JP5482555B2 - Image forming apparatus and program - Google Patents

Description

  The present invention relates to an image forming apparatus and a program.

  2. Description of the Related Art Conventionally, there has been known a control device that controls heating of an object to be heated for melting toner by electromagnetic induction in an electrophotographic fixing process (see, for example, Patent Document 1). The control device includes an exciting coil that heats a heated object by electromagnetic induction, a switching element for controlling power supply to the exciting coil, and a control signal for controlling the operation of the switching element. (Induction Heating) control part. The IH control unit performs switching based on the on-duty value of a predetermined control signal when controlling the switching element to supply constant power to the exciting coil.

JP 2007-264085 A

  An object of the present invention is to provide an image forming apparatus and a program capable of detecting an abnormality of an exciting coil by a simple method.

  In order to achieve the above object, an image forming apparatus according to claim 1 includes a calculating unit that calculates an input power value output to an exciting coil that heats a heated object that melts toner by electromagnetic induction; Detecting means for detecting temperature; and determining means for determining a set power value to be output to the exciting coil based on a difference between the temperature of the heated object detected by the detecting means and a predetermined target temperature; When the number of times that the difference between the input power value calculated by the calculating means and the set power value determined by the determining means is equal to or greater than a predetermined threshold is counted, and the count value increases continuously several times And a judging means for judging that an abnormality has occurred in the exciting coil.

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the determination unit has a difference between the input power value calculated by the calculation unit and the set power value determined by the determination unit. The count value is cleared when it is less than a predetermined threshold value.

  The image forming apparatus according to claim 3 is the image forming apparatus according to claim 1 or 2, wherein the set power value fluctuates and a difference between the previous set power value and the current set power value is determined in advance. If it is equal to or greater than the threshold value, the determination means stops the count operation and clears the count value.

  An image forming apparatus according to a fourth aspect of the present invention is the image forming apparatus according to any one of the first to third aspects, wherein the predetermined power setting value is reached after the initial energization of the image forming apparatus. During the period, the determination means stops the counting operation.

  5. The image forming apparatus according to claim 1, wherein the determining unit is configured to determine a difference between a temperature of the heated body and the predetermined target temperature, and the excitation coil. Information indicating a relationship with the set power value to be output to the power source, and based on the information, a set power value corresponding to the temperature of the heated object detected by the detecting means is determined.

  The program according to claim 6, wherein the computer calculates calculation means for calculating an input power value output to an exciting coil that heats a heated object for melting toner by electromagnetic induction, detecting means for detecting a temperature of the heated object, Based on the difference between the temperature of the heated object detected by the detecting means and a predetermined target temperature, a determining means for determining a set power value to be output to the exciting coil, and an input calculated by the calculating means When the difference between the power value and the set power value determined by the determining means is equal to or greater than a predetermined threshold, and the count value increases continuously several times, an abnormality occurs in the excitation coil It is made to function as a judgment means which judges that it is carrying out.

  According to the first aspect of the present invention, the abnormality of the exciting coil can be detected by a simple method.

  According to the second aspect of the present invention, it is possible to avoid a decrease in the detection accuracy of the excitation coil abnormality.

  According to the invention of claim 3, it is possible to avoid a decrease in the detection accuracy of the abnormality of the exciting coil.

  According to the fourth aspect of the present invention, it is possible to avoid a decrease in the detection accuracy of the excitation coil abnormality.

  According to the invention of claim 5, the set power value can be determined by a simple method.

  According to the invention of claim 6, abnormality of the exciting coil can be detected by a simple method.

1 is a diagram illustrating a configuration of an image forming apparatus. FIG. 3 is a diagram illustrating a configuration of a fixing device. It is a figure which shows the structure of a power supply device. It is a figure which shows the connection relation of a power supply device, a control unit, an exciting coil, and a thermistor. FIG. 6 is a table information showing a relationship between a difference between a fixing belt temperature and a predetermined target temperature and set power. (A)-(C) is a figure which shows the relationship between the input electric power value calculated in the control circuit, and the setting electric power value received from the control unit. It is a flowchart which shows the process performed with a control circuit.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a diagram illustrating a configuration of an image forming apparatus.

  The image forming apparatus in FIG. 1 is a printer 10. The image forming apparatus may be a copier, a multifunction machine, or the like. In the printer 10, the optical scanning device 54 is fixed to the housing 12 constituting the main body of the printer 10, and control for controlling the operation of each part of the optical scanning device 54 and the printer 10 at a position adjacent to the optical scanning device 54. A unit 50 (determining means) is provided. Further, the printer 10 is provided with a power supply device 11 that supplies power to the fixing device 100.

  The optical scanning device 54 scans a light beam emitted from a light source (not shown) with a rotating polygon mirror (polygon mirror), reflects it with a plurality of optical components such as a reflection mirror, and produces yellow (Y), magenta (M), Light beams 60Y, 60M, 60C and 60K corresponding to cyan (C) and black (K) toners are emitted. The light beams 60Y, 60M, 60C, and 60K are guided to the corresponding photoreceptors 20Y, 20M, 20C, and 20K, respectively.

  A paper tray 14 for storing the recording paper P is provided below the printer 10. A pair of registration rollers 16 for adjusting the position of the leading end of the recording paper P is provided above the paper tray 14. An image forming unit 18 is provided at the center of the printer 10. The image forming unit 18 includes four photoconductors 20Y, 20M, 20C, and 20K, which are arranged in a vertical line.

  Charging rollers 22Y, 22M, 22C, and 22K that charge the surfaces of the photoreceptors 20Y, 20M, 20C, and 20K are provided on the upstream side in the rotation direction of the photoreceptors 20Y, 20M, 20C, and 20K. Further, on the downstream side in the rotation direction of the photoconductors 20Y, 20M, 20C, and 20K, developing units 24Y and 24M that develop the Y, M, C, and K toners on the photoconductors 20Y, 20M, 20C, and 20K, respectively. , 24C, 24K are provided.

  The first intermediate transfer member 26 is in contact with the photoconductors 20Y and 20M, and the second intermediate transfer member 28 is in contact with the photoconductors 20C and 20K. The third intermediate transfer member 30 is in contact with the first intermediate transfer member 26 and the second intermediate transfer member 28. Further, a transfer roll 32 is provided at a position facing the third intermediate transfer member 30. The recording paper P is conveyed between the transfer roll 32 and the third intermediate transfer body 30, and the toner image on the third intermediate transfer body 30 is transferred to the recording paper P.

  A fixing device 100 is provided downstream of the paper conveyance path 34 through which the recording paper P is conveyed. The fixing device 100 includes a fixing belt 102 (a body to be heated) and a pressure roller 104. The fixing belt 102 and the pressure roller 104 heat and press the recording paper P to fix the toner image on the recording paper P. The recording paper P on which the toner image is fixed is discharged to a tray 38 provided on the upper portion of the printer 10 by a paper transport roll 36.

  FIG. 2 is a diagram illustrating a configuration of the fixing device 100.

  The fixing device 100 includes a housing 122 in which an opening for entering or discharging the recording paper P is formed. Inside the housing 122, a fixing belt 102 that rotates in the direction of arrow D is provided. A bobbin 108 made of an insulating material is disposed at a position facing the outer peripheral surface of the fixing belt 102. The distance between the bobbin 108 and the fixing belt 102 is about 1 to 3 mm. The bobbin 108 is formed in a substantially arc shape along the outer peripheral surface of the fixing belt 102. An excitation coil 110 is wound around the bobbin 108 a plurality of times in the axial direction (the depth direction in FIG. 2) around the convex portion 108A. Further, a magnetic core 112 made of a magnetic body formed in a substantially arc shape is disposed at a position facing the exciting coil 110.

  A support member 114 is disposed inside the fixing belt 102 so as not to contact the fixing belt 102. Both ends of the support member 114 are fixed to the casing 122 of the fixing device 100.

  The support member 114 includes an arc portion 114A formed in an arc shape facing the fixing belt 102, and a column portion 114B formed in a column shape, and the arc portion 114A and the column portion 114B are integrally formed. A magnetic core 116 is attached to the arc portion 114A of the support member 114 along the arc portion 114A.

  The magnetic core 116 is in contact with the inside of the fixing belt 102. A closed magnetic path is formed between the magnetic core 116 and the magnetic core 112 due to the magnetic field H generated when the exciting coil 110 is energized. The fixing belt 102 includes a heat generation layer in which an eddy current that cancels the magnetic field H flows by electromagnetic induction and generates heat by the eddy current. The heat generating layer is formed of gold, silver, copper, aluminum, zinc, lead, or an alloy thereof. In this way, when the exciting coil 110 is energized, a closed magnetic path of the magnetic field H is formed between the magnetic core 116 and the magnetic core 112, and an eddy current that cancels the magnetic field H flows to the heat generating layer of the fixing belt 102, The fixing belt 102 is heated.

  A pressing pad 118 for pressing the fixing belt 102 outward at a predetermined pressure is fixed to the end surface of the pillar portion 114B of the support member 114. A pressure roll 104 that pressurizes the fixing belt 102 and rotates in the direction of arrow E is disposed at a position facing the outer peripheral surface of the fixing belt 102.

  Here, when the pressure roll 104 presses the fixing belt 102 toward the pressing pad 118, a concave portion 103 is formed in the fixing belt 102 at a contact portion (nip portion) between the fixing belt 102 and the pressure roll 104. Convex portions 105 are formed on both sides. The shape of the nip portion is curved in a direction in which the recording paper P is peeled from the fixing belt 102 when the recording paper P on which the toner T is placed passes. The recording paper P conveyed from the direction of the arrow IN is pressurized and heated at the nip portion and discharged in the direction of the arrow OUT.

  A thermistor 120 (detection means) for measuring the temperature of the back surface of the fixing belt 102 is provided in contact with the back surface of the fixing belt 102. The thermistor 120 measures the temperature of the back surface of the fixing belt 102 by changing the resistance value according to the amount of heat given from the back surface of the fixing belt 102.

  FIG. 3 is a diagram illustrating a configuration of the power supply device 11.

  The power supply device 11 includes a rectifier circuit 201, an inverter circuit 202, a control circuit 203 (calculation means, determination means), and a drive circuit 204. The rectifier circuit 201 is connected to an AC 100V commercial power source 70, and converts (rectifies) AC power from the commercial power source 70 into DC power. The rectifier circuit 201 includes a capacitor 210 as a noise filter, a current transformer 211 that detects current, a bridge rectifier 212, a coil 213 that smoothes an input voltage of the bridge rectifier 212, and a capacitor 214.

  The inverter circuit 202 converts the DC power into AC power again. The inverter circuit 202 includes the above-described exciting coil 110, a capacitor 221 provided in parallel with the exciting coil 110, an insulated gate bipolar transistor (IGBT) 222 for allowing a high-frequency current to flow through the exciting coil 110, and an insulated gate. A diode 223 is provided in parallel with the collector and emitter of the bipolar transistor 222.

  The control circuit 203 detects a zero voltage point at the time of resonance between the exciting coil 110 and the capacitor 221 and outputs an oscillation signal to the drive circuit 204. The control circuit 203 detects the current flowing through the rectifier circuit 201 by the current transformer 211 and stops the oscillation signal output to the drive circuit 204 when an abnormality such as a short circuit of the exciting coil 110 occurs. Further, the control circuit 203 calculates an input power value based on the current flowing through the rectifier circuit 201 and the impedances of the exciting coil 110 and the capacitor 221. The control circuit 203 includes a counter 203A that counts the number of times that the difference between the calculated input power value and the set power value received from the control unit 50 is equal to or greater than a predetermined threshold (for example, ± 150 W).

  The drive circuit 204 outputs a drive signal to the insulated gate bipolar transistor 222 based on the oscillation signal received from the control circuit 203. As a result, a high frequency current flows through the exciting coil 110, and a high frequency magnetic field H is generated between the magnetic core 116 and the magnetic core 112.

  FIG. 4 is a diagram illustrating a connection relationship among the power supply device 11, the control unit 50, the exciting coil 110, and the thermistor 120.

  As shown in FIG. 4, the power supply device 11 is connected to the exciting coil 110, and the control circuit 203 in the power supply device is connected to the control unit 50. The control unit 50 is connected to a thermistor 120 provided on the back side of the fixing belt 102.

  The control unit 50 receives the temperature value of the fixing belt 102 from the thermistor 120. The control unit 50 determines a set power value based on the difference between the temperature value received from the thermistor 120 and a predetermined target temperature, and outputs the determined set power value to the control circuit 203. The predetermined target temperature is a temperature preset in the printer 10 by the manufacturer. Specifically, the control unit 50 has table information indicating the relationship between the difference between the temperature of the fixing belt 102 shown in FIG. 5 and a predetermined target temperature and the set power, and from the thermistor 120 based on the table information. A set power value corresponding to the difference between the received temperature value and a predetermined target temperature is determined, and the determined set power value is output to the control circuit 203. Thereby, the set power value is determined by a simple method. The set power value indicates a power value to be output to the exciting coil 110 in accordance with a difference between the temperature of the fixing belt 102 and a predetermined target temperature.

  In the table information of FIG. 5, first, the set power value is set from 0 w (watts) to 1100 w so that the temperature of the fixing belt 102 increases from room temperature to the toner fixing temperature (about 170 degrees). When the temperature of the fixing belt 102 reaches the toner fixing temperature, the set power value varies between 1100 w and 200 w in accordance with the temperature difference. This is to reduce the power while maintaining the toner fixing temperature. The table information in FIG. 5 is not limited to this. For example, when the temperature of the fixing belt 102 reaches the toner fixing temperature, the set power value may smoothly drop from 1100 w to 200 w.

  Returning to FIG. 4, the control circuit 203 compares the calculated input power value with the set power value received from the control unit 50, and detects whether there is an abnormality in the exciting coil 110. For example, when a rare short (short between windings) of the exciting coil 110 occurs, the load on the exciting coil 110 becomes small, so that the current flowing through the exciting coil 110 increases and the input power value increases. For this reason, when the output input power value greatly deviates from the set power value received from the control unit 50, the control circuit 203 determines that an abnormality has occurred in the excitation coil 110.

  When the control circuit 203 determines that an abnormality has occurred in the exciting coil 110, the control circuit 203 stops the oscillation signal output to the drive circuit 204. As a result, no current is supplied to the exciting coil 110, and the input power value becomes 0w. When the control circuit 203 determines that no abnormality has occurred in the excitation coil 110, the control circuit 203 outputs an oscillation signal to the drive circuit 204 and a current is supplied to the excitation coil 110.

  Hereinafter, a method for detecting abnormality of the exciting coil 110 will be described in detail.

  6A to 6C are diagrams illustrating the relationship between the input power value calculated by the control circuit 203 and the set power value received from the control unit 50. FIG. 6A to 6C indicate the count value of the counter 203A.

  The control circuit 203 determines whether or not the difference between the calculated input power value and the set power value received from the control unit 50 is greater than or equal to a predetermined threshold (for example, ± 150 W) every 100 ms (this is referred to as a feedback cycle). Determine whether. When the difference between the calculated input power value and the set power value received from the control unit 50 is equal to or greater than a predetermined threshold (for example, ± 150 W), the control circuit 203 increases the counter value of the counter 203A by one. .

  As shown in FIG. 6A, the control circuit 203 determines that an abnormality has occurred in the exciting coil 110 when the count value of the counter 203A increases six times in succession. That is, when the abnormal state of the exciting coil 110 continues for 600 ms or longer, the abnormal state of the exciting coil 110 is determined. Note that the control circuit 203 may determine that an abnormality has occurred in the excitation coil 110 when the count value of the counter 203A increases continuously for a plurality of times (two or more times). Further, the difference between the calculated input power value and the set power value received from the control unit 50 may not alternately exceed the threshold value of +150 W and the threshold value of −150 W. For example, the difference between the calculated input power value and the set power value received from the control unit 50 may exceed the threshold of +150 W or the threshold of −150 W at least twice.

  Further, as shown in FIG. 6B, the control circuit 203 causes the difference between the calculated input power value and the set power value received from the control unit 50 to be less than a predetermined threshold value (for example, ± 150 W) even once. If so, the count value of the counter 203A is cleared. As a result, a decrease in the accuracy of detecting the abnormality of the exciting coil 110 is avoided. The control circuit 203 clears the counter 203A even when the fixing device 100 is turned off.

  Further, as shown in FIG. 6C, the control circuit 203 changes the set power value so that the previous set power value (X in FIG. 6C) and the current set power value (FIG. 6C). If the difference from Y) is equal to or greater than a predetermined threshold (for example, ± 100 W), the count operation of the counter 203A is stopped and the count value is cleared. As a result, a decrease in the accuracy of detecting the abnormality of the exciting coil 110 is avoided. Note that the threshold value to be compared with the difference between the previous set power value and the current set power value may be the same as the threshold value to be compared with the difference between the calculated input power value and the set power value received from the control unit 50. Good.

  The control circuit 203 performs a period from the initial energization of the printer 10 to the first feedback cycle (100 ms), that is, from the initial energization of the printer 10 until reaching a predetermined maximum set power value (for example, 1100 w). During the period, the operation of the counter 203A is stopped. As shown in FIG. 5, since the fluctuation of the set power value is large during this period, the control circuit 203 stops the operation of the counter 203A as in FIG. 6C. Therefore, a decrease in the detection accuracy of the abnormality of the exciting coil 110 is avoided.

  FIG. 7 is a flowchart showing processing executed by the control circuit 203.

  First, the control circuit 203 calculates an input power value based on the current flowing through the rectifier circuit 201 and the impedances of the exciting coil 110 and the capacitor 221 (step S1), and receives the set power value from the control unit 50 (step S1). Step S2).

  Next, the control circuit 203 determines whether or not the difference between the calculated input power value and the set power value received from the control unit 50 is greater than or equal to a predetermined threshold (for example, ± 150 W) every 100 ms. (Step S3). If the determination in step S3 is no, the procedure returns to step S1. On the other hand, if the determination in step S3 is YES, the control circuit 203 increases the counter value of the counter 203A by 1 (step S4).

  Next, the control circuit 203 determines whether or not the difference between the previous set power value and the current set power value is greater than or equal to a predetermined threshold (for example, ± 100 W) (step S5). If YES in step S5, the control circuit 203 stops the counting operation of the counter 203A and clears the count value (step S6). Thereafter, the procedure returns to step S1. If the determination in step S5 is NO, the control circuit 203 determines whether or not the count value of the counter 203A has increased continuously (for example, six times) (step S7). If the determination in step S7 is no, the procedure proceeds to step S6. If YES in step S7, the control circuit 203 notifies the control unit 50 of a status code indicating abnormality (step S8). Then, the control unit 50 receives the status code indicating the abnormality, and outputs a command for setting the input power value to 0 W to the control circuit 203. The control circuit 203 receives a command to set the input power value to 0 W from the control unit 50 (step S9).

  Thereafter, the control circuit 203 stops the oscillation signal output to the drive circuit 204 (step S10). As a result, no current is supplied to the exciting coil 110, and the input power value becomes 0w. Then, this process ends.

  The control circuit 203 stops the oscillation signal output to the drive circuit 204 until the status code indicating abnormality is canceled. The status code indicating the abnormality is canceled by turning on the commercial power supply 70 and then turning it on.

  In the present embodiment, the control circuit 203 executes the process of FIG. 4, but the control unit 50 may execute part of the process of FIG. In this case, the control unit 50 includes a counter 203A. In step S1, the control unit 50 receives information on the current flowing from the control circuit 203 to the rectifier circuit 201 and information on the impedances of the exciting coil 110 and the capacitor 221 and calculates an input power value. Since the control unit 50 has the calculated input power value, the set power value, and the counter 203A, the processing of steps S3 to S7 is executed. If YES in step S7, the control unit 50 outputs a command for setting the input power value to 0 W to the control circuit 203. Thereafter, the control circuit 203 performs the process of step S10.

  In the present embodiment, the control unit 50 determines the set power value, but the control circuit 203 may determine the set power value. In this case, the control circuit 203 has the table information of FIG. 5 and receives the temperature value of the fixing belt 102 from the thermistor 120.

  As described above, according to the present embodiment, the printer 10 includes the control circuit 203 that calculates the input power value output to the exciting coil 110 that heats the fixing belt 102 that melts the toner by electromagnetic induction, and the fixing. A thermistor 120 that detects the temperature of the belt 102 and a control unit that determines a set power value to be output to the exciting coil 110 based on a difference between the temperature of the fixing belt 102 detected by the thermistor 120 and a predetermined target temperature. 50. The control circuit 203 counts the number of times that the difference between the input power value and the set power value is greater than or equal to a predetermined threshold value, and if the count value continuously increases a plurality of times, an abnormality occurs in the excitation coil 110. Judge that Therefore, the abnormality of the exciting coil 110 is detected by a simple method.

  The recording medium in which the software program for realizing the function of the printer 10 is recorded is supplied to the printer 10, and the control circuit 203 and the control unit 50 read and execute the program stored in the storage medium. The same effects as in the above embodiment are achieved. Examples of the storage medium for supplying the program include a CD-ROM, a DVD, or an SD card.

  The printer 10 can also achieve the same effect as the above-described embodiment by executing a software program for realizing the functions of the printer 10.

DESCRIPTION OF SYMBOLS 10 Printer 11 Power supply device 50 Control unit 100 Fixing device 102 Fixing belt 104 Pressure roller 110 Excitation coil 120 Thermistor 201 Rectifier circuit 202 Inverter circuit 203 Control circuit 204 Drive circuit

Claims (6)

Calculating means for calculating an input power value output to an exciting coil that heats a heated object that melts toner by electromagnetic induction;
Detecting means for detecting the temperature of the heated object;
Determining means for determining a set power value to be output to the exciting coil based on a difference between the temperature of the heated object detected by the detecting means and a predetermined target temperature;
When the number of times that the difference between the input power value calculated by the calculating means and the set power value determined by the determining means is equal to or greater than a predetermined threshold is counted, and the count value increases continuously several times An image forming apparatus comprising: a determination unit that determines that an abnormality has occurred in the excitation coil.   The determination means clears the count value when the difference between the input power value calculated by the calculation means and the set power value determined by the determination means is less than a predetermined threshold value. The image forming apparatus according to claim 1.   When the set power value fluctuates and the difference between the previous set power value and the current set power value is greater than or equal to a predetermined threshold value, the determination means stops the count operation, and the count value The image forming apparatus according to claim 1, wherein the image forming apparatus is cleared.   The determination unit stops the counting operation during a period from when the image forming apparatus is initially energized until reaching a predetermined maximum set power value. The image forming apparatus described in the item.   The determination unit includes information indicating a relationship between a difference between the temperature of the heated body and the predetermined target temperature and a set power value to be output to the excitation coil, and based on the information, the detection unit 5. The image forming apparatus according to claim 1, wherein a set power value corresponding to the temperature of the heated object detected by the step is determined. Computer
Calculating means for calculating an input power value output to an exciting coil that heats a heated object that melts toner by electromagnetic induction;
Detecting means for detecting the temperature of the object to be heated;
A determining means for determining a set power value to be output to the exciting coil based on a difference between the temperature of the heated object detected by the detecting means and a predetermined target temperature; and an input calculated by the calculating means When the difference between the power value and the set power value determined by the determining means is equal to or greater than a predetermined threshold, and the count value increases continuously several times, an abnormality occurs in the excitation coil A program characterized by functioning as a determination means for determining whether or not

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