JP2018173530A - Image forming apparatus, method for controlling heater, and program - Google Patents

Abstract

The present invention provides a technique capable of performing control according to the capacity of a power supply when power supply to an image forming apparatus is started. An image forming apparatus detects a current value from a current sensor in a state where a fixing heater is energized, and the absolute value of a differential value of the current value within a half-wave period is a predetermined value or less. Measure the length of the period. Then, if the length of the specific period is within the first range, the image forming apparatus executes the first control for controlling the energization to the fixing heater with the first energization pattern, and is out of the first range. If so, the second control is executed to control the energization to the fixing heater with the second energization pattern in which the energization amount to the fixing heater per unit time is smaller than that of the first energization pattern. [Selection] Figure 5

Description

  The present invention relates to an image forming apparatus including a heater, a heater control method, and a program.

  2. Description of the Related Art Conventionally, an image forming apparatus that forms an image by an electrophotographic method is known to include a fixing device having a heater and a heating roller heated by the heater. Also known is a technique for controlling energization to the heater so that the surface temperature of the heating roller becomes a desired temperature. A configuration of a conventional fixing device and heater energization control is disclosed in, for example, Patent Document 1.

JP 2008-090110 A

  The power supply capacity is insufficient, such as when power is limited on the facility side, or when the power distribution board is insufficient or has insufficient capacity, but other devices are using power and the capacity is temporarily insufficient. There is an environment. When the power supply capacity is insufficient, when the power supply to the image forming apparatus is started, a voltage drop occurs due to the inrush current to the heater, the control of the image forming apparatus becomes unstable, or in the worst case, the breaker There is a risk of falling.

  The present invention has been made to solve the above-described problems of the prior art. That is, an object of the present invention is to provide a technique capable of performing control according to the capacity of a power supply when power supply to an image forming apparatus is started.

In order to solve the above problems, the image forming apparatus of the present invention has the following configuration.
A heater that receives supply of power from an external power source, a sensor that outputs a different signal according to the amount of current or voltage supplied to the heater from the external power source, and a controller, the controller including the heater In a state where a current is supplied, a predetermined detection amount is detected by receiving a signal from the sensor, and a length of a specific period in which an absolute value of a differential value of the detection amount within a half wave period is equal to or less than a predetermined value It is measured, and it is determined whether the length of the specific period is within the first range or outside the first range.

  In the image forming apparatus disclosed in this specification, when energization of the image forming apparatus is started in a state where the power supply capacity is insufficient, the current or voltage does not reach the peak value, and the amount of change in the current or voltage is small. The period (specific period with a small differential value) becomes longer. Therefore, in the image forming apparatus, measuring the length of the specific period and determining whether or not the specific period is within the first range is whether or not the power supply capacity is insufficient. It is equivalent to judging. Therefore, when the specific period is outside the first range, the image forming apparatus makes the control of the image forming apparatus unstable by reducing the amount of current supplied to the heater per unit time to make it difficult for the voltage drop to occur. Can be avoided.

  A heater control method and program for realizing the functions of the apparatus are also novel and useful.

  According to the present invention, there is provided a technique capable of performing control according to the capacity of a power supply when power supply to an image forming apparatus is started.

1 is a cross-sectional view illustrating a schematic configuration of a printer according to a first embodiment. FIG. 2 is a block diagram illustrating an electrical configuration of a printer. It is a circuit diagram which shows the electric constitution of a power supply part. It is a flowchart which shows the control procedure concerning heater control. It is a flowchart which shows the control procedure concerning a power supply determination process. It is a flowchart which shows the control procedure regarding the determination processing regarding power supply capacity. It is a figure which shows the relationship between the actual measurement current waveform measured with the current sensor, and time THRESH_TIME. (A) It is a figure which simplifies and shows the current waveform at the time of supplying electric power to the fixing heater by wave number control. (B) It is a figure which simplifies and shows the current waveform at the time of supplying electric power to the fixing heater by wave number control after phase control. It is a figure which shows the relationship between the actual measurement current waveform measured with the current sensor which concerns on Embodiment 2, and the difference of the differential value in a predetermined time interval. 10 is a flowchart illustrating a control procedure related to a determination process related to power supply capacity according to the second embodiment. FIG. 6 is a circuit diagram showing an electrical configuration of a power supply unit according to a third embodiment.

(Embodiment 1)
Hereinafter, a printer as an example embodying an image forming apparatus according to the present invention will be described in detail with reference to the drawings. In the following embodiments, the drawings are drawn with simplified or modified exaggeration as appropriate, and the dimensional ratios, shapes, and the like of the respective parts are not necessarily the same as those in the examples. In the present embodiment, the present invention is applied to a laser printer capable of forming a color image, but it goes without saying that the present invention may be applied to a laser printer capable of forming a monochrome image. Absent.

FIG. 1 is a cross-sectional view illustrating a schematic configuration of the printer according to the first embodiment.
In the figure, a printer 100 is a so-called tandem color laser printer. The printer 100 includes process units 10Y, 10M, 10C, and 10K for each color of yellow (Y), magenta (M), cyan (C), and black (K). The process unit 10 </ b> K includes a photoreceptor 2, a charger 3, and a developing device 4. The other color process units 10Y, 10M, and 10C have the same configuration. In addition, the printer 100 includes a main motor for driving the photosensitive member 2, the developing device 4, and the like. Further, the printer 100 has an exposure device 6 common to each color above the process units 10Y, 10M, 10C, and 10K for each color.

  The exposure device 6 includes a polygon motor for rotationally driving the polygon mirror, a motor driving unit for controlling the polygon motor, and the like.

  Further, the printer 100 includes a transfer belt 7, a thermal fixing device 8, a paper feed tray 91, and a paper discharge tray 92. Further, the heat fixing device 8 includes an upper heating roller 81, a fixing heater 82 disposed in the heating roller 81, a temperature sensor 83 made of, for example, a thermistor element disposed near the heating roller 81, and A pressure roller 84 disposed below the heating roller 81 and a drive motor for driving the heating roller 81 are provided. The heating roller 81 is heated to a predetermined temperature by the fixing heater 82, and the surface temperature of the heating roller 81 is detected by the temperature sensor 83. The fixing heater 82 is an example of the heater of the present invention.

Next, the overall operation of the printer 100 will be briefly described.
The printer 100 is connected to a host device (not shown) such as a personal computer via a network, for example. Further, the printer 100 receives a plurality of print data from a host device and forms an image based on the print data, and a plurality of modes such as a sleep mode and a standby mode that are appropriately set according to the status of the printer 100 when no image is formed. In the following description, the print mode and the sleep mode will be mainly described. In the following description, the entire printing operation in the printing mode will be briefly described. In particular, image formation by the process unit 10K will be described.

  That is, in the printing operation in the printing mode, the printer 100 charges the photoreceptor 2 with the charger 3 and then exposes it with the exposure device 6. Thereby, an electrostatic latent image based on the image data is formed on the surface of the photoreceptor 2. Further, the printer 100 forms a toner image by developing the electrostatic latent image with the developing device 4.

  Further, the printer 100 pulls out the sheets stored in the paper feed tray 91 one by one and conveys them to the transfer belt 7. The transfer belt 7 includes a transfer roller 5 on the inner side of the contact position with the photosensitive member 2, and transfers the toner image on the photosensitive member 2 to the sheet when the sheet passes between the photosensitive member 2 and the transfer roller 5. To do. Further, the printer 100 heats the toner image placed on the sheet by the heating roller 81 of the heat fixing device 8 when the sheet passes between the heating roller 81 and the pressure roller 84 of the heat fixing device 8. To heat-fix the sheet. Thus, the sheet on which the image is formed is discharged to the paper discharge tray 92.

  When performing color printing, the printer 100 forms toner images of the respective colors in the process units 10Y, 10M, and 10C of other colors, and sequentially transfers them to a sheet. Thereby, the toner images of the respective colors are superimposed on the sheet. Then, a color image is formed by fixing the superimposed toner images on the sheet.

FIG. 2 is a block diagram showing the electrical configuration of the printer. Next, the electrical configuration of the printer 100 will be described with reference to FIG.
That is, the printer 100 includes a controller 30 including a CPU 31, a ROM 32, a RAM 33, and an NVRAM (nonvolatile RAM) 34. The printer 100 includes a motor 11 as an example of a DC 24V load, an operation panel 35, a network interface 36, a USB interface 37, and a heat fixing device 8, which are electrically connected to the controller 30. Yes. The motor 11 may be a main motor for driving the photosensitive member 2 and the developing unit 4, a polygon motor provided in the exposure unit 6, or a driving motor for driving the heating roller 81. It may be a combination thereof.

  Further, the printer 100 includes a power supply unit 40 that is electrically connected to the controller 30. In the printing mode, the power supply unit 40 supplies power to the controller 30, the motor 11, and the fixing heater 82 of the heat fixing unit 8. Connected so that it can be supplied.

  The ROM 32 stores various control programs for controlling the printer 100, various settings, initial values, and the like. The RAM 33 is used as a work area from which various control programs are read, or as a storage area for temporarily storing data. The CPU 31 controls each component of the printer 100 while storing the processing result in the RAM 33 or the NVRAM 34 according to the control program read from the ROM 32. The RAM 33 or the NVRAM 34 constitutes a storage unit.

  The CPU 31 is an example of a control unit. The controller 30 may be an example of a control unit. Note that the controller 30 in FIG. 2 is a general term that summarizes hardware used to control the printer 100 such as the CPU 31. Specifically, the controller 30 includes an ASIC (Application Specific Integrated Circuit) and the like. Therefore, the ASIC may be responsible for a part of the function of the controller 30, and a part of the function of the controller 30 is a logic circuit. May be responsible.

  The network interface 36 is hardware for communicating with a host device connected via a network. The USB interface 37 is hardware for communicating with a device connected based on the USB standard. The operation panel 35 is hardware that is responsible for displaying a notification to the user and receiving an instruction input by the user.

FIG. 3 is a diagram illustrating an electrical configuration of the power supply unit, and subsequently, an electrical configuration of the power supply unit 40 will be described with reference to FIG. 3.
In the figure, an AC power of 100 V, for example, is supplied from an external power source 411 to a first input terminal 41 constituting a power input unit of the power supply unit 40. The voltage of the external power supply 411 is not limited to 100V, and may be 200V, for example. The external power source 411 may be a commercial AC power source outside the printer 100 or a power source by a private generator.

  The input terminal of the noise filter 60 is connected to the first input terminal 41 via the first line L1 and the second line L2. The noise filter 60 removes noise and the like from the subsequent stage of the noise filter 60.

  An AC / DC converter 43 is connected to the output terminal of the noise filter 60. The AC / DC converter 43 is connected between the rectifier circuit 42 formed of a diode bridge connected to the output terminal of the noise filter 60 and the output terminal of the rectifier circuit 42, and the smoothing capacitor 431 that smoothes the output current of the rectifier circuit 42. And a transformer 432 having a primary winding connected between the output terminals of the rectifier circuit 42 via a switching element 433, and a rectifying / smoothing circuit 44.

  Therefore, AC power supplied from the first input terminal 41 and output from the output terminal of the noise filter 60 is full-wave rectified by the rectifier circuit 42 and then smoothed by the smoothing capacitor 431. The smoothing capacitor 431 is an example of the capacitor of the present invention, and the AC / DC converter 43 is an example of the converter of the present invention. Further, the smoothing capacitor 431 may be composed of a plurality of capacitors connected in parallel.

  The rectifying / smoothing circuit 44 connected to the secondary winding of the transformer 432 includes a rectifying element 441 and a smoothing capacitor 442, and after rectifying the power output from the secondary winding of the transformer 432 by the rectifying element 441, The output is smoothed by the capacitor 442. For example, the DC 24V power output from the rectifying / smoothing circuit 44 is supplied to the DC 24V load represented by the motor 11 via the first output terminal 45.

  Further, the DC / DC converter 46 is connected to the first output terminal 45 via the second input terminal 52, and therefore, the DC 24V power output from the first output terminal 45 is the DC / DC converter. 46. The DC / DC converter 46 converts 24V power to 3.3V, and the power output from the DC / DC converter 46 is supplied to the controller 30 and the like.

  A shunt regulator 61 is connected between the output side of the rectifying / smoothing circuit 44 and the first output terminal 45. Therefore, the output voltage of the rectifying / smoothing circuit 44 is detected and error amplified by the shunt regulator 61 and fed back to the power supply control IC 63 via the photocoupler 62.

  The power supply control IC 63 is for switching control of the switching element 433 of the AC / DC converter 43.

  One end side of the third line L3 is connected to the first branch point P1 provided on the first line L1, and the other end side of the third line L3 is fixed via the electromagnetic relay 49. The heater 82 is connected to one terminal.

  In addition, one end side of the fourth line L4 is connected to the second branch point P2 provided on the second line L2, and the other end side of the fourth line L4 is, for example, from a triac element. It is connected to the other terminal of the fixing heater 82 through the configured switching element 50. The switching element 50 is a switching element.

  The energization timing of the switching element 50 is controlled by a heater control signal from the controller 30 via the phototriac coupler 51. When the switching element 50 continuously receives an ON signal from the controller 30, the switching element 50 continues to be energized even at the next zero cross timing, and when the ON signal is not continuously received from the controller 30, the next external power supply A non-energized state is established at the zero cross timing of the voltage input from 411. The zero cross timing of the voltage input from the external power supply 411 is an example of the timing at which the voltage value of the external power supply 411 input from the first input terminal 41 passes zero volts.

  In the present embodiment, the electromagnetic relay 49 is disposed on the third line L3 and the switching element 50 is disposed on the fourth line L4. However, the electromagnetic relay 49 is disposed on the third line L3 or the fourth line L4. The electromagnetic relay 49 and the switching element 50 may be arranged in series.

  The contact of the electromagnetic relay 49 is controlled by a relay control signal from the controller 30.

  That is, in the printing mode, the electromagnetic relay 49 is controlled to be in a closed state (energized state) by a relay control signal from the controller 30, and in the sleep mode, the contact is controlled to be in an open state (non-energized state). . Further, in the printing mode, when opening of the cover is detected via a switch (not shown) for detecting opening / closing of the cover of the printer 100, the energized state is changed to the non-energized state by the relay control signal from the controller 30. It is controlled and the safety of the device is ensured.

  The phototriac coupler 51 outputs a control signal to the switching element 50 based on the heater control signal from the controller 30. Accordingly, when the switching element 50 continuously receives the ON signal from the controller 30, the switching element 50 continues to be energized even at the next zero cross timing, and when the ON signal is not continuously received from the controller 30, The non-energized state is entered at the zero cross timing of the incoming external power supply 411.

  Therefore, in the printing mode, the first line L1, the first branch point P1, the third line L3, the electromagnetic relay 49, the switching element 50, the fourth line L4, the second branch point P2, and the second line. Electric power is supplied from the external power source 411 to the fixing heater 82 via L2, thereby heating the heating roller 81. Further, when the electromagnetic relay 49 or the switching element 50 is in a non-energized state, power is not supplied to the fixing heater 82.

  Between the first branch point P1 on the third line L3 and the electromagnetic relay 49, for example, a hall-type current sensor 55 using a hall element is arranged, and the current flowing through the third line L3 That is, the current value (current amount) supplied to the fixing heater 82 can be measured. Specifically, the current sensor 55 has a sampling period sufficiently finer than half of the AC period of the power supplied from the external power supply 411 and sufficiently finer than a time width in which one capacitor input current is generated. The value can be measured. The measured current value is output to the controller 30 as a current sensor signal via the second output terminal 47 and the third input terminal 48 in real time. The current sensor 55 is an example of the current sensor of the present invention.

  As the current sensor, instead of the current sensor 55 capable of measuring the absolute value of the current value of the alternating current flowing on the first line L1, the relative value of the alternating current relative to the current value of zero is used. It is also possible to use a comparison type current sensor capable of measuring the current amount, and the current value and the relative current amount are examples of the detection amount of the present invention. Further, the current sensor 55 is connected between the first input terminal 41 and the first branch point P1 on the first line L1, and between the first input terminal 41 and the second branch point on the second line L2. It may be arranged between P2 and on the fourth line L4.

  However, the AC / DC converter 43 is more disposed when the current sensor 55 is disposed on the third line L3 or the fourth line L4 than when disposed on the first line L1 and the second line L2. Therefore, the current value (current amount) supplied to the fixing heater 82 can be measured (detected) more accurately.

  The first line L1 and the second line L2 correspond to the first line of the present invention, and the third line L3 and the fourth line L4 correspond to the second line of the present invention, respectively. Moreover, the 1st line and the 2nd line point out the electric power path | route for transmitting electric power, and do not necessarily need to be connected mechanically continuously. That is, the power path only needs to have a function of transmitting power, and includes those that are intermittently connected via a switching member, a transformer, or the like.

  A zero cross detection circuit 56 is connected between the third line L3 between the electromagnetic relay 49 and the fixing heater 82 and the fourth line L4 between the second branch point P2 and the switching element 50. When the contact of the electromagnetic relay 49 is closed (energized), the zero cross point of the external power source 411 connected to the first input terminal 41 can be detected and the zero cross signal can be output to the controller 30 in real time. It is.

  FIG. 4 is a flowchart showing a control procedure related to heater control. Next, the control procedure will be described with reference to FIG. Note that the control shown in FIG. 4 is executed by the controller 30 at predetermined time intervals when the printer 100 is turned on or during the print mode period.

  That is, first, in step 1 (hereinafter referred to as S1), the controller 30 determines whether or not it is a print mode for printing the print data transmitted from the host device, and if it is not the print mode (S1: NO), in the next S7, the controller 30 controls the contact of the electromagnetic relay 49 to the OFF state (non-energized state), and this processing is terminated.

  On the other hand, if it is the printing mode (S1: YES), in the next S2, the controller 30 controls the contact of the electromagnetic relay 49 from the off state (non-energized state) to the on state (energized state).

  Next, in S3, the controller 30 determines whether or not printing based on the print data transmitted from the host device is continuing. If printing is not continuing (S3: NO), this process ends. .

  On the other hand, if printing is continuing (S3: YES), in S4, the controller 30 compares the detected temperature value of the temperature sensor 83 with the reference temperature value. In S5, if the detected temperature value of the temperature sensor 83 exceeds the reference temperature value in the comparison in S4, it is determined that it is not necessary to supply power to the fixing heater 82 (S5: NO), and the process returns to S3. .

  If the detected temperature value of the temperature sensor 83 is lower than the reference temperature value in the comparison in S4, the controller 30 determines that power supply to the fixing heater 82 is necessary (S5: YES), and proceeds to S6. To do.

  Next, in S6, the controller 30 controls the energization state of the switching element 50 based on the heater control method set in S20 or S23 shown in FIG. 5 to be described later, thereby supplying power to the fixing heater 82. After that, the process returns to S3. Note that S6 is an example of an energization step and an energization process of the present invention.

  It should be noted that when the printer 100 is turned on, shifted from the sleep mode to the print mode, or when a new print job is started after one continuous print job is completed, FIG. Since the wave number control is set in step S13, power is supplied to the fixing heater 82 by the wave number control.

  FIG. 5 is a flowchart showing a control procedure related to the power source determination process. Next, the control procedure will be described with reference to FIG. Note that the control shown in FIG. 5 is activated when the printer 100 is turned on or when print data is received from the host device and the printer shifts from the sleep mode to the print mode, and thereafter during the print mode period. Executed by the controller 30.

  That is, in S11, the controller 30 sets the value of the counter stored in the RAM 33 or NVRAM 34 to zero, and in the next S12, the controller 30 determines whether or not the contact of the electromagnetic relay 49 is in an on state (energized state). to decide. When the controller 30 determines that the contact of the electromagnetic relay 49 is not in the on state (energized state) (S12: NO), the determination in S12 is performed until the contact of the electromagnetic relay 49 is controlled to be in the on state (energized state). repeat.

  On the other hand, when the printer 100 is in the print mode and the above-described S2 shown in FIG. 4 is executed and the contact of the electromagnetic relay 49 is controlled to be in the ON state (energized state), in S12, the controller 30 It is determined that the contact of relay 49 is in an on state (energized state) (S12: YES), and in next S13, wave number control is set as heater control, and the process proceeds to next S14.

  Next, in S14, the controller 30 acquires the zero cross signal output from the zero cross detection circuit 56, calculates the AC half cycle (Tu) based on the zero cross signal, and proceeds to the next S15. Note that the AC half cycle (Tu) is a half wave of the power cycle of the external power source 411 as shown in FIG.

  Next, in S15, the controller 30 determines whether or not the switching element 50 is energized. If it is determined that the switching element 50 is not energized (S15: NO), the controller 30 returns to S14.

  On the other hand, when the controller 30 supplies power to the fixing heater 82 in order to heat the heating roller 81 in S6 shown in FIG. 4 described above, the controller 30 turns on the switching element 50 in S15. It is determined that the state has been controlled (S15: YES). In the next S16, the controller 30 determines whether or not the first wave in the heater control in the continuous series of print jobs out of the AC power supplied to the fixing heater 82. If it is determined that it is not the first wave (S16: NO), the process returns to S14.

On the other hand, when the controller 30 determines in S16 that the wave is the first wave (S16: YES), in the next S17, a determination process relating to the power supply capacity is executed using the first half wave.
The determination process related to the power supply capacity is the determination process shown in FIG. 6. Next, the control procedure of the determination process related to the power supply capacity will be described with reference to FIG.

  That is, in S31, the controller 30 adds one counter value stored in the RAM 33 or the NVRAM 34. Next, in S <b> 32, the controller 30 acquires the zero cross timing t <b> 0 based on the zero cross signal output from the zero cross detection circuit 56.

  Next, in S33, the controller 30 acquires the output current value of the current sensor 55 from the zero cross timing t0 and sequentially differentiates the current value. Note that S33 is an example of the detection step and the detection process of the present invention. Note that “differentiation” in the present embodiment refers to dividing (dividing) a difference between acquired discrete current values by unit time.

  Next, in S34, the controller 30 calculates a time THRESH_TIME in which the differential value of the current value falls between the threshold value THRESH LEVEL1 and the threshold value THRESH LEVEL2. Note that S33 corresponds to the specific period length measurement step and the specific period length measurement process of the present invention, and the time THRESH_TIME is an example of the specific period of the present invention.

  Specifically, when the capacity of the external power supply 411 connected to the first input terminal 41 of the power supply unit 40 is sufficiently larger than the power supplied to the printer 100, especially the fixing heater 82, for example, 7, the output current value of the current sensor 55 changes to draw a sine waveform or a waveform close thereto, and the differentiated result changes to draw a cosine waveform or a waveform close thereto. .

  However, when the capacity of the external power supply 411 using a private power generator is small, or when the power supply is limited on the equipment side of the external power supply 411 in a factory or an apartment house, the capacity of the switchboard is insufficient or In an environment where the power supply capacity is insufficient, such as when power is being used by another device and the capacity is temporarily insufficient, the peak of the current supplied to the fixing heater 82 is reached. The voltage can be suppressed in the vicinity. Therefore, the current supplied to the fixing heater 82 is constant without increasing, and the output current value of the current sensor 55 changes linearly or nearly in a straight line as shown by a solid line in FIG. 7, for example.

  The differential value of the current value in this case, as shown by a broken line in FIG. 7, changes gradually in a state where the output current of the current sensor 55 is linear or close to a straight line after being gently reduced and then rapidly changed to a vertical direction. After changing in a state of being linear or close to a straight line corresponding to the portion to be changed, it changes rapidly, then changes vertically, and then changes so as to increase gently. Therefore, a time THRESH_TIME in which the differential value of the current value falls between the preset threshold value THRESH LEVEL1 and the threshold value THRESH LEVEL2 is calculated. The threshold value THRESH LEVEL1 and the threshold value THRESH LEVEL2 are set so that the absolute values thereof are the same and the signs of plus / minus are different.

  In this calculation, when the absolute value of the differential value of the current value is used, it is possible to calculate the time THRESH_TIME by comparing the threshold value with the absolute value of the threshold value THRESH LEVEL1 or the threshold value THRESH LEVEL2.

  As described above, in the present embodiment, since the differential value of the supply current to the fixing heater 82 is used to determine the capacity of the external power supply 411, it becomes easy to grasp the distortion (saturation) of the supply current and accurately. The capacity of the external power supply 411 can be determined.

  Next, in S35, the controller 30 calculates the ratio α of the time THRESH_TIME to the AC half cycle (Tu) obtained in S14 shown in FIG. That is, the ratio α = (THRESH_TIME) / (Tu) × 100 is calculated.

  Next, in S36, the controller 30 determines whether or not the ratio α obtained in S35 is in the range of 20% to 30%. If it is determined in S36 that the controller 30 is within the range (S36: YES), it is determined that the capacity of the external power supply 411 is normal, and in the next S37, the controller 30 sets the level 0 to the RAM 33. Or it memorize | stores in NVRAM34 and complete | finishes a process. The determination by the controller 30 in S36 may determine whether it is within the range of 10% or more and 40% or less, but it is determined whether it is within the range of 20% or more and 30% or less. It is more preferable to do this.

  On the other hand, if it is determined in S36 that the controller 30 is not within the range (S36: NO), it is determined that the capacity of the external power source 411 is insufficient or limited, and in the next S38, the controller 30 The level 1 is stored in the RAM 33 or the NVRAM 34, and the process is terminated. In addition, 40% or less, more preferably 30% or less corresponds to the first threshold value of the present invention, and 10% or more, more preferably 20% or more is an example of the second threshold value of the present invention.

  As described above, in this embodiment, when the printer 100 is turned on, when the printer 100 is switched from the sleep mode to the print mode, or when a new print job is started after one continuous print job is completed. The fixing heater 82 is cold. In the state where the fixing heater 82 is cold, the capacity of the external power supply 411 is determined using the half-wave supply current of the first wave in energization to the fixing heater 82, so the external power supply 411 is accurately detected. The capacity can be determined.

  That is, FIG. 8A shows a current waveform when power is supplied to the fixing heater by the 33% duty wave number control. The first-wave supply current waveform A in the energization to the fixing heater 82 is as follows. When the fixing heater 82 is cold, it becomes a large value due to the inrush current. Therefore, since the capacity of the external power supply 411 is determined using the first large supply current waveform A, the capacity of the external power supply 411 can be determined with high accuracy.

  In the case of 33% duty wave number control, as shown in FIG. 8A, power is supplied to the fixing heater after every half wave, so that the half wave is accurately extracted. Therefore, the capacity of the external power supply 411 can be determined with high accuracy.

  FIG. 8B shows a current waveform when the electric power is supplied to the fixing heater by the 33% duty wave number control after the phase control. Even in such a control method, there is a control method for the wave number control. The first supply current waveform B after the change has a large inrush current since the fixing heater 82 is still cold. Therefore, since the capacity of the external power supply 411 is determined using the first supply current waveform B, the capacity of the external power supply 411 can be determined with high accuracy. In this case, 100% power supply control may be used instead of the 33% duty wave number control.

  In the case shown in FIG. 8B, by first performing the phase control, the fixing heater 82 in the cold state can be heated to some extent, and the inrush current when the shift to the wave number control thereafter is suppressed. It becomes possible.

  Next, returning to the description of the control procedure shown in FIG. 5, in S18, the controller 30 determines whether or not the number of determination processes, that is, whether or not the value of the counter is larger than “N”. In the first process, since the number of determination processes is not greater than “N” (S18: NO), in the next S19, the controller 30 determines whether or not the determination level is “0”.

  Next, in S19, when the controller 30 determines that the determination level is “0” (S19: YES), that is, in S36 shown in FIG. 6, the ratio α is in the range of 20% to 30%. If it is determined that it is within the range (S36: YES), in the next S20, the controller 30 stores the normal heater control in the RAM 33 or NVRAM 34, and then resets the counter value in the next S21. Then, the process is terminated.

Therefore, in S6 shown in FIG. 4 described above, the controller 30 supplies power to the fixing heater 82 by normal heater control.
In normal heater control, shortening of the first printout time (hereinafter abbreviated as FPOT) is regarded as important. Therefore, the controller 30 performs the heater control by wave number control in which the electric power from the external power supply 411 is turned on or off every half wave, specifically, wave number control with a high duty, preferably 100% duty. Alternatively, the controller 30 turns on phase control at a predetermined phase angle timing from the zero cross timing every half wave from the external power supply 411, specifically, phase control with a long on period, preferably phase control with a phase angle of zero degrees. To perform heater control. Or you may use the control method which combined them as normal heater control. This normal heater control is an example of the first control of the present invention.

  On the other hand, when the controller 30 determines in S19 that the determination level is not “0” (S19: NO), that is, in S36 shown in FIG. 6, the ratio α is 20% or more and 30% or less. If it is determined that it is not within the range (S36: NO), in the next S23, the controller 30 stores the second heater control in the RAM 33 or the NVRAM 34, and proceeds to the next S24.

  Therefore, in S6 shown in FIG. 4, the controller 30 supplies power to the fixing heater 82 by the second heater control. This second heater control is a control method corresponding to the shortage of the capacity of the external power supply 411 rather than the shortening of the FPOT time. The second heater control is a control method that focuses on reducing the inrush current when the fixing heater 82 is cold and reducing the supply current when the fixing heater 82 is at a high temperature.

The second heater control employs phase control with a phase angle of 90 degrees or more, more preferably phase control with a phase angle of 150 degrees or more. Further, the phase angle is not fixed, and the controller 30 performs energization control so that the phase angle gradually decreases (the energization time becomes longer) with the passage of time so that the warm-up time of the fixing heater 82 is shortened. But it doesn't matter.
In addition, the controller 30 performs energization control such that 100% energization is performed after performing phase control for a certain period of time, that is, several seconds during which an inrush current occurs, so that the warm-up time of the fixing heater 82 is shortened. You can do that.

  Furthermore, wave number control can also be used as the second heater control. For example, in the case of energization control that switches to 100% energization after performing 33% duty wave number control for a predetermined time, the predetermined time may be extended. In addition, in the case of energization control in which the duty value increases as time passes, specifically, the duty value gradually increases as 33%, 67%, and 100% as time passes, the timing for switching the duty value May be delayed. Alternatively, it is possible to use energization control in which the duty value is constant and the wave number control time is gradually increased according to the counter value incremented in S31 shown in FIG. 6 to delay the timing of switching to 100% energization.

  In this case, it can be said that the phase control is suitable for energization control in an environment where the voltage of the external power supply 411 hardly occurs compared to the wave number control and the capacity of the external power supply 411 is insufficient. The second heater control is an example of the second control of the present invention. Furthermore, in the second heater control, the energization amount when the wave number control with a duty value of 33% or 67% or the phase control with a phase angle of 90 degrees or more is smaller than the energization amount of the first heater control. .

  As described above, in this embodiment, when heating the heating roller 81, in S6 shown in FIG. 4, power is supplied to the fixing heater 82 based on the heater control method set in S20 and S23 shown in FIG. Therefore, when power is limited on the facility side, when power supply to the image forming apparatus is started, a voltage drop occurs due to an inrush current to the heater, and control of the image forming apparatus does not become unstable. . In addition, even in an environment where the power supply capacity is insufficient, such as when the power distribution board is insufficient or the capacity is sufficient, but other devices are using power and the capacity is temporarily insufficient, the image forming apparatus When the power supply is started, a voltage drop is not caused by the inrush current to the heater, and the control of the image forming apparatus does not become unstable. Furthermore, there is no possibility that the breaker will drop when power supply to the image forming apparatus is started.

  In the present embodiment, even when the ratio α is 20% or less, power is supplied to the fixing heater 82 by the second heater control. This is because, when the ratio α is 20% or less, when the voltage of the external power supply 411 changes while drawing a distorted waveform close to a triangular wave, unexpected sudden changes occur, and unexpected power (unstable Power) is assumed. Even in such a case, control is performed in the same manner as when the ratio α is 30% or more, that is, when the capacity of the external power supply 411 is insufficient, thereby preventing the control of the image forming apparatus from becoming unstable.

  Next, in S24, the controller 30 determines whether or not printing has been completed. If it is determined that printing has not ended (S24: NO), the controller 30 returns to S23 and continues until the printing is completed. The heater control is maintained. That is, the second heater control is maintained until printing of one sheet or printing of a plurality of continuous sheets is completed.

  On the other hand, if the controller 30 determines in S24 that printing has ended (S24: YES), the process returns to S13, and the controller 30 sequentially executes S13 to S16 again.

  Prior to the start of printing of a new print job, when the controller 30 energizes the switching element 50 to start energization of the fixing heater 82 in S6 of FIG. 4 described above, S15 and In S16, the controller 30 determines YES (S15: YES, S16: YES), and therefore the controller 30 executes the processes of S17 to S21 and S23 to S24 again.

  However, every time the controller 30 executes S17, the counter is incremented in S31 shown in FIG. 6. Therefore, when the controller 30 executes S17 N + 1 times, in S18, the controller 30 determines that the number of determination processes is “N”. (S18: YES), the controller 30 notifies an error in the next S22 and ends the process.

  That is, no electric power is supplied to the fixing heater 82. The error notification may be made by notifying a capacity shortage error of the external power supply 411 using a display on the operation panel 35 or a power supply abnormality lamp, or generating a capacity shortage error sound with a buzzer or the like. Absent. Note that “N” takes any one value from 3 to 10.

  Therefore, if the ratio α does not fall within the range of 20% to 30% continuously N + 1 times, the capacity of the external power supply 411 may be insufficient or unexpected power (unstable power) may be supplied. . That is, an error is notified that the capacity of the printer 100 is insufficient or unstable. Therefore, when power supply to the image forming apparatus is started, it is possible to avoid a voltage drop caused by an inrush current to the heater and an unstable control of the image forming apparatus. In the worst case, it is possible to avoid the phenomenon that the breaker falls or the control of the image forming apparatus becomes unstable.

  In the present embodiment, since the end of printing is determined in S24 shown in FIG. 5, a plurality of prints that are intermittently generated until the controller 30 reports an error in S22 shown in FIG. After the job is processed. However, in S24 shown in FIG. 5, instead of the determination of “printing end?”, “Has a predetermined time passed?”, Specifically, a few seconds, more specifically, an arbitrary time between 1 second and 5 seconds. If it is determined whether the time has elapsed, an error can be notified that the capacity of the external power supply 411 is insufficient or the external power supply 411 is unstable during the warm-up period of the fixing heater 82. .

(Embodiment 2)
FIG. 9 is a diagram illustrating a relationship between an actual current waveform measured by the current sensor according to the second embodiment and a difference between differential values at a predetermined time interval, and FIG. 10 is a determination regarding a power supply capacity according to the second embodiment. It is a flowchart which shows the control procedure regarding a process, and the detail is demonstrated according to FIG. 9 and FIG. 10 below. In addition, in the description, the same code | symbol is attached | subjected and demonstrated to what has the same effect as Embodiment 1. FIG.

  That is, in the first embodiment described above, in S34, the controller 30 is configured to calculate the time THRESH_TIME in which the differential value of the current value falls between the threshold value THRESH LEVEL1 and the threshold value THRESH LEVEL2. However, in the second embodiment, the differential value of the current at the first time point (indicated by t1 in FIG. 9) in the half-wave period and the second time point that is different from the first time point by a constant time tα. A difference X from the differential value of the current value at (indicated by t2 in FIG. 9) is calculated (an example of the difference calculating step and the difference calculating process of the present invention). If the differential value difference X is within the second range, electric power is supplied to the fixing heater 82 under normal heater control. If the differential value difference X is outside the second range, power may be supplied to the fixing heater 82 by the second heater control.

  As shown in the specific control procedure in FIG. 10, in S39, the controller 30 sets the zero cross timing t0 at the first time point t1, and adds the time tα to the zero cross timing t0 at the second time point t2. And set.

  Next, in S40, the controller 30 calculates a difference X between the differential value at the second time point t2 and the differential value at the first time point t1.

  Next, in S41, the controller 30 determines whether or not the absolute value of the difference X is larger than the predetermined value Y, and when the controller 30 determines that the absolute value of the difference X is larger than the predetermined value Y ( (S41: YES), in next S38, the controller 30 stores the level 1 in the RAM 33 or the NVRAM 34, and ends the process.

  In other words, when the current value is distorted due to the shortage of the capacity of the power source, as shown in FIG. For this reason, when a portion where the absolute value of the difference X is larger than a predetermined threshold (predetermined value Y) is detected, the controller 30 stores the level 1 in the RAM 33 or the NVRAM 34 in S38. As a result, the second heater control is stored in the RAM 33 or the NVRAM 34 in S23 shown in FIG.

  On the other hand, when the controller 30 determines in S41 that the absolute value of the difference X is not larger than the predetermined value Y, that is, smaller or equal (S41: NO), in the next S42, the controller 30 The time tα is added to the time point t1 and the second time point t2, respectively.

  Next, in S43, the controller 30 determines whether or not the second time point t2 is greater than or equal to the AC half cycle (Tu) obtained in S14 shown in FIG. If the controller 30 determines that the second time point t2 is greater than or equal to the AC half cycle (Tu) (S43: YES), in the next S37, the controller 30 sets the level 0 to the RAM 33 or the NVRAM 34. To remember. Thereafter, the process ends.

  That is, the first heater control is stored in the RAM 33 or the NVRAM 34 in S20 shown in FIG.

  On the other hand, if the controller 30 determines in S41 that the second time point t2 is not greater than or equal to the AC half cycle (Tu), that is, greater (S43: NO), the process returns to S40, and the next time The difference X between the differential values of the points is obtained.

  In the present embodiment, it is determined whether the absolute value of the difference X between the differential values of the current values is greater than a predetermined threshold (predetermined value Y) while changing the first time point t1 and the second time point t2. I made it. However, by setting a large interval between the first time point t1 and the second time point t2, the difference X between the differential values of the current values without changing the value between the first time point t1 and the second time point t2. It may be determined whether the absolute value of is greater than a predetermined threshold (predetermined value Y).

  In addition, this Embodiment is only a mere illustration and does not limit this invention at all. Therefore, the present invention can be variously improved and modified without departing from the scope of the invention. For example, the image forming apparatus is not limited to a printer, and can be applied as long as it has a function of forming an image by an electrophotographic method, such as a copier, a FAX apparatus, or a multifunction peripheral. The printer 100 according to the embodiment is a color printer and includes four process units 10K, 10C, 10M, and 10Y. However, the printer 100 may be a monochrome printer including one process unit.

  In the first embodiment, the current sensor 55 is used. However, as shown in FIG. 11, a voltage sensor 57 can be used instead of the current sensor 55. In that case, in S33-S34 shown in FIG. 6, it will process based on the voltage value output from an alternating current voltmeter.

  In the first embodiment, when the controller 30 determines in S18 shown in FIG. 5 that the determination level is not “0” (S19: NO), until the printing is completed (S24: YES), In S6 shown in FIG. 4, the controller 30 is configured to supply power to the fixing heater 82 by the second heater control. For example, the controller 30 supplies power to the fixing heater 82 by the second heater control for a certain period of time. Then, the setting is changed to normal heater control, and power is supplied to the fixing heater 82 by normal heater control, so that warm-up can be completed early.

  In the first embodiment, it is determined whether or not the ratio α is in the range of 20% or more and 30% or less, but it is only determined whether or not the ratio α is in the range of 30% or less. Thus, it may be determined whether or not the capacity of the external power source 411 is insufficient.

  In the first embodiment, in S16 shown in FIG. 5, the controller 30 determines whether or not it is the first wave. In subsequent S17, the controller 30 uses the first wave to perform a determination process regarding the power supply capacity. However, instead of using the first wave, the determination process regarding the power supply capacity may be performed using the second and third waves after the first wave.

  Further, in the first embodiment, the current sensor 55 is connected between the first input terminal 41 on the first line L1 and the first branch point P1, and between the first input terminal 41 on the second line L2 and the first input terminal 41. It may be arranged between two branch points P2. In this case, when power is supplied to the fixing heater 82, the current sensor 55 detects a combined current of the current supplied to the fixing heater 82 and the current supplied to the AC / DC converter 43. become. Since the current supplied to the fixing heater 82 is much larger than the current supplied to the AC / DC converter 43, in the present invention, this combined current can be regarded as the current supplied to the fixing heater 82 approximately.

DESCRIPTION OF SYMBOLS 100 Printer 6 Exposure device 8 Thermal fixing device 81 Heating roller 82 Fixing heater 83 Temperature sensor 30 Controller 31 CPU
40 power supply unit 41 first input terminal 42 rectifier circuit 43 AC / DC converter 50 semiconductor switching element 55 current sensors L1 to L4 first to fourth lines P1 to P2 first to second branch points

Claims (21)

A heater that receives power from an external power source;
A sensor that outputs different signals according to the amount of current or voltage supplied to the heater from the external power source; and
A controller,
With
The controller is
In a state where the heater is energized, a predetermined detection amount is detected by receiving a signal from the sensor,
Measure the length of a specific period in which the absolute value of the differential value of the detected amount within a half wave period is equal to or less than a predetermined value,
Determining whether the length of the specific period is within a first range or outside the first range;
An image forming apparatus. The image forming apparatus according to claim 1,
The controller is
If the length of the specific period is within the first range, a first control for controlling energization of the heater with a first energization pattern is executed,
If the length of the specific period is out of the first range, the energization to the heater is controlled by the second energization pattern in which the energization amount to the heater per unit time is smaller than that of the first energization pattern. To execute the second control,
An image forming apparatus. The image forming apparatus according to claim 1 or 2,
The controller is
The length of the specific period is measured when performing wave number control in which power from the external power source is energized or de-energized every half wave,
An image forming apparatus. The image forming apparatus according to claim 3.
The controller is
The length of the specific period is measured in the first half wave when the wave number control is performed.
An image forming apparatus. The image forming apparatus according to any one of claims 1 to 3,
The controller is
When the length of the specific period is less than a first threshold, the length of the specific period is determined to be within the first range, and when the length of the specific period is equal to or greater than the first threshold, the specific Determining that the length of the period is out of the first range;
An image forming apparatus. The image forming apparatus according to any one of claims 1 to 3,
The controller is
If the length of the specific period is less than the first threshold and not less than a second threshold that is shorter than the first threshold, the length of the specific period is determined as the first range, and the length of the specific period If the length of the specific period is less than the second threshold, or if the length of the specific period is less than the second threshold,
An image forming apparatus. The image forming apparatus according to any one of claims 2 to 6,
The controller is
As the second control, after performing the phase control for energizing the current from the external power source at the timing of the predetermined phase angle from the timing when the detection amount becomes zero every half wave, Switch to output pattern control,
An image forming apparatus. The image forming apparatus according to any one of claims 2 to 6,
The controller is
The second control is a phase control in which a current from the external power source is supplied at a timing of a predetermined phase angle from a timing at which the detection amount becomes zero every half wave, and the predetermined phase angle is set to 90 degrees. The phase control is performed as described above.
An image forming apparatus. The image forming apparatus according to any one of claims 2 to 8,
The controller is
Switching from the second control to the first control when a second predetermined time has elapsed after starting the execution of the second control;
An image forming apparatus. The image forming apparatus according to any one of claims 2 to 8,
The controller is
When the second predetermined time has elapsed after starting the execution of the second control, the second control is terminated, and the length of the previous specific period is re-measured.
If the length of the re-measured specific period is within the first range, the first control is executed,
If the remeasured length of the specific period is outside the first range, the second control is executed.
An image forming apparatus. The image forming apparatus according to claim 10.
With a notification unit,
The controller is
Count the number of times the length of the specific period was measured,
When the count value exceeds the threshold number of times, the notification unit is controlled to notify an error.
An image forming apparatus. The image forming apparatus according to any one of claims 1 to 11,
An AC input unit to which power from the external power source is input;
A converter having a rectifier circuit for rectifying an alternating current from the alternating current input unit, and a capacitor for smoothing the current from the rectifier circuit;
A first line that electrically connects the AC input unit and the converter;
A second line electrically connecting the branch point on the first line and the heater;
With
The controller is supplied with power converted by the converter,
The sensor is a current sensor and is disposed on the second line.
An image forming apparatus. A heater that receives power from an external power source;
A sensor that outputs different signals according to the amount of current or voltage supplied to the heater from the external power source; and
A controller,
With
The controller is
In a state where the heater is energized, a predetermined detection amount is detected by receiving a signal from the sensor,
Calculating a difference between the differential value of the detected amount at the first time point and the differential value of the detected amount at the second time point within the half-wave period;
If the difference is within the second range, execute a first control for controlling energization of the heater with a first energization pattern;
If the difference is outside the second range, a second energization pattern that controls the energization of the heater with a second energization pattern that has a smaller energization amount to the heater per unit time than the first energization pattern. Execute control,
An image forming apparatus. A heater that receives power from an external power source;
A sensor that outputs different signals according to the amount of current or voltage supplied to the heater from the external power source; and
A method of controlling the heater of an image forming apparatus comprising:
A detection step of detecting a predetermined detection amount in response to a signal from the sensor while the heater is energized;
A specific period length measurement step of measuring the length of a specific period in which the absolute value of the differential value of the detected amount within a half-wave period is equal to or less than a predetermined value;
An energization step for controlling energization of the heater,
In the energization step, it is determined whether the length of the specific period is within the first range or outside the first range.
The heater control method characterized by the above-mentioned. In the heater control method according to claim 14,
An energization step for controlling energization of the heater,
If the length of the specific period is within the first range, a first control for controlling energization of the heater with a first energization pattern is executed,
If the length of the specific period is out of the first range, the energization to the heater is controlled by the second energization pattern in which the energization amount to the heater per unit time is smaller than that of the first energization pattern. Performing the second control to perform the energization step;
A method for controlling a heater, comprising: A heater that receives power from an external power source;
A sensor that outputs different signals according to the amount of current or voltage supplied to the heater from the external power source; and
A method of controlling the heater of an image forming apparatus comprising:
A detection step of detecting a predetermined detection amount in response to a signal from the sensor while the heater is energized;
A difference calculating step of calculating a difference between a differential value of the detected amount at a first time point and a differential value of the detected amount at a second time point within a half-wave period;
An energization step for controlling energization of the heater,
The energization step of determining whether the difference is within a second range or outside the second range;
The heater control method characterized by the above-mentioned. In the heater control method according to claim 16,
An energization step for controlling energization of the heater,
If the difference is within the second range, execute a first control for controlling energization of the heater with a first energization pattern;
If the difference is outside the second range, a second energization pattern that controls the energization of the heater with a second energization pattern that has a smaller energization amount to the heater per unit time than the first energization pattern. Performing the control, the energization step;
A method for controlling a heater, comprising: A heater that receives power from an external power source;
A sensor that outputs different signals according to the amount of current or voltage supplied to the heater from the external power source; and
An image forming apparatus comprising:
A detection process for detecting a predetermined detection amount in response to a signal from the sensor while the heater is energized;
A specific period length measurement process for measuring the length of a specific period in which the absolute value of the differential value of the detected amount within a half wave period is equal to or less than a predetermined value;
An energization process for controlling energization to the heater,
Determining whether the length of the specific period is within a first range or outside the first range;
A program characterized by having executed. The program according to claim 18, wherein
An energization process for controlling energization to the heater,
If the length of the specific period is within the first range, a first control for controlling the energization of the heater with a first energization pattern is executed,
If the length of the specific period is out of the first range, the energization to the heater is controlled by the second energization pattern in which the energization amount to the heater per unit time is smaller than that of the first energization pattern. Performing the second control to perform the energization process,
Is executed by the image forming apparatus. A heater that receives power from an external power source;
A sensor that outputs different signals according to the amount of current or voltage supplied to the heater from the external power source; and
An image forming apparatus comprising:
A detection process for detecting a predetermined detection amount in response to a signal from the sensor while the heater is energized;
A difference calculation process for calculating a difference between a differential value of the detected amount at a first time point and a differential value of the detected amount at a second time point within a half-wave period;
An energization process for controlling energization to the heater,
Determining whether the difference is within a second range or outside the second range;
A program characterized by having executed. The program according to claim 20, wherein
An energization process for controlling energization to the heater,
If the difference is within the second range, execute a first control for controlling energization of the heater with a first energization pattern;
If the difference is outside the second range, a second energization pattern that controls the energization of the heater with a second energization pattern that has a smaller energization amount to the heater per unit time than the first energization pattern. Executing the control, the energization process,
Is executed by the image forming apparatus.

Images