JP2007060817A - Power supply unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power supply unit that shortens the dead time of an electronic device as much as possible, that is capable of resuming the operation of the electronic device with the minimum replacement of parts required, and that assures safety and reliability. <P>SOLUTION: The power supply unit 110 converts a voltage supplied from a commercial power source to supply electric power to a load. The unit is provided with a current detection circuit 174 that functions as a failure detection means that detects a failure of an output of a power supply circuit 170; a voltage detection circuit 175; a first switching means 121 that switches on and off the power supply to the power supply circuit 170; a second switching means 122 that switches on and off the power supply from the power supply circuit 170 to the load; and a control unit 190 that diagnoses whether it is a failure of the power supply circuit 170 or of the load by the ON/OFF control of the first and second switching means 121, 122, if a failure is detected by the failure detection means. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a power supply device having a protection function.

  An electronic device such as an image forming apparatus includes a power source that steps down from a commercial power source to a voltage necessary for the electronic device to operate, and a load that performs a user's desired operation. FIG. 1 is a diagram illustrating a configuration of an image forming apparatus including a conventional protection circuit. The image forming apparatus 2 includes a load device 30 such as an MCU (Micro Controller Unit) 31, an image processing system IPS 32, and a motor 33, and performs a desired operation in accordance with a print instruction from a user.

  Recently, safety requirements from the market have become very strict. Among them, the power supply device 10 is an input unit of the image forming apparatus and handles a large amount of energy, and thus has various protection circuits. For example, the power supply circuit 10 is provided with a leakage detection circuit 20 and an input overvoltage detection circuit 11 as protection circuits in order to prevent danger that may cause harm to the user and lead to smoke and fire of the image forming apparatus 2. Further, the power supply device 10 is provided with an overcurrent detection circuit 12 and an overvoltage detection circuit 13 in order to prevent a large current or a voltage higher than the set voltage from being generated due to an internal abnormality or an abnormality on the load device 30 side. ing. Further, a large number of fuses 16 to 18 are mounted on the current path connecting the power supply device 10 and the load device 30, so that the protection is made thick and the safety is ensured.

In addition, a voltage higher than the input voltage assumed by the image forming apparatus 2 may be input in the case where the construction of the building in which the image forming apparatus 2 is installed is poor or the power supply situation is poor overseas. In this case, the input overvoltage detection circuit 11 operates to protect the image forming apparatus 2 by turning off the main switch so that no more dangerous voltage is applied. Further, when an assumed abnormal current flows in the image forming apparatus 2 due to a component defect or abnormality, protection is performed by fusing the overcurrent detection circuit 12 or the fuses 16 to 18. As another conventional technique, Patent Document 1 proposes a technique for detecting a load abnormality by sequentially turning on a load and comparing it with an initial current.
JP 2001-228056 A

  However, in the conventional power supply device, the supply destination of the load device 30 from the power supply device 10 is diversified as the image forming apparatus 2 is highly functional, so whether an abnormality has occurred in the power supply device or an abnormality in the load. It was not possible to determine whether this occurred. For this reason, the set replacement | exchange which replaces | exchanges the power supply device 10 and the load apparatus 30 together occupies many when abnormality arises. Further, it takes time to replace the power supply device 10 and the load device 30, and during that time, the image forming apparatus 2 cannot be used, which causes trouble for the user. Further, since the image forming apparatus stops every time an abnormality occurs, the image forming apparatus cannot be used when the user wants to use the image forming apparatus, resulting in a great loss to the user. Moreover, although patent document 1 can detect load abnormality, it cannot discriminate | determine whether it is abnormality in a power supply device or abnormality of a load.

  Therefore, the present invention has been made in view of the above problems, and an object thereof is to provide a power supply device that can determine whether the power supply device is abnormal or the load is abnormal.

  In order to solve the above-described problems, a power supply device according to the present invention is a power supply device that converts a voltage supplied from a commercial power supply and supplies power to a load. A first switch means for turning on / off the power supply to the power supply circuit, a second switch means for turning on / off the power supply from the power supply circuit to the load, and an abnormality detected by the abnormality detection means And control means for diagnosing whether the power supply circuit is abnormal or the load is abnormal by controlling the first and second switch means on and off. According to the present invention, it is possible to determine whether the power supply device is abnormal or the load-side abnormality, so that set replacement can be reduced. In addition, since the location where the failure occurs becomes clear, the time required for replacement can be shortened. Further, since the number of fuses can be reduced, the constant voltage performance can be improved and the reliability can be improved. Furthermore, safety can be secured without relying on a fuse.

  In addition, according to the present invention, it is possible to supply a power supply device that can shorten the stop time of the electronic device as much as possible, can re-operate the electronic device with minimum necessary component replacement, and can ensure safety and reliability. In addition, since safety can be ensured without inserting a fuse for each load device, the problems of constant voltage performance deterioration due to voltage drop due to contact resistance of the fuse and reliability deterioration due to aging deterioration of the fuse are also solved. The Moreover, since sufficient energy is required to blow the fuse, the problem that the fuse cannot be blown and safety cannot be ensured depending on the abnormal level of the load device is solved.

  The control means may turn off the first and second switch means when an abnormality is detected by the abnormality detection means. As a result, the diagnostic program can be executed in the case of an abnormality that does not cause much damage to the power supply device or the load side. The control means may turn on the first switch means after turning off the first and second switch means when an abnormality is detected by the abnormality detection means. Thereby, an abnormality in the power supply circuit can be detected by the abnormality detection means.

  When the abnormality is detected by the abnormality detection means, the control means turns off the first and second switch means, turns on the first switch means, and no abnormality is detected by the abnormality detection means. The second switch means may be turned on. Thereby, it is determined that there is no abnormality in the power supply circuit, and power is supplied to the load. When an abnormality is detected by the abnormality detection means, the control means turns off the first and second switch means, turns on the first switch means, and an abnormality is detected by the abnormality detection means. In this case, the operation of the power supply device may be stopped. As a result, if there is an abnormality in the power supply device, it is possible to avoid increasing damage by stopping the operation of the power supply device.

  When the abnormality is detected by the abnormality detection means, the control means turns off the first and second switch means, turns on the first switch means, and no abnormality is detected by the abnormality detection means. The second switch means may be turned on, and when an abnormality is detected by the abnormality detection means, the operation of the power supply device may be stopped. As a result, the damage can be prevented from increasing.

  The power supply apparatus according to the present invention includes a third switch unit that turns on / off the power supply from the commercial power source, a second abnormality detection unit that detects at least one of a leakage current on the primary circuit side and a smoothing voltage on the primary side. The control means turns off the third switch means when an abnormality is detected by the second abnormality detection means. This will forcibly cut off the power supply from the commercial power supply before moving to the diagnostic program in the event of a ground fault that may cause significant damage to the power supply or damage to the user or an input overvoltage where the commercial power supply is abnormal. it can.

  The power supply device of the present invention includes a voltage converter that converts a voltage from the power supply circuit, a third abnormality detection unit that detects an abnormality in the output of the voltage converter, and a power supply circuit to the voltage converter. And a fourth switch means for turning on / off the power supply, and a fifth switch means for turning on / off the power supply from the voltage converter to the load, wherein the control means detects an abnormality by the third abnormality detection means. Is detected, an abnormality between the power supply circuit and the voltage converter, an abnormality of the voltage converter, and an abnormality of the load are controlled by on / off controlling the fourth and fifth switch means. Diagnose. Thereby, the abnormal part can be specified in detail.

  The control means may turn on the fourth switch means after turning off the fourth and fifth switch means when an abnormality is detected by the third abnormality detection means. As a result, the diagnostic program can be executed in the case of an abnormality that does not cause much damage to the voltage converter or the load side. The control means turns off the fourth and fifth switch means, turns on the fourth switch means, and turns on the third abnormality detection means when an abnormality is detected by the third abnormality detection means. If no abnormality is detected by the above, the fifth switch means may be turned on. Thereby, it is determined that there is no abnormality in the voltage converter, and power can be supplied to the load.

  The control means turns off the fourth and fifth switch means, turns on the fourth switch means, and turns on the third abnormality detection means when an abnormality is detected by the third abnormality detection means. If no abnormality is detected by the above, the fifth switch means may be turned on, and if an abnormality is detected by the third abnormality detection means, the fifth switch means may be turned off. Thereby, a power supply device and a load with abnormality can be separated.

  The control means turns off the fourth and fifth switch means, turns on the fourth switch means, and turns on the fourth switch means when an abnormality is detected by the third abnormality detection means. Turn off. Thereby, when there is an abnormality in the voltage converter, the power supply circuit and the load can be disconnected. The power supply device according to the present invention includes a connection unit capable of disconnecting the connection between the power supply circuit and the load after an abnormality is detected by the abnormality detection unit and the operation of the power supply device is stopped, and the operation of the power supply device And detecting means for detecting the output of the power supply circuit and notifying means for notifying the user that the output of the power supply circuit is at a predetermined level.

  The power supply device of the present invention further includes a switching unit that switches connection between the detection unit and the notification unit for each output of the power supply circuit when there are a plurality of the power supply circuits. The power supply device of the present invention further includes sixth switch means for turning on / off outputs of some of the plurality of power supply circuits by an external signal when there are a plurality of the power supply circuits, and the switching means includes the switching means, After restarting the power supply device, the sixth switch means is disabled, and then the connection between the detection means and the notification means is switched for each output of the power supply circuit.

  The switching means is preferably means for manually switching the connection between the output confirmation means and the notification means. The switching means may be constituted by a photocoupler. It is preferable that the notification means notifies the output state of the power supply circuit by light. It is preferable that the notification means notifies the output state of the power supply circuit by sound. Preferably, the detecting means detects whether the output voltage of the power supply circuit is higher than a predetermined voltage.

  The power supply device of the present invention includes a circuit disconnecting unit that disconnects the circuit between the power supply circuit and the load, and a sixth unit that is inserted between the power supply circuit and the circuit disconnecting unit and that turns on / off the power supply to the load. A switch means; a seventh switch means connected in parallel to the sixth switch means; a current limiting means for limiting current; a backflow preventing means for preventing backflow of current; and an output of the power supply circuit Detecting means for detecting a voltage; and at the time of start-up, the second switch means is turned on, and when the output voltage is at a predetermined level by the detecting means, the first switch means is turned on, and the second switch means And a means for turning off. According to the present invention, it is possible to check whether or not the load device has an abnormality when the electronic device is started up, and thus it is possible to detect the abnormality before the damage expands. In addition, the location where an abnormality has occurred is clarified and normal parts are not replaced, and unnecessary part replacement and labor can be saved.

  The power supply device of the present invention is a power supply device that converts a voltage supplied from a commercial power supply by a power supply circuit and supplies power to a load, circuit cutting means for cutting a circuit between the power supply circuit and the load, Sixth switch means inserted between the power supply circuit and the circuit disconnecting means to turn on and off the power supply to the load, and a seventh switch connected in parallel to the sixth switch means and connected in series Means, current limiting means for limiting current, backflow preventing means for preventing backflow of current, detection means for detecting the output voltage of the power supply circuit, and at the time of start-up, the second switch means is turned on, and the detection means Means for turning on the first switch means and turning off the second switch means when the output voltage is at a predetermined level. According to the present invention, it is possible to check whether or not the load device has an abnormality when the electronic device is started up, and thus it is possible to detect the abnormality before the damage expands. In addition, the location where an abnormality has occurred is clarified and normal parts are not replaced, and unnecessary part replacement and labor can be saved.

  The power supply device of the present invention is preferably stopped when the output voltage is equal to or lower than a predetermined voltage by the detection means. As a result, output abnormality is checked before complete operation, so that unnecessary replacement can be omitted without stressing the fuse. The power supply apparatus of the present invention further includes notification means for notifying the user of an abnormality after stopping the operation of the power supply apparatus when the detection means detects that the output voltage is below a predetermined level. In the power supply device according to the present invention, when the detection unit detects that the power supply circuit does not output a predetermined voltage, the notification unit notifies the user which load is abnormal among a plurality of loads. Is further provided.

  ADVANTAGE OF THE INVENTION According to this invention, the power supply device which can discriminate | determine whether it is abnormality of a power supply device or load can be provided.

  Hereinafter, the best mode for carrying out the present invention will be described. First, the first embodiment will be described. FIG. 2 is a diagram illustrating a configuration of the image forming apparatus 102 including the power supply device according to the first embodiment of the present invention. FIG. 3 is an operation flowchart of the power supply device of the present invention. The image forming apparatus 102 converts the voltage of the commercial power source 1 into a voltage necessary for image formation and supplies power to the load, and an operation necessary for image formation when the voltage is supplied from the power supply apparatus 110. For example, it is composed of a load device 30 such as IPS, MCU or motor.

  The power supply apparatus 110 further includes three power supply on / off means for specifying the location where an abnormality has occurred. It is not certain whether the first power supply on / off means is an abnormality in the power supply device 110 or an abnormality on the load device 30 side, but if an abnormality is detected by the abnormality detection circuit in the power supply circuit, the power supply device 110 is a first switch means 121 having a function of turning off power supply to 110 and then turning it on again. The first switch means 121 can turn on / off the power supply to the power supply circuit. The second power supply on / off means is a second switch means 122 having a function of supplying power to the load device 30 after it is found that the power supply device 110 is operating normally. The power supply from the power supply circuit to the load can be turned on / off by the second switch means 122. The third power supply ON / OFF means is provided from the commercial power supply 1 for an electric leakage that may cause a great damage to the image forming apparatus 102 or a danger to the user or an input overvoltage that causes the commercial power supply 1 to be abnormal. The third switch means 131 has a function of turning on and off the power supply.

  The first and second switch means 121 and 122 are constituted by semiconductor elements such as power transistors, MOS field effect transistors (MOSFETs), power MOSFETs, and IGBTs (Insulated Gate Bipolar Transistors). The third switch means 131 may be configured by a semiconductor element that can be electrically controlled, similarly to the first and second switch means 121 and 122, or may be configured by a switch that can be manually turned on and off. . When the third switch means 131 is configured by a switch that can be manually turned on / off, the switch may be electrically turned on / off using a coil.

  The abnormality detection unit 140 prevents an increase in voltage due to an abnormality in the power supply device 110, a leakage detection unit that protects the user from an electric shock, an input voltage detection unit that protects the image forming apparatus 102 from an abnormality in the commercial power supply 1, and a load It comprises a voltage detection circuit for protecting the device 30 and a current detection circuit for preventing a large amount of current from flowing. As will be described later, the leakage detection unit 181, the input voltage detection unit 182, the current detection circuit 174, the voltage detection circuit 175, the abnormality detection circuit 275, the voltage detection circuit 221, and the abnormality detection circuit 223 of FIG. 140. The signal transmission unit 150 transmits a control signal for turning on and off the switch to the first to third switch units 121, 122, and 131 based on the detection result of the abnormality detection unit 140. As will be described later, the abnormality monitoring unit 183, the abnormality monitoring unit 194 in FIG. 4, and the abnormality monitoring unit 197 in FIG. 5 correspond to the signal transmission unit 150.

  Next, a specific operation will be described. When the image forming apparatus 102 is operating normally, the power supply apparatus 110 supplies power to the necessary load apparatus 30 in order to achieve the image formation requested by the user. However, if an abnormality occurs, the power supply apparatus 110 performs two types of operations. First, in the case of a leakage or an input overvoltage that has a high possibility of causing great damage to the image forming apparatus 102 or harming the user (step S1), the signal transmission unit 150 performs a third process before moving to the diagnostic program. The power supply from the commercial power source 1 is cut off by the switch means 131 (step S2). In this case, in order to minimize damage, display is made to request repair without performing failure diagnosis.

  Secondly, if the signal transmission unit 150 has an abnormality that does not cause much damage to the power supply device 110 or the load device 30 other than the abnormality (step S1), the abnormality detection unit 140 in the power supply device 110 has an abnormality. When detected, the first switch means 121 is turned off in order to cut off and reset the power supply (step S3). At this time, the signal transmission unit 150 simultaneously turns off the second switch unit 122 (step S3). Next, the signal transmission means 150 turns on only the first switch means 121 (step S4), and when no abnormality is detected by the abnormality detection means 140 (step S5), turns on the second switch means 122 (step S5). S6), supplying power to the load device 30 side.

  However, when an abnormality is detected by the abnormality detection unit 140 when the first switch unit 121 is turned on (step S7), the user is notified (step S9) while the operation of the power supply device 110 is stopped (step S7). Step S10). Finally, the signal transmission unit 150 does not detect any abnormality in the power supply device 110 (step S5), turns on the second switch unit 122 (step S5), supplies power to the load device 30 side, When an abnormality is detected by the abnormality detection circuit (step S5), the power supply device 110 is normal and the user is notified that the load device 30 side is abnormal (step S9), while the operation of the power supply device 110 is stopped. (Step S10). Further, the signal transmission unit 150 turns on the second switch unit 122 (step S6), and if no abnormality is detected (step S7), the signal transmission unit 150 determines that it is normal and performs image formation to perform a normal operation (step S8). .

  As described above, by providing a plurality of switch means, it is possible to determine whether the power supply device 110 or the load device 30 side is abnormal, so that set replacement can be reduced. As a result, the location of the failure is clarified, and the time required for replacement can be shortened. Since the number of fuses can be reduced, the constant voltage performance can be improved and the reliability can be improved. Also, safety can be ensured without relying on a fuse.

  FIG. 4 is a diagram illustrating a specific configuration example of the power supply device according to the first embodiment of the present invention. The power supply device 110 includes a third switch means 131 that can turn on / off the power supply from the commercial power supply 1 manually and by an electric signal, a ZCT (zero-phase current transformer) that detects electric leakage, and then a control system load such as a controller. A power supply circuit 160 for supplying power to the power supply, a power supply circuit 170 for supplying power to a drive system load such as a motor, and an abnormality processing unit 180.

  The power supply circuit 160 includes an input filter 161, a primary rectifying / smoothing circuit 162, a step-down transformer T1, a switching element 164, a control circuit 165 for turning on / off the switching element 164, and a secondary that rectifies and smoothes the pulse voltage after step-down. Power is supplied to the load through the rectifying / smoothing circuit 166. The input filter 161 removes high frequency components of the input signal. The primary rectification / smoothing circuit 162 performs rectification / smoothing processing of the input signal. The transformer T1 includes a primary winding L11 to which input power is supplied, a secondary winding L12 that supplies power to a load, and a primary side sub-winding L13.

  The switching element 164 is configured by a semiconductor element such as a power transistor, a MOS field effect transistor (MOSFET), a power MOSFET, or an IGBT (Insulated Gate Bipolar Transistor). Here, the switching element 164 is configured by an N-channel MOSFET. The switching element 164 is connected to the terminal of the primary winding L11 of the transformer T1. The switching element 164 is turned on / off by a switching signal input to the control terminal. When the switching element 164 is composed of a bipolar transistor, the collector-emitter is opened and closed by a switching signal input to the base which is a control terminal. When the switching element 164 is formed of a unipolar transistor, the drain-source is opened and closed by a switching signal input to the gate that is the control terminal. The control circuit 165 sets the control terminal of the switching element 164 so that the voltage generated in the primary side auxiliary winding L13 becomes a preset target voltage based on the voltage generated in the primary side auxiliary winding L13. Control. The secondary rectifying / smoothing circuit 166 includes a diode and a capacitor, and rectifies and smoothes the electric power stored in the transformer T1 by a combination of the diode and the capacitor, and supplies the rectified and smoothed circuit to the load.

  The power supply circuit 170 has a first switch means 121 that can be turned on / off by an electric signal at an input section, an input filter 171, a transformer T2, a switching element 172, a transformer T2, a secondary rectifying and smoothing circuit 173, and a current to the output side. Power is supplied to the load through a current detection circuit 174 for detecting voltage, a voltage detection circuit 175 for detecting voltage, and second switch means 122 provided on the output side. The transformer T2 has a primary winding L21 to which input power is supplied, a secondary winding L22 that supplies power to a load, and a primary side auxiliary winding (not shown). The input filter 171 removes high frequency components.

  The switching element 172 is composed of a semiconductor element such as a power transistor, MOSFET, power MOSFET, or IGBT, for example. Here, the switching element 172 is configured by an N-channel MOSFET. The switching element 172 is connected to the terminal of the primary winding L21 of the transformer T2. The switching element 172 is turned on / off by a switching signal input to the control terminal. When the switching element 172 is composed of a bipolar transistor, the collector-emitter is opened and closed by a switching signal input to the base that is a control terminal. Further, when the switching element 172 is formed of a unipolar transistor, the drain-source is opened and closed by a switching signal input to the gate that is the control terminal. The control circuit (not shown) controls the switching element 172 so that the voltage generated in the primary side auxiliary winding becomes the preset target voltage based on the voltage generated in the primary side auxiliary winding of the transformer T2. Control the control terminal. The secondary rectifying / smoothing circuit 173 includes a diode and a capacitor, and rectifies and smoothes the electric power stored in the transformer T2 by a combination of the diode and the capacitor, and supplies the rectified and smoothed circuit to the load. The current detection circuit 174 detects the secondary overcurrent. The voltage detection circuit 175 detects the smoothed voltage of the secondary rectifying / smoothing circuit 173. The current detection circuit 174 and the voltage detection circuit 175 function as an abnormality detection unit that detects an abnormality in the output of the power supply circuit 170.

  The controller unit 190 includes a switch drive unit 191, a normal voltage determination unit 192, a switch drive unit 193 that can turn on / off the second switch means 122, an abnormality monitoring unit 194, and an operation instruction monitoring unit 195. The switch driving unit 191 sends a control signal for turning on / off the switch to the first switch means 121 based on the control signals from the abnormality monitoring unit 194 and the operation instruction monitoring unit 195. The normal voltage determination unit 192 determines whether the voltage of the secondary circuit of the power supply circuit 170 is a normal voltage based on the monitoring result from the abnormality monitoring unit 194, and sends the result of this determination to the switch drive unit 193. . The switch drive unit 193 sends a control signal for turning on / off the switch to the second switch means 122 based on the control signal from the normal voltage determination unit 192. The abnormality monitoring unit 194 determines that an overcurrent flows and is abnormal when the current detected by the current detection circuit 174 is greater than or equal to a certain level. In addition, the abnormality monitoring unit 194 determines that an abnormality has occurred when the secondary-side smoothed voltage detected by the voltage detection circuit 175 is not at a certain level.

  The abnormality monitoring unit 194 sends a control signal based on the monitoring results of the current detection circuit 174 and the voltage detection circuit 175 to the switch driving unit 191, the normal voltage determination unit 192, and the operation instruction monitoring unit 195. When an abnormality is detected, the abnormality monitoring unit 194 performs a process of diagnosing whether the power supply circuit 170 is abnormal or the load is abnormal by performing on / off control of the first and second switch units 121 and 122. The operation instruction monitoring unit 195 monitors an operation instruction from the user, and sends a control signal corresponding to the instruction from the user to the switch driving unit 191 and the abnormality monitoring unit 194.

  The abnormality processing unit 180 is supplied with power from the control system power supply, and includes a leakage detection unit 181, an input voltage detection unit 182, an abnormality monitoring unit 183, and a switch driving unit 184. The leakage detector 181 detects the difference between the incoming and outgoing AC input currents, and detects the leakage current on the primary circuit side. The input voltage detection unit 182 detects the smoothing voltage of the primary rectification smoothing circuit 162. The leakage detection unit 181 and the input voltage detection unit 182 serve as a second abnormality detection unit. The abnormality monitoring unit 183 turns off the third switch unit 131 when an abnormality is detected by the leakage detection unit 181 or the input voltage detection unit 182. Specifically, the abnormality monitoring unit 183 determines that the leakage is present and the input voltage is abnormal when the difference between the incoming and outgoing AC input current exceeds a certain level. The abnormality monitoring unit 183 determines that the input voltage is abnormal when the smoothing voltage detected by the input voltage detection unit 182 is not at a certain level. When the abnormality monitoring unit 183 determines that there is an abnormality, the abnormality monitoring unit 183 sends a control signal for on / off control of the third switch means to the switch driving unit 184. The switch driving unit 184 turns on / off the third switch unit 131 by controlling the current flowing in the coil L31 for turning on / off the third switch unit 131 based on the control signal from the abnormality monitoring unit 183. To do.

  Next, a specific operation of the power supply device 110 will be described. Since the user uses the device, when the third switch means 131 is manually turned on, power is supplied from the power supply circuit 160 to the control system load including the controller. Thereafter, when the operation instruction monitoring unit 195 in the controller unit 190 detects an operation instruction from the user, an ON signal is transmitted from the switch driving unit 191 to the first switch means 121, and the voltage in the power supply circuit 170 is normal. Is detected by the normal voltage determination unit 192, an ON signal is transmitted from the switch drive unit 193 to the second switch means 122, and power is supplied to the drive system load.

  Next, the operation of the power supply apparatus 110 at the time of abnormality will be described. The operation of the power supply device 110 at the time of abnormality can be classified into three. The first abnormality is an operation at the time of abnormality that may cause great damage to the image forming apparatus or the user. This abnormality indicates an input overvoltage that is a leakage or an input abnormality. In the case of such an abnormality, the abnormality is detected by the voltage detection circuit in the primary rectifying / smoothing circuit 162 of the ZCT 132 or the power supply circuit 160, and the third switch means is supplied from the switch driving unit 184 according to the instruction of the abnormality monitoring unit 183. 131 is turned off. This operation protects the image forming apparatus and the user.

  The second abnormality is an abnormality relating to the power supply circuit 160. This indicates an overcurrent abnormality that is a short circuit failure or an overvoltage abnormality that is a voltage abnormality. In this case, a general protection operation is performed. For example, when an overcurrent is detected, a signal is transmitted to the control circuit 165 that turns on / off the switching element 164, and the operation of the switching element 164 is stopped. Similarly, in the case of an overvoltage, a signal is transmitted to the control circuit 165 and the operation of the switching element 164 is stopped. This provides protection.

  The last is an abnormality related to the power supply circuit 170 or the drive system load. For example, when it is detected by the current detection circuit 174 that the current is abnormal, the signal is transmitted to the abnormality monitoring unit 194, a signal is transmitted from the abnormality monitoring unit 194 to the switch driving unit 191, and the first switching means is transmitted from the switch driving unit 191. 121 is turned off. As a result, after one end protection operation is performed, an ON signal is transmitted again from the switch drive unit 191 to the first switch means 121. If no abnormality is detected by the current detection circuit 174 or the voltage detection circuit 175 at this time, an ON signal is transmitted from the switch drive unit 193 to the second switch means 122 to supply power to the drive system load. If no abnormality is detected as it is, the prescribed operation is continued, but when an abnormality is detected, the user is notified and the operation is stopped.

  Next, a second embodiment of the present invention will be described. FIG. 5 is a diagram illustrating a configuration example of the power supply apparatus 210 according to the second embodiment of the present invention. In addition, the same code | symbol is attached | subjected and demonstrated about the same structure as the power supply device 110 shown in FIG. As shown in FIG. 5, the power supply device 210 is different from the power supply device 110 shown in FIG. 4 in that it includes a voltage conversion unit 220, a power supply circuit 270, and a control unit 290. The power supply circuit 160 supplies power to a control system load such as a controller. The power supply circuit 270 supplies power to a voltage conversion unit 220 equipped with a load of a driving system such as a motor and a DC / DC converter.

  The power supply circuit 270 includes a first switch unit 121, an input filter 271, a primary rectifying / smoothing circuit 272, a transformer T 2, a switching element 273, a secondary rectifying / smoothing circuit 274, an abnormality detection circuit 275, and a second switch unit 122. . The same parts as those of the power supply circuit will be described with the same reference numerals. The input filter 271 removes high frequency components from the input signal. The primary rectifying / smoothing circuit 272 performs a rectifying / smoothing process on the input signal. The secondary rectifying / smoothing circuit 274 includes a diode and a capacitor, and rectifies and smoothes the electric power stored in the transformer T2 by a combination of the diode and the capacitor, and supplies the rectified and smoothed circuit to the load. The abnormality detection circuit 275 includes a current detection circuit that detects an overcurrent on the secondary side and a voltage detection circuit that detects the smoothing voltage of the secondary rectification smoothing circuit 274, and sends the detection result to the abnormality monitoring unit 194.

  The voltage conversion unit 220 converts the voltage from the power supply circuit 270. The voltage converter 220 includes a voltage detection circuit 221, a DC / DC converter 222, an abnormality detection circuit 223, a fourth switch unit 224, and a fifth switch unit 225. Components in the voltage conversion unit 220 are mounted on a predetermined substrate. The voltage converter 220 is supplied with power from the power supply circuit 270 through a harness. The voltage detection circuit 221 detects the output voltage of the power supply circuit 270.

  The DC / DC converter 222 steps down the output voltage of the power supply circuit 270 to a predetermined level voltage with respect to a low voltage load such as an MCU (Micro Controller Unit). The abnormality detection circuit 223 includes a voltage detection circuit and a current detection circuit, and detects an abnormality in the output of the voltage converter 220. The fourth switch means 224 is a switch means for turning on and off the power supply from the power supply circuit 270 to the voltage converter 220. On / off is controlled by an electrical signal, and between the power supply circuit 270 and the voltage converter 220 when turned off. Disconnect. The fifth switch means 225 is a switch means for turning on / off the power supply from the voltage converter 220 to the load, and is controlled to be turned on / off by an electric signal. When the switch is off, the voltage converter 220 is disconnected from the load. The fourth and fifth switch means 224 and 225 are constituted by semiconductor elements such as power transistors, MOSFETs, power MOSFETs, and IGBTs, for example. By controlling on / off of the fourth and fifth switch means 224, 225, the abnormal part can be further clarified.

  Unlike the control unit 190 shown in FIG. 4, the control unit 290 includes a switch driving unit 196, an abnormality monitoring unit 197, and a switch driving unit 198. When an abnormality is detected in the voltage converter 220, the abnormality monitoring unit 197 performs on / off control of the fourth and fifth switch units 224 and 225, for example, an abnormality of the harness between the power supply circuit 270 and the voltage converter 220. Then, it is diagnosed which one of the abnormality of the voltage converter 220 and the abnormality of the load. The abnormality monitoring unit 197 sends control signals for turning on and off the fourth and fifth switch means 224 and 225 to the switch driving units 196 and 198 based on the detection results of the voltage detection circuit 221 and the abnormality detection circuit 223. The switch driving unit 196 sends a control signal for turning on / off the switch to the fourth switch unit 224 based on the monitoring result of the abnormality monitoring unit 197. The switch driving unit 198 sends a control signal for turning on / off the switch to the fifth switch means 225 based on the monitoring result of the abnormality monitoring unit 197.

  A specific operation will be described. Since the user uses the image forming apparatus 102, when the third switch unit 131 is manually turned on, power is supplied from the power supply circuit 160 to the load of the control system. When the operation instruction monitoring unit 195 in the control unit 290 receives an operation instruction signal from the user, the first switch unit 121 is turned on by the switch driving unit 191 and power is supplied to the power supply circuit 270. When it is detected that the power supply circuit 270 is operating normally, the second switch means 122 is turned on by the switch driving unit 193, and a normal voltage is applied to the voltage conversion unit 220 on which the DC / DC converter 222 is mounted. When supplied, the fourth switch means 224 and the fifth switch means 225 are turned on. As a result, power is supplied from the DC / DC converter 222 to a necessary load, and the image forming apparatus operates.

  Next, the operation when an abnormality is detected will be described. The operation at the time of abnormality can be classified into the following three. The first abnormality is detected by the leakage detection unit 181 or the input voltage detection unit 182 in the case of a leakage or input overvoltage that may cause great damage to the user or the image forming apparatus 102. From 184, the third switch means 131 is turned off. Thereby, it becomes possible to protect a user and an image forming apparatus. The second abnormality is that when the power supply circuit 160 becomes abnormal, the operation of the control circuit 165 is stopped and the switch operation is stopped as provided in the normal power supply circuit 160. As a result, further damage to the portion related to the power supply circuit 160 can be prevented.

  The third abnormality is when an abnormality is detected in the power supply system related to the power supply circuit 270. In this case, when an abnormality is detected by the abnormality detection circuit 275, the first, second, fourth, and fifth switch means 121, 122, 224, and 225 are turned off by the respective switch driving units 191, 193, 196, and 198, and the abnormality is detected. A site diagnosis is performed. Thereafter, the first switch means 121 is turned on by a signal from the controller 290 to the switch driver 191. If the first switch means 121 is turned on and no abnormality is detected by the abnormality detection circuit 275, the second switch means 122 is turned on by the switch driver 193.

  If the second switch means 122 is turned on and no abnormality is detected by the abnormality detection circuit 275, the fourth switch means 271 is turned on. By sequentially turning on the switches in this way, it is possible to specify the range of abnormality. For example, if an abnormality is detected by the abnormality detection circuit 275 when the first switch means 121 is turned on, the user is notified that the power supply circuit 270 is abnormal. If an abnormality is detected by the abnormality detection circuit 275 when the second switch means 122 is turned on, the user is notified of a ground fault in the harness system. The abnormality monitoring unit 197 turns on the fifth switch unit 225 when an abnormality is not detected by the abnormality detection circuit 223 when the fourth switch unit 224 is turned on, and detects an abnormality by the abnormality detection circuit 223. It is determined that the load is abnormal, and the fifth switch means 225 is turned off. If an abnormality is detected by the abnormality detection circuit 223 when the fourth switch means 224 is turned on, the user is notified of the abnormality after the DC / DC converter 222 and the fourth switch means 224 is turned off. To do. By controlling as described above, the range of failure can be specified, and the maintenance performance can be improved.

  Next, an image forming apparatus according to a third embodiment of the present invention will be described. Conventionally, a power supply device of an image forming apparatus is equipped with an abnormality detection circuit for the purpose of protecting the image forming apparatus. Examples of the abnormality detection circuit include an overcurrent detection circuit and an overvoltage detection circuit. Specifically, when an abnormality is detected in the image forming apparatus by the abnormality detection circuit, the operation of the power supply device is stopped, and the image forming apparatus is protected from dangers such as smoke and fire. In addition, a method for protecting a power supply apparatus having a plurality of outputs includes all output shut-off that shuts off all other outputs when an abnormality occurs in a certain output.

  However, since the user did not have means for easily confirming whether the power supply apparatus is normally outputting or not, when an abnormality occurs in the image forming apparatus and the operation stops, it is possible to determine which part is abnormal. It was difficult to distinguish. Moreover, in order to confirm whether the power supply device is outputting normally, a jig like a tester was separately required. Therefore, in order to repair the image forming apparatus, it is necessary to replace all parts including normal parts, resulting in waste.

  FIG. 6 is a diagram for explaining a conventional power supply device. In the conventional power supply device 300, power is supplied to the load device from the outputs 1 to 4 of the power supply circuit, and among the outputs 2 to 4 of the power supply circuit, an on / off means 301 for turning on / off the output by an external signal is provided. Is provided. The external signal is transmitted from the control board in the copying machine. However, if an abnormality occurs in the control board that transmits the external signal, it becomes difficult to determine whether the outputs 2 to 4 of the power supply circuit are output. For this reason, in this embodiment, this problem is solved as follows.

  FIG. 7 is a view for explaining an image forming apparatus 400 according to the third embodiment of the present invention. In the power supply apparatus 410 according to the third embodiment, among the outputs of the power supply circuits 411 to 414, the outputs of the power supply circuits 412 to 414 are controlled by an on / off means 415 that can be turned on / off by an external signal. Further, the on / off means 415 is configured to be turned on by voltage supply from the output of the power supply circuit 411. The output confirmation unit 416 is for confirming the outputs of the power supply circuits 412 to 414. Here, the output confirmation unit 416 detects whether the output voltage of the power supply circuits 411 to 413 is higher than a predetermined voltage. The notification means 418 is for notifying the user that the power supply circuits 412 to 414 are outputting normally.

  Specifically, when the image forming apparatus 400 stops operating due to an abnormality, a connector that is a connection unit (described later) that connects the power supply apparatus 410 and the load apparatuses 432 to 434 is disconnected, and the power supply in the power supply apparatus 410 is removed. The switch means 4110 provided at the output of the circuit 411 is manually turned on. By turning on the switch means 4110, the on / off means 415 for turning on / off the outputs of the power supply circuits 412 to 414 is turned on regardless of the external signal. The output confirmation unit 416 confirms whether the output voltages of the power supply circuits 412 to 424 are sequentially output, and the notification unit 418 notifies the user. As a result, the user can determine which output has an abnormality. Further, by sequentially connecting the connectors that have been disconnected from one end, the user can determine which load device 432-434 is abnormal.

  In this way, the user can visually confirm whether or not the power supply device 410 is abnormal. Further, the user can easily check which load device 432 to 434 is connected to stop the image forming apparatus 400. With the above configuration, in the image forming apparatus 400, the location where an abnormality has occurred can be confirmed without a special jig, and there is no waste of replacing normal parts.

  Next, an image forming apparatus according to the third embodiment of the present invention will be specifically described. FIG. 8 is a diagram showing a specific configuration of the image forming apparatus according to the third embodiment of the present invention. The image forming apparatus 400 operates by using the power supplied from the AC power supply 401 through the power supply apparatus 410 by the load device 430. Inside the power supply apparatus 410, power supply circuits 411 to 413 that perform conversion into voltages required by the corresponding load apparatuses 431 to 433 are provided. In FIG. 8, unlike FIG. 7, the power supply circuit 414 is omitted. The switch means 4110 is a switch means for invalidating output off / off by an external signal.

  Among the outputs of the plurality of power supply circuits 411 to 413, the power supply circuits 412 and 413 are outputs that can be turned on / off by an external signal, and the power supply circuit 411 is an output that is always output regardless of the external signal. When there are a plurality of power supply circuits, the on / off means 415 turns on / off the outputs of some of the plurality of power supply circuits by an external signal. The power supply circuits 411 to 413 are provided with detection means for detecting an abnormality corresponding to the output and protection means for protecting the output (not shown). A stop means (not shown) stops the operation of the power supply apparatus 410 when an abnormality is detected by the abnormality detection means.

  The power supply apparatus 410 further includes an output confirmation unit 416, a switching unit 417, a notification unit 418, and a connection unit 419. The connection unit 419 can disconnect the connection between the power supply circuits 411 to 413 and the load devices 431 to 433 after an abnormality is detected by the abnormality detection unit and the operation of the power supply device 410 is stopped. The connection means 419 is configured by connectors 419a to 419c, for example. After the abnormality occurs in the image forming apparatus 400 and the operation of the power supply apparatus 410 is stopped, the power supply apparatus 410 and the load apparatus 430 can be disconnected by the connection unit 419. The output confirmation unit 416 detects and confirms the outputs of the power supply circuits 411 to 413. The output confirmation unit 41 includes, for example, Zener diodes 416a to 416c when confirming whether or not the output voltage of the power supply circuits 411 to 413 is higher than the set voltage. The Zener diodes 416a to 416C are provided corresponding to the power supply circuits 411 to 413, respectively. In the Zener diodes 416a to 416c, a reverse current flows when the reverse voltage exceeds a certain voltage.

  When there are a plurality of power supply circuits, the switching unit 417 switches the connection between the output confirmation unit 416 and the notification unit 418 for each output of the power supply circuits 411 to 413. Here, the switching unit 417 is configured by a relay switch that can manually switch the connection between the output confirmation unit 416 and the notification unit 418. The notification unit 418 notifies the user that the output confirmation unit 416 has detected that the outputs of the power supply circuits 411 to 413 are at a predetermined level. The notification unit 418 notifies the user of the output state of the power supply circuits 411 to 413 by light or sound. Here, the notification means 418 is comprised by the light emitting diode (LED: Light Emitting Diode). In the case where the output state is notified by sound, the notification means 418 may be constituted by a speaker, for example.

  Next, a specific operation will be described. When an abnormality occurs in the image forming apparatus 400 and the operation of the power supply apparatus 410 is stopped, the switch 420 at the input of the image forming apparatus 400 is turned off. Thereafter, the user or the administrator of the image forming apparatus 400 disconnects the power supply apparatus 410 and the load apparatus 430 by removing the connectors 419a to 419c that are the connection means 419. Then, after the switch 420 is turned on again and the power supply apparatus 410 is restarted, the switch unit 4110 is turned on to disable the on / off unit 415. Thereafter, for each output of the power supply circuits 411 to 413, it is confirmed whether or not the light emitting diode as the notification unit 418 is turned on while switching the connection between the output confirmation unit 416 and the notification unit 418 in order by the switching unit 417. Thereby, it can be confirmed whether the power supply circuits 411-413 are outputting normally.

  When the notification means 418 is turned on, it indicates that the power supply circuits 411 to 413 are operating normally. When the notification means 418 is not turned on, it indicates that the corresponding power supply circuits 411 to 413 are abnormal. If the notification means 418 is lit in all the power supply circuits 411 to 413, the power supply circuits 411 to 413 are operating normally, so the connectors 419a to 419c are connected one by one, and the switching means 417 is used for notification. The load devices 431 to 433 in which the means 418 is not lit are searched. If there is a load device 431-433 in which the notification means 418 does not light up, it is abnormal and the load device 431-433 is replaced. With this configuration, it is possible to easily identify whether the power supply device 410 is abnormal or the load device 431 is abnormal.

  FIG. 9 is a diagram illustrating another specific configuration example of the image forming apparatus according to the third embodiment of the present invention. In the example illustrated in FIG. 8, the switching unit 417 manually switches the connection between the output confirmation unit 416 and the notification unit 418. However, in the example of the power supply device 610 illustrated in FIG. 9, the switching unit is automatically switched. Change to configuration. Furthermore, the user is notified only when the outputs of all the power supply circuits 411 to 413 are normally output. Here, the switching unit 617 is configured using a photocoupler including, for example, light emitting diodes 617a and 617c and phototransistors 617b and 617d. A photodiode may be used instead of the phototransistors 617c and 617d.

  Next, a specific operation will be described. When an abnormality occurs in the image forming apparatus 600 and the operation of the power supply apparatus 610 stops, the switch 420 at the input of the image forming apparatus 600 is turned off. Thereafter, the user disconnects the power supply device 610 and the load device 430 by removing the connectors 419a to 419c as the connection means 419. Then, after the switch 420 is turned on again and the power supply device 610 is restarted, the switch unit 4110 is turned on to disable the on / off unit 415.

  When the output voltage of the power supply circuit 411 is normal, a reverse current flows when the reverse voltage of the Zener diode 416a is equal to or higher than a certain voltage, and the light emitting diode 617a emits light. If the light-emitting diode 617a emits strong light, a large photocurrent flows between the collector and base of the phototransistor 617b and is turned on. When the output voltage of the power supply circuit 412 is normal, the reverse voltage of the Zener diode 416b exceeds a certain voltage. In this case, a reverse current flows, and the light emitting diode 617c emits light. If the light emitting diode 617c emits strong light, a large photocurrent flows between the collector and the base of the phototransistor 617d and is turned on. When the output voltage of the power supply circuit 413 is normal, the reverse voltage of the Zener diode 416c exceeds a certain voltage. In this case, a reverse current flows, and the light emitting diode as the notification means 418 emits light. As described above, in this embodiment, whether or not the light emitting diode as the notification unit 418 is turned on while automatically switching the connection between the output confirmation unit 416 and the notification unit 418 for each output of the power supply circuits 411 to 413. It is possible to confirm whether the power supply circuits 411 to 413 are outputting normally.

  FIG. 10 is a diagram illustrating another specific configuration example of the image forming apparatus according to the third embodiment of the present invention. The output confirmation unit 616 includes Zener diodes CR11 to CR23, NOR circuits 16a to 16c, and OR circuits 16d to 16f connected in parallel corresponding to the outputs of the power supply circuits 411 to 413. Zener diodes CR21 to CR23 on one side of the Zener diodes connected in parallel are Zener diodes for confirming that the power supply circuits 411 to 413 are normally outputting, and the Zener diodes CR11 to CR13 on the other side are power supply circuits 411. A Zener diode that detects that the output voltage of ˜413 is abnormally high.

  A specific operation is confirmed by switching by the switching unit 417 in order to confirm whether the image forming apparatus 600 stops operating due to an abnormality and the output voltages of the power supply circuits 411 to 413 are normally output. At this time, for example, when the output voltage of the power supply circuit 411 is abnormally high, the inputs of the NOR circuit 16a are both HIGH level and the output is LOW level, and one of the inputs of the OR circuit 16d is LOW level and the other is HIGH level. Becomes HIGH level. For this reason, the light emitting diode of the notification means 418 lights up. Thus, the notification means 418 lights only when the output voltages of the power supply circuits 411 to 413 are abnormal, so that the user can be notified that the output voltage of the power supply circuit is abnormally high.

  Next, an image forming apparatus according to a fourth embodiment of the present invention will be described. 2. Description of the Related Art Conventionally, an image forming apparatus includes a power supply device that converts an AC voltage into a DC voltage and a load for achieving an image forming function, and the load device operates by receiving power supply from the power supply device. In the unlikely event that an abnormality occurs in the image forming apparatus, a plurality of protection devices are provided in the power supply device or on the load side so as not to harm the user who is using it. For example, the power supply unit is equipped with an overcurrent detection circuit that detects an excessive current due to a short circuit on the load side, an overvoltage detection means that detects an abnormally increased voltage, and between the power supply unit and the load. A cutting means such as a fuse is inserted to further improve safety.

  However, in the configuration in which the protection device detects an abnormality and stops the operation of the electronic device, the following problem occurs. First, when the image forming apparatus is returned after an abnormality has occurred, the location where the abnormality has occurred is unclear, there is a possibility that even a normal part will be replaced, and the part cost is very wasteful. Moreover, it takes time and effort to exchange. Secondly, when protection is performed by a cutting means such as a fuse, if the load in which an abnormality has occurred is unclear, it becomes necessary to replace several fuses in vain. There is a need for a self-diagnosis system for an image forming apparatus that solves the above problems. Hereinafter, an image forming apparatus provided with a self-diagnosis system will be described.

  FIG. 11 is a diagram showing a configuration of an image forming apparatus according to the fourth embodiment of the present invention. The image forming apparatus 700 includes a power supply device 710 that converts a voltage supplied from a commercial power supply by a power supply circuit and supplies power to the load device 730. The power supply device 710 includes an overcurrent detection circuit 711 and an overvoltage detection circuit 712 as protection circuits, and a fuse 713 as a circuit disconnection unit that disconnects the circuit between the power supply circuit and the load. Although not shown in FIG. 11, a power supply circuit is provided on the input side of the overcurrent detection circuit 711. Between the power supply circuit and the load device 730, two switch means of a switch means 714 as a sixth switch means and a switch means 716 as a seventh switch means are inserted in parallel. The sixth and seventh switch means 714 and 716 are composed of semiconductor elements such as power transistors, MOSFETs, power MOSFETs, and IGBTs, for example.

  The switch means 714 is inserted between the power supply circuit and the fuse 713 and functions as sixth switch means for turning on / off the power supply to the load device 730. The switch means 714 is connected to the load device 730 through the fuse 713. On the output side of the power supply device 710, a diode CR2 as detection means for detecting the output voltage of the power supply circuit, an on means 715 for turning on the switch means 714, and an off means 717 for forcibly turning off the switch means 716 are provided. . The switch means 716 connected in series, the resistor R3 as a current limiting means for limiting the current, and a diode CR1 as a backflow prevention means for preventing a backflow of current are connected in parallel to the switch means 714. The switch unit 716 is connected to the load device 730 through the resistor R3, the diode CR1, and the fuse 713. When the power supply device 710 is activated, the switch unit 716 is turned on. When the output voltage is at a predetermined level by the diode CR2, the switch unit 714 is turned on by the on unit 715, and the switch unit 716 is turned off by the off unit 717. It works like this.

  Specifically, in order for the user to use the image forming apparatus 700, when a switch (not shown) is turned on and the image forming apparatus 700 is started, a current flows through a resistor R1 connected in parallel with the switch unit 716. The switch unit 716 is turned on, and power is supplied to the load device 730 through the resistor R3, the diode CR1, and the fuse 713. At this time, when the output voltage of the power supply device 710 is detected by the diode CR2, and the output voltage is a voltage of a predetermined level originally intended by the power supply device 710, the switch means 714 is turned on by the ON means 715 and further turned off. The switch unit 716 is turned off by the unit 717, the image forming apparatus 700 operates normally, and power is supplied to the load device 730. However, when it is confirmed that the correct voltage is not detected by the diode CR2 due to an abnormality in the load device 730, the power supply device 710 stops the operation of the power supply device 710 without being turned on and notifies the user. .

  According to the power supply device of the present invention, it is possible to check whether the load device 730 is abnormal when the image forming apparatus is activated. As a result, it is possible to detect an abnormality before the damage spreads. In addition, the location where an abnormality has occurred is clarified and normal parts are not replaced, and unnecessary part replacement and labor can be saved. Also, since output abnormality is checked before complete operation, useless replacement can be omitted without applying stress to the fuse 713.

  FIG. 12 is a diagram showing a modification of the power supply device according to the fourth embodiment of the present invention. As illustrated in FIG. 12, the power supply device 810 includes an overcurrent detection circuit 711 and an overvoltage detection circuit 712 as protection circuits, and fuses 718 to 720. FIG. 12 shows an example in the case where the power supply apparatus 810 supplies power to a plurality of loads, and diodes CR2, CR4, and CR6 that detect output voltages to the loads are provided for each load. A load device is connected to the outputs 1-3.

  Between the power supply circuit and the load device, two switch means of a switch means 714 as a sixth switch means and a switch means 716 as a seventh switch means are inserted in parallel. The switch means 714 is connected to the load device via the node 1 and the fuse 718 via the output 1 and connected to the load device via the node N3 and the fuse 719 via the output 2 and connected to the load device via the node N4 and the fuse 720 via the output 3. It is connected. Diodes CR2, CR4, and CR6 are output voltage confirmation means for detecting whether the power supply device 810 is outputting an accurate voltage. One end of the switch means 716 is connected to the node N1. The node N1 is connected to the node N2 through the resistor R3 and the diode CR1. The node N2 is connected to the ground via a diode CR2 and a resistor R5. The node N1 is connected to the node N3 through the resistor R4, the diode CR3, and the transistor Tr1. The node N3 is connected to the ground via a diode CR4 and a resistor. The base of the transistor Tr1 is connected to the connection point between the anode of the diode CR2 and the resistor R5.

  The node N1 is connected to the node N4 via the resistor R7, the diode CR5, and the transistor Tr2. The node N4 is connected to the ground via a diode CR6 and a resistor R8. The base of the transistor Tr2 is connected to the connection point between the anode of the diode CR4 and the resistor R6. A connection point between the diode CR6 and the resistor R6 is connected to a switch-on unit 715 for turning on the switch unit 714 and a switch-off unit 717 forcibly turning off the switch unit 716.

  Next, the operation will be described. When the user turns on a main switch (not shown) to use the image forming apparatus, a current flows through the resistor R1, the switch unit 716 is turned on, and the output 1 is normal. , A current flows to the output 1 via the resistor R3 and the diode CR1, and further, a current flows to the ground via the diode CR2. Therefore, if the transistor Tr1 is in the ON enabled state and the output 2 is normal, the transistor Tr1 is turned ON and a current flows to the output 2. Similarly, if the outputs 2 and 3 are normal, a potential is generated in the resistor R8, the ON means 715 is ON, the switch 714 is ON, and the OFF means 171 that is the winding current interruption is ON and the switch means 716 is ON. Is turned off. If any one of the outputs 1 to 3 is abnormal, the switch unit 714 does not operate and the power supply device 810 stops operating.

  When the output voltage is detected to be below a predetermined level by the diodes CR2, CR4, and CR6, which are detection means, the operation of the power supply device 810 is stopped, and then the input of the ON means 715 or OFF means 717 is monitored. An abnormality can be notified to the user by a light emitting diode (notification means) (not shown). In addition, when it is detected by the diodes CR2, CR4, and CR6 that are detection means that the power supply circuit does not output a predetermined voltage, a plurality of diodes (notification means) CR1, CR3, and CR5 that are formed of light emitting diodes are provided. The user can be notified of which of the loads is abnormal.

  In the above-described embodiment, the image forming apparatus has been described as an example of the electronic apparatus provided with the power supply device. However, the present invention is not limited thereto, and can be applied to any electronic apparatus provided with the power supply device. It is.

  Although the preferred embodiment of the present invention has been described in detail above, the present invention is not limited to the specific embodiment, and various modifications, within the scope of the gist of the present invention described in the claims, It can be changed.

It is a figure explaining the structure of the image forming apparatus provided with the conventional protection circuit. 1 is a diagram illustrating a configuration of an image forming apparatus 102 including a power supply device according to a first embodiment of the present invention. It is an operation | movement flowchart of the power supply device of this invention. It is a figure which shows the specific structural example of the power supply device which concerns on 1st Embodiment of this invention. It is a figure which shows the structural example of the power supply device which concerns on 2nd Embodiment of this invention. It is a figure for demonstrating the conventional power supply device. It is a figure for demonstrating the image forming apparatus which concerns on 3rd Embodiment of this invention. It is a figure which shows the specific structure of the image forming apparatus which concerns on 3rd Embodiment of this invention. It is a figure which shows the other specific structural example of the image forming apparatus which concerns on 3rd Embodiment of this invention. It is a figure which shows the other specific structural example of the image forming apparatus which concerns on 3rd Embodiment of this invention. It is a figure which shows the structure of the image forming apparatus which concerns on 4th Embodiment of this invention. It is a figure which shows the modification of the power supply device which concerns on 4th Embodiment of this invention.

Explanation of symbols

102, 400, 600, 700 Image forming apparatus 110, 410, 610, 710 Power supply device 121 First switch means 122 Second switch means 131 Third switch means 224 Fourth switch means 225 Fifth switch means 160 , 170, 270 Power supply circuit 180 Abnormal processing unit 190, 290 Control unit 416, 616 Output confirmation unit 417, 617 Switching unit 418 Notification unit 714, 716 Switch unit

Claims (26)

In a power supply device that converts power supplied from a commercial power supply and supplies power to a load,
An abnormality detection means for detecting an abnormality in the output of the power supply circuit;
First switch means for turning on and off power supply to the power supply circuit;
Second switch means for turning on and off power supply from the power supply circuit to the load;
And a control means for diagnosing whether the power supply circuit is abnormal or the load is abnormal by performing on / off control on the first and second switch means when an abnormality is detected by the abnormality detecting means. Power supply. 2. The power supply apparatus according to claim 1, wherein the control unit turns off the first and second switch units when an abnormality is detected by the abnormality detection unit. 2. The control unit according to claim 1, wherein when an abnormality is detected by the abnormality detection unit, the control unit turns on the first switch unit after turning off the first and second switch units. The power supply described. When the abnormality is detected by the abnormality detection means, the control means turns off the first and second switch means, turns on the first switch means, and no abnormality is detected by the abnormality detection means. The power supply apparatus according to claim 1, wherein the second switch means is turned on. When an abnormality is detected by the abnormality detection means, the control means turns off the first and second switch means, turns on the first switch means, and an abnormality is detected by the abnormality detection means. 2. The power supply device according to claim 1, wherein operation of the power supply device is stopped. When the abnormality is detected by the abnormality detection means, the control means turns off the first and second switch means, turns on the first switch means, and no abnormality is detected by the abnormality detection means. 2. The power supply device according to claim 1, wherein when the second switch unit is turned on and an abnormality is detected by the abnormality detection unit, the operation of the power supply unit is stopped. Third switch means for turning on and off the power supply from the commercial power source;
A second abnormality detecting means for detecting at least one of a leakage current on the primary circuit side and a smoothing voltage on the primary side;
7. The power supply device according to claim 1, wherein the control unit turns off the third switch unit when an abnormality is detected by the second abnormality detection unit. 8. A voltage converter for converting the voltage from the power supply circuit;
Third abnormality detection means for detecting an abnormality in the output of the voltage converter;
Fourth switch means for turning on and off power supply from the power supply circuit to the voltage converter;
And fifth switch means for turning on and off the power supply from the voltage converter to the load,
When the abnormality is detected by the third abnormality detecting means, the control means performs on / off control of the fourth and fifth switch means, thereby causing an abnormality between the power supply circuit and the voltage converter, the voltage conversion The power supply apparatus according to claim 1, wherein the power supply apparatus diagnoses which one of the abnormality of the device and the abnormality of the load. When the abnormality is detected by the third abnormality detecting means, the control means turns off the fourth and fifth switch means and then turns on the fourth switch means. The power supply device according to claim 8. The control means turns off the fourth and fifth switch means, turns on the fourth switch means, and turns on the third abnormality detection means when an abnormality is detected by the third abnormality detection means. 9. The power supply apparatus according to claim 8, wherein when the abnormality is not detected by the step, the fifth switch means is turned on. The control means turns off the fourth and fifth switch means, turns on the fourth switch means, and turns on the third abnormality detection means when an abnormality is detected by the third abnormality detection means. 9. The fifth switch means is turned on when an abnormality is not detected by the above, and the fifth switch means is turned off when an abnormality is detected by the third abnormality detection means. The power supply device described in 1. The control means turns off the fourth and fifth switch means, turns on the fourth switch means, and turns on the fourth switch means when an abnormality is detected by the third abnormality detection means. The power supply device according to claim 8, wherein the power supply device is turned off. Connection means capable of disconnecting the connection between the power supply circuit and the load after an abnormality is detected by the abnormality detection means and the operation of the power supply device is stopped;
Detecting means for detecting an output of the power supply circuit after starting the operation of the power supply device;
The power supply apparatus according to claim 1, further comprising notification means for notifying a user that the output of the power supply circuit is at a predetermined level by the detection means. The power supply apparatus according to claim 13, further comprising a switching unit that switches connection between the detection unit and the notification unit for each output of the power supply circuit when there are a plurality of the power supply circuits. When there are a plurality of the power supply circuits, further comprising sixth switch means for turning on / off the output of some of the plurality of power supply circuits by an external signal,
The switching means switches the connection between the detecting means and the notifying means for each output of the power supply circuit after disabling the sixth switch means after restarting the power supply device. 14. The power supply device according to 13. 15. The power supply apparatus according to claim 14, wherein the switching unit is a unit that manually switches a connection between the output confirmation unit and the notification unit. The power supply apparatus according to claim 13, wherein the switching unit includes a photocoupler. The power supply apparatus according to claim 13, wherein the notification means notifies the output state of the power supply circuit by light. 14. The power supply apparatus according to claim 13, wherein the notification means notifies the output state of the power supply circuit by sound. The power supply apparatus according to claim 13, wherein the detection means detects whether the output voltage of the power supply circuit is higher than a predetermined voltage. Circuit cutting means for cutting a circuit between the power supply circuit and the load;
A sixth switch means inserted between the power supply circuit and the circuit disconnecting means for turning on and off the power supply to the load;
A seventh switch means connected in parallel to the sixth switch means, a current limit means for limiting the current, and a backflow prevention means for preventing a backflow of current;
Detecting means for detecting an output voltage of the power supply circuit;
Means for turning on the second switch means at startup, turning on the first switch means when the output voltage is at a predetermined level by the detection means, and turning off the second switch means; The power supply device according to claim 1, further comprising: In a power supply device that converts a voltage supplied from a commercial power supply by a power supply circuit and supplies power to a load,
Circuit cutting means for cutting a circuit between the power supply circuit and the load;
A sixth switch means inserted between the power supply circuit and the circuit disconnecting means for turning on and off the power supply to the load;
A seventh switch means connected in parallel to the sixth switch means, a current limit means for limiting the current, and a backflow prevention means for preventing a backflow of current;
Detecting means for detecting an output voltage of the power supply circuit;
Means for turning on the second switch means at the time of startup, turning on the first switch means and turning off the second switch means when the output voltage is at a predetermined level by the detection means; A power supply device characterized by that. The power supply device according to claim 21 or 22, wherein the power supply device stops operation when an output voltage is equal to or lower than a predetermined voltage by the detection unit. 23. The power supply device according to claim 21, wherein, when power is supplied to a plurality of loads, the detection unit is provided for each load. 22. The apparatus according to claim 21, further comprising notifying means for notifying the user of an abnormality after stopping the operation of the power supply device when the detecting means detects that the output voltage is below a predetermined level. 23. The power supply device according to 22. When the detection unit detects that the power supply circuit does not output a predetermined voltage, the detection unit further includes a notification unit that notifies the user which load is abnormal among a plurality of loads. The power supply device according to claim 21 or 22.

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