JP2015141223A - Abnormality detection system, electronic equipment, abnormality detection method and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a system and a method capable of appropriately setting a threshold for determining abnormality from a start of a device and of improving safety of the device.SOLUTION: The system, which detects abnormality of a device generating heat during operation and includes a high temperature side placed adjacent or close to the device and a low temperature side on the back side of the high temperature side, comprises: power generation means for generating power from a temperature difference between the high temperature side and the low temperature side; voltage measurement means for measuring power generation voltage of electric power generated by the power generation means; calculation means for predicting the temperature of the high temperature side and the temperature of the low temperature side, and for calculating a threshold for the power generation voltage from the predicted temperatures; and determination means for comparing the power generation voltage measured by the voltage measurement means with the threshold calculated by the calculation means, and for determining abnormality of the device.

Description

  The present invention relates to a system for detecting an abnormality of a device that generates heat during operation, an electronic device including the system, an abnormality detection method, and a program for causing a computer to execute the method.

  Electronic devices such as copying machines, printers, facsimile machines, and multi-functional machines equipped with these using an electrophotographic process include devices that generate heat during operation of a power supply unit, a scanner, a fixing unit, and the like. With the recent demand for energy saving, a technique for converting the heat generated in these devices into electric power and effectively using it has been proposed (see, for example, Patent Documents 1 and 2).

  In addition, a technique for detecting an abnormality of the fixing unit by measuring a fixing surface temperature of the fixing unit using a configuration that converts heat into electric power has been proposed (for example, see Patent Document 3).

  A thermoelectric conversion element (also called a Seebeck element or a Peltier element) is used as a device that converts heat into electric power. This thermoelectric conversion element has a high temperature side surface disposed adjacent to or adjacent to a device that generates heat during operation, for example, a fixing unit, and a low temperature side surface that is the back surface of the high temperature side surface, and generates electric power by the temperature difference between them. To do. When printing is performed using this fixing unit, the time until the high temperature side surface and the low temperature side surface reach a certain temperature does not match as shown in FIG. Cause delay. For this reason, as shown in FIG. 1B, the power generation amount temporarily rises at the time of start-up, and decreases at the time of subsequent printing and settles to a constant amount.

Therefore, the threshold value for determining abnormality is set as one of the following two with respect to the generated voltage.
(1) The threshold value is obtained by adding a certain margin to the peak value of the generated voltage that temporarily rises at startup (threshold value 1 in FIG. 1B).
(2) The above peak value is ignored, and a value obtained by adding a certain margin to a certain amount during printing is set as a threshold value (threshold value 2 in FIG. 1B).

  However, the above threshold setting has the following problems. With respect to the above (1), since the threshold value is large, even if an abnormality occurs and the generated voltage suddenly rises, it is not determined that the abnormality is reached until the threshold value is reached. In addition, since it is larger than the appropriate threshold value at the time of printing as described in (2) above, even if an abnormality occurs during printing, the detection is delayed and the apparatus is damaged. With respect to (2) above, no abnormality can be found at startup, and if an abnormality occurs during that time, the apparatus is damaged.

  Therefore, it has been desired to provide a system and a method that can appropriately set a threshold value for determining an abnormality from the time of startup of the apparatus and can improve the safety of the apparatus.

  In view of the above problems, the present invention is a system for detecting an abnormality of a device that generates heat during operation, and a high temperature side surface that is disposed adjacent to or adjacent to the device and a low temperature side surface that is the back surface of the high temperature side surface. Power generation means for generating power by the temperature difference between the high temperature side and the low temperature side, voltage measurement means for measuring the power generation voltage of the power generated by the power generation means, and according to the time elapsed after starting the device Calculate the expected temperature of the high temperature side and the low temperature side, and compare the calculation voltage that calculates the threshold of the generated voltage from the calculated predicted temperature, the generated voltage measured by the voltage measuring means, and the threshold at the time when the generated voltage was measured And an abnormality detection system including a determination means for determining an abnormality of the apparatus.

  According to the present invention, it is possible to appropriately set a threshold value for determining an abnormality from the time of startup of the apparatus, and it is possible to improve the safety of the apparatus.

The figure which showed the relationship between elapsed time, each temperature, elapsed time, and generated voltage. 1 is a diagram illustrating a schematic configuration of an electronic apparatus according to an embodiment. The figure which illustrated the hardware constitutions of the electronic device. The figure which illustrated the place which attached the thermoelectric conversion element to the apparatus mounted in the electronic device. The figure which illustrated the composition of the power supply system of electronic equipment. The figure which showed the place which divided the process which the abnormality detection system mounted in an electronic device performs in several steps. The flowchart which illustrated the flow of the 1st process which an abnormality detection system performs. The flowchart which illustrated the flow of the judgment process. The figure which illustrated the relationship between the electric power generation voltage and threshold value in an apparatus starting stage. The figure which illustrated the relationship between the electric power generation voltage and threshold value in an apparatus operation | movement start stage. The figure which illustrated the relationship between the electric power generation voltage in an apparatus operation | movement stage, and a threshold value. The figure which illustrated the table referred in order to estimate the temperature of a low temperature side. The figure which showed the relationship between elapsed time, each temperature, elapsed time, and generated voltage. The flowchart which illustrated the flow of the 2nd process which an abnormality detection system performs.

  FIG. 2 is a diagram illustrating a configuration example of an image forming apparatus as an example of an electronic apparatus. The image forming apparatus 10 shown in FIG. 2 is a multifunction device having functions of a printer and a scanner. In addition, the image forming apparatus 10 may be a copying machine, a printer, a facsimile machine, or the like. Here, the image forming apparatus 10 is taken as an example, but the electronic device may be a PC, a server, a television, a projector, a Blu-ray disc recorder, or the like. Further, the electronic device may be a combination of two or more of these devices.

  The image forming apparatus 10 includes an automatic document feeder (ADF) 11, an image reading device 12, a printer unit 13, and a capacitor unit 14. In addition, the image forming apparatus 10 includes an operation panel and input keys (not shown), and can be switched to each mode by an application switching key and input keys displayed on the operation panel. The mode can be set according to the function of the image forming apparatus 10 and includes a copy mode, a print mode, a scan mode, a fax mode, and the like.

  The ADF 11 includes a document feed tray for supplying a document (not shown), a pickup roller for picking up the document from the document feed tray, a separation roller for separating and feeding the documents one by one, and a paper discharge tray for discharging the document. Consists of including. Since this configuration is an example, other configurations may be used, and additional components may be included.

  The image reading device 12 is a scanner, and a transparent contact glass on which an original is conveyed, a light source that emits light to the original through the contact glass, a photoelectric that receives light from the original and converts it into an electrical signal. A conversion element is included. In addition, the image reading device 12 can include a plurality of reflecting mirrors, a condensing lens, an A / D converter that converts an analog signal that is an electrical signal into digital data, and the like. Here, a reflection type device that converts reflected light into an electrical signal is used, but a transmission type device that converts light transmitted through a document into an electrical signal may be used.

  The printer unit 13 is an electrophotographic printer, and includes a writing unit 15, a photosensitive drum 16, a developing unit 17, a transport belt 18, and a fixing unit 19. In addition, the printer unit 13 includes a paper feed tray that stores paper to be supplied onto the transport belt 18, a paper feed roller that feeds the paper one by one, and the photosensitive drum 16 and the transport belt 18 at a predetermined timing. A registration roller or the like that feeds the paper between the two can be provided.

  The writing unit 15 irradiates the surface of the photosensitive drum 16 with writing light based on image information from an image processing unit (not shown), and forms an electrostatic latent image that cannot be seen with the naked eye on the surface. As the writing light, laser light, LED, or the like can be used. The developing unit 17 attaches toner to the electrostatic latent image formed on the surface of the photosensitive drum 16 to form a visible image (toner image) that can be seen with the naked eye.

  The toner image formed on the surface of the photosensitive drum 16 is placed on the transport belt 18 and transferred to the transported paper. The fixing unit 19 applies heat and pressure to the paper on which the toner image is transferred, and fixes the toner image on the paper. The paper on which the toner image is fixed is conveyed to a paper discharge tray and discharged.

  The capacitor unit 14 includes a storage battery as a power storage unit, and generates power by a power generation unit (not shown) and charges the obtained power. The capacitor unit 14 supplies the charged power to each unit or device when the image forming apparatus 10 is in the sleep state. The power storage means may be a capacitor in addition to a storage battery that stores electricity using a chemical reaction.

  The operation of the image forming apparatus 10 when the operation mode set in the image forming apparatus 10 is the copy mode will be briefly described. When a bundle of documents is set on the document feed tray of the ADF 11 and the copy button is pressed, the bundle of documents set is picked up by a pickup roller and separated by a separation roller one by one in the image reading device 12. Feed on contact glass. The image reading device 12 irradiates light on a document sent onto the contact glass, converts the reflected light into an electrical signal by a photoelectric conversion element, converts it into digital data by an A / D converter, and outputs an image. Output as data.

  The image data is sent to a controller (not shown), and various corrections such as shading correction and gamma correction are performed. Then, the corrected image data is given to the writing unit 15 as image information. Shading correction is a correction that makes uneven brightness due to the characteristics of the optical system uniform, and gamma correction is a color correction that allows the color information of the input image to be faithfully reproduced by the printer. It is a correction to be adjusted.

  The writing unit 15 irradiates the surface of the photosensitive drum 16 with laser light or the like based on image information given from a controller (not shown), and forms an electrostatic latent image on the surface. In forming this latent image, the photosensitive drum 16 is uniformly charged in advance by a charging unit (not shown). The writing unit 15 is exposed to a laser beam, an LED, or the like, and forms a pattern to be printed on the surface of the photosensitive drum 16 as an electrostatic latent image.

  The photosensitive drum 16 is attached with toner by the developing unit 17, and a toner image is formed on the surface thereof. As the toner, only a black toner may be used, or a plurality of color toners may be used. Since the photosensitive drum 16 rotates in a constant direction at a constant speed, the toner image formed on the surface is pressed against the paper conveyed at a constant speed and transferred. The toner remaining on the surface of the photosensitive drum 16 after the transfer is removed by a cleaning unit (not shown). The paper is conveyed to a transfer position by a registration roller (not shown) in accordance with the timing of writing by the writing unit 15 and rotation of the photosensitive drum 16.

  The paper on which the toner image has been transferred is conveyed to the fixing unit 19 by the conveyance belt 18 at a constant speed. In the fixing unit 19, first, heat is applied to melt the toner, and then pressure is applied to firmly fix the toner on the paper. The paper on which the toner image is fixed in this manner is discharged to a paper discharge tray.

  The image forming apparatus 10 includes the above-described controller in order to realize a plurality of functions such as a printer and a scanner and to control each unit and apparatus. The configuration of the controller will be briefly described with reference to FIG. The controller 20 includes a CPU 21, a RAM 22, a ROM 23, an HDD 24, and an NVRAM 25. The CPU 21 controls the entire image forming apparatus 10, and the RAM 22 is used as a work space for the CPU 21. The ROM 23 stores a boot program, firmware, and the like. The HDD 24 stores various programs such as an OS and applications for realizing each function, data used by the programs, and the like. The NVRAM 25 stores various setting information and the like.

  The controller 20 is connected to the operation panel 26, the image reading device 12, the printer unit 13, the modem 27, the network I / F 28, the media drive 29, and the like. The operation panel 26 is a touch panel, and functions as an input device that receives input from a user, and a display device that displays input information, an operation status of the image forming apparatus 10, and the like. The modem 27 is connected to a telephone line to realize fax transmission / reception. The network I / F 28 is connected to a network such as the Internet, and realizes communication via the network. The media drive 29 is a unit that reads programs and data recorded on a CD-ROM, DVD, SD card, etc., and writes them.

  When the multifunction device is turned on, the CPU 21 executes a boot program stored in the ROM 23 to activate the multifunction device, reads and activates the OS from the HDD 24, executes an application on the OS, and executes each function. Realize. At that time, the CPU 21 also executes image processing such as shading correction and gamma correction, and inputs the image information after the image processing to the writing unit 15.

  The image forming apparatus 10 realizes each function in each mode such as a copy mode and a printer mode by executing the application. The image forming apparatus 10 also includes a sleep mode in which the apparatus is stopped if there is no operation or access for a certain period of time. This mode is a mode introduced with the recent energy saving. In the sleep mode, it is only necessary to have power for starting to start the device when the next operation or access is made, and power supply other than that is unnecessary, so that power consumption can be reduced. In order to secure this starting power, a capacitor unit 14 is provided, and power can be supplied from the capacitor unit 14 at the time of starting.

  The capacitor unit 14 can store electric energy by supplying power from an external power source when the image forming apparatus 10 is activated. In the image forming apparatus 10, heat is generated by the operation of the image reading device 12, a power supply unit (not shown), the fixing unit 19, and the like. Therefore, a thermoelectric conversion element as a power generation unit that converts heat from these devices into electric power. It has. If the capacitor unit 14 is charged with the electric power generated by the thermoelectric conversion element, the power supplied from the external power source can be reduced or eliminated, and the power consumption can be further reduced.

  With reference to FIG. 4, the thermoelectric conversion element attached to the fixing unit 19 will be described. The fixing unit 19 includes a fixing roller 30 that melts the toner by applying heat, and a pressure roller that fixes the toner to the paper by applying pressure (not shown). The thermoelectric conversion element 31 is disposed adjacent to or adjacent to the fixing roller 30, and has a high temperature side surface 32 facing the fixing roller 30 and a low temperature side surface 33 on the back side of the high temperature side surface 32. The thermoelectric conversion element 31 is attached to a duct 35 including a fan 34 that generates an airflow, the high temperature side 32 receives heat from the fixing roller 30, and the low temperature side 33 is exposed to the airflow flowing in the duct 35 to be cooled to room temperature. It has come to be.

  The thermoelectric conversion element 31 is connected to a storage battery 36 for charging the generated power, and a voltage measuring means 37 is provided between the thermoelectric conversion element 31 and the storage battery 36. The voltage measuring means is, for example, a voltage measuring circuit and measures the generated voltage. The thermoelectric conversion element 31 generates power by the temperature difference between the high temperature side surface 32 and the low temperature side surface 33.

  The configuration of the power supply system of the image forming apparatus 10 including the thermoelectric conversion element 31 and the capacitor unit 14 will be described in detail with reference to FIG. In power generation using the thermoelectric conversion element 31, heat to be converted into electric power is required. In the image forming apparatus 10, as shown in FIG. 4, there is a fixing unit 19 as an apparatus that generates heat during operation, and in addition, there are an image reading apparatus 12, a power supply unit, and the like. Here, only the fixing unit 19 is taken up as the apparatus, and the fixing roller 30 of the fixing unit 19 is referred to as the heat generating component 40.

  The fixing unit which is the fixing unit 19 includes a heat generating component 40, a thermoelectric conversion element 31 disposed adjacent to or adjacent to the heat generating component 40, and a fan 34. As shown in FIG. 4, the thermoelectric conversion element 31 is attached to a duct (not shown), and a fan 34 is provided in the duct. The thermoelectric conversion element 31 is most preferably disposed adjacent to a portion (heat source) where the temperature of the device that generates heat is highest, but is adjacent when the heat source rotates like the fixing roller 30. In some cases, it may not be possible to place them. For example, it can arrange | position in the position spaced apart about 0.5-1 mm from the heat source. Since this is an example, it is not limited to this interval.

  The image forming apparatus 10 is connected to an external power source 41 by a power cable having an outlet plug, and power is supplied to the fixing unit. The power is also supplied to a power supply unit (PSU) 42, converted from alternating current to direct current, and supplied to each device in the image forming apparatus 10. The image forming apparatus 10 includes a storage battery 43 as the capacitor unit 14, a discharger 44 that extracts power from the storage battery 43, and a switching circuit that switches between using the power extracted by the discharger 44 and the power from the PSU 42. 45. Various devices that consume power are connected to the switching circuit 45 as the load 46. For this reason, the image forming apparatus 10 can operate each apparatus by supplying power from the storage battery 43 even when the external power supply 41 cannot be used such as during a power failure.

  The image forming apparatus 10 stores the electric power from the fixing unit in the storage battery 43 via the diode 47 and the charger 48. The diode 47 allows current to flow only in one direction, and here, current flows from the heat generating component 40 toward the charger 48. It is also possible to use a switch instead of the diode 47 to switch the current to flow to the charger 48 when power is generated. The charger 48 converts the voltage of the portion exceeding the nominal voltage of the storage battery 43 into a current and charges the storage battery 43. When the circuit included in the charger 48 is turned off, the connection with the thermoelectric conversion element 31 is disconnected, and thus power generation by the thermoelectric conversion element 31 is stopped.

  The image forming apparatus 10 includes a control circuit 49 that gives various instructions to the fan 34, the discharger 44, the switching circuit 45, the load 46, and the charger 48, and a temperature measurement circuit 50 that measures the temperature in the image forming apparatus 10. And. The instructions from the control circuit 49 are instructions for starting and stopping the fan 34, and discharging, switching, charging start and end for the discharger 44, the switching circuit 45, the load 46, and the charger 48, This is an instruction to start or stop the apparatus.

  In FIG. 5, the electric power generated by the thermoelectric conversion element 31 can be sent to the fan 34 via the control circuit 49, and the electric power is supplied from the charger 48 and the discharger 44 to the load 46 without passing through the switching circuit 45. Can be supplied.

  Further, the image forming apparatus 10 is provided with a voltage measurement circuit (not shown) as voltage measurement means for measuring the voltage of the storage battery 43 on a line connecting the charger 48 and the storage battery 43. The control circuit 49 is provided with a monitoring circuit 51 as a judging means for monitoring the heat generating component 40 and determining the abnormality in order to detect the abnormality of the heat generating component 40.

  The voltage detection circuit is used by the control circuit 49 to monitor the voltage of the storage battery 43. The monitoring circuit 51 compares the voltage of the storage battery 43 monitored by the control circuit 49 with the threshold value for the generated power voltage obtained by calculation, and determines the abnormality of the heat generating component 40. In order to determine this abnormality, the thermoelectric conversion element 31, the voltage measurement circuit, and the monitoring circuit 51 are used. The abnormality detection system includes these.

  When the thermoelectric conversion element 31 is attached to the fixing unit 19, which is an example of a device that generates heat during operation, and the generated voltage is measured, it rises at a certain rate immediately after startup as shown in FIG. When it reaches, it drops, and then settles to a constant voltage. For this reason, as shown in FIG. 6, the operation of the fixing unit 19 is started up at a constant rate until it reaches a peak, at the start-up stage of the apparatus when it drops from the peak and settles at a constant voltage, and at a constant voltage. The apparatus can be divided into a plurality of stages, ie, the apparatus operation stage.

  The apparatus activation stage is from the start of the activation of the fixing unit 19 until the temperature of the high temperature side surface 32 reaches a preset temperature setting value. The apparatus operation start stage is from the start of printing after the temperature of the high temperature side 32 reaches the temperature set value until the temperature of the low temperature side 33 reaches a constant temperature. This is because the temperature of the low temperature side surface 33 usually reaches a certain temperature with a delay. The apparatus operation stage is after the temperature of the low temperature side surface 33 has reached a constant temperature after a certain time (tsec) has elapsed from the start of printing.

  Here, although it divided into three steps, two may be sufficient and four or more may be sufficient. The reason for dividing into a plurality of stages in this manner is to set an appropriate threshold value in each stage and detect an abnormality appropriately as soon as possible to stop the fixing unit 19 quickly and ensure safety. .

  The overall processing flow performed by the abnormality detection system will be described with reference to FIG. When the target for detecting an abnormality is the fixing unit 19, the abnormality detection system performs processing in three stages as shown in FIG. When the fixing unit 19 is activated, the process starts from Step 700. In step 710, an abnormality in the apparatus activation stage is determined. If an abnormality is detected, the process proceeds to step 720 to notify the fixing unit 19 of the abnormality detection and stop the fixing unit 19. For this reason, the abnormality detection system can include notification means for notifying abnormality detection. If no abnormality is detected, the process proceeds to step 730.

  In step 730, the activation of the fixing unit 19 is completed, and printing is started in step 740. That is, the fixing operation by the fixing unit 19 is started. In step 750, an abnormality in the apparatus operation start stage is determined. If an abnormality is detected, the process proceeds to step 720 and the fixing unit 19 is stopped. If no abnormality is detected, the process proceeds to step 760.

  In step 760, after the elapse of tsec from the start of printing, the apparatus is switched to the apparatus operation stage. In step 770, an abnormality in the apparatus operation stage is determined. If an abnormality is detected, the process proceeds to step 720 and the fixing unit 19 is stopped. If no abnormality is detected, the process proceeds to step 780. In step 780, the normal operation is performed. When the printing is finished, the process proceeds to step 790, and this process is finished. Normal operation here is normal fixing operation

  Processing for determining an abnormality at each stage will be described with reference to FIG. This process can be started when the fixing unit 19 is activated, but may be started before that. Starting from step 800, in step 810, the temperatures of the high temperature side surface 32 and the low temperature side surface 33 provided in the thermoelectric conversion element 31 are predicted. The temperature can be obtained as a predicted temperature by calculating using a calculation formula or the like. Details will be described later. In step 820, the threshold value of the power generation potential of the power generated by the thermoelectric conversion element 31 is calculated from the predicted temperature. This threshold value can also be calculated using a calculation formula or the like. Details of this will also be described later.

  In step 830, the fixing unit 19 is activated and the thermoelectric conversion element 31 generates power. In step 840, the generated voltage of the generated power is measured by the voltage measurement circuit. In step 850, the threshold value calculated in step 820 is compared with the measured power generation voltage. If it is less than the threshold value, it is determined that there is no abnormality in step 870, and if it exceeds the threshold value, it is determined that there is an abnormality in step 880. And detect anomalies. When it is determined that there is an abnormality, the process proceeds to step 890 and the process is terminated.

  Since the relationship between the time elapsed since the start of the fixing unit 19 and the power generation voltage is different as shown in FIG. 6, the temperatures of the predicted high temperature side 32 and low temperature side 33 are calculated by different calculation methods. Then, a threshold value is calculated from these temperatures. Since an appropriate threshold value can be set at each stage, when an abnormality is detected, the fixing unit 19 can be stopped immediately, and the safety of the fixing unit 19 can be improved by this immediate stop. Hereinafter, the temperature calculation method and the threshold value calculation method will be described specifically for each stage.

  At the apparatus activation stage when the fixing unit 19 is activated, as shown in FIG. 9A, the generated voltage increases at a constant rate as time elapses. For this reason, it is appropriate that the threshold value for the generated voltage has a certain margin and increases at the same rate as the generated voltage. That is, when the relationship between the elapsed time and the generated voltage can be expressed by a linear function of time, the slope is set to the same value for the actual measurement value and the threshold value, and the intercept of the actual measurement value is 0. The intercept can be set to a constant value. By setting to such a value, as shown in FIG. 9B, even if an abnormality occurs during the apparatus startup stage, the abnormality can be detected quickly, and the fixing unit 19 is stopped immediately. Can be made. Since it can be stopped immediately, even if it takes damage, it can be minimized.

The temperature of the hot side surface 32 is substantially equal to the fixing surface temperature of the fixing roller 30 of the fixing unit 19. For this reason, the predicted value of the temperature of the high temperature side surface 32 can be calculated as the predicted value of the fixing surface temperature. The predicted value T _H (° C.) of the fixing surface temperature can be calculated by the following equation 1, for example. Incidentally, the predicted value T _H, in addition to following formula 1, can also be obtained using the table or the like.

  In the above formula 1, t is the time (sec) that has elapsed since the fixing unit 19 was started, and A is the fixing temperature rise curve (° C./sec). The fixing temperature rise curve A is one parameter and is a value unique to the apparatus. If the apparatus takes 4 seconds for the fixing surface temperature to reach the set fixing temperature of 200 ° C., A = 200/4 = 50 (° C./sec).

The predicted value T _C (° C.) of the temperature of the low temperature side surface 33 can be calculated by the following equation 2, for example. Incidentally, the predicted value T _C, in addition to following equation 2, can also be obtained using the table or the like.

In the above formula 2, t is the time (sec) that has elapsed since the fixing unit 19 was started, as in formula 1, and B is the low temperature side temperature rise curve (° C./sec). The low temperature side temperature rise curve B is one parameter and is a value unique to the apparatus. The low temperature side temperature rise curve B can be obtained from the result of an experiment conducted in advance.

The generated voltage of the thermoelectric conversion element 31 can be determined by the temperature of the high temperature side surface 32 and the temperature of the low temperature side surface 33. The relationship between the generated voltage and the temperature of the high temperature side surface 32 and the low temperature side surface 33 varies depending on the type of the thermoelectric conversion element 31, but here, the value obtained by dividing the difference between the temperature of the high temperature side surface 32 and the temperature of the low temperature side surface 33 by 10 is given. It demonstrates as what uses the thermoelectric conversion element 31 which has the relationship used as a generated voltage. Therefore, the predicted value E _G (V) of the generated voltage also has a similar relationship, and can be calculated by the following Equation 3.

The threshold E _th (V) with respect to the generated voltage can be calculated by the following equation 4. In Equation 4, α is a constant margin (V), and any appropriate value can be used.

The determination of the abnormality in the apparatus start-up stage of the fixing unit 19 is performed based on the comparison result by comparing the measured value E _m (V) of the generated voltage measured by the voltage measuring circuit with the threshold value E _th (V). Specifically, if the threshold value _{E th} ≧ Found _{E m,} the fixing unit 19 is determined to be _normal, if E th _{<E m,} is determined to be abnormal.

Here, when calculating with α = 1 (V), A = 50 (° C./sec), B = 30 (° C./sec) and elapsed time 3 (sec), the predicted value of the temperature of the high temperature side surface 32 is calculated. T _H is 0.99 ° C. from equation 1, the predicted value _{T C} of the temperature of the cold side 33 can be calculated with the equation 2 90 ° C.. Predicted value E _G of the power generation voltage can be calculated as 6V from equation 3, the threshold E _th may be calculated to 7V from equation 4. Therefore, if the power generation voltage measured at the time of 3 sec after starting the fixing unit 19 is 7V or less, it is determined to be normal, and if it is greater than 7V, it is determined to be abnormal.

  At the device operation start stage, as shown in FIG. 10A, the generated voltage decreases as time elapses. This is because there is a delay in the temperature rise of the high temperature side surface 32 and the temperature rise of the low temperature side surface 33, and the temperature of the low temperature side surface 33 rises even though the temperature of the high temperature side surface 32 becomes constant. This is because. In this case as well, it is appropriate that the threshold value for the generated voltage has a certain margin and decreases at the same rate as the generated voltage. By setting to such a value, as shown in FIG. 10B, even if an abnormality occurs during the apparatus operation start stage, the abnormality can be detected immediately, and the fixing unit 19 can be detected immediately. Can be stopped.

The temperature of the hot side surface 32 is substantially equal to the fixing surface temperature of the fixing roller 30 of the fixing unit 19. For this reason, the predicted value of the temperature of the high temperature side surface 32 can be calculated as the predicted value of the fixing surface temperature. At this stage, since the fixing surface temperature is the set fixing temperature, the predicted value T _H (° C.) of the fixing surface temperature can be set to the set fixing temperature. For example, if setting the fixing temperature to 200 ° C., the fixing surface temperature, i.e. the predicted value T _H of the temperature of the hot side 32, it can be predicted with 200 ° C..

Predicted value T _C of the temperature of the cold side 33 can be calculated by the formula 2. The predicted value T _C can also be determined using a table or the like. Further, the predicted value E _G and the threshold E _th of the power generation voltage can be calculated using the above formula 3 and formula 4. Abnormality determination in the apparatus operation start phase of the fixing unit 19 compares the measured value E _m of the power generation voltage measured by the voltage measurement circuit, and a threshold E _th, performed on the basis of the comparison result. Specifically, if the threshold value _{E th} ≧ Found _{E m,} the fixing unit 19 is determined to be _normal, if E th _{<E m,} is determined to be abnormal.

  In the apparatus operation stage, as shown in FIG. 11A, a steady state is entered, and the generated voltage becomes substantially constant. Also in this case, it is appropriate that the threshold value for the generated voltage is a value having a certain margin. By setting to such a value, as shown in FIG. 11B, even if an abnormality occurs during the operation of the apparatus, the abnormality can be detected immediately, and the fixing unit 19 can be quickly installed. Can be stopped.

Temperature of the hot side 32, like the device operation start stage, that is a fixing temperature that has already been set, the fixing temperature set may be a prediction value T _H of the temperature of the hot side 32. The temperature of the cold side surface 33 also settles at a constant temperature in the apparatus operation stage. This temperature varies depending on the setting value of the fixing temperature and the configuration of the fixing unit 19. Therefore, pre-conducted experiments, using the results obtained by the experiment, the relationship between the set value determined by implementing as a table or the like, it is possible to obtain the predicted value T _C.

  FIG. 12 is a diagram illustrating an example of a table in which the setting value of the fixing temperature and the temperature of the low temperature side surface 33 are associated with each other. In this example, a temperature 20 ° C. lower than the fixing temperature is set as the temperature of the low temperature side surface 33.

For example, if setting the fixing temperature to 200 ° C., the predicted value T _H of the temperature of the hot side 32, it can be expected to 200 ° C., the predicted value T _C of the temperature of the cold side 33, 12 With reference to the table shown, it can be predicted to be 180 ° C. Predicted value E _G and the threshold E _th of the power generation voltage can be calculated using the above formula 3 and formula 4. Abnormality determination in the apparatus operation start phase of the fixing unit 19 compares the measured value E _m of the power generation voltage measured by the voltage measurement circuit, and a threshold E _th, performed on the basis of the comparison result. Specifically, if the threshold value _{E th} ≧ Found _{E m,} the fixing unit 19 is determined to be _normal, if E th _{<E m,} is determined to be abnormal.

  When printing is completed, heating of the fixing roller 30 is stopped. It takes some time for the heating to stop and return to room temperature. When the next printing is requested until the temperature returns to the normal temperature, the temperature of the high temperature side surface 32 increases from the midway temperature until the temperature returns to the normal temperature to the set fixing temperature as shown in FIG. Will do. The same applies to the temperature of the low temperature side surface 33. Since the above formulas 1 and 2 are calculation formulas for calculating each temperature when the temperature rises from the normal temperature to the set fixing temperature, when these calculation formulas are used as they are, an accurate temperature cannot be predicted.

  As shown in FIG. 13 (b), the generated voltage also has a substantially constant difference between the temperature of the high temperature side surface 32 and the temperature of the low temperature side surface 33 until it returns to room temperature. Should be almost the same as the predicted value in the previous device operation stage. However, if each temperature is calculated by the above formulas 1 and 2, different predicted values are calculated, so the generated voltage cannot be obtained accurately, and as a result, an appropriate threshold value cannot be set. .

  The temperature in the middle of returning to the normal temperature varies depending on the printing interval (operation interval or elapsed time) from the end of the previous (previous) printing to the start of the current activation. The temperature also changes depending on the temperature of the high temperature side surface 32 and the low temperature side surface 33 in the previous printing, and the rate at which the temperature decreases (temperature attenuation slope). For this reason, it is possible to predict an accurate temperature in the apparatus start-up stage by correcting the calculation formula using the elapsed time or the like. Then, an accurate generated voltage can be obtained, and as a result, an appropriate threshold value can be set.

The temperature X _a (° C.) of the high temperature side surface 32 in the previous printing can be acquired from the set fixing temperature. The temperature X _b (° C.) of the low temperature side surface 33 in the previous printing can be obtained from the table shown in FIG. The elapsed time t _m (min) can be obtained by using a clock function or the like provided in the image forming apparatus 10. The temperature decay slope Y (° C./min) can be obtained by previously obtaining an experiment and storing it in a storage device. The slope Y of temperature decay is a value unique to the apparatus.

  The abnormality detection system further includes an acquisition unit that acquires at least the information on the elapsed time, acquired by the acquisition unit, and the monitoring circuit 51 serving as a determination unit corrects the calculation formula using the acquired information. Can do. By performing such correction, the control becomes complicated, but an abnormality can be determined with higher accuracy than when correction is not performed.

  The overall processing flow of the abnormality detection system at this time will be described with reference to FIG. The overall flow is substantially the same as the flow shown in FIG. 7, but a flow for acquiring print interval information (print interval information) is added in step 1410. Then, in the determination of each abnormality such as step 1420, the calculation formula is corrected using the acquired information, each temperature is obtained using the corrected calculation formula, and the threshold value is calculated. Since the other processing steps are the same as the processing steps shown in FIG. 7, the description thereof is omitted here.

The following formulas 5 and 6 show the calculation formulas corrected by the information obtained from the above formulas 1 and 2. In addition, said Formula 3 and Formula 4 can be used as it is as a calculation formula for calculating the predicted value E _G of the generated voltage and the threshold value E _th . Then, the measured power generation voltage can be compared with a threshold value to determine whether the fixing unit 19 is abnormal.

In Formula 5 and Formula _{6, X} a -Y × _{t m} and _X b -Y × _{t m} is the middle of the temperature to return to normal temperature as described above. By performing the correction for adding the temperatures, it is possible to predict the accurate temperatures of the high temperature side surface 32 and the low temperature side surface 33 in the apparatus startup stage.

  In the above description, the temperature of the high temperature side surface 32 and the low temperature side surface 33 after starting the device that generates heat during operation has been predicted using a linear function formula. When an approximate expression such as an exponential function is obtained, it is also possible to predict using the approximate expression. By using the approximate expression, it is possible to predict the temperatures with higher accuracy.

  Further, the number of devices that the abnormality detection system detects abnormality is not limited to one, and it is also possible to detect abnormality of a plurality of devices. In this case, a device detection unit that detects which device has started and started operation is required, and parameters such as A and B corresponding to the device detected by the device detection unit are acquired from a storage device or the like, It can be used to predict the temperature of the hot side 32 and the cold side 33. In addition, a predicted power generation voltage can be obtained using an expression for calculating a power generation voltage corresponding to the device, and a threshold value can be calculated from the obtained power generation voltage. Then, in the same manner as described above, the measured power generation voltage and the threshold value can be compared to determine an abnormality. Note that when the user instructs the start of a job called printing, the fixing unit 19 related to printing starts the operation, so that the apparatus can detect from the contents of the job that the user instructs to start. Since this is an example, it can be detected by other methods.

  The processing executed by the abnormality detection system, electronic device, abnormality detection method and program of the present invention has been described in detail so far with reference to the embodiments shown in the drawings, but the present invention is limited to the above-described embodiments. Is not to be done. Therefore, other embodiments, additions, changes, deletions, and the like can be changed within a range that can be conceived by those skilled in the art, and as long as the effects and advantages of the present invention are exhibited in any aspect, the present invention It is included in the range. Therefore, the present invention can also provide a recording medium on which a program is recorded. This program can also be provided via a network when a download request is received.

DESCRIPTION OF SYMBOLS 10 ... Image forming apparatus, 11 ... ADF, 12 ... Image reading apparatus, 13 ... Printer unit, 14 ... Capacitor unit, 15 ... Writing unit, 16 ... Photoconductor drum, 17 ... Developing unit, 18 ... Conveyor belt, 19 ... Fixing Unit, 20 ... Controller, 21 ... CPU, 22 ... RAM, 23 ... ROM, 24 ... HDD, 25 ... NVRAM, 26 ... Operation panel, 27 ... Modem, 28 ... Network I / F, 29 ... Media drive, 30 ... Fixing Roller, 31 ... Thermoelectric conversion element, 32 ... High temperature side, 33 ... Low temperature side, 34 ... Fan, 35 ... Duct, 36 ... Storage battery, 37 ... Voltage measuring means, 40 ... Heat generating component, 41 ... External power supply, 42 ... PSU, 43 ... Storage battery, 44 ... Discharger, 45 ... Switching circuit, 46 ... Load, 47 ... Diode, 48 ... Charger, 49 ... Control circuit, 5 ... temperature measuring circuit, 51 ... monitoring circuit

JP 2004-361553 A JP 2011-107499 A JP 2013-033134 A

Claims (10)

A system for detecting an abnormality in a device that generates heat during operation,
A power generation means having a high temperature side surface disposed adjacent to or adjacent to the device and a low temperature side surface behind the high temperature side surface, and generating power by a temperature difference between the high temperature side surface and the low temperature side surface;
Voltage measuring means for measuring the generated voltage of the power generated by the power generating means;
Calculating means for predicting the temperature of the high temperature side surface and the low temperature side surface, and calculating a threshold value of the generated voltage from the predicted temperature;
An abnormality detection system comprising: a determination unit that compares the generated voltage measured by the voltage measurement unit with the threshold value calculated by the calculation unit to determine abnormality of the device.   2. The abnormality detection according to claim 1, wherein the calculation unit divides the operation of the apparatus into a plurality of stages, and calculates the temperatures of the high-temperature side surface and the low-temperature side surface predicted by different calculation methods for each step. system.   The plurality of stages include an apparatus start-up stage until the temperature of the high temperature side reaches a set temperature set value, and the temperature of the low temperature side is constant after the temperature of the high temperature side reaches the temperature set value. The abnormality detection system according to claim 2, comprising three stages: an apparatus operation start stage until a temperature is reached, and an apparatus operation stage after the temperature of the low-temperature side surface reaches a constant temperature.   The information processing apparatus further includes acquisition means for acquiring information on the set operation interval of the apparatus, and the calculation means uses the information on the operation interval acquired by the acquisition means to predict the high temperature side surface and the low temperature side surface. The abnormality detection system of any one of Claims 1-3 which correct | amends the temperature of.   The acquisition means further acquires a temperature set value set for the immediately preceding operation of the apparatus, and the calculation means is predicted using the temperature set value acquired by the acquisition means. The abnormality detection system according to claim 4, wherein temperatures of the high temperature side surface and the low temperature side surface are corrected.   The abnormality according to any one of claims 1 to 5, further comprising notification means for notifying the apparatus and stopping the operation of the apparatus when the determination means determines that there is an abnormality and detects the abnormality. Detection system.   Including a plurality of power generation means and a device detection means for detecting a device that has started operation among a plurality of devices that generate heat during operation, wherein the calculation means is adjacent to the device detected by the device detection means Alternatively, the temperature of the high temperature side and the low temperature side of the power generation means arranged nearby is predicted, the threshold value of the generated voltage is calculated from the predicted temperature, and the determination means is measured by the voltage measurement means, The power generation voltage of the power generated by the power generation means arranged adjacent to or adjacent to the device detected by the device detection means is compared with the threshold value calculated by the calculation means, and the device detection means The abnormality detection system according to claim 1, wherein an abnormality of the detected device is determined.   An electronic apparatus comprising: an apparatus that generates heat during operation; and an abnormality detection system that detects an abnormality of the apparatus according to any one of claims 1 to 6. A method for detecting an abnormality in a device that generates heat during operation,
A high temperature side surface disposed adjacent to or near the device and a low temperature side surface behind the high temperature side surface, the high temperature side surface of the power generation means for generating electricity by a temperature difference between the high temperature side surface and the low temperature side surface, Predicting the temperature of the low temperature side surface and calculating a threshold value for the generated voltage of the power generated by the power generation means from the predicted temperature;
Generating power by the power generation means;
Measuring the generated voltage of the power generated by the power generation means;
Comparing the measured power generation voltage with the calculated threshold value, and determining an abnormality of the device.   A program for causing a computer to execute the abnormality detection method according to claim 9.