JP2014085522A - Image forming apparatus and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multifunction machine 100 configured to improve safety for a fixing heater and to be available until the end of the service life of a triac, thereby improving economical efficiency.SOLUTION: A multifunction machine 100 include: lifetime calculation means 403 which calculates lifetime of a triac 310 at the start of supplying power to a fixing heater 309; lifetime determination means 405 which determines, when a safe relay 313 cuts off power supplied to the fixing heater 309, whether the calculated lifetime of the triac 310 exceeds a preset lifetime; and safe relay control means 402 which keeps the safe relay 313 cutting off the power supplied to the fixing heater 309, even if power is supplied again, when the above determination indicates that the lifetime of the triac 310 has exceeded the set lifetime.

Description

  The present invention relates to an image forming apparatus and an image forming method. More specifically, the present invention relates to an image forming apparatus and an image forming apparatus capable of improving safety with respect to a fixing heater and improving economy by using the switching element until the end of its service life. Regarding the method.

  In an electrophotographic technique, an image forming apparatus that directly or indirectly transfers a toner image formed on a photoreceptor to a recording medium and forms the toner image on the recording medium. A fixing unit is provided that heats and pressurizes the toner image to fix the toner image on the recording medium.

  The fixing unit is provided with a heat roller. The heat roller has a hollow inside and contains a halogen lamp as a heating source (heater). By the heat generated when the halogen lamp is lit. The roller surface is heated.

  In other words, it utilizes the conversion of electrical energy (power supply to the halogen lamp) into heat energy (generated heat), and thereby the temperature of the heat roller is controlled by on / off control to the halogen lamp. Can do.

  For the on / off control of the halogen lamp, a triac (TRIAC) which is a switching element of a semiconductor device is applied, and the detected temperature of the fixing unit is feedback-controlled.

  Here, conventionally, there is a fixing heater control device that averages the number of times the heater is turned on, extends the heater life, suppresses power consumption, and prevents the occurrence of flicker. In this example, a plurality of fixing heaters are provided, the number of times each of the fixing heaters is turned on is stored, and control is performed so as to average based on the number of times of turning on / off when the heater is turned on or off. When detecting this, the fixing heater control device is stopped and an abnormality is notified.

  However, in the above-described conventional technology, the lifetime is determined (predicted) by counting the number of times the heater is turned on / off (or including the energization time). The target of such lifetime is a halogen lamp or a heat roller. The device such as the triac that controls the on / off of the halogen lamp is not subject to the judgment of the lifetime. The device includes electronic parts such as a fuse and an electrolytic capacitor in addition to the triac. For this reason, the device may fail before the halogen lamp or heat roller reaches the end of its life. On the other hand, a large and expensive device may be selected by designing under excessive compensation.

  In any case, from the viewpoint of recycling, it is necessary to predict the life of the halogen lamp and the heat roller, and also to monitor the life of the control system device for controlling on / off of the halogen lamp. At present, monitoring of the lifetime of such devices has not been established.

  In particular, halogen lamps generate a larger inrush current when the device is cold-started (starting up) than when the device is on standby or during image formation processing. The determination of the service life is likely to cause errors.

  For example, the temperature of the fixing unit is 160 ° C. during the image forming process, and at this time, an inrush current of 10 A to 20 A flows in the triac. On the other hand, the temperature of the fixing unit is 100 ° C. during standby and an inrush current of 40 A to 50 A flows, and the temperature of the fixing unit is 30 ° C. during startup and an inrush current of 70 A to 80 A flows. I know there is a gap.

  In order to deal with such a problem, for example, in Japanese Patent Application Laid-Open No. 2007-3720 (Patent Document 1), the recording medium on which the toner image is formed is subjected to heating and pressurizing treatment, thereby the toner image. Is used in an image forming apparatus provided with a fixing unit that fixes an image on a recording medium, and the fixing unit is provided with a heating source that converts electrical energy into thermal energy. There is disclosed a temperature control device for an image forming apparatus that is controlled by on / off to maintain a fixing temperature at the fixing unit at a predetermined temperature. The temperature control device for an image forming apparatus classifies and accumulates the number of times the switching element is turned on and off for each state including at least when the image forming apparatus is started up, during standby, and during image forming processing. Accumulating means, upper limit value storing means for each state for storing upper limit values of the number of on / off times of the switching elements for each state, cumulative results for each state by the cumulative means for each state, and upper limit values for each state Comparison means for comparing the upper limit value for each state stored in the storage means, and when the result of comparison by the comparison means is that the cumulative result exceeds the upper limit value in at least one of the states, an abnormality is determined And an abnormal time process execution control means for executing abnormal time processing including warning and forced stop in a predetermined order when an abnormality is determined by the determining means. As a result, it is possible to accurately determine the lifetime of a temperature control device including a switching element for controlling on / off of the heat source of the fixing unit, and to design the device with the minimum necessary compensation. It has an excellent effect.

JP 2007-3720 A

  However, in the invention described in Patent Document 1, before the switching element such as the triac actually breaks down and reaches the end of its life, the use of the switching element is prohibited. .

  By the way, it is known that the switching element, in particular, the triac will be in a short circuit state (short mode) with a probability of about 70% when it fails (breaks). When the switching element fails in the short mode, the fixing unit (heating roller) continues to be heated, and the image forming apparatus ignites and emits smoke, resulting in a dangerous state.

  Therefore, as a safety standard requirement, when the temperature of the heating roller reaches a preset temperature, a thermostat is provided to cut off the energization to the fixing heater, but when the thermostat operates, the heating roller already emits smoke or There is a problem that off-flavors occur. The thermostat is usually a one-shot type thermostat that cannot be restored (cannot be restored) once the energization to the fixing heater is interrupted once in order to prevent the restoration by the user. For this reason, if the thermostat operates, there is a problem that the operated thermostat must be replaced with a new one.

  In order to solve such a problem, a safety relay that cuts off the power to the fixing heater by inputting predetermined information is further provided, and the safety relay is operated at a stage before the thermostat is operated. The safety relay is controlled by software to avoid the operation of the thermostat. Specifically, the safety relay cuts off the power supply to the heating roller when the temperature of the heating roller reaches a preset temperature lower than the temperature at which the thermostat operates.

  Here, the heating roller normally has an excessive temperature rise, ie, a temperature rise overshoot in the initial stage of heating. Therefore, the safety relay is provided with a time lag that is inoperative in the initial stage of heating. That is, the safety relay monitors the temperature of the heating roller after a predetermined time has elapsed from the start of energization, and is configured not to operate in the initial stage of heating. Also, depending on the usage conditions of the user beyond the manufacturer's assumptions, a malfunction may occur in which the safety relay operates erroneously. Therefore, even if the safety relay is activated, the user can When the power is turned on again, the safety relay is configured so that the fixing heater can be energized again.

  However, when the triac fails in the short mode, the user repeats turning off and on the power supply even though the safety relay is activated. In spite of the presence of a safety relay, the thermostat may operate because the temperature of the heating roller has become equal to or higher than the preset temperature. For this reason, the safety relay does not function properly, and the above-described problem relating to the thermostat occurs again. Such a problem cannot be solved by the invention described in Patent Document 1.

  Accordingly, the present invention has been made to solve the above-described problem, and is an image forming apparatus capable of improving the safety with respect to the heating roller and improving the economy by using the switching element until the end of its life. And an image forming method.

  In order to solve the above-described problems and achieve the object, an image forming apparatus according to the present invention includes a fixing heater whose energization is controlled by turning on / off a switching element, and a temperature of a heating roller heated by the fixing heater. Is an image forming apparatus provided with a safety relay that cuts off the power supply to the fixing heater when a preset predetermined temperature is exceeded, and employs the following configuration.

  That is, when the energization of the fixing heater is started, the image forming apparatus calculates the lifetime of the switching element, and when the safety relay cuts off the energization of the fixing heater. Life determining means for determining whether the life of the switching element exceeds a preset set life, and when the result of the determination is that the life of the switching element exceeds the set life, the power is turned on again. The safety relay control means for maintaining the energization interruption of the fixing heater by the safety relay.

  In addition, the lifetime calculation means is configured to integrate the switching element ON / OFF count when the temperature of the heating roller is equal to or lower than a predetermined temperature, and the switching element ON / OFF count when the temperature is equal to or lower than the predetermined temperature. Value, the integrated value of the number of times the switching element is turned on / off when the temperature inside the device is below the specified temperature, or the integrated value of the number of times the switching device is turned on / off since the device was first used This is calculated as the lifetime of the switching element.

  In addition, when the life of the switching element exceeds the set life, the display device further includes a display unit that displays a screen for prompting replacement of the switching element.

  Further, the safety relay control means releases the energization interruption of the fixing heater by the maintained safety relay when the switching element is replaced with a new switching element after the energization interruption of the fixing heater by the safety relay is maintained. At the same time, the calculated lifetime of the switching element is reset.

  According to another aspect of the present invention, there is provided a fixing heater whose energization is controlled by turning on / off a switching element, and a safety relay for interrupting energization of the fixing heater when the temperature of the heating roller exceeds a predetermined temperature. Can be provided as an image forming method of an image forming apparatus.

  That is, in the image forming method, when the energization to the fixing heater is started, the life of the switching element is calculated, and when the safety relay interrupts the energization to the fixing heater, the calculated switching is performed. The step of determining whether or not the lifetime of the element exceeds a preset set lifetime, and as a result of the determination, when the lifetime of the switching element exceeds the set lifetime, even if the power is turned on again, And a step of maintaining the energization interruption of the fixing heater by the safety relay. Even with this configuration, the same effect as described above can be obtained.

  Further, the present invention can be provided as a program for causing a computer to circulate individually via a telecommunication line or the like. In this case, the central processing unit (CPU) realizes the control operation in cooperation with each circuit other than the CPU according to the program of the present invention.

  Each means realized by using the program and the CPU can also be configured by using dedicated hardware. The program can also be distributed in a state where it is recorded on a computer-readable recording medium such as a CD-ROM.

  According to the image forming apparatus and the image forming method of the present invention, it is possible to improve safety with respect to the fixing heater and to improve economy by using the switching element until the life of the switching element is reached.

1 is a diagram illustrating a configuration of a multifunction machine according to the present invention. It is a figure which shows the structure of the operation part which concerns on this invention. It is a figure which shows the structure of the control system hardware of the multifunctional device which concerns on this invention. FIG. 2 is a functional block diagram of a multifunction machine according to an embodiment of the present invention. It is a flowchart for showing the execution procedure of the embodiment of the present invention. It is a figure which shows the exchange screen displayed on the touch panel of embodiment of this invention.

  Hereinafter, an embodiment of an image forming apparatus according to the present invention will be described with reference to the accompanying drawings for understanding of the present invention. In addition, the following embodiment is an example which actualized this invention, Comprising: The thing of the character which limits the technical scope of this invention is not. In addition, the alphabet “S” added in front of the numbers in the flowcharts means steps.

<Image forming apparatus>
Hereinafter, an image forming apparatus according to an embodiment of the present invention will be described.

  FIG. 1 is a diagram showing a configuration of a multifunction machine according to the present invention. However, details of each part not directly related to the present invention are omitted. The image forming apparatus according to the present invention corresponds to, for example, a printer or a multi-functional machine equipped with a printer, a copy, a scanner, a fax machine, etc. Function as. The operation of the MFP 100 (MFP: Multi Function Peripheral) when using the copy function will be briefly described below.

  First, when the user uses the multifunction device 100, the document P is placed on the document table 101 a or the automatic document feeder 101 b provided on the upper surface of the multifunction device 100, and the copy function setting is input from the operation unit 102. To do. The operation unit 102 displays a print screen (such as an initial screen) related to the copy function provided by the MFP 100, and a plurality of setting item keys related to the copy function are displayed in a selectable manner. The user inputs setting conditions related to the copy function via the print screen.

  When the user completes the input of the setting conditions, the user presses the start key provided on the operation unit 102 to cause the multifunction peripheral 100 to start the copy function process.

  When the multifunction device 100 starts processing of the copy function, the light emitted from the light source 104 is reflected by the image reading unit 103 to the document placed on the document table 101a. The reflected light is guided to the image sensor 108 by the mirrors 105, 106, and 107. The guided light is photoelectrically converted by the image sensor 108 and subjected to basic correction processing, image quality processing, compression processing, and the like, and image data corresponding to the document is generated.

  An image forming unit 109 transfers the image data as a toner image. The image forming unit 109 is provided with a photosensitive drum 110. The photosensitive drum 110 rotates in a predetermined direction at a constant speed, and around the charger drum, the exposure unit 112, the developing unit 113, the transfer unit 114, the cleaning unit 115, and the like in that order from the upstream side in the rotation direction. Is arranged.

  The charger 111 uniformly charges the surface of the photosensitive drum 110. The exposure unit 112 irradiates the charged surface of the photosensitive drum 110 with a laser based on the image data to form an electrostatic latent image. The developer 113 forms a toner image by attaching toner to the formed electrostatic latent image. The formed toner image is transferred to a recording medium (for example, a sheet) by the transfer device 114. The cleaning unit 115 removes excess toner left on the surface of the photosensitive drum 110. A series of these processes is executed by rotating the photosensitive drum 110.

  The sheets are conveyed from a plurality of paper feed cassettes 116 provided in the multi function peripheral 100. When the sheet is conveyed, the sheet is pulled out from any one of the sheet feeding cassettes 116 to the conveying path by a pickup roller 117. Each of the paper feed cassettes 116 stores sheets of different paper types, and the sheets are fed based on the setting relating to the setting condition.

  The sheet pulled out to the conveyance path is fed between the photosensitive drum 110 and the transfer device 114 by the conveyance roller pair 118 and the registration roller pair 119. When fed, the toner image is transferred to the sheet by the transfer device 114 and conveyed to the fixing device 120.

  When the sheet on which the toner image is transferred passes between a heating roller 121 and a pressure roller 122 provided in the fixing device 120, heat and pressure are applied to the toner image, and the visible image is fixed to the sheet. Is done. The heat amount of the heating roller 121 is optimally set according to the paper type, and the fixing is performed appropriately. The visible image is fixed on the sheet, the image formation is completed, and the sheet on which the visible image is fixed is discharged to the discharge tray 123 through the fixing device 120, and is stacked and stored.

  Through the above procedure, the multifunction peripheral 100 provides a copy function to the user.

  FIG. 2 is a diagram showing the configuration of the operation unit according to the present invention. The user uses the operation unit 102 to input setting conditions for image formation as described above, and to confirm the input setting conditions. When the setting conditions are input, a touch panel 201 (operation panel), a touch pen 202, and operation keys 203 provided in the operation unit 102 are used.

  The touch panel 201 adopts an analog resistance film method, and has a structure in which a translucent upper film and a lower glass substrate are overlapped via a spacer, and each of the upper film and the lower glass substrate. A transparent electrode layer made of ITO (Indium Tin Oxide) or the like is provided on the facing surface. Further, when the upper film is pressed by the user, the transparent electrode layer on the upper film side and the transparent electrode layer on the lower glass substrate side corresponding to the pressed position are in contact with each other. By applying a voltage to the upper film or the lower glass substrate and taking out a voltage value corresponding to the pressed position from the lower glass substrate or the upper film, a coordinate value (pressed position) corresponding to the voltage value is detected. When the detected pressing position is included in a display area such as a setting item key in the screen displayed on the touch panel, the contents of the setting item are input (set).

  In addition, a display unit such as an LCD (Liquid Crystal Display) is provided below the lower glass substrate. The display unit displays a screen such as an initial screen or a copy function screen, for example. A specific screen is displayed above. As a result, the touch panel 201 has both a function of inputting setting conditions and the like and a function of displaying the setting conditions and the like.

  In addition, a touch pen 202 is provided in the vicinity of the touch panel 201, and when the user touches the tip of the touch pen 202 with the touch panel 201, the coordinate value corresponding to the contact position (pressed position) is the same as described above. Then, the user can press and select the displayed setting item key or the like with the touch pen 202.

  Further, a predetermined number of operation keys 203 are provided in the vicinity of the touch panel 201, and for example, a ten key 204, a start key 205, a clear key 206, a stop key 207, a reset key 208, and a power key 209 are provided.

  Next, the configuration of the control system hardware of the multifunction peripheral 100 will be described with reference to FIG. FIG. 3 is a schematic configuration diagram of control system hardware in the multifunction machine. However, details of each part not directly related to the present invention are omitted.

  The control circuit of the MFP 100 includes a CPU (Central Processing Unit) 301, a ROM (Read Only Memory) 302, a RAM (Random Access Memory) 303, an HDD (Hard Disk Drive) 304, a driver 305 corresponding to each driving unit, and the above-described components. The operation unit 306 (102), the temperature (environment temperature of the multifunction device 100) or the temperature sensor 307 for detecting the temperature of the multifunction device 100, and the fixing device 120 are connected by an internal bus 308.

  In the fixing device 120, one terminal of a fixing heater 309 such as a halogen lamp is electrically connected to one terminal of an AC power supply 311 via a triac 310 corresponding to a switching element, and the fixing heater 309 is also connected. The other terminal is electrically connected from the fixing heater 309 side to the other terminal of the AC power supply 311 via the thermostat 312 and the safety relay 313. The thermistor 314 for detecting the temperature of the heating roller 121 is installed on the heating roller 121 heated by the fixing heater 309.

  Here, the CPU 301 is connected to the triac 310, the safety relay 313, and the thermistor 314. For example, the RAM 303 is used as a work area, and the program stored in the ROM 302, the HDD 304, etc. is executed. Based on the execution result, data from the driver 305, the operation unit 306, the triac 310, the safety relay 313, the thermistor 314, etc. are exchanged, or predetermined data is transmitted. The operation of each driving unit shown in 2 is controlled. Also, each means (shown in FIG. 4) described later other than the drive unit is realized by the CPU 301 executing a program. The ROM 302, the HDD 304, and the like store programs and data for realizing each means described below.

<Embodiment of the present invention>
Next, the configuration and execution procedure according to the embodiment of the present invention will be described with reference to FIGS. 4 and 5. FIG. 4 is a functional block diagram of the multifunction machine of the present invention. FIG. 5 is a flowchart for illustrating the execution procedure of the present invention.

  First, when the user turns on the power of the multifunction device 100 (FIG. 5: S101), the energization control means 401 and the safety relay control means 402 of the multifunction device 100 are activated, and the safety relay control means 402 is connected to the safety relay 313. The state is confirmed, and it is determined whether or not the energization interruption of the fixing heater 309 by the safety relay 313 is maintained (FIG. 5: S102).

  As a result of the determination, a case where the energization interruption of the fixing heater 309 by the safety relay 313 is maintained (FIG. 5: S102 YES) will be described later.

  On the other hand, as a result of the determination, when the safety relay 313 does not maintain the interruption of the energization of the fixing heater 309 (FIG. 5: S102 NO), the safety relay control unit 402 determines that the predetermined time ( (For example, several seconds, etc.)

  Here, the start time of the safety relay control unit 402 is shifted by a predetermined time from the start of energization because the heating of the fixing heater 309 is heated for a predetermined time after the energization of the fixing heater 309 is started. This is because the safety relay control means 402 does not operate the safety relay 313 correspondingly because temperature rise overshoot (over temperature rise) of the roller 121 occurs.

  On the other hand, when the energization interruption of the fixing heater 309 by the safety relay 313 is not maintained, in other words, when the energization of the fixing heater 309 by the safety relay 313 is possible, the energization control unit 401 turns on / off the triac 310. Then, energization to the fixing heater 309 of the fixing device 120 is started (FIG. 5: S103).

  Next, when the energization control unit 401 starts energizing the fixing heater 309, the lifetime calculation unit 403 of the multifunction peripheral 100 calculates the lifetime of the triac 310 (FIG. 5: S104).

  The method for calculating the lifetime of the triac 310 by the lifetime calculation unit 403 may be any method, and examples thereof include the following four types of methods.

  The first method is a method in which the integrated value of the number of times the triac 310 is turned on / off when the temperature of the heating roller 121 is equal to or lower than a predetermined temperature is used as the lifetime of the triac 310. In this method, for example, the life calculation unit 403 detects the temperature of the heating roller 121 at the start of energization via the thermistor 313 capable of detecting the temperature of the heating roller 121, and the detected temperature is set in advance. Counts the number of times the triac 310 is turned on / off when the temperature is below the cold temperature (for example, 30 degrees), and adds the counted number of times of on / off to the previous number of on / off stored in a predetermined memory. And calculated as an integrated value. Here, for example, when the temperature of the heating roller 121 rises due to repeated ON / OFF of the triac 310 and the temperature detected by the thermistor 313 exceeds the first cold temperature, the life calculation means In step 403, the calculation is stopped, and the ON / OFF count (integrated value) calculated so far is stored in the memory. Thereafter, when the MFP 100 is started, the life calculation unit 403 detects the temperature of the heating roller 121, and when the detected temperature is equal to or lower than the first cold temperature, the triac 310 Calculate the number of on / off times. In this way, the number of times the triac 310 is turned on / off when the temperature of the heating roller 121 is equal to or lower than the predetermined temperature, in other words, the integrated value of the number of times the triac 310 is turned on / off when the multifunction device 100 is started (warm-up). Is the life of the triac 310. Here, when the fixing heater 309 is energized in the heating roller 121 having a temperature equal to or lower than the first cold temperature, the inrush current increases, so that damage to the triac 310 is great and the life of the triac 310 is shortened. Therefore, it can be said that the integrated value of the number of on / off times of the triac 310 when the temperature of the heating roller 121 is equal to or lower than a predetermined temperature is a value reflecting the life of the triac 310.

  The second method is a method in which the integrated value of the number of times the triac 310 is turned on / off when the temperature is equal to or lower than a predetermined temperature is used as the lifetime of the triac 310. In this method, for example, the lifetime calculation unit 403 detects the temperature at the start of energization of the fixing heater 309 via the temperature sensor 307 that detects the temperature (environment temperature of the multifunction peripheral 100) installed in advance. Similarly, an integrated value of the number of on / off times of the triac 310 when the air temperature is equal to or lower than a preset second cold temperature (for example, 15 degrees) is calculated. When the ambient temperature of the multifunction peripheral 100 rises and the temperature of the temperature sensor 307 exceeds the second cold temperature, the life calculation unit 403 stops the calculation.

  The third method is a method in which the integrated value of the number of on / off times of the triac 310 when the in-machine temperature of the multifunction peripheral 100 is equal to or lower than a predetermined temperature is used as the lifetime of the triac 310. In this method, for example, the lifetime calculation unit 403 detects the in-machine temperature at the start of energization via the temperature sensor 307 that detects the in-machine temperature of the multifunction machine 100 installed in advance, and the in-machine temperature is set in advance. An integrated value of the number of on / off times of the triac 310 when the temperature is not more than the third cold temperature (for example, 15 degrees) is calculated. When the in-machine temperature rises due to the activation of the multi-function device 100 and the in-machine temperature by the temperature sensor 307 exceeds the third cold temperature, the life calculation unit 403 stops the calculation.

  The fourth method is a method in which the integrated value (total value) of the number of times the triac 310 is turned on / off after the MFP 100 is first used is used as the lifetime of the triac 310. In this method, for example, the multifunction device 100 is installed as a product at a predetermined location, and the lifetime calculation unit 403 calculates an integrated value of the number of times the triac 310 is turned on / off after the first use. This calculation is continued until it is determined that the lifetime of the triac 310 has come. In the present invention, any of the four methods can be employed.

  Now, when the lifetime calculation means 403 calculates the lifetime of the triac 310, the energization control means 401 has no reason for some reason, for example, the power of the multifunction device 100 is cut off (FIG. 5: S105 YES). The energization to the fixing heater 309 is continued through the on / off of the triac 310. Here, when the energization of the fixing heater 309 is continued, for example, a copy function by the image forming unit 404 or a print function is provided.

  When any reason occurs (FIG. 5: S105 NO), the energization control unit 401 stops energizing the fixing heater 309 and ends all the processes.

  In S105 YES, when the energization to the fixing heater 309 is continued, the above-described safety relay control unit 402 is activated after a predetermined time has elapsed from the energization start time, and the heating roller via the thermistor 313 is activated. While detecting the temperature of 121, it is determined whether the detected temperature has exceeded a predetermined operating temperature (for example, 160 degrees) (FIG. 5: S106).

  Here, the operating temperature is a temperature for operating the safety relay, and is usually a temperature at a stage before the fixing heater 309 is overheated and ignites and smokes. The operating temperature is set to a temperature lower than the operating temperature of the thermostat 312 installed between the safety relay 313 and the fixing heater 309.

  When the detected temperature is equal to or lower than the operating temperature in S106 (FIG. 5: S106 NO), the safety relay control unit 402 returns to S103 without operating the safety relay 313. The energization control unit 401 continues energizing the fixing heater 309.

  On the other hand, if the detected temperature exceeds the operating temperature as a result of the determination in S106 (FIG. 5: S106 YES), the safety relay control means 402 operates the safety relay 313. That is, the safety relay control means opens the contact of the safety relay 313 that electrically connects the fixing heater 309 and the AC power supply 311, disconnects the electrical connection between the fixing heater 309 and the AC power supply 311, The energization to the fixing heater 309 is cut off (FIG. 5: S107). As a result, the energization of the fixing heater 309 is stopped, and the temperature of the heating roller 121 is prevented from excessively rising.

  When the safety relay control unit 402 cuts off the power supply to the fixing heater 309, the life determination unit 405 is notified to that effect, and the life determination unit 405 that has received the notification is calculated by the life calculation unit 403. It is determined whether or not the lifetime of the triac 310 that has been set exceeds a preset lifetime (FIG. 5: S108).

  Here, the set life is set corresponding to the life of the triac 310 calculated by the life calculation means 403. For example, when the life of the triac 310 is an integrated value of the number of on / off operations of the triac 310 when the temperature of the heating roller 121 is equal to or lower than a predetermined temperature, the set life is set to several tens of thousands of times. In addition, when the life of the triac 310 is an integrated value of the number of times the triac 310 is turned on / off after the MFP 100 is first used, the set life is set to several million times. Note that the set lifetimes for both are completely different.

  In S108, if the result of the determination is that the life of the triac 310 is less than or equal to the set life (FIG. 5: S108 NO), the life determination means 405 causes the safety relay 313 to be activated due to the life of the triac 310. It determines that it is not operating, and notifies the fact to the safety relay control means 402. Upon receiving the notification, the safety relay control means 402 displays a message to resume heating of the fixing heater 309 when the power is turned off and then on again via the display means 406 (FIG. 5: S109).

  Thus, even if the safety relay 313 is activated, if the user confirms the message and turns off the power and then turns it on again, the energization to the fixing heater 309 is resumed and the fixing heater 309 is raised. It will be warmed.

  Specifically, returning to S101, the multifunction device 100 is activated (FIG. 5: S101), and the safety relay control unit 402 confirms the state of the safety relay 313, and then the fixing heater by the safety relay 313 is used. 309 is not maintained (FIG. 5: S102 NO), the contact of the safety relay 313 is closed, the fixing heater 309 and the AC power supply 311 are electrically connected, and the fixing heater 309 is connected. Resume energization. Then, the energization control unit 401 starts energizing the fixing heater 309 (FIG. 5: S103).

  In this case, since the operation of the safety relay 313 is highly likely to be a malfunction regardless of the life of the triac 310, the energization control unit 401 thereafter turns on and off the triac 310. Thus, energization of the fixing heater 309 is continued.

  On the other hand, if the result of the determination in S108 is that the life of the triac 310 has exceeded the set life (FIG. 5: S108 YES), the life determination means 405 causes the safety relay 313 to be activated due to the life of the triac 310. It determines with having act | operated, and notifies the fact to the safety relay control means 402. The safety relay control means 402 that has received the notification maintains the interruption of the energization of the fixing heater 309 by the safety relay 313 even when the power is turned on again (FIG. 5: S110).

  Specifically, the safety relay control unit 402 stores a signal (data) for instructing opening of the contact of the safety relay in a predetermined nonvolatile memory, and after the user turns off the power, Even if the safety relay 403 is turned on, the safety relay control unit 402 refers to the nonvolatile memory to check the state of the safety relay 313 and determine that the safety relay 313 keeps the energization interruption of the fixing heater 309. (FIG. 5: S102 YES), the energization interruption of the fixing heater 309 by the safety relay 313 is maintained.

  In this case, the operation of the safety relay 313 is likely to have occurred in connection with the life of the TRIAC 310, in other words, the failure of the TRIAC 310 (for example, the short mode). Even if it is made, the energization interruption of the fixing heater 309 by the safety relay 313 is maintained, and the temperature of the heating roller 121 is controlled so as not to rise any more.

  Accordingly, since the heating of the fixing heater 309 is completely stopped after the end of the life of the triac 310, it is possible to reliably prevent the occurrence of ignition, smoke, odor and the like due to excessive heating of the heating roller 121, It is possible to ensure safety. Further, since the triac 310 is used until the end of its life, it is excellent in economic efficiency.

  Further, since the operation of the thermostat 312 can be prevented by operating the safety relay 313 first, problems related to the thermostat 312, for example, when the thermostat 312 is a one-shot type, have been activated. It is also possible to prevent the thermostat 312 from being replaced.

  When the life determining means 405 determines that the safety relay 313 has been activated due to the life of the triac 310, the life detecting means 405 notifies the display means 406 to that effect, and the display means 406 that has received the notification An exchange screen prompting the exchange of 310 is displayed on the touch panel 201 (FIG. 5: S111).

  On the replacement screen 600, as shown in FIG. 6, a message 601 indicating that the triac 310 of the fixing device 120 has reached the end of life, a message 602 indicating that heating of the heating roller 121 has been stopped, and a service person are notified. A message 603 for prompting the user is displayed. As a result, it is possible to prompt the user to replace the triac 310 after the end of its life.

  Now, when the user who sees the replacement screen 600 calls a service man and asks the service man to replace the triac 310 after the end of the life with a new triac 310 (FIG. 5: S112 YES), the life calculation means 403 Detects the replacement of the triac 310 and notifies the safety relay control means 402 to that effect. Receiving the notification, the safety relay control unit 402 releases the interruption of energization of the fixing heater 309 by the maintained safety relay 313 (FIG. 5: S113). Further, the lifetime calculating means 403 resets the calculated lifetime of the triac 310 by setting the integrated value of the number of on / off times of the triac 310 stored in the memory to zero (FIG. 5: S114).

  As a result, when the triac 310 is replaced with a new one, the safety relay 313 operates normally and the life of the triac 310 is newly calculated.

  As described above, in the MFP 100 according to the present invention, when energization to the fixing heater 309 is started, the life calculation means 403 for calculating the life of the triac 310 and the safety relay 313 are connected to the fixing heater 309. When the energization of the triac 310 is interrupted, the life determination means 405 for determining whether or not the calculated life of the triac 310 exceeds a preset life, and as a result of the determination, the life of the triac 310 is determined to be the set life. And the safety relay control means 402 for maintaining the interruption of energization of the fixing heater 309 by the safety relay 313 even when the power is turned on again.

  Thereby, while improving the safety | security with respect to the fixing heater 309, it becomes possible to improve economical efficiency by using until the lifetime of the triac 310 is reached.

  In the embodiment of the present invention, the triac 310 is adopted as the energization control means of the fixing heater 309, but any element may be used as long as it is a switching element.

  In the embodiment of the present invention, the one-shot type thermostat 312 is adopted. However, the present invention is not limited to this, and any thermostat may be used.

  In the embodiment of the present invention, the MFP 100 is configured to include each unit. However, a program that realizes each unit may be stored in a storage medium, and the storage medium may be provided. In the configuration, the multifunction device 100 reads the program, and the multifunction device 100 implements the respective units. In that case, the program itself read from the recording medium exhibits the effects of the present invention. Furthermore, it is possible to provide a method for storing the steps executed by each means in a hard disk.

  As described above, the image forming apparatus and the image forming method according to the present invention are useful not only for multi-function machines but also for copying machines, printers, etc., and increase the safety of the fixing heater and use it until the life of the switching element is reached. This is effective as an image forming apparatus and an image forming method capable of improving economy.

DESCRIPTION OF SYMBOLS 100 MFP 120 Fixing device 121 Heating roller 124 Fixing heater 125 Thermistor 401 Energization control means 402 Safety relay control means 403 Life calculation means 404 Image forming means 405 Life determination means 406 Display means

Claims (5)

A safety relay that cuts off the power supply to the fixing heater when the temperature of the heating roller heated by the fixing heater exceeds a predetermined temperature when the current is controlled by turning on / off the switching element. In an image forming apparatus comprising:
When energization of the fixing heater is started, a lifetime calculating means for calculating the lifetime of the switching element;
Life determination means for determining whether or not the calculated life of the switching element exceeds a preset set life when the safety relay cuts off the energization to the fixing heater;
A safety relay control means for maintaining the interruption of energization of the fixing heater by the safety relay even when the power is turned on again when the life of the switching element exceeds the set life as a result of the determination. An image forming apparatus. The life calculating means is an integrated value of the number of times the switching element is turned on / off when the temperature of the heating roller is equal to or lower than a predetermined temperature, an integrated value of the number of times the switching element is turned on / off when the temperature is equal to or lower than a predetermined temperature, Either the integrated value of the number of on / off times of the switching element when the internal temperature of the device is below the specified temperature, or the integrated value of the number of on / off times of the switching element since the device was first used The image forming apparatus according to claim 1, wherein the image forming apparatus calculates the life of the switching element. The image forming apparatus according to claim 1, further comprising a display unit configured to display a screen for prompting replacement of the switching element when the life of the switching element exceeds the set life. The safety relay control means releases the energization interruption of the fixing heater by the maintained safety relay when the switching element is replaced with a new switching element after maintaining the energization interruption of the fixing heater by the safety relay. The image forming apparatus according to any one of Items 1-3. An image forming apparatus comprising: a fixing heater in which energization is controlled by turning on / off a switching element; and a safety relay that interrupts energization of the fixing heater when the temperature of the fixing heater exceeds a predetermined temperature. In the image forming method of
When energization of the fixing heater is started, calculating the life of the switching element;
Determining whether or not the calculated life of the switching element exceeds a preset set life when the safety relay cuts off the energization to the fixing heater;
And maintaining the interruption of energization of the fixing heater by the safety relay even when the power is turned on again when the life of the switching element exceeds the set life as a result of the determination. Forming method.