Anomaly detection device, processing device, and anomaly detection method

Abstract

To detect an abnormality of a short circuit protection element by a simple device configuration, and reduce power consumption.SOLUTION: An abnormality detection device 10 includes: a power supply unit 11 that supplies power source power to a terminal component 20 serving as a load; a short circuit protection element 12 that is arrayed between the power supply unit 11 and the terminal component 20; and a control unit 130 for controlling the power supply unit 11. The control unit 130 detects abnormalities in the short circuit protection element 12 and the terminal component 20 on the basis of a first voltage VA on the power supply unit 11 side of the short circuit protection element 12 and a second voltage VB on the terminal component 20 side of the short circuit protection element 12.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an abnormality detection device, a processing device, and an abnormality detection method. [Background technology]

[0002] Conventionally, in processing devices such as image forming devices, power supply circuits have been known that use short-circuit protection elements such as fuses to protect loads such as driving components and detection components at the terminals from overcurrent. This power supply circuit supplies power from the power source to the load through a bundled cable via the short-circuit protection element.

[0003] Wires can become damaged by metal sheets inside the processing equipment and come into contact with the sheet metal, or get caught when tightening screws. When this happens, a short-circuit current flows through the wires, and to protect them, the short-circuit protection element melts down, cutting off the power supply. Irreversible short-circuit protection elements, like fuses, must be replaced to restore operation. In particular, in recent processing equipment, short-circuit protection elements are often placed on the control board, so replacing the short-circuit protection element also means replacing the control board.

[0004] Also, as a configuration for preventing fuse blowout, a connection circuit is known that is provided in a machine tool and detects overcurrent in the power supply supplied from a power supply device to a fuse and multiple connected devices as loads via multiple interfaces to protect the connected devices (see Patent Document 1). The connection circuit (FIG. 1) of the first embodiment of Patent Document 1 includes a short-circuit checker and a power supply control unit. The short-circuit checker detects whether the power line and ground line connected to each interface are short-circuited, and if there is no short, the power supply control unit outputs an operation command to the power supply device. The short-circuit checker checks for continuity between the power line and ground line by contacting terminals, similar to checking for short circuits using a continuity tester.

[0005] The connection circuit (Fig. 3) of the second embodiment of Patent Document 1 includes an ammeter between the power supply device (fuse) and multiple connection devices (interfaces). Based on the current value detected by the ammeter, the power supply control unit detects whether the power line and the ground line are short-circuited, and if they are not short-circuited, outputs an operation command to the power supply device. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2018-143029 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the first connection circuit of Patent Document 1 requires the placement of an interface, a short-circuit checker, and a power supply for the short-circuit checker, resulting in a complex device configuration. Similarly, the second connection circuit of Patent Document 1 also requires the inclusion of an ammeter, resulting in a complex device configuration, and furthermore, the ammeter acts as a load even when normal, resulting in extra power consumption.

[0008] An object of the present invention is to detect an abnormality in a short-circuit protection element with a simple device configuration and to reduce power consumption. [Means for solving the problem]

[0009] In order to solve the above problem, the abnormality detection device of the invention described in claim 1 comprises: a power supply unit that supplies power from the power supply to the load; a short-circuit protection element disposed between the power supply unit and the load; a control unit that controls the power supply unit, The control unit detects an abnormality in the short circuit protection element and the load based on a first voltage on the power supply unit side of the short circuit protection element and a second voltage on the load side of the short circuit protection element. death, The control unit causes the power supply unit to output constant current power during a constant current period, and detects abnormalities in the short circuit protection element and the load. .

[0011] Claim 2 The invention described in claim 1 In the abnormality detection device described in The constant current is a current smaller than the rated current of the short circuit protection element.

[0012] Claim 3 The invention described in of Anomaly detection device teeth, a power supply unit that supplies power from the power supply to the load; a short-circuit protection element disposed between the power supply unit and the load; a control unit that controls the power supply unit, the control unit detects an abnormality in the short circuit protection element and the load based on a first voltage on the power supply unit side of the short circuit protection element and a second voltage on the load side of the short circuit protection element; The load is plural, a plurality of the short-circuit protection elements are provided corresponding to the plurality of loads, The control unit detects abnormalities in each of the short circuit protection elements and each of the loads based on a first voltage on the power supply unit side of each of the short circuit protection elements and a second voltage on the load side of each of the short circuit protection elements. death, The control unit causes the power supply unit to output power of a constant current smaller than the rated current of the short-circuit protection element having the smallest rated current during a constant current period, and detects abnormalities in each of the short-circuit protection elements and each of the loads. .

[0014] Claim 4 The invention described in claim 3 In the abnormality detection device described in There are a plurality of constant current periods, the plurality is n (n is a natural number of 2 or more), The control unit causes the power supply unit to output power supply power of a constant current smaller than the rated current of the short circuit protection element having the i-th smallest rated current during the i-th constant current period (i is a natural number from 1 to n), and detects abnormalities in each of the short circuit protection elements and each of the loads.

[0015] Claim 5 The invention described in claim 1 to 4 In the abnormality detection device according to any one of the above, When an abnormality is detected in the short-circuit protection element or the load during the constant current period, the control unit stops the output of the power supply power from the power supply unit during the constant current period.

[0016] Claim 6 The invention described in claim 1 to 5 In the abnormality detection device according to any one of the above, When the control unit detects that the short-circuit protection element and the load are normal, the control unit causes the power supply unit to output power supply power of a rated voltage of the load after the constant current period.

[0017] Claim 7 The invention described in claim 1 to 6 In the abnormality detection device according to any one of the above, The control unit causes the power supply unit to output the constant current power supply power by current limiting activation.

[0018] Claim 8 The invention described in claims 1 to 7 In the abnormality detection device according to any one of the above, The control unit notifies a notification unit of the detection result of the abnormality.

[0019] Claim 9 The invention described in claims 1 to 8 In the abnormality detection device according to any one of the above, The abnormality is a short circuit of the short circuit protection element, a meltdown of the short circuit protection element, or a disconnection of the load. The abnormality detection device of the invention described in claim 10 comprises: a power supply unit that supplies power from the power supply to the load; a short-circuit protection element disposed between the power supply unit and the load; a control unit that controls the power supply unit, the control unit detects an abnormality in the short circuit protection element and the load based on a first voltage on the power supply unit side of the short circuit protection element and a second voltage on the load side of the short circuit protection element; The abnormality is a disconnection of the load.

[0020] Claim 11 The processing device of the invention described in From claim 1 10 an abnormality detection device according to any one of the preceding claims; and the load.

[0021] Claim 12The invention described in claim 11 In the processing device described in The processing device is an image forming device that forms an image on a sheet of paper.

[0022] Claim 13 The invention described in A method for detecting an abnormality in the supply of power from a power source to a load, comprising: The power supply section supplies power to the load. power supply The process and A control unit detects abnormalities in the short circuit protection element and the load based on a first voltage on the power supply unit side of a short circuit protection element disposed between the power supply unit and the load and a second voltage on the load side of the short circuit protection element. control Process and fruit, The control unit causes the power supply unit to output power of a constant current smaller than the rated current of the short-circuit protection element having the smallest rated current during a constant current period, and detects abnormalities in each of the short-circuit protection elements and each of the loads. . The invention described in claim 14 is A method for detecting an abnormality in the supply of power from a power source to a load, comprising: a power supply step in which the power supply unit supplies power from the power supply to the load; a control step in which a control unit detects an abnormality in the short circuit protection element and the load based on a first voltage on the power supply unit side of a short circuit protection element disposed between the power supply unit and the load and a second voltage on the load side of the short circuit protection element, The load is plural, a plurality of the short-circuit protection elements are provided corresponding to the plurality of loads, the control unit detects abnormalities in each of the short circuit protection elements and each of the loads based on a first voltage on the power supply unit side of each of the short circuit protection elements and a second voltage on the load side of each of the short circuit protection elements; During the constant current period, the control unit causes the power supply unit to output power supply power of a constant current smaller than the rated current of the short-circuit protection element with the smallest rated current, and detects abnormalities in each of the short-circuit protection elements and each of the loads. The invention described in claim 15 is the anomaly detection method described in claim 14, There are a plurality of constant current periods, the plurality is n (n is a natural number of 2 or more), The control unit causes the power supply unit to output power supply power of a constant current smaller than the rated current of the short circuit protection element having the i-th smallest rated current during the i-th constant current period (i is a natural number from 1 to n), and detects abnormalities in each of the short circuit protection elements and each of the loads. The invention described in claim 16 is A method for detecting an abnormality in the supply of power from a power source to a load, comprising: a power supply step in which the power supply unit supplies power from the power supply to the load; a control step in which a control unit detects an abnormality in the short circuit protection element and the load based on a first voltage on the power supply unit side of a short circuit protection element disposed between the power supply unit and the load and a second voltage on the load side of the short circuit protection element, The abnormality is a disconnection of the load. [Effects of the Invention]

[0023] According to the present invention, an abnormality in a short circuit protection element can be detected with a simple device configuration, and power consumption can be reduced. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a block diagram showing a functional configuration of a processing device according to a first embodiment of the present invention; [Figure 2] 4 is a timing chart of various signals of the abnormality detection device in a normal state according to the first embodiment. [Figure 3] 4 is a timing chart of various signals of the abnormality detection device according to the first embodiment when an abnormal short circuit occurs. [Figure 4] 4 is a timing chart of various signals of the abnormality detection device according to the first embodiment when a blown fuse abnormality occurs. [Figure 5] 4 is a timing chart of various signals of the abnormality detection device according to the first embodiment when an abnormality occurs in which a component is removed. [Figure 6] FIG. 10 is a block diagram showing a functional configuration of a processing device according to a second embodiment of the present invention. [Figure 7] 10 is a timing chart of various signals of the abnormality detection device in a normal state according to the second embodiment. [Figure 8] 10 is a timing chart of various signals of the abnormality detection device according to the second embodiment when an abnormal short circuit occurs. [Figure 9] 10 is a timing chart of various signals of the abnormality detection device according to the second embodiment when a blown fuse abnormality occurs. [Figure 10] 10 is a timing chart of various signals of the abnormality detection device according to the second embodiment when an abnormality occurs in the case where a component is removed. DETAILED DESCRIPTION OF THE INVENTION

[0025] First and second embodiments of the present invention will be described in detail below with reference to the accompanying drawings, although the present invention is not limited to the illustrated examples.

[0026] (First embodiment) A first embodiment of the present invention will be described with reference to Figures 1 to 5. First, the device configuration of this embodiment will be described with reference to Figure 1. Figure 1 is a block diagram showing the functional configuration of a processing device 1 of this embodiment.

[0027] As shown in Fig. 1, the processing device 1 of this embodiment has a load, supplies power to the load, and performs various processes. Here, the processing device 1 is described as an image forming device that forms an image on paper, such as a copier, printer, or MFP (Multifunction Peripheral). However, the processing device 1 may be a processing device other than an image forming device.

[0028] The processing device 1 includes an abnormality detection device 10 and an end component 20 as a load. The end component 20 is one of the loads within the processing device 1. When the processing device 1 is an image forming device, the end component 20 is one of the driving components such as an image forming unit, or the detection components such as various sensors.

[0029] The abnormality detection device 10 includes a power supply unit 11, a short-circuit protection element 12, a control circuit 13, and a display unit 14. The control circuit 13 is a control circuit on a control board and includes a control unit 130. The control unit 130 includes a constant current control circuit 131, an abnormality detection circuit 132, and a CPU (Central Processing Unit) 133.

[0030] The power supply unit 11 is a power supply unit that generates and outputs power supply for the terminal component 20 from power input from a commercial power source or the like. Under the control of the constant current control circuit 131, the power supply unit 11 outputs power supply power at a constant current for a predetermined constant current period when the supply of power supply to the terminal component 20 starts, and after the constant current output, outputs power supply power at the rated voltage of the terminal component 20 for normal operation. The constant current in this embodiment is a current having a constant current value within (smaller than) the rated current of the short-circuit protection element 12.

[0031] The power supply unit 11 also has an output switch 111. The output switch 111 is configured by, for example, a p-type MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), and turns on and off the output of power supply power from the power supply unit 11 in response to a control signal from the control unit 130 (constant current control circuit 131).

[0032] The short-circuit protection element 12 is composed of a fuse or a component including a fuse, and is arranged on the power supply line of the power supply from the power supply unit 11 to the terminal component 20. The short-circuit protection element 12 is an element that melts down when a current greater than the rated current of the short-circuit protection element 12 flows, thereby preventing a large power supply current from flowing to the terminal component 20 and protecting the terminal component 20.

[0033] The constant current control circuit 131 is a circuit unit that detects the voltage at point A (referred to as voltage VA) and the voltage at point B (referred to as voltage VB) during a constant current period, calculates and detects the voltage of the short-circuit protection element 12 from (VB - VA), calculates the value of the current flowing through the short-circuit protection element 12 from (the detected voltage value of the short-circuit protection element 12) / (the specific resistance value of the short-circuit protection element 12), generates a control signal for the power supply unit 11 to make the calculated current value a constant current, and outputs the control signal to the power supply unit 11. Point A is a point on the power supply line between the output terminal of the power supply unit 11 and the input terminal of the short-circuit protection element 12. Point B is a point on the power supply line between the output terminal of the short-circuit protection element 12 and the input terminal of the terminal component 20.

[0034] In addition, the constant current control circuit 131 receives a status signal from the abnormality detection circuit 132 indicating the normal / abnormal state of the short circuit protection element 12 and the terminal component 20 (power supply to the terminal component 20), and when the status signal indicates an abnormality, generates a control signal for turning off the output switch 111 and outputs it to the power supply unit 11 (output switch 111).

[0035] The abnormality detection circuit 132 is a circuit section that detects the voltage values ​​of the voltage VA at point A and the voltage VB at point B as the voltage of the short circuit protection element 12 during the constant current period, converts them into analog to digital (A / D) values, and outputs them to the CPU 133. When status information of the short circuit protection element 12 and the terminal component 20 (power supply to the terminal component 20) is input from the CPU 133, it generates a status signal corresponding to the status information and outputs it to the constant current control circuit 131.

[0036] The CPU 133 controls each part of the processing device 1. The CPU 133 reads a program stored in a storage unit (not shown) such as a flash memory mounted in the control circuit 13, loads the program into a RAM (Random Access Memory) (not shown) mounted in the control circuit 13, and executes various processes in cooperation with the loaded program.

[0037] During the constant current period, the CPU 133 determines whether the state of the short circuit protection element 12 and the terminal component 20 (power supply to the terminal component 20) is normal or abnormal, and the event that occurs when the state is abnormal, from the digital voltage VA and voltage VB input from the abnormality detection circuit 132, using the condition information in Table I below, and outputs the determination result, indicating whether the state is normal or abnormal, to the abnormality detection circuit 132 as state information. [Table 1] Here, the power supply voltage is the voltage at the output end of the power supply unit 11 during the constant current period (when constant current output control is in progress). The voltage VA0 is the product of the specific resistance of the short-circuit protection element 12 and the current value of the short-circuit protection element upper limit current of the short-circuit protection element 12. The short-circuit protection element upper limit current is the current that flows through the short-circuit protection element 12 when a short circuit occurs on the output side of the short-circuit protection element 12 during constant current control of the power supply unit 11. It is smaller than the rated current of the short-circuit protection element 12 (the current at which melting occurs) and is the upper limit current at which melting does not occur. The voltage VB0 is the power supply voltage minus (the specific resistance of the short-circuit protection element 12 and the steady-state current value of the terminal component 20 (load)). The steady-state current value of the terminal component 20 is the value of the steady-state current that flows through the terminal component 20 when a constant current flows through the short-circuit protection element 12 during the constant current period.

[0038] Number 4 in Table I indicates that the short circuit protection element 12 and the terminal component 20 (power supply to the terminal component 20) are in a normal state. Numbers 1 to 3 in Table I indicate that the short circuit protection element 12 and the terminal component 20 (power supply to the terminal component 20) are in an abnormal state.

[0039] Number 1 in Table I indicates an abnormal state, and the abnormal event is fuse blowing. A fuse blowing is an event in which a current greater than the rated current flows through the short-circuit protection element 12, causing the fuse to blow, and no current flows through the short-circuit protection element 12.

[0040] Number 2 in Table I indicates that the state is abnormal and the abnormal event is a component disconnection. A component disconnection is an event in which the end component 20 is disconnected from the power line between the short circuit protection device 12 and the end component 20, and no current flows through the end component 20.

[0041] Number 3 in Table I indicates an abnormal state, and the abnormal event is a short circuit. A short circuit occurs when the power line between the short circuit protection element 12 and the terminal component 20 is grounded (for example, when the bundled wires of the power line are damaged by sheet metal and come into contact with each other, or when a screw gets caught when being tightened, causing grounding), and the output side of the short circuit protection element 12 is short-circuited, preventing current from flowing to the terminal component 20.

[0042] In particular, in the connection circuit of the first embodiment of the above-mentioned conventional Patent Document 1, it is possible to determine whether point B is short-circuited by determining whether the voltage VB is 0 [V], but even if it is determined that the voltage VB is 0 [V], it is not possible to distinguish between a blown circuit (number 1) and a short circuit (number 3). Furthermore, in the connection circuit of the first embodiment of Patent Document 1, even if it is determined that the voltage VB is other than 0 [V], it is not possible to distinguish between a normal circuit (number 4) and a component disconnection (number 2).

[0043] Furthermore, in the connection circuit of the second embodiment of the above-mentioned conventional Patent Document 1, although it is possible to detect the current at point B, even if it is determined that the current at point B is 0 [A], it is not possible to distinguish whether it is a meltdown at number 1, a component detachment at number 2, or a short circuit at number 3.

[0044] In addition, the CPU 133 displays the status and event determination results (whether the status is normal or abnormal, and the events when the status is abnormal) of the short-circuit protection element 12 and the terminal component 20 (power supply to the terminal component 20) on the display unit 14, and notifies the user of the processing device 1.

[0045] The display unit 14 is configured by an LCD (Liquid Crystal Display), an EL (ElectroLuminescent) display, or the like, and displays various display information on the display screen in accordance with instructions from the CPU 133.

[0046] Next, the operation of the processing device 1 will be described with reference to Figs. 2 to 5. Fig. 2 is a timing chart of various signals of the abnormality detection device 10 under normal conditions. Fig. 3 is a timing chart of various signals of the abnormality detection device 10 when an abnormal short circuit occurs. Fig. 4 is a timing chart of various signals of the abnormality detection device 10 when an abnormal blowout occurs. Fig. 5 is a timing chart of various signals of the abnormality detection device 10 when an abnormal component removal occurs.

[0047] 2, the operation of the processing device 1 in a normal state (a state in which no abnormality occurs) from the start-up of the control circuit 13 to the supply of power supply power at the rated voltage to the end component 20 will be described. In Fig. 2, the timing charts of the signals "control power supply", "CPU operation", "power supply output voltage", "power supply output current", "voltage VA", and "voltage VB" are shown by solid lines, and the same applies to Figs. 3 to 5.

[0048] "Control power supply" indicates the voltage of the power supply supplied to the control circuit 13. "CPU operation" indicates the on / off state of the operation of the CPU 133. "Power supply output voltage" indicates the voltage value of the power supply output from the power supply unit 11. "Power supply output current" indicates the current value of the power supply current output from the power supply unit 11. "Voltage VA" indicates the voltage value at point A. "Voltage VB" indicates the voltage value at point B.

[0049] When the processing device 1 is powered on, a power supply (not shown) for the control circuit 13 connected to a commercial power source starts supplying power to the control circuit 13, and the control power supply rises to the voltage of the power supply for operating the control circuit 13. When the control circuit 13 is started by the supply of power, the CPU 133 starts up and starts operating. Then, the CPU 133 causes the constant current control circuit 131 to start (turn on) the power supply unit 11 to output constant current power supply power for a constant current period via the abnormality detection circuit 132, and also turns on the output switch 111.

[0050] After the constant current period begins, the constant current control circuit 131 increases the power supply output voltage of the power supply power output from the power supply unit 11 to a power supply voltage corresponding to the rated voltage of the terminal component 20, and makes the power supply output current of the power supply power output from the power supply unit 11 a constant current. In accordance with the power supply output voltage, the voltage VA is increased to the rated voltage (power supply voltage) of the terminal component 20. As a result, the voltage VB becomes a voltage value (voltage VB1) that is lower than the voltage VA by the voltage drop of the constant current load current in the short circuit protection element 12. The power supply output current during the constant current period is set to a current value equal to or lower than the short circuit protection element upper limit current. As a result, the short circuit protection element 12 does not fuse.

[0051] During the constant current period, the constant current control circuit 131 controls the current of the source power output from the power supply unit 11 to a constant current, and the abnormality detection circuit 132 and CPU 133 monitor the state of the source power supply to the terminal component 20. The constant current period is a period that includes the time required to detect an abnormality in the state of the source power supply to the terminal component 20 and to stop the power supply unit 11 when an abnormality occurs.

[0052] During the constant current period, the abnormality detection circuit 132 detects the voltages VA and VB and outputs them to the CPU 133. During this constant current period, the CPU 133 determines that the state is normal, as indicated by number 4 in Table I, and, in accordance with the determination result, the abnormality detection circuit 132 keeps the output switch 111 of the power supply unit 11 on via the constant current control circuit 131, causing the power supply unit 11 to continue outputting power from the power supply unit 11. In addition, in accordance with the determination result, the CPU 133 displays on the display unit 14 that the short-circuit protection element 12 and the terminal component 20 (the power supply power supply to the terminal component 20) are in a normal state.

[0053] Then, after the constant current period (end), the constant current control circuit 131 causes the power supply unit 11 to start outputting power supply power at the rated voltage of the terminal component 20. Therefore, the voltage VA remains at the rated voltage. The voltage VB becomes a voltage value that is smaller than the voltage VA by the voltage drop due to the rated voltage control in the short circuit protection element 12. The current flowing through the terminal component 20 after the constant current period is set to a current value lower than the short circuit protection element upper limit current, and the short circuit protection element 12 does not melt down.

[0054] Next, referring to Figure 3, we will explain the operation of the processing device 1 from the start-up of the control circuit 13 in the case where an abnormality occurs in which the power line between the short-circuit protection element 12 and the terminal component 20 is grounded and a short circuit occurs on the terminal component 20 side (a short circuit on the output side of the short-circuit protection element 12).

[0055] As shown in Fig. 3, the processing device 1 operates in the same manner as in the normal state of Fig. 2 until the start of the constant current period. Then, the constant current control circuit 131 causes the power supply unit 11 to start outputting constant current power supply power during the constant current period. However, because the output terminal of the short-circuit protection element 12 is short-circuited, the power supply output voltage and voltage VA of the power supply power output from the power supply unit 11 as the power supply output do not rise to the rated voltage of the terminal component 20 (become voltage VA0), and voltage VB becomes 0 [V].

[0056] A large power supply output current flows through the short circuit protection element 12 due to a short circuit, but because of the constant current control, the power supply output current becomes the short circuit protection element upper limit current, and the short circuit protection element 12 does not fuse. In this way, the current value of the constant current is set in advance so that a power supply output current smaller than the rated current flows through the short circuit protection element 12 when a short circuit occurs.

[0057] During the constant current period, the abnormality detection circuit 132 detects the voltages VA and VB and outputs them to the CPU 133. During this constant current period, the CPU 133 determines that the abnormality is in the state of number 3 in Table I, which is a short-circuit event, and the abnormality detection circuit 132 turns off the output switch 111 of the power supply unit 11 via the constant current control circuit 131 in accordance with the determination result, thereby stopping the output of power from the power supply unit 11. Furthermore, in accordance with the determination result, the CPU 133 displays on the display unit 14 that the states of the short-circuit protection element 12 and the terminal component 20 (the power supply power supply to the terminal component 20) are abnormal and that a short circuit has occurred on the output side of the short-circuit protection element 12.

[0058] The constant current period is set to a period during which the output of power supply power from power supply unit 11 can be stopped within the period if abnormality detection circuit 132 and CPU 133 detect an abnormality. Therefore, if a short-circuit abnormality occurs, the constant current period passes without stopping the output of power supply power from power supply unit 11, and power supply power of the rated voltage is input to short-circuit protection element 12, preventing a current greater than the rated current from flowing through short-circuit protection element 12 and causing it to fuse. After the output of power supply power from power supply unit 11 is stopped, the power supply output voltage and voltages VA and VB become 0 [V], and the power supply output current also becomes 0 [A].

[0059] Next, with reference to FIG. 4, the operation of the processing device 1 from the start of the control circuit 13 when an abnormality occurs in which the short circuit protection element 12 has melted will be described.

[0060] As shown in Fig. 4, the processing device 1 operates in the same manner as in the normal state of Fig. 2 until the start of the constant current period. Then, the constant current control circuit 131 causes the power supply unit 11 to start outputting constant current power for the constant current period. However, because the short-circuit protection element 12 is blown, the power supply output voltage value and voltage VA of the power supply output from the power supply unit 11 rise to the power supply voltage corresponding to the rated voltage, but the power supply output current does not flow through the short-circuit protection element 12. In other words, the current value of the current flowing through the short-circuit protection element 12 and the terminal component 20 is 0 [A]. The voltage VB is 0 [V].

[0061] During the constant current period, the abnormality detection circuit 132 detects the voltages VA and VB and outputs them to the CPU 133. During this constant current period, the CPU 133 determines that the abnormal state is that of number 1 in Table I, which indicates a meltdown event, and the abnormality detection circuit 132 turns off the output switch 111 of the power supply unit 11 via the constant current control circuit 131 in accordance with the determination result, thereby stopping the output of power from the power supply unit 11. Furthermore, in accordance with the determination result, the CPU 133 displays on the display unit 14 that the states of the short-circuit protection element 12 and the terminal component 20 (the power supply to the terminal component 20) are abnormal and that a meltdown event of the short-circuit protection element 12 has occurred.

[0062] After the power supply unit 11 stops outputting power from the power supply, the power supply output voltage and voltages VA and VB become 0 [V], and the power supply output current also remains at 0 [A].

[0063] Next, with reference to FIG. 5, the operation of the processing device 1 from the start of the control circuit 13 when an event of the terminal component 20 coming off as an abnormal state occurs will be described.

[0064] As shown in Fig. 5, the processing device 1 operates in the same manner as in the normal state of Fig. 2 until the start of the constant current period. Then, the constant current control circuit 131 causes the power supply unit 11 to start outputting constant current power for the constant current period. However, because the terminal component 20 is disconnected from the power line of the power supply unit 11, the power supply output voltage and voltage VA of the power supply output from the power supply unit 11 rise to the power supply voltage corresponding to the rated voltage, but no current flows through the terminal component 20. As a result, the voltage VB becomes the same voltage value as the voltage VA via the short-circuit protection element 12.

[0065] During the constant current period, the abnormality detection circuit 132 detects the voltages VA and VB and outputs them to the CPU 133. During this constant current period, the CPU 133 determines that the abnormality is in the state of number 2 in Table I, which is a component removal event, and the abnormality detection circuit 132 turns off the output switch 111 of the power supply unit 11 via the constant current control circuit 131 in accordance with the determination result, thereby stopping the output of power from the power supply unit 11. Furthermore, in accordance with the determination result, the CPU 133 displays on the display unit 14 that the states of the short-circuit protection element 12 and the terminal component 20 (the power supply power supply to the terminal component 20) are abnormal and that a component removal event of the terminal component 20 has occurred.

[0066] After the power supply unit 11 stops outputting power from the power supply, the power supply output voltage and voltages VA and VB become 0 [V], and the power supply output current also becomes 0 [A].

[0067] As described above, according to this embodiment, the processing device 1 includes an abnormality detection device 10 and an end component 20. The abnormality detection device 10 includes a power supply unit 11 that supplies power supply power to the end component 20, a short-circuit protection element 12 arranged between the power supply unit 11 and the end component 20, and a control unit 130 that controls the power supply unit 11. The control unit 130 detects abnormalities in the short-circuit protection element 12 and the end component 20 based on a first voltage VA on the power supply unit 11 side of the short-circuit protection element 12 and a second voltage VB on the end component 20 side of the short-circuit protection element 12.

[0068] Therefore, abnormalities in the short circuit protection element 12 and the terminal part 20 can be detected with a simple device configuration without using an interface, a short circuit checker, or an ammeter, and since no elements that act as a load, such as an ammeter, are placed on the power supply line, the power consumption of the processing device 1 can be reduced, especially during normal operation.

[0069] Furthermore, during the constant current period, the control unit 130 causes the power supply unit 11 to output constant current power supply power, and detects abnormalities in the short circuit protection element 12 and the terminal component 20. The constant current is a current smaller than the rated current of the short circuit protection element 12. This makes it possible to prevent the short circuit protection element 12 from melting down due to the flow of the rated current, and also makes it possible to detect abnormalities.

[0070] Furthermore, the control unit 130 causes the display unit 14 to display status information as a result of the detection of normality / abnormality. This allows the user to visually recognize status information such as the normality / abnormality state and the abnormal event, and to take prompt and appropriate action in the event of an abnormality. The notification unit is not limited to the display unit 14. The notification unit may be another notification unit, such as a light illumination unit that notifies status information by lighting or blinking a light source, or an audio output unit that has an amplifier and speaker and notifies status information by audio output.

[0071] The abnormality is a short circuit in the short circuit protection element 12, a meltdown of the short circuit protection element 12, or a detached terminal component 20. Therefore, a short circuit in the short circuit protection element 12, a meltdown of the short circuit protection element 12, or a detached terminal component 20 can be accurately detected, and appropriate measures can be taken depending on the detected abnormality.

[0072] Furthermore, the processing device 1 is an image forming device that forms an image on a sheet of paper. Therefore, since an abnormality can be detected with a simple device configuration without blowing out the short circuit protection element 12, the size and cost of the image forming device can be reduced.

[0073] Furthermore, the control unit 130 stops the output of power supply power from the power supply unit 11 during the constant current period when an abnormality is detected in the short circuit protection element 12 or the terminal component 20. This makes it possible to reliably prevent the short circuit protection element 12 from melting during the constant current period (before power supply power is supplied at the rated voltage).

[0074] Furthermore, when the control unit 130 detects that the short circuit protection element 12 and the terminal component 20 are normal, after the constant current period, the control unit 130 causes the power supply unit 11 to output power supply power at the rated voltage of the terminal component 20. This reliably prevents the short circuit protection element 12 from blowing out, and allows the terminal component 20 to be supplied with power supply power at the rated voltage to operate properly.

[0075] (Second embodiment) A second embodiment of the present invention will be described with reference to Figures 6 to 10. First, the device configuration of this embodiment will be described with reference to Figure 6. Figure 6 is a block diagram showing the functional configuration of a processing device 1a of this embodiment.

[0076] In the first embodiment described above, the configuration was such that an abnormality was detected when power was supplied to one end component 20 of the processing device 1, whereas in the second embodiment, the configuration is such that an abnormality was detected when power was supplied to multiple end components of the processing device.

[0077] 6, the processing device 1a of this embodiment, like the processing device 1 of the first embodiment, has a load, supplies power to the load to operate it, and performs various processes, and will be described as an image forming device, for example. In the processing device 1a, parts that are the same as those of the processing device 1 are given the same reference numerals, and the different parts will be mainly described.

[0078] The processing device 1a includes an abnormality detection device 10a and end components 21, 22, and 23 as loads. The end components 21, 22, and 23 have the same rated voltage. Although the processing device 1a is described here as including three end components 21, 22, and 23, the number of end components may be two or four or more.

[0079] The abnormality detection device 10a has a power supply unit 11, short-circuit protection elements 121, 122, and 123, a control circuit 13a, and a display unit 14. The short-circuit protection element 121 is a short-circuit protection element similar to the short-circuit protection element 12, and is arranged on the power supply line for the power supply from the power supply unit 11 to the terminal component 21. The short-circuit protection element 122 is a short-circuit protection element similar to the short-circuit protection element 12, and is arranged on the power supply line for the power supply from the power supply unit 11 to the terminal component 22. The short-circuit protection element 123 is a short-circuit protection element similar to the short-circuit protection element 12, and is arranged on the power supply line for the power supply from the power supply unit 11 to the terminal component 23. The rated currents of the short-circuit protection elements 121, 122, and 123 are each set in advance, and may have different configurations or the same configurations. Here, for example, the rated currents of the short circuit protection elements 121, 122, and 123 are different, and the rated current of the short circuit protection element 121 is the smallest, the rated current of the short circuit protection element 122 is the second smallest, and the rated current of the short circuit protection element 123 is the largest.

[0080] The control circuit 13a includes a control unit 130a. The control unit 130a includes a constant current control circuit 131a, an abnormality detection circuit 132a, and a CPU 133a. During a constant current period, the constant current control circuit 131a detects the voltage VA at point A, the voltage (referred to as voltage VB1) at point B1 corresponding to short-circuit protection element 121, the voltage (referred to as voltage VB2) at point B2 corresponding to short-circuit protection element 122, and the voltage (referred to as voltage VB3) at point B3 corresponding to short-circuit protection element 123, and calculates and detects the voltages of the short-circuit protection elements 121, 122, and 123 using (VB1-VA), (VB2-VA), and (VB3-VA). This is a circuit section that calculates the sum of the current values ​​flowing through the short circuit protection elements 121, 122, and 123 using (voltage value of element 121) / (specific resistance value of short circuit protection element 121)+(detected voltage value of short circuit protection element 122) / (specific resistance value of short circuit protection element 122)+(detected voltage value of short circuit protection element 123) / (specific resistance value of short circuit protection element 123), and generates a control signal for the power supply unit 11 to make the sum of the calculated current values ​​a constant current, and outputs the control signal to the power supply unit 11.

[0081] Point B1 is a point on the power supply line between the output end of short circuit protection element 121 and the input end of terminal component 21. Point B2 is a point on the power supply line between the output end of short circuit protection element 122 and the input end of terminal component 22. Point B3 is a point on the power supply line between the output end of short circuit protection element 123 and the input end of terminal component 23.

[0082] Furthermore, similar to the constant current control circuit 131 of the first embodiment, the constant current control circuit 131a receives a status signal from the abnormality detection circuit 132a indicating the normal / abnormal state of the short circuit protection elements 121, 122, 123 and the terminal components 21, 22, 23 (power supply power supply to the terminal components 21, 22, 23), and when the status signal indicates an abnormality, generates a control signal for turning off the output switch 111 and outputs it to the power supply unit 11 (output switch 111).

[0083] The constant current in this embodiment refers to a current having a constant current value of the power supply power output from the power supply unit 11, and is a constant current with a number of stages corresponding to the different rated currents (three in this example) of the short circuit protection elements 121, 122, and 123. The three stages of constant current are referred to as the first constant current, the second constant current, and the third constant current, in order from smallest to largest. The first constant current is a current within (smaller than) the rated current of the short circuit protection element 121, which has the smallest rated current. The second constant current is a current within (smaller than) the rated current of the short circuit protection element 122, which has the second smallest rated current. The third constant current is a current within (smaller than) the rated current of the short circuit protection element 123, which has the largest rated current.

[0084] During the constant current period, the constant current control circuit 131a first causes the power supply unit 11 to output power supply power of the first constant current having the smallest current value, then causes the power supply unit 11 to output power supply power of the second constant current having the second smallest current value, and finally causes the power supply unit 11 to output power supply power of the third constant current having the largest current value. Within the constant current period, the period during which the first constant current is output is referred to as the first constant current period, the period during which the second constant current is output is referred to as the second constant current period, and the period during which the third constant current is output is referred to as the third constant current period.

[0085] If a short circuit occurs in the power supply line between the short circuit protection element and the terminal component, almost all of the current of the power supply power output from the power supply unit 11 flows to the short circuit protection element where the short circuit occurred. For example, if a short circuit occurs in the power supply line between the short circuit protection element 121 and the terminal component 21, almost all of the current of the power supply power output from the power supply unit 11 flows to the short circuit protection element 121. Therefore, if the second constant current is suddenly applied during the constant current period, the short circuit protection element 121 may melt. Similarly, if the third constant current is suddenly applied during the constant current period, the short circuit protection elements 121 and 122 may melt.

[0086] Furthermore, when the first constant current is applied, the abnormality detection circuit 132a may not be able to detect a short circuit in the short circuit protection elements 122 and 123, which have a large rated current. Similarly, when the second constant current is applied, the abnormality detection circuit 132a may not be able to detect a short circuit in the short circuit protection element 123, which has a large rated current.

[0087] For this reason, the constant current control circuit 131a first flows a first constant current during a first constant current period of the constant current period, detects a short circuit in the short circuit protection element 121 during the first constant current period, and if detected, stops the power supply power output of the power supply unit 11 (turns off the output switch 111). If the power supply power output is not stopped during the first constant current period, the constant current control circuit 131a flows a second constant current, detects a short circuit in the short circuit protection element 122 during the second constant current period, and if detected, stops the power supply power output of the power supply unit 11. If the power supply power output is not stopped during the second constant current period, the constant current control circuit 131a flows a third constant current, and detects a short circuit in the short circuit protection element 122 during the third constant current period, and if detected, stops the power supply power output of the power supply unit 11.

[0088] Therefore, the first constant current period is set to a period having a time required to detect an abnormality in short-circuit protection element 121 and stop the power supply power output of power supply unit 11 in the event of the abnormality. The second constant current period is set to a period having a time required to detect an abnormality in short-circuit protection element 122 and stop the power supply power output of power supply unit 11 in the event of the abnormality. The third constant current period is set to a period having a time required to detect an abnormality in short-circuit protection element 123 and stop the power supply power output of power supply unit 11 in the event of the abnormality.

[0089] The abnormality detection circuit 132a is a circuit section that detects the voltage values ​​of the short-circuit protection elements 121, 122, and 123 during the constant current period, namely, the voltage VA at point A, the voltage VB1 at point B1, the voltage VB2 at point B2, and the voltage VB3 at point B3, performs A / D conversion, and outputs the detected voltages to the CPU 133a, and when status information of the short-circuit protection elements 121, 122, and 123 and the terminal components 21, 22, and 23 (power supply to the terminal components 21, 22, and 23) is input from the CPU 133, generates a status signal corresponding to the status information, and outputs the signal to the constant current control circuit 131a.

[0090] Similar to the CPU 133 of the first embodiment, during the constant current period, the CPU 133a determines whether the status of the short-circuit protection elements 121, 122, 123 and the terminal components 21, 22, 23 (power supply power supply to the terminal components 21, 22, 23) is normal or abnormal from the digital voltages VA, VB1, VB2, VB3 input from the abnormality detection circuit 132a, using the condition information of Table I above, and if the status is abnormal, the event and the location where the event occurred, and outputs the determination result indicating whether the status is normal or abnormal to the abnormality detection circuit 132a as status information. More specifically, for each pair of voltages VA and VB1, voltages VA and VB2, and voltages VA and VB3, the state and abnormal event are determined independently, and if an abnormal event occurs, point B1 (corresponding short circuit protection element 121 or terminal component 21), point B2 (corresponding short circuit protection element 122 or terminal component 22), or point B3 (corresponding short circuit protection element 123 or terminal component 23) corresponding to the corresponding pair is determined to be the location of the occurrence.

[0091] In addition, the CPU 133a displays the results of determining the status, event, and location of occurrence of the short-circuit protection elements 121, 122, 123 and terminal components 21, 22, 23 (power supply to terminal components 21, 22, 23) (whether the status is normal or abnormal, the event when the status is abnormal, and the location where the event occurred) on the display unit 14, and notifies the user of the processing device 1.

[0092] Next, the operation of the processing device 1a will be described with reference to Figs. 7 to 10. Fig. 7 is a timing chart of various signals of the abnormality detection device 10a in a normal state. Fig. 8 is a timing chart of various signals of the abnormality detection device 10a when an abnormal short circuit occurs. Fig. 9 is a timing chart of various signals of the abnormality detection device 10a when an abnormal blowout occurs. Fig. 10 is a timing chart of various signals of the abnormality detection device 10a when an abnormal component removal occurs.

[0093] 7, the operation of the processing device 1 in a normal state (a state in which no abnormality occurs) from the start-up of the control circuit 13a to the supply of power supply power of the rated voltage to the end components 21, 22, and 23 will be described. In Fig. 7, the timing charts of the signals "control power supply," "CPU operation," "power supply output voltage," "power supply output current," "voltage VA," "voltage VB1," "voltage VB2," and "voltage VB3" are shown by solid lines, and the same is true in Figs. 8 to 10.

[0094] "CPU operation" indicates the on / off state of the operation of CPU 133a. "Power supply output current" indicates the current value of the power supply current output from power supply unit 11, in other words, the sum of the current values ​​of the currents flowing through short-circuit protection elements 121, 122, and 123. "Voltage VB1" indicates the voltage value at point B1. "Voltage VB2" indicates the voltage value at point B2. "Voltage VB3" indicates the voltage value at point B3.

[0095] When the processing device 1a is powered on, a power supply (not shown) for the control circuit 13 connected to a commercial power source starts supplying power to the control circuit 13, and the control power supply voltage is increased to the voltage of the power supply power required to start up the control circuit 13. When the control circuit 13 is started up by the supply of power, the CPU 133a starts up and starts operating. Then, the CPU 133a causes the constant current control circuit 131a to start (turn on) the power supply unit 11 to output constant current power for a constant current period via the abnormality detection circuit 132a, and also turns on the output switch 111.

[0096] After the constant current period starts, a first constant current period starts, and constant current control circuit 131a increases voltage VA of the power supply power output from power supply unit 11 to a power supply voltage corresponding to the rated voltage of terminal components 21, 22, and 23, and the power supply output current is set to a first constant current which is passed through short circuit protection elements 121, 122, and 123 to terminal components 21, 22, and 23. The short circuit protection element upper limit current during the first constant current period is a current which flows through short circuit protection element 121 when a short circuit occurs on the output side of short circuit protection element 121 during control of the first constant current of power supply unit 11, and is an upper limit current which is smaller than the rated current of short circuit protection element 121 and does not cause short circuit protection element 121 to fuse.

[0097] Therefore, voltage VB1 has a voltage value lower by the voltage drop of the current flowing from voltage VA to short circuit protection element 121. Voltage VB2 has a voltage value lower by the voltage drop of the current flowing from voltage VA to short circuit protection element 122. Voltage VB3 has a voltage value lower by the voltage drop of the current flowing from voltage VA to short circuit protection element 123.

[0098] After the first constant current period starts, the second constant current period starts, and the constant current control circuit 131a changes the power supply output current to a second constant current, which is passed to the terminal components 21, 22, and 23 via the short circuit protection elements 121, 122, and 123. The short circuit protection element upper limit current during the second constant current period is the current that flows through the short circuit protection element 122 when a short circuit occurs on the output side of the short circuit protection element 122 during control of the second constant current of the power supply unit 11, and is the upper limit current at which the short circuit protection element 122 will not fuse.

[0099] After the second constant current period starts, the third constant current period starts, and the constant current control circuit 131a changes the power supply output current to the second constant current, which is passed to the terminal components 21, 22, and 23 via the short circuit protection elements 121, 122, and 123. The short circuit protection element upper limit current during the third constant current period is the current that flows through the short circuit protection element 123 when a short circuit occurs on the output side of the short circuit protection element 123 during control of the third constant current of the power supply unit 11, and is the upper limit current at which the short circuit protection element 123 will not fuse.

[0100] During the constant current periods (first to third constant current periods), the current flowing through the short circuit protection elements 121, 122, and 123 does not exceed the short circuit protection element upper limit current, and therefore the short circuit protection elements 121, 122, and 123 are not blown out.

[0101] During the constant current period, the constant current control circuit 131a controls the current of the power supply power output from the power supply unit 11 to a constant current, and the abnormality detection circuit 132a and CPU 133a monitor the states of the short-circuit protection elements 121, 122, 123 and the terminal components 21, 22, 23 (power supply power supply to the terminal components 21, 22, 23). The constant current period functions as a period for monitoring whether the states of the short-circuit protection elements 121, 122, 123 and the terminal components 21, 22, 23 (power supply power supply to the terminal components 21, 22, 23) are normal / abnormal.

[0102] During the first constant current period, the abnormality detection circuit 132a detects the voltages VA, VB1, VB2, and VB3 and outputs them to the CPU 133a. During this first constant current period, the CPU 133a determines that the state is normal, as indicated by number 4 in Table I, and the abnormality detection circuit 132a, in response to this determination, keeps the output switch 111 of the power supply unit 11 on via the constant current control circuit 131a, causing the power supply unit 11 to continue outputting power. The CPU 133a also displays on the display unit 14 that the short-circuit protection elements 121, 122, and 123 and the end components 21, 22, and 23 (the supply of power to the end components 21, 22, and 23) are normal.

[0103] Then, after the constant current period (end), the constant current control circuit 131a causes the power supply unit 11 to start outputting power supply power at the rated voltage of the terminal components 21, 22, and 23. As a result, the voltage VA remains at the rated voltage. The voltage VB1 becomes a voltage value lower than the voltage VA by the amount of the voltage drop of the current for rated voltage control in the short circuit protection element 121. The voltage VB2 becomes a voltage value lower than the voltage VA by the amount of the voltage drop of the current for rated voltage control in the short circuit protection element 122. The voltage VB3 becomes a voltage value lower than the voltage VA by the amount of the voltage drop of the current for rated voltage control in the short circuit protection element 123. Since the current flowing through the short circuit protection elements 121, 122, and 123 after the constant current period does not exceed the short circuit protection element upper limit current, the short circuit protection elements 121, 122, and 123 are not blown out.

[0104] Next, the operation of the processing device 1a from the start of the control circuit 13a will be described with reference to Fig. 8 when an abnormality occurs in which the power supply line between the short circuit protection element and the terminal component is grounded and a short circuit occurs on the terminal component side (a short circuit at the output end of the short circuit protection element). Here, as an example, a case where a short circuit occurs on the output side of the short circuit protection element 122 will be described.

[0105] As shown in Fig. 8, the processing device 1a operates in the same manner as in the normal state of Fig. 7 until the start of the constant current period. Then, the constant current control circuit 131a causes the power supply unit 11 to start outputting power at a first constant current during the first constant current period of the constant current period. However, because the output terminal of the short-circuit protection element 122 is short-circuited, the voltage of the power supply output from the power supply unit 11 and the voltage VA do not rise to the rated voltage of the terminal components 21, 22, and 23. Instead, although voltages VB1 and VB3 rise, voltage VB2 remains at 0 V.

[0106] Then, the constant current control circuit 131a starts outputting power supply power at the second constant current during the second constant current period to the power supply unit 11. However, because the output terminal of the short-circuit protection element 122 is short-circuited, the voltage of the power supply power output from the power supply unit 11 as the power supply output voltage and the voltage VA do not rise to the rated voltage of the terminal components 21, 22, and 23, and although the voltages VB1 and VB3 rise, the voltage VB2 remains at 0 [V].

[0107] During the first and second constant current periods, a large current flows through the short circuit protection element 122, but the first and second constant currents keep the power supply output current below the short circuit protection element upper limit current, and the short circuit protection element 122 does not melt down.

[0108] During the first and second constant current periods, the abnormality detection circuit 132a detects the voltages VA, VB1, VB2, and VB3 and outputs them to the CPU 133a. During this second constant current period, the CPU 133a determines, based on (the voltages VA and VB2), that the abnormality is in the state of abnormality No. 3 in Table I, causing a short circuit event, and that the location of the occurrence is the short-circuit protection element 122. In response to this determination, the abnormality detection circuit 132a turns off the output switch 111 of the power supply unit 11 via the constant current control circuit 131a, thereby stopping the output of power from the power supply unit 11. The CPU 133a also displays on the display unit 14 that the state of the short-circuit protection element 122 (or the supply of power to the corresponding end component 22) where the abnormality occurred is abnormal, and that a short circuit has occurred on the output side of the short-circuit protection element 122 as an event.

[0109] During the second constant current period, the output of power supply power from power supply unit 11 is stopped, preventing the third constant current during the third constant current period from flowing through short-circuit protection element 122 and causing it to melt. Furthermore, since short-circuit protection elements 121 and 123 are not short-circuited, a current equal to or less than the upper limit current of the short-circuit protection element flows through them even during control of the second constant current, preventing them from melting. After the output of power supply power from power supply unit 11 is stopped, the power supply output voltage and voltages VA, VB1, VB2, and VB3 become 0 [V]. The current value of the current flowing through short-circuit protection element 121 and terminal component 21 becomes 0 [A]. The current value of the current flowing through short-circuit protection element 122 and terminal component 22 becomes 0 [A]. The current value of the current flowing through short-circuit protection element 123 and terminal component 23 becomes 0 [A].

[0110] In addition, the abnormality detection circuit 132a and the CPU 133a may detect a short circuit on the output side of the short circuit protection element 122 and stop the power supply power output of the power supply unit 11 not only during the second constant current period, but may also occur during the first constant current period.

[0111] Next, the operation of the processing device 1a from the start of the control circuit 13 when an abnormality occurs in which the short circuit protection element has melted will be described with reference to Fig. 9. Here, as an example, the case where the short circuit protection element 121 has melted will be described.

[0112] As shown in Figure 9, the processing device 1a operates in the same manner as in the normal state of Figure 7 until the start of the constant current period. Then, the constant current control circuit 131a causes the power supply unit 11 to start outputting power at a first constant current during the first constant current period of the constant current period. However, because the short-circuit protection element 121 is blown, the voltage value of the power supply power output from the power supply unit 11 as the power supply output voltage and the voltage VA rise to the power supply voltage corresponding to the rated voltage, but the current of the power supply power does not flow through the short-circuit protection element 121. The current value of the current flowing through the short-circuit protection element 121 and the terminal component 21 becomes 0 [A]. The voltage VB1 becomes 0 [V].

[0113] A current smaller than the short circuit protection element upper limit current flows through the short circuit protection element 122 and the terminal component 22. The voltage VB2 has a voltage value lower than the voltage VA by the amount of the voltage drop of the current in the short circuit protection element 122. A current smaller than the short circuit protection element upper limit current flows through the short circuit protection element 123 and the terminal component 23. The voltage VB3 has a voltage value lower than the voltage VA by the amount of the voltage drop of the current in the short circuit protection element 123.

[0114] During the first constant current period, the abnormality detection circuit 132a detects the voltages VA, VB1, VB2, and VB3 and outputs them to the CPU 133a. During this first constant current period, the CPU 133a determines, based on (the voltages VA and VB1), that the abnormality is in the state of abnormality No. 1 in Table I, resulting in a blown-out event, and that the location of the occurrence is the short-circuit protection element 121. In response to this determination, the abnormality detection circuit 132a turns off the output switch 111 of the power supply unit 11 via the constant current control circuit 131a, thereby stopping the output of power from the power supply unit 11. The CPU 133a also displays on the display unit 14 that the state of the short-circuit protection element 121 (and the supply of power to the corresponding end component 21) at the location of the occurrence is abnormal and that a blown-out event of the short-circuit protection element 121 has occurred.

[0115] After the power supply unit 11 stops outputting power from the power supply, the power supply output voltage and voltages VA, VB1, VB2, and VB3 become 0 [V]. The current value of the current flowing through the short circuit protection element 121 and the terminal component 21 becomes 0 [A]. The current value of the current flowing through the short circuit protection element 122 and the terminal component 22 becomes 0 [A]. The current value of the current flowing through the short circuit protection element 123 and the terminal component 23 becomes 0 [A].

[0116] Next, the operation of the processing device 1a from the start of the control circuit 13 when an event of component detachment of an end component occurs as an abnormal state will be described with reference to Fig. 10. Here, as an example, a case where component detachment occurs in the end component 23 will be described.

[0117] As shown in Fig. 10, processing device 1a operates in the same manner as in the normal state of Fig. 7 until the start of the constant current period. Then, constant current control circuit 131a causes power supply unit 11 to start outputting constant current power supply power during the constant current period. However, because terminal component 23 is disconnected from the power supply line of power supply unit 11, the voltage value of the power supply power output from power supply unit 11 as the power supply output voltage and voltage VA rise to the power supply voltage corresponding to the rated voltage, but no current flows through terminal component 23. As a result, voltage VB3 becomes the same voltage value as voltage VA via short-circuit protection element 123.

[0118] A current smaller than the short circuit protection element upper limit current flows through the short circuit protection element 121 and the terminal component 21. The voltage VB1 has a voltage value lower than the voltage VA by the amount of the voltage drop of the current in the short circuit protection element 121. A current smaller than the short circuit protection element upper limit current flows through the short circuit protection element 122 and the terminal component 22. The voltage VB2 has a voltage value lower than the voltage VA by the amount of the voltage drop of the current in the short circuit protection element 122.

[0119] During the first constant current period, the abnormality detection circuit 132a detects the voltages VA, VB1, VB2, and VB3 and outputs them to the CPU 133a. During this first constant current period, the CPU 133a determines based on (the voltages VA and VB3) that the abnormality is in the state of number 2 in Table I, that the event is a component removal, and that the location of the abnormality is the short-circuit protection element 123. In response to this determination, the abnormality detection circuit 132a turns off the output switch 111 of the power supply unit 11 via the constant current control circuit 131a, thereby stopping the output of power from the power supply unit 11. The CPU 133 also displays on the display unit 14 that the state of the short-circuit protection element 123 (and the corresponding supply of power to the peripheral component 23) where the abnormality occurred is abnormal, and that a component removal event of the peripheral component 23 has occurred.

[0120] After the power supply unit 11 stops outputting power from the power supply, the power supply output voltage and voltages VA, VB1, VB2, and VB3 become 0 [V]. The current value of the current flowing through the short circuit protection element 121 and the terminal component 21 becomes 0 [A]. The current value of the current flowing through the short circuit protection element 122 and the terminal component 22 becomes 0 [A]. The current value of the current flowing through the short circuit protection element 123 and the terminal component 23 becomes 0 [A].

[0121] As described above, according to this embodiment, the processing device 1a includes the abnormality detection device 10a and three end components 21, 22, and 23. The abnormality detection device 10a includes the power supply unit 11, three short-circuit protection elements 121, 122, and 123 corresponding to the end components 21, 22, and 23, and the control unit 130a. The control unit 130a detects abnormalities in the short-circuit protection elements 121, 122, and 123 and the end components 21, 22, and 23 based on the first voltage VA on the power supply unit 11 side of each short-circuit protection element 121, 122, and 123 and the end components 21, 22, and 23, respectively.

[0122] Furthermore, the connection circuit (FIG. 2) of a modified example of Patent Document 1 includes multiple sets of fuses, interfaces, and connected devices, and supplies power from the power supply to each connected device via each fuse and each interface in order, and also includes a short-circuit checker and a power supply control unit. In order for the power supply control unit to detect overcurrent in the power supply power supplied to multiple connected devices, it must sequentially switch the connections between the short-circuit checker and multiple interfaces, and checking sequentially takes time equal to the number of connected devices.

[0123] In contrast, the processing device 1a can detect abnormalities in the short-circuit protection elements 121, 122, 123 and the terminal components 21, 22, 23 with a simple device configuration without using an interface, short-circuit checker, or ammeter, and since no elements that create a load, such as an ammeter, are placed on the power supply line, the power consumption of the processing device 1a can be reduced, especially during normal operation. Furthermore, since there is no need for switching operations to detect voltages on the power supply lines of the multiple terminal components 21, 22, 23, the processing load can be reduced and the time required to detect an abnormality can be shortened.

[0124] Furthermore, during the constant current period (the first constant current period of the three constant current periods), the control unit 130a causes the power supply unit 11 to output power supply power of a first constant current that is smaller than the rated current of the short circuit protection element 121, which has the smallest rated current, and detects abnormalities in the short circuit protection elements 121, 122, 123 and the terminal components 21, 22, 23 during the constant current period (first constant current period).

[0125] If a second constant current larger than the first constant current is initially passed through the short-circuit protection elements 121, 122, and 123, and the output side of the short-circuit protection element 121 is short-circuited, a large current may flow through the short-circuited short-circuit protection element 121, causing it to melt. Similarly, if a third constant current larger than the first constant current is initially passed through the short-circuit protection elements 121, 122, and 123, and the output side of the short-circuit protection element 121 or 122 is short-circuited, a large current may flow through the short-circuited short-circuit protection element 121 or 122, causing it to melt. Therefore, by passing the first constant current through the short-circuit protection elements 121, 122, and 123 during the initial first constant current period, even if any of the short-circuit protection elements 121, 122, and 123 is short-circuited, melting of the short-circuit protection elements 121, 122, and 123 during the first constant current period can be prevented, and an abnormality can be detected.

[0126] Furthermore, the control unit 130a causes the power supply unit 11 to output power supply power of an ith constant current that is smaller than the rated current of the short-circuit protection element (short-circuit protection element 122 or 123) having the ith smallest rated current during the ith (i=1, 2, or 3) constant current period, thereby detecting an abnormality in the short-circuit protection elements 121, 122, and 123 and the terminal components 21, 22, and 23. Therefore, by flowing the ith constant current to the short-circuit protection elements 121, 122, and 123 during the ith constant current period, even if any of the short-circuit protection elements 121, 122, and 123 is short-circuited, by stopping the power supply power of the power supply unit 11 during the ith constant current period, it is possible to prevent the short-circuit protection elements 121, 122, and 123 from melting during the ith constant current period, and it is possible to reliably detect an abnormality (particularly a short circuit in the short-circuit protection element having the ith smallest rated current).

[0127] The above description of the embodiment is merely an example of a suitable anomaly detection device, processing device, and anomaly detection method according to the present invention, and the present invention is not limited to this.

[0128] For example, in the first and second embodiments, as shown in the timing charts of FIGS. 2 to 5 and 7 to 10, the constant current (the first to third constant currents) rises sharply at the start of the constant current period (the first to third constant current periods), but this is not limiting. For example, the control unit 130 (130a) may be configured to cause the power supply unit 11 to output the constant current (the first to third constant currents) by current-limiting activation. Current-limiting activation is a function possessed by the power supply unit, and is a function that gradually increases the current value from a reduced current state to a set current in a circuit in which an inrush current initially flows, such as a capacitor. Corresponding to the above embodiments, by using current-limiting activation to reduce the current of the power supply power from a reduced state to a constant current (the first to third constant currents), erroneous detection of normality / abnormality of the short-circuit protection element and terminal components can be prevented.

[0129] In the first and second embodiments, the abnormality detection circuit 132 (132a) and the CPU 133 (133a) are separate entities, but this is not limiting. The CPU 133 (133a) may be included in the abnormality detection circuit 132 (132a).

[0130] In the first and second embodiments, the power supply unit 11 and the control unit 130 (130a) are separate entities, but this is not limiting. At least part of the control unit 130 (130a) (for example, the constant current control circuit 131 (131a), the abnormality detection circuit 132 (132a), and the CPU 133 (133a)) may be included in the power supply unit 11.

[0131] In the first and second embodiments, the short-circuit protection elements 12, 121, 122, and 123 are configured to be fuses or components including fuses, but this is not limiting. The short-circuit protection elements 12, 121, 122, and 123 may be configured to be other short-circuit protection elements, such as breakers. When the short-circuit protection elements are breakers, tripping the breaker corresponds to blowing the fuse.

[0132] Furthermore, the detailed configurations and operations of the components constituting the processing devices 1 and 1a in the above-described embodiments can be modified as appropriate without departing from the spirit of the present invention. [Explanation of symbols]

[0133] 1,1a Processing equipment 10,10a Anomaly detection device 20, 21, 22, 23 End parts 11 Power supply section 111 Output Switch 12,121,122,123 Short-circuit protection elements 13, 13a Control circuit 130, 130a Control unit 131, 131a Constant current control circuit 132,132a Abnormality detection circuit 133,133a CPU 14 Display section

Claims

1. a power supply unit that supplies power from the power supply to the load; a short-circuit protection element disposed between the power supply unit and the load; a control unit that controls the power supply unit, the control unit detects an abnormality in the short circuit protection element and the load based on a first voltage on the power supply unit side of the short circuit protection element and a second voltage on the load side of the short circuit protection element; The control unit outputs constant current power to the power supply unit during a constant current period, and detects abnormalities in the short-circuit protection element and the load.

2. 2. The abnormality detection device according to claim 1, wherein the constant current is a current smaller than a rated current of the short-circuit protection element.

3. a power supply unit that supplies power from the power supply to the load; a short-circuit protection element disposed between the power supply unit and the load; a control unit that controls the power supply unit, the control unit detects an abnormality in the short circuit protection element and the load based on a first voltage on the power supply unit side of the short circuit protection element and a second voltage on the load side of the short circuit protection element; The load is plural, a plurality of the short-circuit protection elements are provided corresponding to the plurality of loads, the control unit detects abnormalities in each of the short circuit protection elements and each of the loads based on a first voltage on the power supply unit side of each of the short circuit protection elements and a second voltage on the load side of each of the short circuit protection elements; The control unit outputs power supply power of a constant current that is smaller than the rated current of the short-circuit protection element with the smallest rated current during a constant current period to the power supply unit, and detects abnormalities in each short-circuit protection element and each load.

4. There are a plurality of constant current periods, the plurality is n (n is a natural number of 2 or more), The abnormality detection device described in claim 3, wherein the control unit causes the power supply unit to output power supply power of a constant current smaller than the rated current of the short-circuit protection element having the i-th smallest rated current during the i-th constant current period (i is a natural number from 1 to n), thereby detecting abnormalities in each of the short-circuit protection elements and each of the loads.

5. 5. The abnormality detection device according to claim 1, wherein the control unit stops the output of power from the power supply unit during the constant current period if an abnormality is detected in the short-circuit protection element or the load during the constant current period.

6. 6. The abnormality detection device according to claim 1, wherein the control unit, when detecting that the short-circuit protection element and the load are normal, causes the power supply unit to output power at a rated voltage of the load after the constant current period.

7. The abnormality detection device according to claim 1 , wherein the control unit causes the power supply unit to output the constant current power supply power by current limiting activation.

8. The abnormality detection device according to claim 1 , wherein the control unit notifies a notification unit of the abnormality detection result.

9. The abnormality detection device according to claim 1 , wherein the abnormality is a short circuit in the short circuit protection element, a meltdown of the short circuit protection element, or a disconnection of the load.

10. a power supply unit that supplies power from the power supply to the load; a short-circuit protection element disposed between the power supply unit and the load; a control unit that controls the power supply unit, the control unit detects an abnormality in the short circuit protection element and the load based on a first voltage on the power supply unit side of the short circuit protection element and a second voltage on the load side of the short circuit protection element; The abnormality detection device detects a disconnection of the load.

11. The abnormality detection device according to any one of claims 1 to 10; and the load.

12. The processing device according to claim 11, wherein the processing device is an image forming device that forms an image on a sheet.

13. A method for detecting an abnormality in the supply of power from a power source to a load, comprising: a power supply step in which the power supply unit supplies power from the power supply to the load; a control step in which a control unit detects an abnormality in the short circuit protection element and the load based on a first voltage on the power supply unit side of a short circuit protection element disposed between the power supply unit and the load and a second voltage on the load side of the short circuit protection element, The control unit causes the power supply unit to output power at a constant current that is smaller than the rated current of the short-circuit protection element with the smallest rated current during a constant current period, and detects abnormalities in each of the short-circuit protection elements and each of the loads.

14. A method for detecting an abnormality in the supply of power from a power source to a load, comprising: a power supply step in which the power supply unit supplies power from the power supply to the load; a control step in which a control unit detects an abnormality in the short circuit protection element and the load based on a first voltage on the power supply unit side of a short circuit protection element disposed between the power supply unit and the load and a second voltage on the load side of the short circuit protection element, The load is plural, a plurality of the short-circuit protection elements are provided corresponding to the plurality of loads, the control unit detects abnormalities in each of the short circuit protection elements and each of the loads based on a first voltage on the power supply unit side of each of the short circuit protection elements and a second voltage on the load side of each of the short circuit protection elements; The control unit causes the power supply unit to output power at a constant current that is smaller than the rated current of the short-circuit protection element with the smallest rated current during a constant current period, and detects abnormalities in each of the short-circuit protection elements and each of the loads.

15. There are a plurality of constant current periods, the plurality is n (n is a natural number of 2 or more), The abnormality detection method according to claim 14, wherein the control unit causes the power supply unit to output power supply power of a constant current smaller than the rated current of the short-circuit protection element having the i-th smallest rated current during the i-th constant current period (i is a natural number from 1 to n), thereby detecting abnormalities in each of the short-circuit protection elements and each of the loads.

16. A method for detecting an abnormality in the supply of power from a power source to a load, comprising: a power supply step in which the power supply unit supplies power from the power supply to the load; a control step in which a control unit detects an abnormality in the short circuit protection element and the load based on a first voltage on the power supply unit side of a short circuit protection element disposed between the power supply unit and the load and a second voltage on the load side of the short circuit protection element, The abnormality detection method, wherein the abnormality is a disconnection of the load.

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