JP2002354797A - Power supply - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a switching power supply used for an image forming device, allowing the abnormality details to be minutely detected. SOLUTION: The switching power unit compares a value detected by an output voltage detector circuit VSEN11 of a first power supply circuit for 5 V output voltage 10 with both a first upper limit threshold and a first lower limit threshold, processes setting of a PWM pulse output to be 0% if the value falls beyond the range of the first upper/lower limit thresholds, and suspends the power supply operation to stop all outputs. Next, it writes the data indicating abnormality in a critical region at 5 V output voltage into a nonvolatile memory 12. Then compares the detected value with both a second upper limit threshold lower than the first upper limit threshold and a second lower limit threshold higher than the first lower limit threshold, if the value falls beyond the range of the second upper/lower limit thresholds, also writes the data indicating abnormality in a critical region at 5 V output voltage into a nonvolatile memory 12. The read digital data will be used for update operations of PWM pulse ON duty, when being within the range of upper/lower limit thresholds.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply used in an apparatus such as an image forming apparatus such as a copying machine, a printer, and a facsimile, and more particularly, to detection of an abnormality in the power supply.

[0002]

2. Description of the Related Art As a conventional overcurrent protection technique, for example,
Japanese Patent Application Laid-Open No. 2000-092744 discloses that when an abnormality is detected in a 24V system that supplies power to an option side, a control system power supply system 5V supplementarily generates 1
A technique for supplying 0V power to the option side is disclosed. Japanese Patent Application Laid-Open No. 2000-333459 discloses that
There are two power supply circuits, one is a control system, and the other is a drive system. It has a power supply cutoff means to the drive system in accordance with an instruction from the microcomputer which is supplied with power by the control system during energy saving. At the time of detection, use the power supply cutoff means to the drive system,
A technique for performing overcurrent protection has been disclosed. In addition, JP
Japanese Patent Application Publication No. 000-014144 discloses a technique in which when an overcurrent is detected, a switch signal is turned off by a latch circuit, and a command to turn off the latch circuit resets the reset circuit and returns the switch signal to a normal operation state. ing. Further, a technique relating to a method of performing primary side overcurrent protection in a switching power supply that performs constant voltage output control by digital control has been filed.

[0003] The following two methods are known for detecting an abnormality in a DC power supply device using a conventional analog. The first method is a method of preventing and detecting an abnormality in the power output unit using a fuse. A fuse is attached to each output voltage circuit or each supply destination, and an abnormal output is detected by confirming a broken portion of the fuse. Circuit destination, abnormal output supply destination,
Or, the abnormal circuit part was confirmed. The second method is a method in which abnormality prevention and detection of overcurrent and overvoltage are performed by electronic interruption, and an LED is attached to each output voltage circuit or each supply destination. When an abnormality occurs, the output supply is stopped by the electronic cutoff and the LED is turned off.
The abnormal destination was determined by checking the part where the LED was turned off.

[0004]

In the first abnormality detection method, when an abnormality occurs, the fuse is damaged, and the cost of replacing the fuse each time occurs. In addition, the second method is an electronic cutoff method, which is a method capable of re-outputting when the cause of the abnormality is removed, and has an advantage that a cost such as replacement of a fuse does not occur. However, it is possible to confirm which part of the abnormality has occurred, but it is not possible to confirm the details of the abnormality, and whether the abnormality is an overcurrent due to a short circuit, overvoltage, or no power output. It is difficult to immediately know whether the operation is a protection circuit operation due to overheat detection.

[0005] Generally, peripheral devices are often attached to a copying machine. For example, there are a finisher 9 having a function of aligning output paper sheets, an LCT capable of storing large-capacity blank paper, and the like. Power is also supplied to these peripheral devices from the power supply unit of the image forming apparatus main body, but when docking the peripheral devices to the copier, it is thought that there is a possibility that the harness will be pinched due to a work mistake and short-circuited. Was done.

When a short circuit occurs as described above, the internal circuit is protected by detecting an overcurrent on the power supply side and operating the protection circuit, but the output is stopped due to any abnormality. It was difficult to find out, and the cause had to be checked manually. In some cases, it has been necessary to bring an oscilloscope to a user to check which part of the overcurrent protection circuit and the overvoltage protection circuit of the power supply device has operated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and has as its object to enable the details of an abnormality of a power supply device to be confirmed in detail and to promptly cope with the problem.

[0008]

In order to achieve the above object, in a power supply device according to the present invention, one of transformers is provided.
A primary circuit for switching and supplying power to a secondary winding in response to a PWM pulse, a secondary circuit for rectifying a voltage generated in a secondary winding of the transformer and supplying power to a load, and an output of the secondary circuit; A power supply unit having a control unit having a communication function while generating a PWM pulse defined in accordance with a detection unit for detecting an abnormality of the power supply unit, a memory in which the detected abnormality content is written, A memory content retrieving means for retrieving the content of the memory using the communication function of the control means.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. In the present embodiment, abnormal contents such as output voltage, output current, and temperature are stored in a non-volatile memory on a power supply device, and data in the non-volatile memory is read from an external device using a personal computer or the like via a memory content extracting unit. In this way, the details of the abnormality can be checked in detail, and a quick response can be taken.

FIG. 1 shows the configuration of a switching power supply as a power supply for an image forming apparatus according to the present embodiment. FIG. 2 is an external view of a copying machine as an example of a device to which the present invention can be applied. In FIG. 2, reference numeral 1 denotes a contact glass having a scanner unit at the bottom, 2 denotes an automatic document feeder (ADF), 3 denotes an operation unit, 4 denotes a power sub key, 5 denotes a front cover, 6 denotes a paper feed tray, and 7 denotes a main power supply. A switch 8 is a toner cover, and 9 is a finisher.

Since the configuration of the switching power supply device (hereinafter referred to as a power supply device) of FIG. 1 and output voltage control by PWM control of digital processing are known, they will be briefly described here. In FIG. 1, the power supply device mainly includes an AC power supply rectifying unit 15, a first power supply circuit 10, a second power supply circuit 20,
A digital control unit 11. The nonvolatile memory 12 is connected to the digital control unit 11. Under the control of the digital control unit 11, writing and reading to and from the nonvolatile memory 12 are performed.

The first power supply circuit 10 outputs a voltage Vout 11 of, for example, 24 V and supplies it to the image forming apparatus main body 13. The second power supply circuit 20 has a voltage Vout2 of 5 V, for example.
1 is supplied to the image forming apparatus main body 13. The digital control unit 11 has a pulse generating means for generating a PWM pulse having a duty ratio and a pulse width according to the output voltages of the first and second power supply circuits 10 and 20, and has a communication function. The communication unit is connected to a communication unit of the CPU 14 of the image forming apparatus main body 13 via a connector provided in the power supply device.

In the AC power supply rectifier 15, the AC voltage applied to the AC voltage input terminals IN1 and IN2 is rectified and smoothed by a diode bridge DB1 and a capacitor C1 via a noise filter NF, and then the first and second power supplies are rectified. Circuit 1
Added to 0,20. The rectified and smoothed current flows through the resistor R1 and the relay Ra1, thereby closing the contact point Ra1 of the relay Ra1 and applying the voltage of the power supply B1 to the Vcc terminal of the digital control unit 11 via the diode D1. The control unit 11 starts the operation.

The first power supply circuit 10 includes a transformer T11 and a transistor FE for switching the current of the primary winding thereof.
T11, a driver DRIV11 for driving the FET11,
Current detection circuit ISEN1 for detecting switching current
A diode D11 for rectifying and smoothing the output of the primary and secondary windings;
It is configured as shown by a diode D12, a choke coil CH11, a capacitor C11, an output current detection circuit ISEN12, an output voltage detection circuit VSEN11, and the like. The driver DRIV11 includes a digital controller 1
A PWM pulse is input from one output port PWM11. The detection value of the current detection circuit ISEN11 is input to the input port Iin11 of the digital control unit 11.

The second power supply circuit 20 comprises a transformer T21 and a transistor FE for switching the current of the primary winding thereof.
T21, a driver DRIV21 for driving the FET21,
Current detection circuit ISEN2 for detecting switching current
A diode D21 for rectifying and smoothing the output of the primary and secondary windings;
It is configured as shown by a diode D22, a choke coil CH21, a capacitor C21, an output current detection circuit ISEN22, an output voltage detection circuit VSEN21, and the like. The driver DRIV21 includes a digital control unit 1
A PWM pulse is input from one output port PWM21. The detection value of the current detection circuit ISEN21 is input to the input port Iin21 of the digital control unit 11.

Further, the output voltage of the tertiary winding of the transformer T21 is rectified and smoothed by a diode D31 and a capacitor C31, then converted to a constant voltage by a constant voltage circuit CV31 and applied to the Vcc terminal of the digital control unit 11. ing.

The digital control unit 11 has five A / D conversion input ports If11, If12, Vf11, Vf21,
Th, and the first information value such that the output voltage value of the first power supply circuit 10, the output current value, the output voltage value of the second power supply circuit, the output current value, and the temperature value of the overheat protection circuit are inputted. An output voltage detection circuit VSEN11 of the power supply circuit 10, an output current detection circuit ISEN12, an output voltage detection circuit VSEN21 of the second power supply circuit 20, an output current detection circuit ISEN22,
And five power supply overheat detection circuits TSEN.

The above five information values are read out at a constant cycle. At the time of reading, A / D conversion is performed to convert the data into digital data. The digital data is compared with a threshold value. If the digital data exceeds the threshold value, an abnormality process is performed and the information is written to the nonvolatile memory 12. The data in the non-volatile memory 12 is read out by a command from the CPU 14 of the image forming apparatus main body 13 via a communication unit, and is read out from the image forming apparatus main body 1.
3 is displayed on the display unit.

A power supply operating the display unit, or a CP
If there is an abnormality in the power supply for operating the U14, the input power supply of the image forming apparatus main body 13 is turned off, and the digital control unit 1 is turned off.
A method can be adopted in which the connector connected to the communication unit of the first CPU 14 is disconnected, and the contents of the nonvolatile memory 12 are read out via a memory contents extracting means having a UART communication function. In this way, when there is an abnormality in the power supply device, it is possible to confirm what the abnormality is by a simple method.

The detailed operation procedure will be described below with reference to flowcharts shown in FIGS. FIG. 3 shows the operation after the power is turned on.
Is turned on, an AC voltage of 100 V is applied to the power supply device. The applied AC voltage turns on the relay RA1 via the noise filter NF and the rectifier diode bridge DB1. As a result, the power B1 is supplied to the digital control unit 11, and the digital control unit 11 enters an operation state. The digital control unit 11 first performs initialization of various registers. Next, execution of the 200 μs timer is permitted, and an infinite loop is entered.

In FIG. 4, when a 200 μs timer interrupt occurs, A
/ D conversion is permitted. Then, exit the interrupt. A
When the execution of the / D conversion is permitted, first, the process of converting the analog value of the A / D conversion port destination set by default into a digital value starts. When the A / D conversion is completed, the processing moves to the flowchart of FIG.

In the process shown in FIG. 5, the port to which the A / D conversion has been performed is determined. Since port 0 is set by default, the first branch goes to the right and shifts to the flowchart of 5V output voltage control in FIG.

In FIG. 6, data converted to digital data is read. Here, it is determined whether the read digital data is equal to or larger than a threshold value indicating an abnormality of the output voltage.
Although omitted in the flowchart, the threshold is set with two values of the upper limit and the lower limit of the output voltage, and the upper and lower thresholds are set with the first threshold and the second threshold, respectively.

The first threshold value is a danger area which, if deviated from this, may lead to a system stop of the image forming apparatus main body 13, damage to the power supply device, a failure, etc. This indicates a caution area indicating that the apparatus does not lead to damage or failure, but may lead to some kind of system abnormality.

The operation when the threshold value is deviated will be described. An output voltage value of the power supply device is detected, and the detected voltage value is compared with a first upper threshold value and a first lower threshold value.
A process of setting the M pulse output to 0% is performed, the operation of the power supply device is stopped, and all outputs are stopped. Next, the generation of the A / D conversion end interrupt and the 200 μs interrupt are prohibited, and 5 V
Data indicating that an abnormality in the dangerous area has occurred in the output voltage is written in the nonvolatile memory 12, and the process exits from the interrupt.

Next, the output voltage value is compared with a second upper threshold value lower than the first upper threshold value and a second lower threshold value higher than the first lower threshold value, and deviated from the second upper threshold value and the second lower threshold value range. In this case, data indicating that an abnormality in the attention area has occurred at the output voltage of 5 V is written to the nonvolatile memory 12,
Return to the original routine. If the read digital data is within the range of the upper threshold and the lower threshold, the PWM pulse is ON.
The next A / D conversion port destination is changed to port 1 using the duty update calculation, the generation of the AD conversion end interrupt is permitted, and the interrupt is exited.

Next, when an A / D conversion end interrupt occurs, the process returns to FIG. Since the A / D conversion port destination is set to port 1, "AD conversion channel is 1?" Goes to the right and shifts to the flowchart of 24V output voltage control in FIG.

In FIG. 7, data converted into digital data is read. Here, it is determined whether the read digital data is equal to or larger than a threshold value indicating an abnormality of the output voltage.
Although omitted in the flowchart as in the case of the 5V output voltage control, the upper limit and the lower limit of the output voltage are set as the threshold, and the upper and lower thresholds are respectively set to the first threshold. , A second threshold value. The first threshold value is a danger area which, if deviated, would lead to system stoppage of the image forming apparatus main body 13, damage to the power supply device, failure, etc., and the second threshold value would result in system stoppage, power supply device damage even if deviated. This indicates a caution area indicating that a failure does not occur but may lead to some kind of system abnormality.

The operation when the threshold value is deviated will be described. An output voltage value of the power supply device is detected, and the detected voltage value is compared with a first upper threshold value and a first lower threshold value. If the output voltage value is out of the first upper threshold value and the first lower threshold value range, the PWM pulse output is immediately reduced to 0%. Is performed, and the operation of the DC power supply device is stopped. In this case, stop only 24V output,
In some cases, the control state is maintained without stopping the control 5V.
Next, the generation of the A / D conversion end interrupt and the 200 μs interrupt is prohibited, and data indicating that an abnormality in the danger area has occurred at the 24 V output voltage is written to the non-volatile memory 12 to exit the interrupt.

Next, the output voltage value is compared with a second upper threshold value lower than the first upper threshold value and a second lower threshold value higher than the first lower threshold value, and deviated from the second upper threshold value and the second lower threshold value range. In this case, data indicating that an abnormality in the attention area has occurred at the output voltage of 24 V is written in the nonvolatile memory 12, and the process returns to the original routine. If the read digital data is within the range of the upper threshold value and the lower threshold value, the next A / D conversion port destination is changed to port 2 using the update operation of the PWM pulse ON duty, and the generation of the AD conversion end interrupt is permitted. And exit the interrupt.

Next, when an A / D conversion end interrupt occurs, the process returns to FIG. Since the A / D conversion port destination is set to port 2, "AD conversion channel is 2?" Goes to the right and shifts to the flowchart of the 5V secondary side overcurrent protection control in FIG.

In FIG. 8, data converted to digital data is read. Here, it is determined whether the read digital data is equal to or larger than a threshold value indicating an abnormality of the output current.
With respect to the upper limit threshold value of the output current,
A threshold has been set. The first threshold value is a danger area that, if deviated from this value, would lead to system stoppage of the image forming apparatus main body 13, damage to the power supply device, failure, etc., and the second threshold value would result in system outage, power supply device damage, This is a caution area that indicates that a failure may not occur, but may lead to some kind of system abnormality.

The operation when the threshold value is deviated will be described. The output current value of the power supply device is detected, and the detected current value is compared with the first upper threshold value. If the detected current value exceeds the first upper threshold value, a process of immediately setting the PWM pulse output to 0% is performed. Is stopped, and all outputs are stopped. Next, generation of the A / D conversion end interrupt and the 200 μs interrupt is prohibited, and data indicating that an abnormality in the danger area has occurred in the 5V output current is written to the non-volatile memory 12 to exit the interrupt.

Next, the output current value is compared with a second upper threshold value lower than the first upper threshold value, and when the output current value deviates from the second upper threshold value, data indicating that an abnormality in the attention area has occurred at a 5 V output current. Is written into the nonvolatile memory 12, and the process returns to the original routine. If the read digital data is within the second upper threshold value, the A / D conversion port destination is changed to port 3, the generation of the AD conversion end interrupt is permitted, and the interrupt is exited.

Next, when an A / D conversion end interrupt occurs, the process returns to FIG. Since the A / D conversion port destination is set to port 3, "AD conversion channel is 3?" Goes to the right and shifts to the flowchart of 24V secondary side overcurrent protection control in FIG.

In FIG. 9, data converted to digital data is read. Here, it is determined whether the read digital data is equal to or larger than a threshold value indicating an abnormality of the output current.
The threshold is set to have a first threshold and a second threshold, respectively, with respect to the upper limit threshold of the output current. The first threshold value is a danger area which, if deviated, would lead to system stoppage of the image forming apparatus main body 13, damage to the power supply device, failure, etc., and the second threshold value would result in system stoppage, power supply device damage even if deviated. This indicates a caution area indicating that a failure does not occur but may lead to some kind of system abnormality.

The operation when the threshold value is deviated will be described. The output current value of the power supply device is detected, and the detected current value is compared with the first upper threshold value. If the detected current value exceeds the first upper threshold value, a process of immediately setting the PWM pulse output to 0% is performed. Stop the operation. In this case, only the 24V output may be stopped, and the control state may be maintained without stopping the control 5V. Next, the generation of the A / D conversion end interrupt and the 200 μs interrupt is prohibited, and data indicating that an abnormality in the danger area has occurred in the 24 V output current is written to the non-volatile memory, and the interrupt exits.

Next, the output current value is compared with a second upper threshold value lower than the first upper threshold value. If the output current value deviates from the second upper threshold value, data indicating that an abnormality in the attention area has occurred at the 24 V output current is obtained. Write to the non-volatile memory 12 and return to the original routine. If the read digital data is within the second upper limit threshold, the A / D conversion port destination is changed to port 4, the generation of the AD conversion end interrupt is permitted, and the interrupt is exited.

Next, when an A / D conversion end interrupt occurs, the process returns to FIG. Since the A / D conversion port destination is set to port 4, it does not correspond to any of the branching processes, so the flow shifts to the overheat protection control flowchart of FIG.

In FIG. 10, data converted into digital data is read. Here, it is determined whether the read digital data is equal to or greater than a threshold value indicating an abnormality in the overheating temperature. As the threshold value, a first threshold value and a second threshold value are set for the power supply device detected temperature, respectively. If the first threshold value is out of this range, the power supply device may be damaged or malfunction, and the image forming apparatus main body 13 may be damaged.
The second threshold value indicates a danger area that may lead to system stoppage, etc., but deviating from this value does not result in system stoppage, damage to the power supply device, or failure, but may lead to some kind of system abnormality. It indicates a caution area.

The operation when the threshold value is deviated will be described. The temperature of the power supply device is detected, and the detected temperature value is compared with the first upper threshold value.
A process of setting the pulse output to 0% is performed, the operation of the DC power supply is stopped, and all outputs are stopped. Next, AD
The generation of the conversion end interrupt and the 200 μs interrupt are prohibited, and the data indicating that the abnormality in the dangerous area has occurred in the temperature inside the power supply device is written in the nonvolatile memory 12 and the interrupt is exited.

Next, the temperature value is compared with a second upper threshold value lower than the first upper threshold value. If the temperature value deviates from the second upper threshold value, data indicating that an abnormality in the caution area has occurred in the temperature inside the power supply device. Is written into the nonvolatile memory 12, and the process returns to the original routine. If the read digital data is within the second upper threshold, the A / D conversion port destination is changed to port 0, and A
The generation of the D conversion end interrupt is prohibited, and the process exits from the interrupt.

Since the above five interrupt processes are completed within 200 μs, next, a 200 μs timer interrupt is generated again, and the generation of the A / D conversion interrupt is permitted in the 200 μs timer interrupt process. The processing in the A / D conversion interrupt is repeated. This A / D conversion interrupt process is repeated as long as the digital control unit 11 is powered on.

According to the flow described above, the first and second P
A WM pulse is output, and the driver DRIV11 of the first power supply circuit 10 and the driver DRI of the second power supply circuit 20 are output.
V21, and as a result, voltages of 24V and 5V are output, respectively. Thereafter, the output voltage detection circuits VSEN11 and VSEN21 to 200
The output voltage value is read in the μs cycle, and the ON duty of the PWM pulse is varied based on the read feedback value. Thereby, the PWM control is performed so that the output voltage becomes constant.

The digital control unit 11 performs the above-described output constant voltage control, and at the same time, performs the abnormality monitoring control of the voltage, current, temperature and the like. As described above, the abnormality monitoring control has an upper limit and a lower limit of the output voltage and the current.
A first threshold and a second threshold are set for the lower threshold, respectively.

The voltage data detected by VSEN11 and VSEN21 is the PWM data to DRIV11 and DRIV21.
At the same time as the information value of the pulse ON duty calculation, it also becomes data for comparing with the upper threshold value and the lower threshold value to confirm whether or not the threshold value is exceeded. First, a comparison is made with the first upper limit threshold value to determine whether or not it has exceeded the threshold value. Next, it is compared with the first lower threshold value to determine whether the value is lower than the first lower threshold value. If it is out of these ranges, it is determined that the vehicle is in the danger area and the DRIV
A process of setting the PWM pulse ON duty to 11 and 21 to 0% is performed, the operation of the power supply device is stopped, and all outputs are stopped.

Next, the generation of the A / D conversion end interrupt and the 200 μs interrupt is prohibited, and data indicating that an abnormality in the dangerous area has occurred at the 5 V output voltage is written to the nonvolatile memory 12, and the interrupt is exited. Next, a second upper threshold value lower than the first upper threshold value and a second lower threshold value higher than the first lower threshold value are compared with each other. Indicating that an abnormality in the attention area has occurred (when the detected value of the VSEN 21 is abnormal, the output voltage of the first power supply circuit 10 is abnormal, the VSEN 22
Is abnormal, the output voltage of the second power supply circuit 20 is written to the nonvolatile memory 12 and the process returns to the original routine.

If the read digital data is within the range between the upper threshold value and the lower threshold value, the next A / D conversion port is used for the update operation of the PWM pulse ON duty.
To allow the generation of the AD conversion end interrupt, and exit the interrupt.

The current data detected by ISEN 21 and 1SEN 22 is performed in the same manner as the case of the voltage data. The detected current data is compared with the first upper threshold, and if the current data exceeds the first upper threshold, DRIV1
The duty ratio of the PWM pulse to 1, 21 is set to 0%, the operation of the power supply is stopped, and all outputs are stopped. Next, generation of the A / D conversion end interrupt and the 200 μs interrupt is prohibited, and data indicating that a danger area abnormality has occurred in the output current (if the detection value of ISEN21 is abnormal, the output current of the first power supply circuit 10 is abnormal). , If the detected value of ISEN22 is abnormal, the output current of the second power supply circuit 20 is abnormal)
Is written to the non-volatile memory 12 to exit the interrupt.

Next, a comparison is made with a second upper threshold lower than the first upper threshold. If the second upper threshold is deviated from the second upper threshold, data indicating that an abnormality in the attention area has occurred in the output current is stored in the nonvolatile memory 12. Write and return to the original routine. next,
Compared with a second upper threshold lower than the first upper threshold, if the value deviates from the second upper threshold, data indicating that an abnormality in the caution area has occurred in the temperature in the power supply device is stored in the nonvolatile memory 12.
And return to the original routine. Overheat detection circuit TS
The output value of EN11 is the same as the voltage and current data.

Next, the temperature data detected by the TSEN 11 is compared with a first upper threshold value. If the temperature data exceeds the first upper threshold value, the PWM pulse ON duty to the DRIV 11 and DRIV 12 is immediately set to 0%. Stop the operation of the power supply and stop all outputs.

Next, the generation of the A / D conversion end interrupt and the 200 μs interrupt are prohibited, and data indicating that a dangerous area abnormality has occurred in the temperature of the power supply device is written in the non-volatile memory 12 and the interrupt is exited. Then, the data is compared with a second upper threshold lower than the first upper threshold, and when deviated from the second upper threshold, data indicating that an abnormality in the caution area has occurred in the temperature in the power supply device is written to the nonvolatile memory 12. Return to the original routine.

The nonvolatile memory 12 in which the data of the abnormal content is written can be read out by giving a command to the digital control unit 11 using the communication function of the UART.

By providing the above functions, when an abnormality occurs in the power supply and the voltage output stops,
The back cover of the image forming apparatus main body 13 is opened to make the power supply main body (see FIG. 11) visible, and the output unit connector (C
N101 to CN112), the connector of the communication unit (CN113) is connected to an external personal computer, and the contents of the nonvolatile memory 12 can be read out to the personal computer via the UART. However, at this time, the main switch of the image forming apparatus main body 13 is turned on, and the 100 V AC voltage is applied to the power supply apparatus in order to put the digital control unit 11 of the power supply apparatus into the operating state and read out the contents of the nonvolatile memory 12. ing.

The contents of the abnormality are read out to a personal computer, and it can be confirmed which power supply circuit has an abnormal output current, whether the output voltage is overvoltage, whether the output voltage is not output at all, or whether the protection circuit has been activated by detecting overheating. . As a result, the operation of identifying the abnormal portion can be performed quickly. Further, since the threshold value is set in two stages of a first threshold value indicating that the image is in the dangerous area and a second threshold value indicating that the image is in the caution area, only the security of the image forming apparatus main body 13 is ensured. Instead, it is possible to grasp the precursor of the abnormality of the image forming apparatus main body 13.

[0056]

According to the first aspect of the present invention, an abnormality in the power supply device is detected, the details of the detected abnormality are written in the nonvolatile memory, and the communication function provided in the control means such as the digital control unit is used. The contents of the memory such as a non-volatile memory can be taken out of the power supply device outside, so that the contents of the abnormality can be stored, and the contents of the memory can be read and displayed on a display unit of a device such as an image forming apparatus. Even when the system of the image forming apparatus fails, the contents of the memory can be taken out from the outside, so that the analysis can be performed efficiently.

According to the second aspect of the present invention, the threshold value for comparing whether the power supply is abnormal or not is set in two stages, so that not only the protection operation for preventing the failure and destruction of the power supply but also the protection operation is prevented. Thus, it is possible to grasp the precursor of the abnormality of the image forming apparatus.

According to the third aspect of the present invention, by incorporating a memory in the power supply device, an abnormality occurs in a system that outputs power to the outside, and even when the CPU on the device main body cannot operate. The abnormal contents can be written in the memory by the sole operation of the control means of the power supply device.

According to the fourth aspect of the present invention, by using the UART which is widely used as the communication means in the control means, it is possible to use the existing hardware at a low cost and to use the existing software resources to make a slight improvement. UART
Functions can be used.

According to the fifth aspect of the present invention, the power supply device is provided with a connector for connecting the power supply device and the device body,
Normally, a cable from the communication unit of the device main body CPU is connected, and when taking out the memory contents from outside the power supply unit, the connector can be connected to the cable from the memory contents taking out means, so that during normal use, The contents of the error can be displayed on the operation unit of the device, and even when the device is in the system down state, the contents of the error can be checked in detail by reading the data in the non-volatile memory from the outside via the memory content extraction means using a personal computer or the like. It is possible to quickly deal with the analysis of the cause of the system down.

According to the present invention, the output voltage value of the power supply device is detected, the detected voltage value is compared with the first upper threshold value and the first lower threshold value, and the first upper threshold value and the first lower threshold value are detected. If it is out of the range, the operation of the DC power supply is stopped, the contents are written into the memory, and the output voltage value is set to the second upper threshold lower than the first upper threshold and to the second upper threshold higher than the first lower threshold. When the output voltage deviates from the first threshold, the contents are written to the memory when the output voltage deviates from the first upper threshold and the second upper threshold and the second lower threshold. Damage can be prevented, but even if the power supply is damaged due to unexpected output voltage abnormalities, drive circuit damage, transformer winding abnormalities, etc., it is important to determine which system caused the damage. Investigation is to be carried out quickly. Further, since the second threshold value is provided, it is possible to obtain a precursor of an abnormality that does not lead to a system down of the device.

According to the present invention, the output current value of the power supply device is detected, and the detected current value is compared with the first upper limit threshold value. The operation is stopped, the contents are written into the nonvolatile memory, and the current detection value is compared with a second upper threshold lower than the first upper threshold.
By writing the contents to the memory, even if the output current deviates from the second threshold value, it is possible to prevent the basic power supply device from being damaged. Even if the power supply device is damaged due to breakage of the power supply or an abnormality in the winding of the transformer, it is possible to promptly determine the cause of the failure in the power supply system. Further, since the second threshold value is provided, it is possible to obtain a precursor of an abnormality that does not lead to a system down of the device.

According to the present invention, the temperature value of the power supply device is detected, and the detected temperature value is compared with the first upper threshold value. If the detected temperature value exceeds the first threshold value, the operation of the DC power supply device is stopped. At the same time as stopping, the content is written to the non-volatile memory, and the detected temperature value is compared with a second upper threshold value lower than the first upper threshold value. If the detected temperature value exceeds the second upper threshold value, the content is written to the memory. By doing so, even if the detected temperature deviates from the first threshold value, it is possible to prevent damage to the basic power supply device, but in the unlikely event that the output voltage is abnormal due to unexpected situations, the drive circuit is damaged, or the transformer is damaged. Even when the power supply device is damaged due to a winding abnormality or the like, it is possible to promptly determine the cause of the failure due to which system abnormality. Further, since the second threshold value is provided, it is possible to obtain a precursor of an abnormality that does not lead to a system down of the device.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a switching power supply as a power supply for an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is an external view showing an example of a copying machine to which the present invention can be applied.

FIG. 3 is a flowchart showing an operation after the power is turned on.

FIG. 4 is a flowchart showing the operation of a 200 μs interrupt timer.

FIG. 5 is a flowchart showing A / D conversion end interrupt processing;

FIG. 6 is a flowchart showing operations of 5V output control and output voltage detection.

FIG. 7 is a flowchart showing operations of 24V output control and output voltage detection.

FIG. 8 is a flowchart showing an operation of detecting a 5V output current.

FIG. 9 is a flowchart showing an operation of detecting a 24V output current.

FIG. 10 is a flowchart showing an operation of overheat detection.

FIG. 11 is an external view of a power supply unit of the power supply device.

[Explanation of symbols]

 Reference Signs List 10 First power supply circuit 11 Digital control unit 12 Non-volatile memory 13 Image forming apparatus main body 14 CPU of image forming apparatus main body 13 20 Second power supply circuit T11, T12 Transformer FET11, FET12 Transistor DRIV11, DRIV21 Driver ISEN11, ISEN21 Output current detection circuit VSEN11, VSEN21 Output voltage detection circuit TSEN11 Temperature detection circuit CN101-113 Connector

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) G03G 21/00 520 G03G 21/00 520 H04N 1/00 H04N 1/00 C F-term (Reference) 2C061 AP03 AP04 HV04 HV23 HV45 HV60 2H027 DA03 DA11 DE04 DE07 DE09 EA15 EC06 EC07 EC10 EE07 EE08 EE10 EF01 EJ17 EK01 EK04 EK06 EK13 HA02 HA04 HA10 HA12 HB06 HB16 HB17 JC16 ZA01 5C062 AA42 AA07 AB41 AB23A41B DD04 EE02 EE08 EE10 FD01 FD31 FD41 FF09 FF16 FG05 VV03 XX12 XX15 XX35 XX38 XX42

Claims (8)

[Claims] 1. A primary-side circuit for switching and supplying power to a primary winding of a transformer in response to a PWM pulse, and rectifying a voltage generated in a secondary winding of the transformer and supplying power to a load.
A power supply device comprising: a secondary circuit; and a control unit that generates a PWM pulse defined according to an output of the secondary circuit and has a communication function. A power supply device, comprising: a memory in which the details of the abnormality detected by the detecting means are written; and a memory contents extracting means for extracting contents of the memory by using a communication function of the control means. 2. The power supply device according to claim 1, wherein the detection means sets two levels of thresholds for comparing the abnormality. 3. The power supply device according to claim 1, wherein said memory is built-in. 4. The power supply device according to claim 1, wherein the communication function of the control unit is a UART. 5. A connector which is normally connected to a device body using the power supply device via a cable, and a connector to which a cable for extracting memory contents is connected when extracting the memory contents. The power supply device according to claim 1. 6. The detection means detects an output voltage value of the power supply device, compares the detected voltage value with a first upper threshold value and a first lower threshold value, and calculates a voltage value from the first upper threshold value and the first lower threshold value range. When the power supply device is deviated, the operation of the power supply device is stopped, and the content is written into the memory, and the output voltage value is higher than the second upper threshold value and the first lower threshold value that are lower than the first upper threshold value. 2 Compare with the lower threshold,
When the value is out of the range of the second upper threshold and the second lower threshold,
The power supply device according to any one of claims 1 to 5, wherein the contents are written in the memory. 7. The detecting means detects an output current value of the power supply device, compares the detected current value with a first upper threshold value, and if the detected current value exceeds the first upper threshold value, detects an operation of the power supply device. And writing the content to the memory, and comparing the output current value with a second upper threshold lower than the first upper threshold. The power supply device according to any one of claims 1 to 6, wherein the power is written in the memory. 8. The detection means detects a temperature value of the power supply device, compares the detected temperature value with a first upper threshold value, and stops the operation of the power supply device if the detected temperature value exceeds the first threshold value. At the same time, the content is written to the memory, and the temperature value is compared with a second upper threshold lower than the first upper threshold, and if the temperature exceeds the second upper threshold, the content is written to the memory. The power supply device according to any one of claims 1 to 7, wherein the power supply device is configured as described above.