JP6969427B2 - Image forming device, control method and program - Google Patents

Description

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

In an image forming apparatus equipped with a fixing heater, if the fixing heater becomes hot due to soft runaway or the like, there is a risk of ignition or smoke generation. In order to prevent the danger, a technique (hereinafter, appropriately referred to as "high temperature detection") for cutting off the power supply to the fixing heater when the temperature sensor detects a temperature exceeding the set temperature is already known.

In addition, the occurrence of high temperature detection is regarded as a fatal abnormality, and in order not to pose a danger to the user, the device is not restored when the power is turned off / on, and it is not restored unless the serviceman cancels the abnormality. .. For example, Patent Document 1 discloses a technique for prohibiting the restart of an apparatus when the detected failure is a predetermined specific failure.

When high temperature detection occurs, the fixing unit is replaced on the assumption that it is broken. At this time, it is determined by the new product detection control whether or not the device has been replaced, and the device cannot be used unless it is replaced with a new product.
On the other hand, the occurrence of high temperature detection may be suspected to be false detection. For example, in the case of false detection due to noise, the fixing unit is replaced even though the fixing unit is not damaged, which increases the service cost. Therefore, it is desired to reduce the increase in service cost due to false positives.

However, in the conventional device, even if the high temperature detection by the NC sensor is erroneously detected, the fixing unit is replaced, which causes a problem that the service cost is wasted.

An object of the present invention is to reduce a service cost by detecting a case where high temperature detection is erroneous detection in a device having a function of detecting high temperature of a fixing heater.

In order to solve the above-mentioned problems, the image forming apparatus according to the present invention includes a first sensor for detecting the temperature of the fixing heater, a second sensor for detecting the temperature of the fixing heater, and at least the first sensor. The first sensor detects a high-voltage detection means for detecting a high-voltage abnormality in which the temperature detected by the sensor exceeds the first high-voltage detection value, a high-voltage output abnormality detecting means for detecting a high-voltage output abnormality due to arc discharge of a high-voltage power supply, and the first sensor. When the high-voltage abnormality is detected by the temperature, the temperature detected by the second sensor does not exceed the second high-voltage detection value, and the high-voltage output abnormality detecting means detects the high-voltage output abnormality. Is equipped with a false positive determination means that determines that it is a false positive, prohibits recovery by restarting the machine by the user, and makes a setting that does not require new detection control when replacing the fixing unit. It is a feature.

According to the present invention, in a device having a function of detecting a high temperature of a fixing heater, it is possible to detect a case where the high temperature detection is an erroneous detection and reduce the service cost.

It is a figure explaining the configuration example and the operation outline of a copying machine. It is a figure explaining the fixing heater and the sensor configuration of one Embodiment. It is a figure explaining the structural example of the high temperature detection circuit of one Embodiment. It is a figure explaining the abnormal discharge detection of the high voltage power source of one Embodiment. It is a flowchart explaining an example of the control flow when the false positive determination means of Embodiment 1 detects a high temperature abnormality of NC sensor. In one embodiment, it is a figure explaining the display example of the occurrence of an abnormality on an operation panel. It is a flowchart explaining the operation example which determines whether or not it is a false positive by using a plurality of temperatures detected by a thermopile by the false positive determination means of Embodiment 2. It is a flowchart explaining the operation example which determines whether or not it is a false detection by using a plurality of temperatures detected by a high AC high voltage generation part by the false positive determination means of Embodiment 3. It is a flowchart explaining the operation example which automatically controls to continue a normal operation without notifying the occurrence of abnormality of high temperature detection when the false detection determination means of Embodiment 4 determines false detection. It is a flowchart explaining the operation example which logs the information which the false positive determination means of Embodiment 5 determined as false positive.

Hereinafter, embodiments will be described with reference to the drawings. For the sake of clarity, the following description and drawings have been omitted or simplified as appropriate. In each drawing, components and corresponding parts having the same configuration or function are designated by the same reference numerals, and the description thereof will be omitted.

A copying machine will be described as an example of an image forming apparatus having a function of detecting a high temperature of a fixing heater to which an embodiment of the present invention is applied.
FIG. 1 is a diagram illustrating a configuration example and an operation outline of the copying machine.
The copying machine 100 includes a reading device 125 for reading a document, an image forming unit 112 for forming an image, an ADF 113 (automatic document transporting device), a document ejection tray 114 for stacking documents sent from the ADF 113, and the like. It also has a paper feed unit 119 including paper feed cassettes 115 to 118, a paper discharge unit (paper output tray 120) for stacking recording paper, and the like.

Next, the copying operation in the copying machine 100 will be described.
The document D is set on the document table 121 of the ADF 113, and the print key is pressed by an operation unit (not shown). As a result, the uppermost document D on the platen 121 is sent out in the direction of arrow B1 by the rotation of the pickup roller 122. Then, due to the rotation of the document transport belt 123, the document is fed onto the contact glass 124 fixed to the reading device 125, and the document is stopped there.

The image of the document D placed on the contact glass 124 is read by the reading device 125 located between the image forming unit 112 and the contact glass 124. The reading device 125 includes a light source 126 that illuminates the original D on the contact glass 124, an optical system 127 that forms an image of the original image, a photoelectric conversion element 128 including a CCD that forms an image of the original image, and the like. After the image reading is completed, the document D is transported in the direction of arrow B2 by the rotation of the document transport belt 123 and discharged onto the document ejection tray 114. In this way, the originals D are fed one by one onto the contact glass 124, and the original images are read by the reading device 125.

A photoconductor 130, which is a latent image carrier, is arranged inside the image forming unit 112. Around the photoconductor 130, there are a charging device 131 as a charging means, a writing device 132 as an exposure means, a developing device 133 as a developing means, a transfer device 134 as a transfer means, a cleaning device 135 as a cleaning means, and the like. It is arranged and constitutes an image forming unit 300 as a toner image forming means.
The photoconductor 130 is rotationally driven clockwise in FIG. 1 and uniformly charges the surface to a predetermined potential by the charging device 131. Further, the writing device 132 irradiates the laser beam L light-modulated according to the image information read by the reading device 125, and exposes the surface of the uniformly charged photoconductor 130 with the laser beam L to be photosensitive. An electrostatic latent image is formed on the surface of the body 130.

When the electrostatic latent image passes through the portion facing the developing device 133 due to the surface movement of the photoconductor 130, toner is supplied from the developing device 133 and developed, so that the toner image is formed on the surface of the photoconductor 130. It is formed. Further, as the photoconductor 130 moves on the surface, the toner image on the photoconductor 130 moves to the portion facing the transfer device 134. Then, the toner image on the photoconductor 130 is transferred to the transfer paper P, which is a recording body fed between the photoconductor 130 and the transfer device 134, by the transfer bias between the transfer device 134 and the photoconductor 130. The surface of the photoconductor 130 after the transfer of the toner image is performed is cleaned by the cleaning device 135.

A recording body such as a transfer paper P is housed in a plurality of paper feed cassettes 115 to 118 arranged below the image forming unit 112, and the transfer paper P is directed from any of the paper feed cassettes 115 to 118 in the direction of arrow B3. The toner image formed on the surface of the photoconductor 130 is transferred to the surface of the transfer paper P as described above. The transfer paper P on which the toner image is transferred is conveyed to the fixing portion of the fixing device 1 in the image forming portion 112 as shown by an arrow B4. When the transfer paper P passes through the fixing portion of the fixing device 1, the toner image transferred to the surface of the transfer paper P is fixed by the action of heat and pressure. The transfer paper P that has passed through the fixing portion of the fixing device 1 is conveyed by the output roller pair 137, and is discharged to the output tray 120 and stacked as shown by the arrow B5.

Next, the configurations of the fixing heater and the temperature detection sensor will be described.
FIG. 2 is a diagram illustrating a fixing heater and a sensor configuration.
In the direct heat (DH) fixing method using the QSU (Quick Start-Up) technology, the fixing heater 61 is covered with a thin fixing sleeve 62, which is locally heated by the light-shielding plate 63. Achieves rapid launch.

The thermopile 53 detects the temperature on the surface of the fixing sleeve 62. The power supply to the fixing heater 61 is controlled according to the detected temperature. Further, when the fixing heater 61 becomes excessively high temperature for some reason and the detected temperature becomes high, the control is such that the high temperature detection abnormality is notified and the power supply to the fixing heater 61 is cut off immediately (hereinafter, ". Called "high temperature detection").

Further, there is a thermistor 71 for detecting the temperature of the pressure roller 70. If printing is started when the pressure roller 70 is not warm, heat is immediately taken away by the paper, and high ppm (Page Per Minute, the number of printable sheets per minute) cannot be secured. Therefore, the system is such that the thermistor 71 detects whether or not the pressurizing roller 70 has warmed up, and after the temperature is warmed up, the paper feed is controlled.

Further, the NC sensor 51 is a non-contact sensor and is inferior in responsiveness to the thermopile 53, but has the advantages of being approved and having a low cost. By mounting the NC sensor 51, it is possible to prevent the danger of ignition or the like even when the thermopile 53 is broken. The thermostat 59 is slower in response than the thermopile 53 and the NC sensor 51, and is used for the purpose of preventing the fire from spreading outside the machine.

Next, a configuration example of a high temperature detection circuit that detects the high temperature of the fixing heater will be described.
FIG. 3 is a diagram illustrating a configuration example of a high temperature detection circuit.
The high temperature detection circuit 50 includes an NC sensor 51 as a first sensor, a thermopile 53 as a second sensor, a high temperature detection means (high temperature detection unit) 55, and an AD (Analog Digital) converter 57, and goes to a fixing heater 61. Control the power supply of.
When the high temperature detecting means 55 detects a high temperature abnormality in which the temperature of the temperature sensor that detects the temperature of the fixing heater 61 exceeds the high temperature detection set temperature (first high temperature detection value set and held in advance), the high temperature detecting means 55 supplies power to the fixing heater. Executes the high temperature detection function to block. FIG. 3 shows a configuration example in which the high temperature detecting means 55 includes a comparator 551, a latch circuit 555, a relay 555, and a differential amplifier 557.

Further, the control unit 30 shown in FIG. 3 is a control means that functions as a controller that controls the entire image forming apparatus. The control unit 30 includes a CPU (Central Processing Unit) 301, a ROM (Read Only Memory) 302, a RAM (Random Access Memory) 303, and the like. The CPU 301 executes a calculation function or the like according to a program or data stored in the ROM 302, and uses the RAM 303 as a work memory to control each part of the image forming apparatus to execute basic processing as the image forming apparatus.

The thermopile 53 detects the temperature of the fixing heater 61 and outputs a voltage corresponding to the detected temperature to the comparator 551 and the AD converter 57.
The AD converter 57 AD-converts the output voltage and outputs it to the control unit 30. In the control unit 30, the CPU 301 acquires the temperature detected by the thermopile 53 according to the voltage-temperature table held in the ROM 302 in advance.

The NC sensor 51 is a sensor composed of two elements, a detection thermistor 511 and a compensation thermistor 513. The detection thermistor 511 detects infrared radiation from the fixing heater 61, and the compensation thermistor 513 detects the atmospheric temperature.
One end of the detection thermistor 511 and the compensation thermistor 513 is connected to GND (reference potential), respectively. The other ends of the detection thermistor 511 and the compensation thermistor 513 are each connected to a power source via a resistor. The voltage of the power supply is not particularly limited.

When the temperature detected by the detection thermistor 511 and the compensation thermistor 513 changes, the divided voltage level changes. The output divided by the compensation thermistor 513 and the output divided by the detection thermistor 511 are input to the differential amplifier, and the differentially amplified voltage (differential voltage) is input to the AD converter 57. Further, the output divided by the compensation thermistor 513 is also input to the AD converter 57.
The AD converter 57 converts the output divided by the differential voltage and the compensation thermistor 513 into digital signals, and outputs the digital signals to the control unit 30. In the control unit 30, the CPU 301 converts each input digital signal into a detection temperature by the temperature table provided in advance in the ROM 302, and converts the temperature corresponding to the differential voltage into the output divided by the compensation thermistor 513. Get the corresponding temperature.

The high temperature detecting means 55 controls the power supply to the fixing heater 61 by using the voltage received from the thermopile 53 or the NC sensor 51.
The comparator 551 compares the voltage output from the thermopile 53 or the NC sensor 51 with the voltage corresponding to the preset high temperature detection set temperature (for example, 250 ° C.), and fixes the voltage when the high temperature detection set temperature is exceeded. It is determined that the temperature of the heater 61 is abnormal, and the relay 555 is immediately shut off to cut off the power supply to the fixing heater. At the same time, when the high temperature detecting means 55 (comparator 551) detects a high temperature abnormality, the control unit 30 is notified.
The latch circuit 553 is provided so that the result of high temperature detection is not cleared even if the temperature once becomes high and the temperature drops with the passage of time.

When the high temperature detecting means 55 notifies the control unit 30 that the high temperature abnormality has been detected, the control unit 30 displays the abnormality on the operation panel.
When a high temperature abnormality is detected, the image forming apparatus is moved to the stopped state by the control of the control unit 30, and the stopped state is not released by turning the power of the user off / on so as not to pose a danger to the user. The image forming apparatus cannot be restored unless the serviceman cancels the abnormality.
Further, the procedure at the time of restoration is different between the high temperature detection by the thermopile 53 and the high temperature detection by the NC sensor 51. In the image forming apparatus, replacement of the fixing unit is optional when the high temperature is detected by the thermopile 53, but replacement of the fixing unit is indispensable when the high temperature is detected by the NC sensor. This is because the thermopile 53 has a high responsiveness, so that the relay can be cut off before the fixing unit 61 is damaged, but the NC sensor 51 has a slow responsiveness, so there is a high possibility that the fixing unit 61 is damaged. Because. Therefore, when the high temperature is detected by the NC sensor 51, the image forming apparatus is configured to detect whether the fixing unit is new or not at the time of restoration, and the mechanism is such that restoration cannot be performed unless it is detected that the fixing unit is new. ..

Next, a high-voltage output abnormality detecting means for detecting a high-voltage output abnormality due to an arc discharge of a high-voltage power supply (HVP) will be described.
FIG. 4 is a diagram illustrating abnormal discharge detection of a high voltage power supply.
The control unit 30 shown in FIG. 4 is the same as that in FIG.
The AC high-voltage generation unit 21 as a high-voltage output abnormality detecting means is a means for generating an applied voltage applied to a static elimination needle (not shown) according to an instruction from the control unit 30. The static eliminator needle is a means for separating the recording medium from the photosensitive drum by static electricity charged on the recording medium by the transfer process.

The control unit 30 instructs the voltage applied to the static elimination needle (Pk-Pk target voltage value) determined in advance for proper separation, and operates the AC high-voltage generation unit 21.
The control unit 30 converts the instructed Pk-Pk target voltage value into a PWM signal (control target value of AC high voltage output) and transmits it to the AC high voltage generation unit 21.

In the AC high voltage generation unit 21, the PWM signal received from the control unit 30 is analog-converted by the D / A converter 218 and input to the first comparison circuit 215 as the AC high voltage output target reference voltage value.
In a normal state, the first comparison circuit 215 passes the AC high voltage output target reference voltage value to the AC drive control unit 212, and based on this voltage value, the AC drive control unit 212 has an AC high voltage output of Pk-Pk. The AC transformer unit 211 that boosts the power supply is driven and controlled so that the constant voltage is maintained, and the AC transformer output is applied to the static elimination needle.

The AC high voltage output applied to the static eliminator is usually a very large output with a Pk-Pk voltage of 8.0k to 12.0kV, so for safety reasons, an excessive current flowed through the static eliminator to which the AC high voltage is output. Occasionally, an AC high-voltage overcurrent detection unit 213 for detecting an abnormality is provided.
A predetermined overcurrent detection value is set in advance in the AC high voltage overcurrent detection unit 213 in order to detect the current of the AC high voltage output flowing through the static elimination needle as an overcurrent.
When the AC high voltage overcurrent detection unit 213 detects that the current of the AC high voltage output exceeds the preset overcurrent detection value at the time of AC high voltage output, the information is first via the second comparison circuit 216. It is input to the comparison circuit 215.

The SC signal is a signal indicating an abnormality from the AC high voltage generation unit 21 when the output is turned off. The control unit 30 detects a high voltage output abnormality by receiving an SC signal from the AC high voltage generation unit 21.

Here, the relationship between the high temperature abnormality of the temperature detection sensor including the NC sensor 51, the server mobile 53, etc. and the high voltage output abnormality by the high voltage power supply (for example, the AC high voltage generation unit 21) will be described.
Some of the high temperature detection of the temperature sensor is suspected to be caused by noise. For example, there is a case where high temperature detection occurs in the NC sensor when the temperature of the heating thermopile and the pressure thermistor is not high.
One of the causes is that high voltage detection is erroneously detected due to the influence of noise from the high voltage power supply. In a high-voltage power supply, for example, in a situation where a logging abnormality occurs, the high-voltage power supply scatters a large level of noise, and the temperature detection sensor may erroneously detect the noise. It ends up.

When a high temperature abnormality is detected in the temperature detected by the NC sensor 51, the image forming apparatus is controlled to the stopped state by the control unit 30 as described above. In addition, in the conventional image forming apparatus, in addition to the serviceman canceling the abnormality, the image forming apparatus cannot be restored unless the fixing unit is replaced (new article detection control). This was the same even if the high temperature abnormality detected by the NC sensor 51 was a false detection.
Therefore, in one embodiment of the present invention, the image forming apparatus is moved to the stopped state, but the temperature of the thermopile 53 at the time of detecting high temperature is confirmed, and if the temperature is not high, the output abnormality signal of the high voltage power supply is abnormal. When it is an output, it is displayed on the operation panel that there is a high possibility of false detection, and the new product detection control after the abnormality is cleared is omitted.

More specifically, when the NC sensor 51 detects a high temperature, (1) whether the other temperature sensor (thermopile) of the fixing heater 61 detects a high temperature, and (2) the high voltage power supply arc discharges to disperse noise. When the conditions (1) and (2), such as whether or not such a state is established, occur at the same time, it is determined that there is a possibility of false detection.
If there is a possibility of false detection, an abnormal display is displayed on the operation panel to prohibit recovery by restarting the user's machine, and new product detection control is omitted.

In one embodiment, a false positive determination means that realizes the above-mentioned function is provided.
The false detection determination means first confirms the above-mentioned conditions (1) and (2) when it detects a high temperature abnormality in which the temperature detected by the NC sensor 51 as the first sensor exceeds the first high temperature detection value (1) and (2). Perform the process of detection). Specifically, as the above-mentioned condition (1), the temperature detected by the thermopile 53 is referred to, and it is confirmed that the referred temperature does not exceed the second high temperature detection value. As the condition (2), the output from the high voltage output abnormality detecting means (AC high voltage generation unit 21) is referred to, and a process for confirming that the high voltage output abnormality has been detected is performed.
Next, the false positive determination means determines whether or not both the conditions (1) and (2) are satisfied, and if the conditions (1) and (2) are satisfied, the false positive determination process and the false positive determination process are performed. If it is determined to be detected, recovery by restarting the machine by the user is prohibited, and a setting process that does not require new detection control at the time of replacing the fixing unit is performed.

As an example, the false positive determination means can be realized as a program to be executed by the control unit 30. Further, the false positive determination means may be partially or wholly configured by hardware. For example, as in an embedded system, it may be realized by a combination of hardware and software, or may be configured by any one of hardware, firmware, and software, or a combination of two or more of these.
Hereinafter, each embodiment of the operation example of the false positive determination means will be described with reference to the drawings. Further, the description will be made on the premise that the control unit 30 executes each process executed by the false positive determination means.

<Embodiment 1>
FIG. 5 is a flowchart illustrating an example of a control flow when the false detection determination means of the first embodiment detects a high temperature abnormality of the NC sensor.
When the high temperature detecting means 55 detects by the comparator 551 that the differential output of the NC sensor 51 is a high temperature abnormality (for example, 2 volts or more) exceeding the first high temperature detection value (YES in S11), it relays in hardware. The 555 is shut off (S12).
After that, the control unit 30 refers to whether or not the thermopile 53 at the time of high temperature detection has reached a high temperature (for example, 200 ° C. or higher) (S13).

When the thermopile 53 is not above 200 ° C. (not high temperature) (NO in S13), it is further referred to whether or not the AC high voltage generator 21 has detected a high voltage abnormality of the high voltage power supply when the high voltage is detected (S14). ). When a high voltage abnormality is detected (YES in S14), it is regarded as high temperature detection due to noise, and the occurrence of the high temperature detection abnormality is displayed and the possibility of false detection is displayed (S15). Based on the display, the serviceman cancels the abnormality (S16).
Then, the flow of new product detection at the time of abnormality cancellation is deleted, and in the case of false detection, it is no longer necessary to replace the fixing unit, which can lead to a reduction in service cost.

Further, when the thermopile 53 is 200 ° C. or higher in step S13 (YES in S13), or when the high pressure abnormality is not detected in step S14 (NO in S14), it is determined that the high temperature detection abnormality has occurred. Displayed on the operation panel (S17). In this case, after the abnormality is cleared by the serviceman and the fixing unit is replaced, the flow is to detect that the fixing unit is new.

FIG. 6 is a diagram illustrating an example of displaying an abnormality on the operation panel in one embodiment.
In step S15 of FIG. 5, the control unit 30 displays the high temperature detection on the operation panel and notifies the user of the occurrence of an abnormality. FIG. 6 shows an example of displaying the abnormality number and contents and the possibility of erroneous detection on the operation panel when the abnormality occurrence notification is given.

According to the present embodiment, in the case of false detection of NC sensor high temperature detection due to noise, by setting so that the fixing unit does not need to be replaced, the fixing unit that can be continuously used is replaced unnecessarily. It is possible to reduce the service cost.

<Embodiment 2>
In this embodiment, an operation example of determining whether or not the thermopile temperature monitoring period is erroneous detection will be described in consideration of not only the high temperature detection of the NC sensor but also the temperature before the occurrence of an abnormality.
The image forming apparatus is configured to hold one or more temperatures detected in a predetermined period set in advance by the thermopile 53 in a region that can be referred to by the control unit 30.
When the control unit 30 (false detection determination means) is notified of the high temperature detection, the temperature detected by the thermopile 53 when the NC sensor 51 detects the high temperature abnormality, and one or more held in the referenceable area. It is determined whether or not it is a false positive by referring to the temperature.

FIG. 7 is a flowchart illustrating an operation example in which the false positive determination means determines whether or not false positive is detected by using a plurality of temperatures detected by the thermopile. FIG. 7 is an operation example in which step S21 is added to the operation of FIG. The processing of the same step number as in FIG. 5 is the same as in FIG.
By referring to the temperature of the thermopile 53 not only when an abnormality occurs in high temperature detection but also, for example, before an arbitrary time from the time when an abnormality occurs in high temperature detection, for example, 500 ms before and 1000 ms before (S21), the accuracy of noise determination can be improved. increase. As an example, it is set twice before 500 ms and 1000 ms before, but the time and the number of times do not matter. If the temperature before the occurrence of the abnormality in the high temperature detection is not 200 ° C. or higher (NO in S21), the process proceeds from steps S14 to S16 (processing for determining noise).

The control unit 30 may be configured to include, for example, a RAM 303 a temperature holding means for holding one or more temperatures detected by the thermopile 53, or to hold the temperature holding means in another recording area that can be referred to by the CPU 301. You may.
According to this embodiment, it is possible to improve the accuracy of determining whether or not it is a false positive.

<Embodiment 3>
In this embodiment, an operation example of determining whether or not the abnormality detection period of the high-voltage power supply is erroneous detection will be described in consideration of not only the detection result at the time of high temperature detection but also the detection result before the occurrence of the abnormality.
The image forming apparatus is configured to hold the detection result of one or more high voltage output abnormalities detected in a predetermined period set by the AC high voltage generation unit 21 in a region that can be referred to by the control unit 30. The preset predetermined period may be the same as or different from the predetermined period for holding the temperature detected by the thermopile 53 in the second embodiment. Further, the number of detection results of the high voltage output abnormality to be held may be the same as or different from the temperature of the second embodiment.
When the high temperature detection is notified, the control unit 30 (false detection determination means) has one or more held in the referenceable area in addition to the detection result of the high voltage output abnormality when the NC sensor 51 detects the high voltage abnormality. With reference to the detection result of the high voltage output abnormality, it is determined whether or not the detection is erroneous.

FIG. 8 is a flowchart illustrating an operation example in which the false positive determination means determines whether or not false positive is detected by using a plurality of temperatures detected by the AC high voltage generation unit. FIG. 8 is an operation example in which step S31 is added to the operation of FIG. The processing of the same step number as in FIG. 5 is the same as in FIG.
Noise determination can be made by referring to the confirmation of the high-voltage abnormality of the high-voltage power supply not only when the high-voltage detection abnormality occurs, but also, for example, before an arbitrary time from the time of the high-voltage detection abnormality, for example, 500 ms before and 1000 ms before (S31). Increase the accuracy of. As an example, it is set twice before 500 ms and 1000 ms before, but the time and the number of times do not matter. If a high-voltage abnormality of the high-voltage power supply is detected before the occurrence of the high-voltage detection abnormality (YES in S31), the process proceeds from steps S15 to S16 (processing for determining noise).

The control unit 30 may be configured to provide, for example, a high voltage abnormality holding means for holding one or more high voltage output abnormalities detected by the AC high voltage generation unit 21 in the RAM 303, or another recording area that can be referred to by the CPU 301. It may be configured to hold in.
According to this embodiment, it is possible to improve the accuracy of determining whether or not it is a false positive.

<Embodiment 4>
In the present embodiment, an operation example in which the normal operation of the image forming apparatus is controlled to be continued without notifying the occurrence of an abnormality in the high temperature detection when the false detection determination means determines false detection will be described.
When the control unit 30 determines that a false detection is made, the control unit 30 does not notify the user of the occurrence of high temperature detection, and continues the normal operation.

FIG. 9 is a flowchart illustrating an operation example in which when the false detection determination means determines false detection, automatic control is performed so that normal operation is continued without notifying the occurrence of an abnormality in high temperature detection. The processing of the same step number as in FIG. 5 is the same as in FIG.
Similar to the first embodiment, the control unit 30 performs the processes of steps S11 to S14, and when the high voltage abnormality is detected (YES in S14), the control unit 30 releases the cutoff state of the relay 555 of the high temperature detecting means 55. Then, the power supply to the fixing heater 61 is restarted.
In this way, when the possibility of erroneous detection is high, the image forming apparatus can be used as it is without issuing an abnormality notification of the occurrence of high temperature detection.
According to the present embodiment, by detecting that the high temperature detection of the fixing heater is an erroneous detection, it is not necessary to replace the fixing unit and the serviceman does not have to go to the site. Further, there is an effect that the service cost can be reduced.

<Embodiment 5>
In this embodiment, an operation example of holding the information determined to be false detection will be described.
The control unit 30 has a logging function for recording the information determined to be false detection in a writable area (false positive information holding means) when it is determined to be false detection.
FIG. 10 is a flowchart illustrating an operation example of logging information determined by the false positive determination means to be false positive. The processing of the same step number as in FIG. 5 is the same as in FIG.
Similar to the first embodiment, the control unit 30 performs the processes of steps S11 to S15, and when the possibility of false detection is high, the control unit 30 writes the information (log information) determined to be false detection to the false detection information holding means. , The process of step S16 is executed.
The false positive information holding means is preferably provided in, for example, a recording area that can be referred to by the CPU 30.

According to this embodiment, by reading the log information recorded in the false positive information holding means at a necessary timing, it is possible to grasp information such as when false positive is detected (false positive rate), and it is used as input information for design. It has the effect of being able to.

It should be noted that two or more of the above-described embodiments can be combined. For example, an operation example in which step S31 of FIG. 8 is added to the operation example of FIG. 7 is also possible. Further, it is also possible to combine the fifth embodiment and the second to fourth embodiments. For example, an operation example of the fourth embodiment, a log storage of the log of the step S51 of FIG. 5 between steps S14 and S41 of FIG. Processing can be added.
By combining the respective embodiments, it is possible to further improve the accuracy of determining whether or not the error is detected, or to acquire information for improving the accuracy of the error detection.

According to each of the above-described embodiments, the service cost (request for replacement of the fixing device by a serviceman, service) is performed by detecting the case where the high temperature detection is erroneous detection in the device provided with the function of detecting the high temperature of the fixing heater. It is possible to reduce the cost of services such as requesting the image forming apparatus to release an abnormality by a man.

In each embodiment, when all or a part of the false positive determination means is realized by a program, the program is stored by using various types of non-transitory computer readable medium. And can be supplied to a computer (including an image forming apparatus). Non-transient computer-readable media include various types of tangible storage media. Examples of non-temporary computer-readable media include magnetic recording media, optomagnetic recording media. The program may also be supplied to the computer by various types of transient computer readable medium. Examples of temporary computer-readable media include electrical, optical, and electromagnetic waves. The temporary computer-readable medium can supply the program to the computer via a wired communication path such as an electric wire and an optical fiber, or a wireless communication path.

The present invention is not limited to the embodiments shown above. Within the scope of the present invention, each element of the above embodiment can be changed, added, or converted into a content easily conceivable by those skilled in the art.

21 AC high voltage generator 30 Control unit 50 High temperature detection circuit 51 NC sensor 53 Thermopile 55 High temperature detection means 57 AD converter 61 Fixing heater 551 Comparator 555 Latch circuit 555 Relay 557 Differential amplifier

Japanese Unexamined Patent Publication No. 2006-94045

Claims (7)

The first sensor that detects the temperature of the fixing heater and
The second sensor that detects the temperature of the fixing heater and
A high temperature detecting means for detecting a high temperature abnormality in which the temperature detected by at least the first sensor exceeds the first high temperature detection value, and
High-voltage output abnormality detection means for detecting high-voltage output abnormality due to arc discharge of high-voltage power supply,
When the high temperature abnormality is detected by the temperature detected by the first sensor, the temperature detected by the second sensor does not exceed the second high temperature detection value, and the high voltage output abnormality detecting means outputs the high voltage. If an abnormality is detected, it is judged as a false detection, recovery by restarting the machine by the user is prohibited, and false detection judgment is made to eliminate the need for new detection control when replacing the fixing unit. Means and
An image forming apparatus characterized by being equipped with. Further provided with a temperature holding means for holding one or more temperatures detected by the second sensor for a predetermined period set in advance.
Whether the false detection determination means is a false detection by referring to the temperature detected by the second sensor when the high temperature abnormality is detected and one or more temperatures held by the temperature holding means. The image forming apparatus according to claim 1, wherein it is determined whether or not the image is formed. Further, a high voltage abnormality holding means for holding one or more detection results of the high voltage output abnormality detected by the high voltage output abnormality detecting means is provided for a predetermined period set in advance.
The false detection determination means refers to the detection result of the high voltage output abnormality held by the high voltage abnormality holding means and the detection result of the one or more high voltage output abnormality held by the high voltage abnormality holding means in addition to the detection result of the high voltage output abnormality when the high voltage abnormality is detected. The image forming apparatus according to claim 1 or 2, wherein it determines whether or not it is a false positive. Any one of claims 1 to 3, wherein the false detection determination means, when the false positive determination means is determined, continues the normal operation without notifying the user of the occurrence of the high temperature abnormality. The image forming apparatus according to. The image forming apparatus according to any one of claims 1 to 4, wherein the false detection determination means includes means for holding information determined to be false detection. The first sensor that detects the temperature of the fixing heater and
The second sensor that detects the temperature of the fixing heater and
A high temperature detecting means for detecting a high temperature abnormality in which the temperature detected by at least the first sensor exceeds the first high temperature detection value, and
It is a control method in an image forming apparatus including a high voltage output abnormality detecting means for detecting a high voltage output abnormality due to an arc discharge of a high voltage power source.
When the high temperature abnormality is detected by the temperature detected by the first sensor, the temperature detected by the second sensor does not exceed the second high temperature detection value, and the high voltage output abnormality detecting means outputs the high voltage. If an abnormality is detected, it is determined to be a false positive and it is determined to be a false positive.
If it is determined that the false positive is detected, it is set to prohibit the recovery by restarting the machine by the user and to eliminate the need for new detection control at the time of replacing the fixing unit.
A control method characterized by that. The first sensor that detects the temperature of the fixing heater and
The second sensor that detects the temperature of the fixing heater and
A high temperature detecting means for detecting a high temperature abnormality in which the temperature detected by at least the first sensor exceeds the first high temperature detection value, and
An image forming apparatus provided with a high-voltage output abnormality detecting means for detecting a high-voltage output abnormality due to an arc discharge of a high-voltage power supply.
When the high temperature abnormality is detected by the temperature detected by the first sensor, the temperature detected by the second sensor does not exceed the second high temperature detection value, and the high voltage output abnormality detecting means outputs the high voltage. If an abnormality is detected, a judgment process to determine that it is a false positive, and
If the false positive is determined, the setting process that prohibits the recovery by restarting the machine by the user and makes the setting process that does not require the new detection control at the time of replacing the fixing unit, and the setting process.
A program to execute.

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