Power supply unit, image forming apparatus, recording apparatus, and power control method

Abstract

To prevent inappropriate power from being supplied to an external device in which a power source device supplies power, when the power source device fails.SOLUTION: A power source device, which has a first power source line to which power is supplied from power supply means, a second power source line connected to an external device, connection means which connects the first power source line and the second power source line, and is operable in any one of a first operation mode of transmitting power from the first power source line to the second power source line and a second operation mode of not permitting power transmission, discharge means which is connected to the second power source line, and is operable in any one of a third operation mode of lowering a voltage of the second power source and a fourth operation mode of not lowering the voltage, voltage monitoring means for monitoring a voltage of the second power source line, and control means for controlling operation of the connection means and the discharge means, determines whether or not to supply power to the second power source line, on the basis of the control state of the connection means and the discharge means, and the voltage of the second power source line monitored by the voltage monitoring means.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a power supply device having a connection circuit and a discharge circuit, an image forming apparatus, Recording device, and a power supply control method. [Background Art]

[0002] Conventionally, a thermal head type inkjet recording apparatus includes a power supply unit that supplies power to a heater mounted on a recording head serving as an ink ejection unit and a control circuit that controls the heater. Patent Document 1 discloses a configuration in which a relay circuit is connected between a power supply unit and a recording head to supply power. Patent Document 2 discloses a configuration in which driving power for a recording head is discharged based on a reset signal in order to prevent the recording head from being damaged due to over-power being supplied to the recording head when the supply voltage is unstable due to a power outage or the like. [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Unexamined Patent Publication No. 2016-224561 [Patent Document 2] Japanese Unexamined Patent Publication Sho 63-77757 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] In such a power supply device that supplies power to an external device, unintended power may be supplied to the external device due to failure of circuit elements such as a relay circuit and a discharge circuit. In such a case, there has been a problem that a failure of the power supply device may cause a failure of the external device to which the power supply device supplies power.

[0005] The present invention has been made in view of the above problem, and an object of the present invention is to prevent inappropriate power from being supplied to an external device to which the power supply device supplies power when the power supply device fails. [Means for solving the problem]

[0006] The power supply device of the present invention, which solves the above-mentioned problems, A first power line from which power is supplied by a power supply means, A second power line connected to an external device, A connection means that connects the first power line and the second power line and is capable of operating in either a first operating mode that enables power transmission from the first power line to the second power line, or a second operating mode that does not enable power transmission, A discharge means connected to the second power line, capable of operating in either a third operating mode that reduces the voltage of the second power line or a fourth operating mode that does not reduce the voltage, Voltage monitoring means for monitoring the voltage of the second power line, The connection means and the control means for controlling the operation of the discharge means, A power supply device having, The control means is When the connection means is controlled to operate in the second operating mode and the discharge means is controlled to operate in the fourth operating mode, if the voltage of the second power line is above a threshold, the first abnormality notification information is output. When the connection means is controlled to operate in the second operating mode and the discharge means is controlled to operate in the third operating mode, if the voltage of the second power line is above the threshold, the second abnormality notification information is output. The first abnormality notification information and the second abnormality notification information are different from each other. It is characterized by the following: [Effects of the Invention]

[0007] In the event of a power supply failure, this prevents the power supply from supplying inappropriate power to external devices that it is powering. [Brief explanation of the drawing]

[0008] [Figure 1] Configuration diagram of the recording device according to Embodiment 1 [Figure 2] Block diagram of the recording device according to Embodiment 1 [Figure 3] Block diagram of the recording head according to Embodiment 1 [Figure 4] Operational diagram of the discharge circuit according to Embodiment 1 [Figure 5] Configuration diagram of the power supply board according to Embodiment 1 [Figure 6] Flowchart showing an inspection sequence according to Embodiment 1 [Figure 7] Diagram showing power supply operation during an inspection sequence according to Embodiment 1 [Figure 8] Configuration diagram of a power supply board according to Embodiment 2 [Figure 9] Flowchart showing an inspection sequence according to Embodiment 2 [Figure 10] Diagram showing power supply operation during an inspection sequence according to Embodiment 2 DESCRIPTION OF EMBODIMENTS

[0009] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the claimed invention. Although a plurality of features are described in the embodiments, not all of the plurality of features are essential to the invention, and the plurality of features may be arbitrarily combined. Furthermore, in the accompanying drawings, identical or similar configurations are denoted by the same reference numerals, and overlapping descriptions are omitted.

[0010] <Embodiment 1> FIG. 1 is a configuration diagram of a recording apparatus 1 according to the present embodiment. The recording apparatus 1 is an example of an image forming apparatus, and includes a first conveyance unit 101, a second conveyance unit 102, and one or more recording heads 100.

[0011] The first conveyance unit 101 and the second conveyance unit 102 are examples of conveyance apparatuses for conveying a sheet S, which is a sheet-shaped recording medium. The sheet S is conveyed by the second conveyance unit 102 winding the sheet S conveyed by the first conveyance unit 101. The sheet S is, for example, rolled paper (roll paper), cloth, a plastic film, or the like. The recording head 100 performs recording processing on the conveyed sheet S from above to form an image on the recording medium.

[0012] A plurality of recording heads 100 are arranged along the conveyance direction in accordance with a conveyance path. In the present embodiment, the recording heads include four line-type recording heads corresponding to four colors: Bk (black), Y (yellow), M (magenta), and C (cyan). Note that the number of colors and the number of recording heads 100 are not limited to four. Ink of each color is supplied to the recording head 100 from an unillustrated ink tank via an ink tube, respectively. The recording head 100 includes a replaceable head 103 mounted with a heater, nozzles and the like, a control board 104, and a power supply board 105, which are electrically connected to each other.

[0013] The recording head 100 is mounted with a plurality of nozzles and corresponding heaters, and ejects ink in response to electrical signals from a recording control unit described later. Further, the replaceable head 103 is attachable to and detachable from the control board 104, the power supply board 105, and an unillustrated ink tank, and can be replaced.

[0014] Figure 2 is a control block diagram of the recording apparatus 1. An image controller 200 performs image processing to convert original data of a recording image into data that can be handled by a recording head control unit 203. The data processed by the image controller 200 is transmitted to the recording head control unit 203 via a communication interface (I / F) 201. As described above, the recording heads 100 are arranged in the recording apparatus 1 for each color, and are controlled by the recording head control unit 203.

[0015] An engine control unit 202 controls the entire engine of the recording apparatus 1. A conveyance control unit 204 controls actuators included in the first conveyance unit 101 and the second conveyance unit 102 shown in Figure 1. Further, timing control for conveyance of a recording medium may be performed based on data acquired from a sensor 205.

[0016] A recording head control unit 203 generates control signals for controlling the recording heads 100 based on image data obtained from the image controller 200. The recording head control unit 203 also performs adjustment of ejection timing among the plurality of recording heads 100 and the like.

[0017] The recording head 100 comprises a power supply unit 207 and a replacement head 103. The power supply unit 207 comprises a control board 104 and a power supply board 105, as shown in Figure 1. The power supply unit 207 is an example of a power supply unit according to this embodiment, and the replacement head 103 is an example of an external device to which power is supplied by the power supply unit.

[0018] The control board 104 includes a replacement head control unit 206, which controls the power supply board and the replacement head 103 based on control signals received from the recording head control unit 203. The replacement head control unit 206 also converts the data unpacked by the recording head control unit 203 into data corresponding to the nozzle row of the head and transmits it to the replacement head 103.

[0019] Figure 3 is a block diagram illustrating the configuration of a power supply system that controls the power supply circuit on the power supply board 105 to supply power to the replacement head 103. In Figure 3, solid lines connecting blocks indicate power lines used for transmitting and receiving power, and dotted lines indicate signal lines used for transmitting and receiving control signals.

[0020] The AC power supply 300 and the AC / DC converter 301 are located inside the recording device 1. The AC power supply 300 supplies DC power of voltage V1 to the DC / DC converters 303 and 304 of the power supply board 105 provided on each recording head 100 of the recording device 1 via the AC / DC converter 301.

[0021] <Power supply board> The DC / DC converter 303 supplies 12V DC power to the DC / DC converters 305 and 306 on the power supply board 105, and to the DC / DC converter 307 on the control board 104.

[0022] The DC / DC converter 305 generates DC power of voltage VHT from the power supplied from the DC / DC converter 303, which is then supplied to the heater drive circuit 311 of the interchangeable head 103. The DC voltage of voltage VHT output from the DC / DC converter 305 is supplied to the connection circuit 313 via the power line 316 (first power line). The power supplied to the connection circuit 313 is converted to voltage HBVHT and supplied to the heater drive circuit 311 via the power line 317 (second power line).

[0023] The DC / DC converter 306 generates DC power of voltage HVDD from the power supplied by the DC / DC converter 303, which is then supplied to the logic circuit 310 of the exchange head 103. The DC voltage of voltage HVDD output from the DC / DC converter 306 is converted by the connection circuit 315 and input to the logic circuit 310 of the exchange head 103.

[0024] The DC / DC converter 304 supplies DC power of voltage VH to the heater 312 of the replacement head 103 of the recording head 100 via the power line 318 (third power line).

[0025] The power controller 309 controls the on / off state of the DC / DC converter 304 and can also change the power supply voltage VH output by the DC / DC converter 304. In addition, the power controller 309 can detect power outages or power cuts by monitoring the power supply voltage V1 input from the AC / DC converter 301 to the DC / DC converter 304.

[0026] The connection circuits 313 and 315 can be fitted with relay elements including solid-state relays and mechanical relay switches. The connection circuits 313 and 315 are controlled by the control circuit 308, which can switch the connection operation on or off according to the ink ejection operation sequence. In the following description, the mode in which the connection circuit 313 connects to transmit power supplied from the DC / DC converter 305 to the heater drive circuit 311 is referred to as the first operating mode (on state), and the mode in which it does not transmit power is referred to as the second operating mode (off state). Similarly, the mode in which the connection circuit 315 enables the transmission of power supplied from the DC / DC converter 306 to the logic circuit 310 is referred to as the first operating mode (on state), and the mode in which it does not transmit power is referred to as the second operating mode (off state). The connection circuits 313 and 315 can control the timing at which the power output from the DC / DC converters 305 and 306 is supplied to the heater drive circuit 311 and the logic circuit 310. For example, when the recording device 1 is started up, the control circuit 308 controls the power supply to be started in the following order: logic circuit 310, heater drive circuit 311, and heater 312.

[0027] A second power line 317, which connects the connection circuit 313 to the heater drive circuit 311, is connected to a discharge circuit 314 controlled by a control circuit 308. The operation of the discharge circuit 314 will be described later with reference to Figure 4.

[0028] <Control board> The DC / DC converter 307 generates DC power of voltage V2 supplied to the control circuit 308 of the control board 104. However, depending on the devices used in the control circuit 308 or other devices mounted on the control board 104, the DC / DC converter 307 may supply power at a voltage different from V2. For example, different voltages may be supplied for logic power supplies and analog power supplies.

[0029] The control circuit 308 is a control unit such as a microcontroller, and by executing a program stored in memory (not shown), it realizes control of the power supply unit 207, including the control processing shown in Figure 6, which will be described later. The control circuit 308 also generates a timing signal that can determine ink ejection from the recording head 100 in response to image data (not shown) input from outside the recording head 100, and inputs a control signal to the logic circuit 310.

[0030] The explanation will assume that the voltages of each power line are V1 > VH > VHT > HVDD ≈ V2.

[0031] <Replacement Head> Multiple heaters 312 and heater drive circuits 311 are provided for multiple ink nozzles (not shown) mounted on the recording head 100, but only one of each is shown in Figure 3. The logic circuit 310 selects which heater to drive from the multiple heaters 312 based on a control signal from the control circuit 308. The heater drive circuit 311 receives an on / off signal from the logic circuit 310 and drives the DMOS (Double-Diffused MOSFET) of the heater 312. The heater drive circuit 311 also performs voltage level conversion of the signal from the logic circuit 310, which is generated based on the voltage HVDD, to the voltage VHT for driving the DMOS. As a result, the heater 312 of the replacement head 103 heats up and ink is ejected.

[0032] The operation of the discharge circuit 314 will be explained using Figure 4. Since a large current flows through the heater 312, a capacitor is connected to the power line 318 that supplies voltage VH on the replacement head 103 side to achieve low impedance. On the other hand, the larger the capacitance of the capacitor, the slower the discharge of the charge stored in the capacitor. Therefore, if the operation of the AC / DC converter 301 that supplies voltage V1 stops at time T0 due to a power outage or the like, the voltage of the power line 318 that supplies voltage VH will drop more slowly than the power lines that supply voltages HVDD and HBVHT. In this embodiment, the power controller 309 monitors the voltage of the power output by the AC / DC converter 301 and can detect when the output voltage drops below a threshold, thereby determining that there has been a power outage.

[0033] Here, during the period tooff, when the voltage of the power line supplying voltage HVDD is lower than the minimum voltage Voff required for the operation of the logic circuit 310, the operation of the logic circuit 310 becomes unstable, and the output of the logic circuit 310 may become undefined. For this reason, the logic circuit 310 may output a signal to turn on the heater drive circuit 311 during the period tooff. Here, if there is still voltage remaining on the second power line 317 that supplies power to the heater drive circuit 311, as shown by the dotted line, the heater drive circuit 311 may unintentionally drive the heater 312 when the logic circuit 310 outputs a signal to turn on the heater drive circuit 311. This may cause ink to be ejected from the replacement head 103, potentially causing the recording head 100 to fail.

[0034] Therefore, the power supply unit 207 according to this embodiment has a discharge circuit 314 for discharging the charge accumulated in the power line 317 that supplies power to the heater drive circuit 311 before the voltage supplied to the logic circuit 310 falls below Voff.

[0035] The discharge circuit 314 can operate in a third operating mode (on state) that reduces the voltage of the power line 317, and a fourth operating mode (off state) that does not reduce the voltage of the power line 317. In the event of a power outage, the discharge circuit 314 operates in the third operating mode, and the voltage of the heater drive circuit 311 is reduced during the tooff period when the output of the logic circuit 310 is undefined, thereby preventing the heater 312 from being driven. It is also possible to prevent the heater 312 from operating by discharging the power line 318 that supplies voltage VH instead of the power line 317 that supplies voltage HBVHT. However, since the amount of charge accumulated in the power line 318 that supplies voltage VH is larger than that of the power line 317 that supplies voltage VHT, the capacity of the circuit device required for discharge must be increased when connecting the discharge circuit to the power line 318. For this reason, in this embodiment, the voltage of the power line 317 that supplies power of voltage HBVHT, which has a smaller capacity for the circuit device required for discharge, is reduced.

[0036] Figure 5 illustrates the structure of the connection circuit 313 and discharge circuit 314 in the power supply board 105 in this embodiment. The power of the output voltage VHT in the first power line 316 connecting the DC / DC converter 305 and the connection circuit 313 is supplied to the second power line 317 at voltage HBVHT via the field-effect transistor (FET) 500, which is the switch part of the connection circuit 313. The power of voltage HBVHT supplied from the second power line 317 is for driving the heater, and a capacitive load 504 is connected to the second power line 317, which connects the connection circuit 313 and the heater drive circuit 311. In addition, a discharge circuit 314, which consists of an FET 501 and a thermistor 503, is connected to the second power line 317, and the discharge current is converted into temperature by the thermistor 503, which includes a PTC (Positive Temperature Coefficient) thermistor, to limit the amount of current. The power controller 309 communicates with the control circuit 308, monitors the voltage of the second power line 317, and transmits the monitored voltage value to the control circuit 308 as voltage monitoring information. The control circuit 308 includes an abnormality determination unit 505, which analyzes the voltage monitoring information obtained from the power controller and determines whether at least one of the connection circuit 313 and the discharge circuit 314 is abnormal based on the voltage value of the power line 317. If the abnormality determination unit 505 determines that at least one of the connection circuit 313 and the discharge circuit 314 is abnormal, the control circuit 308 decides not to supply power to the second power line 317 and outputs an abnormality notification signal to the outside of the recording head 100. If the control circuit 308 determines that there is no abnormality in the connection circuit 313 and the discharge circuit 314, it decides to supply power to the second power line 317. The control circuit 308 can also switch the operating state (on / off) of the connection circuit 313 and the discharge circuit 314.

[0037] In the first operating mode of the connection circuit 313, the control circuit 308 applies a voltage above the gate threshold between the gate and source of the FET 500 of the connection circuit 313 (turns it on), causing current to flow from the first power line 316 to the second power line 317. In the second operating mode, the control circuit 308 prevents current from flowing from the first power line 316 to the second power line 317 by not applying a voltage above the gate threshold between the gate and source of the FET 500 of the connection circuit 313.

[0038] In the third operating mode, the control circuit 308 applies a voltage above the gate threshold between the gate and source of the FET 501 in the discharge circuit 314 (turns it on), causing the charge accumulated on the power line 317 to flow to ground through the discharge circuit 314, thereby lowering the voltage on the power line 317. In the fourth operating mode, the control circuit 308 prevents the voltage on the power line 317 from dropping by not applying a voltage above the gate threshold between the gate and source of the FET 501.

[0039] Furthermore, the control circuit 308 may be controlled exclusively, for example, by operating the connection circuit 313 in the ON state while operating the discharge circuit 314 in the OFF state. This prevents overcurrent from flowing from the DC / DC converter 305 to ground via the connection circuit 313 and the discharge circuit 314. The fuse 502 provided in the first power line 316 is a fuse element that protects the replacement head 103 by opening the first power line 316 when a current exceeding a predetermined amount flows through the first power line 316, thereby preventing excessive current from flowing to the replacement head 103.

[0040] As explained in Figures 4 and 5, the power supply board 105 may malfunction due to failures in semiconductors that act as switch elements in the connection circuit 313 and the discharge circuit 314. In such cases, current may flow unintentionally to the replacement head 103, potentially causing it to fail. Thus, failures in locations other than the power supply board 105 can increase the number of faulty parts that need to be replaced, make it more difficult to pinpoint the fault location, and increase repair costs. Therefore, the power supply board 105 is required to detect when an abnormality (failure) occurs in at least one of the connection circuit 313 or the discharge circuit 314 and operate in a way that prevents unintended current from flowing to the replacement head 103.

[0041] Using Figures 6 and 7, the power control sequence for detecting failures in the connection circuit 313 and discharge circuit 314 in this embodiment will be described. Figure 6 is a flowchart showing an example of the process performed in the inspection sequence. Figure 7 is a diagram illustrating the change in the voltage of the second power line 317, which changes according to the process shown in the flowchart in Figure 6. Each processing step (Step) in Figure 7 indicates the timing at which the process referenced by the reference numerals in Figure 6 is performed.

[0042] The reference voltage Vth is a voltage threshold used to determine whether the power supply board 105 is functioning correctly, and is used in the abnormality determination unit 505 to perform abnormality determination processing. Part of the determination process performed by the abnormality determination unit 505 is shown below in Figure 7.

[0043] The processing sequence shown in Figure 6 is executed by the power supply unit 207 during the process of starting up the recording head 100. At S600, power is supplied from the AC / DC converter 301 to the DC / DC converters 304 and 307, and voltage V2 is supplied to the control circuit 308, which then starts up the control circuit 308.

[0044] In S601, the control circuit 308 operates the connection circuit 313 and the discharge circuit 314 in the OFF state. That is, the control circuit 308 operates the connection circuit 313 in the second operating mode and the discharge circuit 314 in the fourth operating mode. Here, after time t0 has elapsed, the control circuit 308 determines that the operation of the connection circuit 313 and the discharge circuit 314 in the OFF state is normal, provided that the voltage of the power line 317 is below the voltage threshold Vth (Y in S602). Provided that the voltage of the power line 317 is above the voltage threshold Vth (N in S602), the control circuit 308 determines that the connection circuit 313 has a short circuit failure and proceeds to S607.

[0045] In S603, the control circuit 308 sets the connection circuit 313 to the ON state (first operating mode) and the discharge circuit 314 to the OFF state (fourth operating mode). If, after time t1 has elapsed, the voltage of the power line 317 exceeds the voltage threshold Vth (Y in S604), the control circuit 308 determines that the operation in the control state where the connection circuit 313 is ON and the discharge circuit 314 is OFF is normal, and proceeds to S605. Provided that the voltage of the second power line 317 is less than or equal to the voltage threshold Vth (N in S604), the control circuit 308 determines that the connection circuit 313 is in an open state (open fault) or the discharge circuit 314 is in a short state (short fault), and proceeds to S607.

[0046] In S605, the control circuit 308 operates the connection circuit 313 in the off state (second operating mode) and the discharge circuit 314 in the on state (third operating mode). If, after time t2 has elapsed, the voltage of the power line 317 is less than the voltage threshold Vth (Y in S606), the control circuit 308 determines that the operation in the control state where the connection circuit 313 is off and the discharge circuit 314 is on is normal, and proceeds to S609. If the voltage of the second power line 317 is greater than or equal to the voltage threshold Vth (N in S606), the control circuit 308 determines that the discharge circuit 314 may be in an open fault state and unable to discharge, and proceeds to S607.

[0047] In S607, the control circuit 308 transmits an abnormality notification signal to notify that an abnormality has occurred in at least one of the connection circuit 313 and the discharge circuit 314. For example, the abnormality determination unit 505 may notify the user that an abnormality has occurred via an output interface (not shown) such as a display or light-emitting diode (LED) provided by the recording device 1. In one example, the control circuit 308 may transmit an abnormality notification signal that includes a type indicating the abnormality that has occurred. For example, if the control circuit 308 determines in S602 that the voltage of the second power line 317 is above a voltage threshold, the abnormality notification signal may be controlled to display a message on the display (not shown) of the recording device 1 that includes information indicating the possibility of a short-circuit failure in the connection circuit 313. Similarly, if the voltage of the power line 317 is below a voltage threshold in S604, the control circuit 308 may be controlled to display a message on the display (not shown) of the recording device 1 that includes information indicating the possibility of an open-circuit failure in the connection circuit 313 or a short-circuit failure in the discharge circuit 314. Similarly, if S606 determines that the voltage of the second power line 317 is above a voltage threshold, the abnormality notification signal may be controlled to display a message on the display (not shown) of the recording device 1 that includes information indicating the possibility of an open fault in the discharge circuit 314. Alternatively, different LEDs may be lit depending on the type of abnormality that may have occurred.

[0048] In S608, the control circuit 308 terminates abnormally without supplying voltage VH to the heater 312, even if the voltage of the power line supplying voltage HVDD and the voltage of the first power line 316 supplying voltage VHT are rising via the power controller 309. For example, in S608, the power controller 309 may be controlled to prevent power from being supplied from the DC / DC converter 303 to the heater 312. Alternatively, the control circuit 308 may perform control operations so that the connection circuit 313 operates in the off state (second operating mode) and the discharge circuit 314 operates in the on state (third operating mode), regardless of the possibility of failure. In other words, in S608, by preventing power from being supplied to at least one of the heater 312 and the heater drive circuit 311, improper power supply to the replacement head 103 is prevented, which could lead to a failure of the replacement head 103.

[0049] In S609, the control circuit 308 sets the connection circuit 313 to the ON state and the discharge circuit 314 to the OFF state, and in S610, it raises the voltage of the power line 318 that supplies voltage VH, thereby completing the inspection sequence shown in Figure 6 successfully. When switching the ON / OFF state of the connection circuit 313 and the discharge circuit 314, the switching may be performed while providing a period in which both the connection circuit 313 and the discharge circuit 314 are operating in the OFF state, as shown in Figure 7. This prevents overcurrent from flowing due to simultaneous power transmission by the connection circuit 313 and discharge by the discharge circuit 314 caused by a timing difference in the control.

[0050] As described above, the control circuit 308 according to this embodiment determines whether at least one of the connection circuit 313 and the discharge circuit 314 is malfunctioning based on the control state of the connection circuit 313 and the discharge circuit 314 and the voltage of the power line to which the discharge circuit 314 is connected. If the control circuit 308 determines that either one is malfunctioning (an abnormality has occurred), it decides not to supply power to the recording head 100. As a result, even if a circuit malfunction occurs, the operation of the recording device 1 can be stopped without inducing a malfunction of the recording head 100. This allows the recording device 1 to be restored by replacing only the power supply board 105 or the power supply unit 207, thus reducing the number of faulty parts and lowering the effort and cost of repairs.

[0051] <Embodiment 2> In this embodiment, a configuration is described in which a circuit for relaying power from a different power source is connected to the power supply line for supplying the voltage HBVHT in the power supply board of Embodiment 1. Note that the same configurations, functions, and processes as in Embodiment 1 are described using the same reference numerals and their explanation is omitted.

[0052] The power supply board 800 in this embodiment will be described with reference to Figure 8. The power supply board 800 in this embodiment has a DC / DC converter 801, to which a power line (fourth power line) 811 for supplying voltage VHTCK is connected. A power line (fifth power line) 812 including a current limiting resistor 804 is connected to the fourth power line 811 via a connection circuit 802 composed of an FET 803, and the fifth power line 812 is connected to the second power line 317. The connection circuit 802, which relays the power of voltage VHTCK supplied by the DC / DC converter 801, is a short check circuit (short CHK circuit) provided for short checks in the exchange head 103. The connection circuit 802 has the same configuration as the connection circuit 313 and is controlled by the control circuit 308, which can switch the connection operation on / off. In the following description, the mode in which the connection circuit 802 transmits power supplied from the DC / DC converter 801 to the fifth power line 812 is referred to as the first operating mode (on state), and the mode in which no power is transmitted is referred to as the second operating mode (off state). By operating the connection circuit 313 in the off state and the connection circuit 802 in the on state, and limiting the current to prevent damage to the replacement head 103 during inspection, a short circuit in the replacement head 103 can be checked by monitoring the voltage. This embodiment describes an inspection sequence for differentiating between a failure in the connection circuit 802 and failures in the connection circuit 313 and discharge circuit 314 that were inspected in Embodiment 1.

[0053] The power control sequence in this embodiment will be explained using Figures 9 and 10. Figure 9 is a flowchart of a power control method that performs an inspection to determine whether the operation of the power supply device 207 in this embodiment is abnormal and controls the power supply. Figure 10 is a diagram that explains the voltage change of the second power line 317 that supplies the voltage HBVHT, following the flowchart in Figure 9. In this embodiment, the voltage value of the short check circuit is made different from the voltage HBVHT and compared with a voltage threshold Vth2 for abnormality determination to determine whether the short check circuit is abnormal or not. This makes it possible to distinguish whether the failure is in the connection circuit 313 or the connection circuit 802 when a failure is detected.

[0054] In S901, the control circuit 308 operates the connection circuit 313, the discharge circuit 314, and the connection circuit 802 in the OFF state. In S902, the control circuit 308 determines whether the voltage of the power line 317 is lower than the second voltage threshold Vth2 after time t0 has elapsed. If it determines that the voltage of the power line 317 is lower than the second voltage threshold Vth2 (Y in S902), the control circuit 308 determines that the operation of the connection circuit 313, the discharge circuit 314, and the connection circuit 802 in the OFF state is normal and proceeds to S903. If it determines that the voltage of the power line 317 is equal to or greater than the second voltage threshold Vth2 (N in S902), the control circuit 308 determines that either the connection circuit 313 or 802 has a short circuit failure and proceeds to S913.

[0055] In S913, the control circuit 308 determines whether the voltage of the second power line 317 is higher than the first voltage threshold Vth. If it determines that the voltage of the second power line 317 is higher than the first voltage threshold Vth (Y in S913), the control circuit 308 determines that the connecting circuit 313 has a short circuit failure (S914). If it determines that the voltage is less than or equal to the first threshold Vth (N in S913), the control circuit 308 determines that the connecting circuit 802 has a short circuit failure (S915).

[0056] The processing in S903 to S906 is the same as S603 to S606 in Figure 6, except that the connection circuit 802 operates in the OFF state, so the explanation is omitted.

[0057] In S907, the control circuit 308 operates with the connection circuit 313 and discharge circuit 314 in the off state and the connection circuit 802 in the on state. In S908, the control circuit 308 determines whether the voltage of the power line 317 is higher than the second voltage threshold Vth2 and lower than the first threshold Vth after time t3 has elapsed. If it is determined that the voltage of the power line 317 is higher than the second voltage threshold Vth2 and lower than the first threshold Vth (Y in S908), the control circuit 308 determines that the operation with the connection circuit 313 and discharge circuit 314 in the off state and the connection circuit 802 in the on state is normal. If it is determined that the voltage of the second power line 317 is less than or equal to the second voltage threshold Vth2, or greater than or equal to the first threshold (N in S908), the control circuit 308 determines that the connection circuit 802 has an open fault and proceeds to S909.

[0058] In S911, the control circuit 308 starts the connection circuit 313 in the ON state and the discharge circuit 314 and connection circuit 802 in the OFF state, supplying power to the heater drive circuit 311 from the second power line 317. Subsequently, in S912, the control circuit 308 raises the voltage of the third power line 318 to supply power to the heater 312. S909 and S910 are the same as S607 and S608 in Figure 6, so their explanation is omitted.

[0059] As explained above, in this embodiment, in addition to the conditions for On and Off of the short-circuit check circuit in Embodiment 1, the connection circuit 802, which is the short-circuit check circuit, is turned On in S907. Then, in S908, the connection circuits 313, 802, and discharge circuit 314 are determined to be normal, provided that Vth > voltage of the second power line 317 > Vth2. The control circuit 308 then decides to supply power to the heater drive circuit 311 and heater 312 if it determines that the connection circuits 313, 802, and discharge circuit 314 are normal. Furthermore, if the control circuit 308 determines that at least one of the connection circuits 313, 802, and discharge circuit 314 is abnormal, it controls the power supply to the heater 312 not to be provided. Alternatively, the control circuit 308 may control the system so as not to supply power to the heater drive circuit 311 if it determines that at least one of the connection circuits 313, 802, and the discharge circuit 314 is abnormal.

[0060] As described above, the recording device 1 according to this embodiment can detect faults even if there are multiple connection circuits for supplying power to external devices. Furthermore, it is possible to identify the location of the fault by varying the voltage of the supplied power.

[0061] <Other Embodiments> The processes S601, S603, and S605 shown in Figure 6, and S901, S903, S905, and S907 shown in Figure 9, can be arbitrarily changed in order.

[0062] This disclosure includes the following communication control device, communication control method, and program.

[0063] (Item 1) A first power line from which power is supplied by a power supply means, A second power line connected to an external device, A connection means that connects the first power line and the second power line and is capable of operating in either a first operating mode that enables power transmission from the first power line to the second power line, or a second operating mode that does not enable power transmission, A discharge means connected to the second power line, capable of operating in either a third operating mode that reduces the voltage of the second power line or a fourth operating mode that does not reduce the voltage, Voltage monitoring means for monitoring the voltage of the second power line, The connection means and the control means for controlling the operation of the discharge means, A power supply device having, The power supply device is characterized in that the control means determines whether or not to supply power to the second power line based on the control state of the connection means and the discharge means and the voltage of the second power line monitored by the voltage monitoring means.

[0064] (Item 2) The power supply device according to item 1, characterized in that the control means does not supply power to the second power line when the connection means is controlled to operate in the second operating mode and the discharge means is controlled to operate in the fourth operating mode, provided that the voltage of the second power line is above a threshold.

[0065] (Item 3) The power supply device according to item 1 or 2, characterized in that the control means does not supply power to the second power line when the connection means is controlled to operate in the first operating mode and the discharge means is controlled to operate in the fourth operating mode, provided that the voltage of the second power line is below a threshold.

[0066] (Item 4) The power supply device according to any one of items 1 to 3, characterized in that the control means does not supply power to the second power line on the condition that the voltage of the second power line is below a threshold when a first time has elapsed since the operation of the connection means was switched to the first operating mode and the operation of the discharge means was switched to the fourth operating mode.

[0067] (Item 5) The power supply device according to any one of items 1 to 4, characterized in that the control means does not supply power to the second power line when the connection means is controlled to operate in the second operating mode and the discharge means is controlled to operate in the third operating mode, provided that the voltage of the second power line is above a threshold value.

[0068] (Item 6) The power supply device according to item 5, characterized in that the control means does not supply power to the second power line on the condition that the voltage of the second power line is above the threshold when a second time has elapsed since the operation of the connection means was switched to the second operating mode and the operation of the discharge means was switched to the third operating mode.

[0069] (Item 7) The power supply device according to any one of items 1 to 6, characterized in that the control means supplies power to the second power line on the condition that the voltage of the second power line is below a threshold when the connection means is controlled to operate in the second operating mode and the discharge means is controlled to operate in the fourth operating mode.

[0070] (Item 8) The power supply device according to any one of items 1 to 7, characterized in that the control means supplies power to the second power line on the condition that the voltage of the second power line is higher than a threshold when the connection means is controlled to operate in the first operating mode and the discharge means operates in the fourth operating mode.

[0071] (Item 9) The power supply device according to item 8, characterized in that the control means supplies power to the second power line on the condition that the voltage of the second power line is higher than a threshold when a first time has elapsed since the operation of the connection means was switched to the first operating mode and the operation of the discharge means was switched to the fourth operating mode.

[0072] (Item 10) The power supply device according to any one of items 1 to 9, characterized in that the control means supplies power to the second power line on the condition that the voltage of the second power line is below a threshold when the connection means is controlled to operate in the second operating mode and the discharge means operates in the third operating mode.

[0073] (Item 11) The power supply device according to item 10, characterized in that the control means supplies power to the second power line on the condition that the voltage of the second power line is below the threshold when a second time has elapsed since the operation of the connection means was switched to the second operating mode and the operation of the discharge means was switched to the third operating mode.

[0074] (Item 12) The power supply device according to any one of items 1 to 11, characterized in that the control means has a notification means for notifying an abnormality when it decides not to supply power to the second power line.

[0075] (Item 13) The power supply device according to any one of items 1 to 12, characterized in that the control means controls the operation of the connection means and the discharge means such that the discharge means does not operate in the third operating mode while the connection means is operating in the first operating mode.

[0076] (Item 14) The external device comprises a heater that ejects ink by heat and a heater drive circuit that drives the heater. The power supply device according to any one of items 1 to 13, characterized in that the second power line supplies power to the heater drive circuit.

[0077] (Item 15) The heater is equipped with a third power line that supplies power to it. The power supply device according to item 14, characterized in that the control means controls the power supply from the third power line to the heater to stop when it is decided not to supply power to the second power line.

[0078] (Item 16) The power supply device according to any one of items 1 to 15, characterized in that the first power supply line includes a fuse element that protects against current exceeding a predetermined amount flowing to the second power supply line.

[0079] (Item 17) The power supply is provided as described in any one of items 1 through 16, The external device is a replaceable head comprising a heater that ejects ink by heat and a heater drive circuit that drives the heater. The second power line supplies power to the heater drive circuit. The image forming apparatus is characterized in that the interchangeable head forms an image on a recording medium by ejecting ink using heat.

[0080] (Item 18) The power supply device further comprises a third power line that supplies power to the heater, The image forming apparatus according to item 17, characterized in that the control means controls the supply of power from the third power line to the heater to stop when it is determined not to supply power to the second power line.

[0081] (Item 19) A first power line from which power is supplied by a power supply means, A second power line connected to an external device, A connection means that connects the first power line and the second power line and is capable of operating in either a first operating mode that enables power transmission from the first power line to the second power line, or a second operating mode that does not enable power transmission, A discharge means connected to the second power line, capable of operating in either a third operating mode that reduces the voltage of the second power line or a fourth operating mode that does not reduce the voltage, Voltage monitoring means for monitoring the voltage of the second power line, The connection means and the control means for controlling the operation of the discharge means, A power control method performed by a power supply device having, A power supply control method characterized by comprising a decision step of determining whether or not to supply power to the second power supply line based on the control state of the connection means and the discharge means by the control means and the voltage of the second power supply line monitored by the voltage monitoring means.

[0082] The present invention can also be realized by supplying a program that implements one or more of the functions of the above-described embodiments to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. It can also be realized by a circuit (e.g., an ASIC) that implements one or more functions.

[0083] The invention is not limited to the embodiments described above, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, claims are attached to disclose the scope of the invention. [Explanation of Symbols]

[0084] 1: Recording device, 100: Recording head, 103: Replacement head, 104: Control board, 105, 800: Power supply board, 207: Power supply unit, 305: DC / DC converter, 313, 802: Connection circuit, 314: Discharge circuit, 308: Control circuit, 309: Power controller, 310: Logic circuit, 311: Heater drive circuit, 312: Heater, 505: Anomaly detection unit

Claims

1. A first power line from which power is supplied by a power supply means, A second power line connected to an external device, A connection means that connects the first power line and the second power line and is capable of operating in either a first operating mode that enables power transmission from the first power line to the second power line, or a second operating mode that does not enable power transmission, A discharge means connected to the second power line, capable of operating in either a third operating mode that reduces the voltage of the second power line or a fourth operating mode that does not reduce the voltage, Voltage monitoring means for monitoring the voltage of the second power line, The connection means and the control means for controlling the operation of the discharge means, A power supply device having, When the control means is controlling the connection means to operate in the second operating mode and the discharge means to operate in the fourth operating mode, if the voltage of the second power line is above a threshold, it outputs first abnormality notification information. When the connection means is controlled to operate in the second operating mode and the discharge means is controlled to operate in the third operating mode, if the voltage of the second power line is above the threshold, the second abnormality notification information is output. A power supply device characterized in that the first abnormality notification information and the second abnormality notification information are different from each other.

2. The power supply device according to Claim 1, wherein the control means further determines whether or not to supply power to the second power line based on the control state of the connection means and the discharge means and the voltage of the second power line monitored by the voltage monitoring means.

3. The power supply device according to claim 2, characterized in that the control means does not supply power to the second power line on the condition that the voltage of the second power line is above a threshold when the connection means is controlled to operate in the second operating mode and the discharge means is controlled to operate in the fourth operating mode.

4. The power supply device according to claim 2, characterized in that the control means does not supply power to the second power line when the connection means is controlled to operate in the first operating mode and the discharge means is controlled to operate in the fourth operating mode, provided that the voltage of the second power line is below a threshold.

5. The power supply device according to claim 4, characterized in that the control means does not supply power to the second power line on the condition that the voltage of the second power line is below a threshold when a first time has elapsed since the operation of the connection means was switched to the first operating mode and the operation of the discharge means was switched to the fourth operating mode.

6. The power supply device according to claim 2, characterized in that the control means does not supply power to the second power line when the connection means is controlled to operate in the second operating mode and the discharge means is controlled to operate in the third operating mode, provided that the voltage of the second power line is above a threshold value.

7. The power supply device according to claim 6, characterized in that the control means does not supply power to the second power line on the condition that the voltage of the second power line is above the threshold when a second time has elapsed since the operation of the connection means was switched to the second operation mode and the operation of the discharge means was switched to the third operation mode.

8. The power supply device according to claim 2, characterized in that the control means supplies power to the second power line on the condition that the voltage of the second power line is below a threshold when the connection means is controlled to operate in the second operating mode and the discharge means operates in the fourth operating mode.

9. The power supply device according to claim 2, characterized in that the control means supplies power to the second power line on the condition that the voltage of the second power line is higher than a threshold when the connection means is controlled to operate in the first operating mode and the discharge means operates in the fourth operating mode.

10. The power supply device according to claim 9, characterized in that the control means supplies power to the second power line on the condition that the voltage of the second power line is higher than a threshold when a first time has elapsed since the operation of the connection means was switched to the first operating mode and the operation of the discharge means was switched to the fourth operating mode.

11. The power supply device according to claim 2, characterized in that the control means supplies power to the second power line on the condition that the voltage of the second power line is below a threshold when the connection means is controlled to operate in the second operating mode and the discharge means is controlled to operate in the third operating mode.

12. The power supply device according to claim 11, characterized in that the control means supplies power to the second power line on the condition that the voltage of the second power line is below the threshold when a second time has elapsed since the operation of the connection means was switched to the second operation mode and the operation of the discharge means was switched to the third operation mode.

13. The power supply device according to claim 2, characterized in that it has a notification means for notifying an abnormality when the control means decides not to supply power to the second power line.

14. The power supply device according to claim 1, characterized in that the control means controls the operation of the connection means and the discharge means such that the discharge means does not operate in the third operating mode while the connection means is operating in the first operating mode.

15. The external device comprises a heater that ejects ink by heat and a heater drive circuit that drives the heater. The power supply device according to claim 2, characterized in that the second power line supplies power to the heater drive circuit.

16. The heater is equipped with a third power line that supplies power to it. The power supply device according to claim 15, characterized in that the control means controls the power supply from the third power line to the heater to stop when it is determined not to supply power to the second power line.

17. The power supply device according to claim 1, characterized in that the first power line includes a fuse element that protects against current exceeding a predetermined amount flowing to the second power line.

18. A power supply device as described in Claim 2, The external device is a replaceable head comprising a heater that ejects ink by heat and a heater drive circuit that drives the heater. The second power line supplies power to the heater drive circuit. The image forming apparatus is characterized in that the interchangeable head forms an image on a recording medium by ejecting ink using heat.

19. The power supply device further comprises a third power line that supplies power to the heater, The image forming apparatus according to claim 18, characterized in that the control means controls the supply of power from the third power line to the heater to stop when it is determined not to supply power to the second power line.

20. A power supply device according to claim 1, A notification means that notifies of an abnormality based on the first abnormality notification information or the second abnormality notification information, A recording device characterized by comprising the following features.

21. A first power line from which power is supplied by a power supply means, A second power line connected to an external device, A connection means that connects the first power line and the second power line and is capable of operating in either a first operating mode that enables power transmission from the first power line to the second power line, or a second operating mode that does not enable power transmission, A discharge means connected to the second power line, capable of operating in either a third operating mode that reduces the voltage of the second power line or a fourth operating mode that does not reduce the voltage, Voltage monitoring means for monitoring the voltage of the second power line, The connection means and the control means for controlling the operation of the discharge means, A power control method performed by a power supply device having, When the connection means is operating in the second operating mode and the discharge means is operating in the fourth operating mode, and the voltage of the second power line monitored by the voltage monitoring means is above a threshold, a first output step outputs first abnormality notification information. When the control means controls the connection means to operate in the second operating mode and the discharge means to operate in the third operating mode, if the voltage of the second power line monitored by the voltage monitoring means is greater than or equal to the threshold, a second output step outputs second abnormality notification information. Includes, A power supply control method characterized in that the first abnormality notification information and the second abnormality notification information are different from each other.

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