomes the normal power WL + WF from the commercial power supply 301. At this time, the power (WL + WF) supplied to the fixing unit 23 is adjusted to the lowest voltage within the voltage range of the commercial power supply 301 (for example, when the voltage range is 100 to 127 V, the lower limit voltage is 100 V). It is desirable to set.

  While the electric power from the battery 455 is being supplied to the load 460 by the above steps S807 and S808, the charging voltage Vc of the battery 455 detected by the battery voltage detection circuit 457 is changed by the constant voltage control circuit 458 in step S809. It is monitored whether or not the voltage VL is maintained at or above the lower limit voltage VL that can be boosted to the voltage Vd required for driving the load 460. In step S810, it is monitored whether the temperature detection value VHb of the thermistor 406 has become equal to or higher than the lower limit temperature TL1 at which the fixing device 23 can be fixed.

  Here, when the charging voltage Vc of the battery 455 falls below VL (NO in step S809), or when the temperature detection value of the thermistor 406 (that is, the temperature of the fixing device 23) becomes equal to or higher than TL1 (in step S810). (YES) proceeds to step S811. In step S811, the power supplied to the fixing device 23 is returned to the normal power WL. Specifically, for example, the reference voltage Vs 326 (see FIG. 9) in the driver 315 of the fixing control circuit 330 is lowered by an amount corresponding to the power WF increased in step S808, and the input power limit value to the fixing device 23 is decreased. It can be realized by lowering.

  In step S 812, the battery 455 is disconnected from the load 460 by turning off the switch 463.

(Effect of power control by this procedure example 3)
The effect of power control in consideration of the presence / absence of the print request and / or the charged state of the battery 455 and / or the temperature of the fixing device 23 will be described.

  FIG. 17 shows the time transition of the power supply amount to the fixing device for each of the temperature <TL1 of the fixing device 23 of the present embodiment and the temperature ≧ TL1 of the fixing device 23 of the present embodiment. In FIG. 17, a solid line a in (B) indicates the amount of power supplied to the fixing device 23 when the temperature of the fixing device 23 in this embodiment is less than TL1, and a broken line b in (C) indicates the fixing in this embodiment. The power supply amount to the fixing device when the temperature of the device 23 is equal to or higher than TL1 is shown. Also, the solid line c and the broken line d in (A) indicate the time transition of the temperature of the fixing device when the temperature of the fixing device 23 of the present embodiment <TL1 accompanying the power supply to the fixing device, and the fixing device 23 of the present embodiment. The time transition of the temperature of the fixing device when temperature ≧ TL1 is shown.

  By detecting the temperature of the fixing device 23 and predicting the start-up speed of the laser beam printer 100, even when the temperature of the fixing device 23 is lower than the lower limit temperature TL at which fixing is possible, when the temperature is TL1 or more, only the normal power WL is obtained. Therefore, the laser beam printer 100 can be started up on demand when the charged state of the battery 455 is insufficient. Can be greatly increased. In addition, useless use of the battery 455 can be prevented, leading to energy saving.

[Other Embodiments]
In each of the above-described embodiments, the electromagnetic induction heating type fixing device 23 is used. However, other types of fixing devices can also be used. In the present embodiment, a ceramic sheet heater type fixing device will be described.

(Configuration example of fixing device of this embodiment)
FIG. 18 is a diagram showing a cross-sectional structure of a ceramic sheet heating heater type fixing device 600 according to the present embodiment.

  Reference numeral 610 denotes a stay, and the stay 610 includes a main body 611 having a U-shaped cross section that supports the ceramic heater 640 in an exposed manner, and a pressure unit 613 that presses the main body toward the pressure roller 620 facing the main body 611. It is configured. Here, in the ceramic sheet heating heater, the heating element may be on the side opposite to the nip part described later, or the heating element may be on the nip part side. Reference numeral 614 denotes a heat resistant film (hereinafter abbreviated as “film”) having a circular cross section that is externally fitted to the stay 610.

  The pressure roller 620 forms a pressure nip portion (fixing nip portion) N with the film 614 sandwiched between the pressure roller 620 and acts as film outer surface contact driving means for driving the film 614 to rotate. The film driving roller / pressure roller 620 includes a cored bar 620a, an elastic body layer 620b made of silicon rubber or the like, and an outermost release layer 620c. Then, the film 614 is sandwiched with a predetermined pressing force by a bearing means / biasing means (not shown) and is placed in pressure contact with the surface of the ceramic heater 640. The pressure roller 620 applies a conveyance force to the film by a frictional force between the pressure roller 620 and the outer surface of the film 614 when driven by the motor M.

  FIG. 19 is a diagram illustrating a specific structural example of the ceramic sheet heater 640. 19A is a cross-sectional view of the ceramic sheet heater 640, and FIG. 19B shows the surface on which the heating element 601 is formed.

  The ceramic sheet heater includes a ceramic insulating substrate 607 such as SiC, AlN, Al2O3, a heating element 601 formed by paste printing or the like on the insulating substrate surface, and a protective layer such as glass protecting the heating element. 606. On the protective layer, a thermistor 605 as a temperature detecting element for detecting the temperature of the ceramic sheet heater and a temperature fuse 602 as a means for preventing overheating are disposed. The thermistor 605 is disposed via an insulator having a withstand voltage so that an insulation distance can be secured with respect to the heating element 601. However, as a means for preventing excessive temperature rise, a thermo switch or the like may be used in addition to the thermal fuse.

  The heating element 601 includes a portion that generates heat when power is supplied, a conductive portion 603 connected to the heat generating portion, and an electrode portion 604 to which power is supplied via a connector. The length is almost the same as the maximum possible recording paper width LF. The HOT side terminal of the AC power supply is connected to one of the two electrodes 604 via a thermal fuse 602. The electrode portion is connected to a TRIAC 639 that controls the heating element, and is connected to the NEUTRAL terminal of the AC power supply.

  FIG. 20 is a diagram showing a configuration of the fixing control circuit 630 in the present embodiment. The fixing control circuit 630 is based on a ceramic sheet heater, but can be replaced with the fixing control circuit 330 in FIG.

  In the laser beam printer 100 according to the present embodiment, the commercial power supply 301 is supplied to the heating element 601 of the ceramic sheet heating heater 640 through an AC filter (not shown), thereby generating heat from the heating element 601 of the ceramic sheet heating heater. Let The power supply to the heating element 601 is controlled by the triac 639 to be energized or interrupted. The resistors 631 and 632 are bias resistors for the triac 639, and the phototriac coupler 633 is a device for isolating the primary and secondary. The triac 639 is turned on by energizing the light emitting diode of the phototriac coupler 633. The resistor 634 is a resistor for limiting the phototriac current, and is turned on / off by the transistor 635. The transistor 635 operates in accordance with an ON signal sent from the image formation control circuit 316 via the driver circuit 650 and the resistor 636. The driver circuit 650 includes a current effective value detection circuit 652, an oscillation circuit 655, a reference voltage Vs indicated by comparators 653 and 654 such as a comparator, and a clock generation unit 651.

  In addition, the AC power is input to the zero cross detection circuit 618 via an AC filter (not shown). The zero-cross detection circuit 618 notifies the clock generation unit 651 by a pulse signal that the commercial power supply 301 has a voltage lower than a certain threshold value. Hereinafter, this signal transmitted to the clock generation unit 651 is referred to as a ZEROX signal. The clock generation unit 651 detects the edge of the pulse of the ZEROX signal.

  The temperature detected by the thermistor 605 is detected as a partial pressure of the resistor 637 and the thermistor 605 and is A / D input to the image formation control circuit 316 as a TH signal. The temperature of the ceramic sheet heater 640 is monitored by the image formation control circuit 316 as a TH signal, and the result of comparison with the set temperature of the ceramic sheet heater set inside the image formation control circuit 316 is compared with the image formation control. The analog signal from the D / A port of the circuit 316 or PWM is transmitted to the clock generator 651.

  The clock generation unit 651 calculates the power to be supplied to the heating element 601 constituting the ceramic sheet heater from the signal sent from the engine control circuit 316, and the phase angle θ (phase control) corresponding to the supplied power. Convert to. The zero-cross detection circuit 618 outputs a ZEROX signal to the clock generation unit 651. The clock generation unit 651 synchronizes and transmits an ON signal to the transistor 635, and energizes the heater 640 at a predetermined phase angle θa.

  FIG. 21 shows a waveform of the energized state.

  The ZEROX signal is a repetitive pulse having a period T (= 1/50 sec) determined from the commercial power supply frequency (50 Hz), and this is transmitted to the image forming control circuit 316. The central portion of the pulse has a phase of 0 °, 180 ° of the commercial power supply. The timing at which the voltage and the voltage become 0 V (zero cross) is shown.

  The image formation control circuit 316 transmits an ON signal for turning on the triac 639 after a predetermined timing from the zero cross timing as described above, and the heating element at a predetermined phase angle θa in the half wave of the commercial power supply voltage (sine wave). Control is performed such that energization of the (heater) 601 is started. The triac 639 is turned off at the next zero cross timing, and energization to the heating element 601 is started at the same phase angle angle θa by the on signal in the next half wave. Further, it is turned off at the next zero cross timing.

  Since the heating element 601 is a resistor, the voltage waveform applied to both ends of the heating element is equal to the flowing current waveform, and as shown in FIG. When increasing the power supply to the heater, the timing for transmitting the ON signal from the zero cross is advanced, and conversely when reducing the power supply, the timing for transmitting the ON signal from the zero cross is delayed. The temperature of the ceramic sheet heater 640 is controlled by performing this control for one period or for each of a plurality of periods as necessary.

  625 in FIG. 20 is a current transformer for detecting the current flowing to the ceramic sheet heater 640 of the fixing device 600. The effective value of the detected current detected by the current transformer 625 is measured by a current effective value detection circuit 652 constituted by an IC or the like that detects the current effective value, and the detected current (voltage) value is (− ) A predetermined reference voltage Vs 654 is transmitted to the (+) input terminal of the comparator 653 to the input terminal, and the comparator 653 compares both values. When the detected current value is larger than the reference voltage Vs654, the comparator 653 sets a predetermined time (from the zero cross timing to transmission of the ON signal so as not to exceed the current corresponding to the reference voltage Vs654) ( It outputs to the clock generation unit 651 so as to be equal to or greater than a predetermined phase angle.

  As described above, the image formation control circuit 316 constantly monitors the current, determines the phase angle so as not to exceed the predetermined maximum effective current from the detected average current, and calculates the maximum to the ceramic sheet heater 640. The power is controlled.

  If the heating element reaches a thermal runaway due to a failure of the image formation control circuit 316 or the like and the temperature fuse 602 reaches a predetermined temperature or higher, the temperature fuse 602 is opened. When the temperature fuse 602 is opened, the energization path to the ceramic sheet heater 640 is interrupted, and the energization to the heating element 601 is interrupted, so that protection in the event of a failure is achieved.

(Example of power control of this embodiment)
In the above configuration, in this embodiment, power control is performed as follows.

  The image formation control circuit 316 turns off the switch 463 and operates the charging circuit 456 to charge the battery 455 when the laser beam printer 100 is on standby or when power supply from the battery 455 is unnecessary.

  When the fixing device 23 is used, such as when an image forming operation is started, the image forming control circuit 316 turns on the switch 463 and drives the load 460 with the electric power from the battery 455. Therefore, the amount of power consumed by the load 460 due to the power supply from the battery 455 is not consumed from the commercial power supply, so that there is a surplus with respect to the maximum power defined from the maximum current of the commercial power supply.

  For example, when the temperature of the fixing device 23 is raised, a current of 11 A flows on the primary side (AC side) of the fixing control circuit 630, and a current of 3 A flows on the primary side (AC side) of the switching power supply circuit 470. Suppose that Assuming about 1 A of variation such as power depending on the input voltage in the fixing control circuit 630, the total power is (assuming that the power factor cos θ of the fixing control circuit 630 and the switching power supply circuit 470 is 1). 15A (= 11A + 3A + 1A), which is within the maximum current 15A of the commercial power supply, that is, within the allowable power 1500 W (= 100 V × 15 A).

  Under such conditions, if the current value on the primary side (AC side) of the switching power supply circuit 470 is reduced by 2 A due to power supply from the capacitor 455 to the load 460, the load 460 is driven by the power from the capacitor 455. During this time, the power for 2 A (200 W = 100 V × 2 A) is not consumed from the commercial power source, so that there is a surplus for the maximum supply current of the commercial power source.

  For this reason, the image forming apparatus control circuit 316 reduces the energization phase angle to the ceramic sheet heater 640 corresponding to the input power limit value to the fixing device 600 to the 0 ° side corresponding to 2A, thereby fixing the fixing device. The input power limit value to 23 is increased. Accordingly, assuming that the primary side (AC side) of the fixing control circuit 630 is 13A, the primary side (AC side) of the switching power supply circuit 470 is 1A, and the variation is about 1A, the total current is similarly 15A (= 13A + 1A + 1A). It will be within the maximum allowable power of commercial power. Of course, in actual design, it is necessary to take into account design variations so as not to exceed the maximum current that can be supplied by the commercial power supply.

  As described above, even in the configuration using the ceramic sheet heating heater type fixing device as in the present embodiment, as in the case of the electromagnetic induction heating type fixing device, the battery 455 is provided in the laser beam printer 100, When the fixing device 600 is activated, electric power is supplied from the battery 455 to a load 460 such as a motor other than the fixing device 600. Therefore, while the power supply from the battery 455 is being performed, the power limit value to the fixing device 600 can be increased by an amount corresponding to the surplus power. By effectively utilizing the surplus power as the startup power of the fixing device 600, the startup time of the fixing device can be shortened.

  Then, in the same way as described in the first to third procedure examples, the presence / absence of a print request and / or the charge state of the battery 455 and / Alternatively, power control is performed in consideration of the temperature of the fixing device 600. Thereby, it can detect at arbitrary intervals until the charging voltage Vc of the battery 455 becomes almost full, and the overcharge of the battery 455 can be prevented.

  Further, until the battery 455 is in a usable charge state, the presence or absence of a print request is continuously checked at an arbitrary interval, and the battery 455 can be charged quickly. At the same time, when starting up the laser beam printer 100, the power supply for starting up the laser beam printer 100 is prioritized over the charging of the battery 455, and charging of the battery 455 allows the power supply for starting up the laser beam printer 100. It can be prevented from being inhibited. Further, the temperature of the fixing device 600 is detected to predict the startup speed of the laser beam printer 100. Even when the temperature of the fixing device 600 is lower than the lower limit temperature TL at which fixing is possible, when the temperature is TL1 or more, the battery 455 is not used only with the normal power WL, and the fixing temperature can be fixed within 15 sec. become. Therefore, it is possible to greatly increase the chances of on-demand startup of the laser beam printer 100 when the state of charge of the battery 455 is insufficient.

  In addition, useless use of the battery 455 can be prevented, leading to energy saving. By supplying electric power from the battery 455 to a load 460 such as a motor other than the fixing device 600, the power limit value to the fixing device 600 is equivalent to the surplus power while the electric power is supplied from the power storage device 455. Can be increased. By effectively utilizing the surplus power as the startup power of the fixing device 600, the startup time of the fixing device 600 can be shortened. In addition, since the fixing device 600 does not require a plurality of heat sources such as a main heater and a sub-heater, the structure of the fixing device can be simplified and turned on depending on the performance of the image forming apparatus and the printing speed. Demand fixing can be realized.

1 is a schematic configuration diagram of a laser beam printer according to an embodiment. It is a figure which shows the structure of the scanner unit of the laser beam printer which concerns on this embodiment. It is a figure which shows the cross-sectional structure of the fixing device of the electromagnetic induction heating system in this embodiment. It is a figure which shows the front structure of the fixing device of the fixing device of the electromagnetic induction heating system in this embodiment. It is a figure which shows the fixing belt guide member which comprises the fixing device in this embodiment. It is the figure which represented the mode of generation | occurrence | production of the alternating magnetic flux typically. FIG. 3 is a diagram illustrating a layer configuration of a fixing belt in the present embodiment. It is a figure which shows the structure of the electric power feeding control system of the laser beam printer in this embodiment. FIG. 2 is a block diagram illustrating a configuration of a fixing control circuit in the present embodiment. It is a figure which shows the switching current in the fixing control circuit in this embodiment. It is a figure explaining the limiter operation | movement which restrict | limits the maximum electric power thrown into the fixing device in this embodiment. It is a figure explaining the voltage dependence of the maximum electric power thrown into the fixing device in this embodiment. It is a figure which shows the structural example of the image formation control circuit of this embodiment. It is a flowchart which shows the procedure example 1 of the electric power control operation | movement which considered the charge condition of the electrical storage device in this embodiment, and / or the temperature of a fixing device. It is a figure explaining the effect of the power control operation by the procedure example 1 of FIG. 13B. It is a flowchart which shows the procedure example 2 of the electric power control operation | movement which considered the charge condition of the electrical storage device in this embodiment, and / or the temperature of a fixing device. It is a flowchart which shows the procedure example 3 of the electric power control operation | movement which considered the charge condition of the electrical storage device in this embodiment, and / or the temperature of a fixing device. It is a figure explaining the effect of the electric power control operation | movement by the procedure example 3 of FIG. It is a figure which shows the cross-sectional structure of the fixing device of the ceramic sheet | seat exothermic heater type in other embodiment. It is a figure which shows the specific structural example of the ceramic planar heating heater in other embodiment. It is a figure which shows the structure of the fixing control circuit in other embodiment. The waveform at the time of energizing to the heater in other embodiments is shown. It is a figure which shows the relationship between the fixing electric power in the conventional electromagnetic induction heating system fixing device, and the time to reach printable temperature.

Claims (11)

A fixing unit that includes a heating element that generates heat using electric power supplied from a commercial power supply, and that fixes the toner image to the transfer material by applying heat of the heating element to the transfer material on which the toner image is formed; An image forming apparatus having
Power limiting means for limiting power supplied from a commercial power source to the fixing means to a predetermined limit level;
Charge / discharge power storage means;
Control means for controlling power supply from the power storage means;
An image forming apparatus comprising: an adjusting unit configured to adjust the restriction level according to a control state by the control unit. The control means controls power supply from the power storage means to a load excluding the fixing means,
While the control means instructs the power supply from the power storage means to the load excluding the fixing means, the adjustment means sets the limit level of the power supplied to the fixing means to an amount corresponding to the power supply. The image forming apparatus according to claim 1, wherein the image forming apparatus is increased only by a predetermined amount.   The image forming apparatus according to claim 1, wherein the control unit supplies power from the power storage unit when heating of the fixing unit is started. It further has a print request presence / absence detecting means for detecting the presence / absence of a print request,
The control unit controls power supplied to the chargeable / dischargeable power storage unit according to a detection result by the print request presence / absence detection unit at least upon power-on or when returning from the energy saving mode. The image forming apparatus according to claim 1.   The control means executes power supply to the chargeable / dischargeable power storage means when the print request presence / absence detecting means detects that there is no print request when the power is turned on or when returning from the energy saving mode. Item 5. The image forming apparatus according to Item 4.   When the control means detects a print request by the print request presence / absence detection means during power supply to the chargeable / dischargeable power storage means, the power supply to the chargeable / dischargeable power storage means is stopped. The image forming apparatus according to claim 4. A storage amount detecting means for detecting a storage amount of the storage means; and a temperature detecting means for detecting a temperature of the fixing means,
The control means includes
When the amount of electricity stored in the electricity storage means detected by the electricity storage amount detection means is greater than or equal to a predetermined amount, and when the temperature of the fixing means detected by the temperature detection means is less than a predetermined temperature, Supplying power to the load;
While supplying power from the power storage means to the load, monitoring the power storage amount of the power storage means and the temperature of the fixing means by repeating detection by the power storage amount detection means and the temperature detection means,
The power supply from the power storage unit to the load is cut off when the power storage amount of the power storage unit becomes less than the predetermined amount, or when the temperature of the fixing unit exceeds the predetermined temperature. An image forming apparatus according to any one of claims 1 to 6.   The image forming apparatus according to claim 1, wherein the fixing unit is an electromagnetic induction heating type fixing device.   8. The image forming apparatus according to claim 1, wherein the fixing unit is a ceramic sheet heater type fixing device. A fixing unit that includes a heating element that generates heat using electric power supplied from a commercial power supply, and that fixes the toner image to the transfer material by applying heat of the heating element to the transfer material on which the toner image is formed; An image forming apparatus control method comprising:
A power limiting step of limiting the power supplied from a commercial power source to the fixing means to a predetermined limit level;
A charging step for charging the chargeable / dischargeable power storage means;
A control step of controlling power supply from the power storage means to a load excluding the fixing means;
An adjustment step for increasing the limit level of the power supplied to the fixing unit by an amount corresponding to the power supply while the power supply is instructed from the power storage unit to the load excluding the fixing unit in the control step. An image forming apparatus control method comprising:   A computer-executable program for realizing the control method of the image forming apparatus according to claim 10.

Images