KR20120057510A - Image forming apparatus and control method thereof - Google Patents

Abstract

PURPOSE: An image forming device and a control method thereof are provided to quickly and smoothly turn a power switch on/off. CONSTITUTION: A switch circuit unit(19) includes a soft power switch(191). The soft power switch is switched into a turn-on state and a turn-off state by manipulation of a user. The switch circuit unit outputs a switch signal corresponding to the state of the soft power switch. A power control unit(14) selectively supplies DC power outputted from a power unit(12) to an image forming unit(11) according to the switch signal. If AC power is turned off by a mechanical power switch(13), a discharging circuit unit(15) discharges remaining power of the power unit.

Description

Image forming apparatus and control method thereof {IMAGE FORMING APPARATUS AND CONTROL METHOD THEREOF}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus and a control method thereof, and more particularly, to an image forming apparatus having a mechanical power switch, a soft power switch, and a control method for turning on / off a power source.

An image forming apparatus such as a printer, a fax machine, a multifunction printer, or the like includes a power supply unit such as a switched mode power supply (SMPS) to supply power. The power supply unit receives the AC power, converts it, and supplies a predetermined level of DC power. In addition, the image forming apparatus includes only a mechanical power switch (hereinafter referred to as a "mechanical power switch") that turns on / off the input of the AC power to turn the power on / off by a user's operation. In addition, a soft power switch (hereinafter referred to as a "soft power switch") for turning on / off the supply of DC power is provided.

At the output terminal of the DC power supply of the power supply unit, a capacitor of considerable capacity is provided to stabilize the output voltage. However, when the user turns off the power using the soft power switch and immediately turns on the power using the mechanical power switch, the image forming apparatus may not be properly powered on by the residual power charged in the capacitor of the power supply. There is a number. In this case, in order to properly power on, it is necessary to wait until the capacitor of the power supply is discharged (for example, several minutes to 10 minutes), which is very inconvenient for the user, and if the user is not aware of this situation, There is a risk of misunderstanding.

Accordingly, an object of the present invention is to provide an image forming apparatus and a method of controlling the same, which enable a user to quickly and smoothly turn on / off power using a power switch.

It is also an object of the present invention to provide an image forming apparatus and a method of controlling the same, which can eliminate misunderstanding of a malfunction when a user turns on / off a power using a power switch.

An object of the present invention is an image forming apparatus, comprising: an image forming unit for forming an image; A power supply unit converting the input AC power to output a DC power of a predetermined level for the operation of the image forming unit; A mechanical power switch for inputting or cutting off the AC power; A switch circuit unit including a soft power switch to be turned on or off according to a user's operation, and outputting a switch signal corresponding to a state of the soft power switch; A power control unit for selectively supplying the DC power output from the power supply unit to the image forming unit according to the switch signal; When the AC power is cut off by the mechanical power switch, it may be achieved by an image forming apparatus including a discharge circuit part for discharging the remaining power of the power part.

The power control unit cuts off the DC power supplied to the image forming unit according to the switch signal before the AC power is cut off, and the power supply unit is set by the mechanical power switch after the remaining power is discharged. The AC power may be input again to resume supply of the DC power.

The image forming apparatus may further include a zero crossing detection unit configured to detect a zero point of the waveform of the AC power and output a detection signal, wherein the discharge circuit unit may discharge residual power of the power supply unit based on the detection signal. have.

The image forming apparatus may further include a delay circuit unit which delays a detection signal of the zero crossing detection unit and outputs the delayed signal to the discharge circuit unit.

The discharge circuit unit includes a resistor unit having one end connected to an output terminal of the DC power source of the power source unit; It may be connected between the other end of the resistor portion and the ground, it may include a switching device unit for turning on / off according to the level of the detection signal.

The object of the present invention is an image forming unit for forming an image, a power source for converting the input AC power to output a predetermined level of DC power for the operation of the image forming unit, and for inputting or blocking the AC power A switch power circuit including a mechanical power switch and a soft power switch which is turned on or off according to a user's operation, and outputs a switch signal corresponding to a state of the soft power switch; and from the power supply unit according to the switch signal. A control method of an image forming apparatus, comprising: a power control unit for selectively supplying the output DC power to the image forming unit, the method comprising: forming an image by supplying the DC power to the image forming unit; When the AC power is cut off by the mechanical power switch, the control method of the image forming apparatus may be achieved by discharging the remaining power of the power supply unit.

The control method of the image forming apparatus may include: shutting off the DC power supplied to the image forming unit according to the switch signal before the AC power is cut off; After the residual power is discharged, the method may further include resuming the input of the AC power and the supply of the DC power by the mechanical power switch.

The control method of the image forming apparatus may further include detecting a zero point of a waveform of the AC power and outputting a detection signal, wherein the discharging includes discharging the remaining power of the power supply unit based on the detection signal. It may include the step of.

The control method of the image forming apparatus may further include delaying the detection signal, and the discharging may include discharging the remaining power of the power supply unit based on the delayed detection signal.

The above object of the present invention is a power supply control system for driving an image forming unit of an image forming apparatus, comprising: a mechanical power switch for switching supply and interruption of AC power; A switch control unit which selects one of a turn-on state and a turn-off state and outputs a switch signal in response to the turn-on state; A power control unit for detecting whether the AC power is supplied or cut off, and for supplying DC power to the image forming unit based on the switch signal; It can also be achieved by a power supply control system including a discharge unit for discharging the residual power when the AC power is cut off.

An object of the present invention is a power supply control system including an image forming unit and controlling a power supply of an image forming apparatus operable in a soft power-off state and a power-on state, wherein the first power source is input to remove the first power source. A power supply unit which converts the power supply into a second power source and outputs the second power source to the image forming unit; When the power-on state from the soft power-off state, it can be achieved by a power supply control system including a control unit for controlling the power supply unit to output the second power when the first power is input.

The power supply unit may further include a discharge unit configured to selectively output the second power supply to the image forming unit.

The discharge unit may selectively discharge the remaining power remaining in the power supply unit.

The discharge unit may discharge the remaining power remaining in the power supply unit when the input of the first power is cut off when the power-on state is changed from the soft power-off state.

The discharge unit may not discharge the remaining power remaining in the power supply unit when a predetermined time elapses after the first power is input from the soft power-off state to the power-on state.

The power control system may further include a detector configured to detect whether the first power is cut off, and the discharge unit may selectively discharge the residual power according to a detection result of the detector.

The detecting unit may include a zero crossing detecting unit detecting whether the first power is blocked based on the zero crossing of the first power.

The controller may detect whether the power-on state is from the soft power-off state and control the power supply unit to output the second power.

The control unit may control the power supply unit not to output the second power supply to the image forming unit when the power-on state becomes the soft power-off state.

The first power source may be an AC power source, and the second power source may be a DC power source.

The object of the present invention is a power control method of an image forming apparatus operable in a soft power off state and a power on state, the method comprising: detecting whether the image forming apparatus is in the power on state from the soft power off state; Wow; Determining whether AC power is input to the image forming apparatus when the image forming apparatus is brought into the power on state from the soft power off state; Discharging the remaining power remaining in the power supply section of the image forming apparatus when the image forming apparatus is turned into the power-on state in the soft power-off state and the input of the AC power is cut off. It can also be achieved by the method.

As described above, according to the present invention, the user can quickly and smoothly turn on / off the power using the power switch.

In addition, according to the present invention, it is possible to eliminate misunderstandings of malfunction when the user turns on / off the power using the power switch.

1 is a block diagram showing the configuration of an image forming apparatus according to an embodiment of the present invention.
FIG. 2 is a circuit diagram showing a part of the configuration of the power supply unit shown in FIG. 1;
3A and 3B are circuit diagrams showing an example of the configuration of the power supply control unit shown in FIG.
FIG. 4 is a circuit diagram showing an example of the configuration of the switch circuit section shown in FIG. 1;
FIG. 5 illustrates another example of the power control unit shown in FIG. 1;
6 is a circuit diagram illustrating a zero crossing detection unit according to an embodiment of the present invention.
7 illustrates an example of a waveform of a detection signal according to an embodiment of the present invention.
8 is a circuit diagram showing an example of the configuration of the discharge circuit portion according to an embodiment of the present invention;
9 shows an example of an output signal of a delay circuit according to an embodiment of the present invention,
10 is a flowchart illustrating a control method of an image forming apparatus according to an embodiment of the present invention.

Hereinafter, an embodiment of the present invention will be described in detail. 1 is a block diagram showing the configuration of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus 1 may be implemented by a printer, a fax machine, a multifunction printer, or the like which forms an image on a printing medium such as paper. As shown in FIG. 1, the image forming apparatus 1 includes an image forming unit 11, a power supply unit 12, a mechanical power switch 13, a switch circuit unit 19, a power supply control unit 14, and a discharge circuit unit 15. ). The image forming unit 11 forms an image on the printing medium. The image forming unit 11 forms an image in various ways, such as a laser method or an inkjet method. The power supply unit 12 receives AC power as an input, converts the input AC power, and outputs DC power having a predetermined voltage level required for the operation of the configuration of the image forming unit 11 and the like. The DC power output by the power supply unit 12 is referred to as a "first DC power supply" for convenience, and the level of the first DC power supply may be various, such as 5V, 3.3V, 24V, etc. One may have a plurality of outputs as well. The mechanical power switch 13 has an on or off state and allows AC power to be selectively input to the power supply unit 12 according to a user's operation. The switch circuit unit 19 includes a soft power switch 191 which is turned on or off according to a user's operation, and outputs a switch signal nPOWER_SW corresponding to the state of the soft power switch 191. The switch signal nPOWER_SW is a low signal or a high signal. For example, the switch signal nPOWER_SW may be about OV when the signal is low and about 5V when the signal is High.

The power controller 14 may allow the first DC power output from the power supply unit 12 to be selectively supplied to the image forming unit 11 according to the switch signal nPOWER_SW of the switch circuit unit 19. Detects a switch signal nPOWER_SW. The DC power output by the power control unit 14 to the image forming unit 11 is referred to as "second DC power supply" for convenience. The discharge circuit unit 15 discharges the remaining power remaining in the power supply unit 12 when the AC power is cut off, for example, when the AC power is not input by the mechanical power switch 13.

In addition, the image forming apparatus 1 may further include a controller (see 18 of FIG. 3) for controlling the image forming unit 11 or the like as a whole. The main controller 18 may be implemented as an ASIC provided with a CPU, an I / O controller, and the like. In addition, the image forming apparatus 1 has a configuration, not shown, such as a panel unit for receiving a user's operation on printing through a keypad or the like, an LCD such as an operation state of the image forming apparatus 1, or the like. Nonvolatile program memory such as a display unit, a ROM storing a program executed by the controller 18, a flash memory, and the like, and a volatile main such as RAM temporarily loaded so that a program stored in the program memory can be executed by the controller 18. A scanning unit having a CCD or CIS element capable of scanning an image on a printing medium such as a backup memory for storing backup data such as a memory, a phone number, a user ID, a battery for supplying power to the backup memory, paper, and the like AFE (Analog Front End), which converts analog signals output by the unit into digital signals, and images about data transmitted from the AFE The image processing unit may further include at least one of a line interface unit (LIU) for performing an interface with a PSTN network, and a modem unit for performing modulation or demodulation on a signal transmitted and received through the LIU.

FIG. 2 is a circuit diagram showing a part of the configuration of the power supply unit 12 shown in FIG. The power supply unit 12 may be implemented as a switched mode power supply (SMPS) for converting an AC power input to output a DC power. The power supply unit 12 shown in FIG. 2 uses a 5V voltage (5V_SMPS) as an output DC power supply as an example, but this is only an example and may be a different level of voltage, or in addition to 3.3V and / or 24V. It may further include a configuration for further outputting a voltage. The power supply unit 12 includes a capacitor C21 having a predetermined capacity (for example, 3300 uF) provided at the output terminal 5V_SMPS of the DC power supply to stabilize the output voltage.

FIG. 3A is a circuit diagram showing an example of the configuration of the power supply control unit 14 shown in FIG. 1. The power control unit 14 may include a first power control module 14A, a second power control module 14B, and a third power control module 14C. The first power control module 14A receives the first DC power output from the output terminal 5V_SMPS of the power supply unit 12. Based on the first DC power source, the first power source control module 14A selectively outputs the second DC power source from the output terminal 5V. In addition, the first power supply control module 14A includes a selection control stage for receiving a selection control signal. Based on the selection control signal, the first power control module 14A selectively outputs the second DC power supply. The selection control signal may include a first selection control signal and a second selection control signal respectively output from the second power control module 14B and the third power control module 14C.

The second power control module 14B is supplied with power in accordance with the second DC power from the output terminal 5V of the first power control module 14A. Therefore, the second DC power supply from the output terminal 5V of the first power supply control module 14A is fed back to the second power supply control module 14B. In addition, the second power control module 14B may input the switch signal nPOWER_SW from the switch circuit unit 19. Based on the second DC power supply and the switch signal nPOWER_SW, the second power supply control module 14B outputs the first selection control signal. The first selection control signal may be input to the first power control module 14A to selectively control whether the second DC power is output.

The third power control module 14C receives the first DC power output from the output terminal 5V_SMPS of the power supply unit 12. In addition, the third power supply control module 14C may input the switch signal nPOWER_SW from the switch circuit unit 19. According to the switch signal nPOWER_SW and whether or not the first DC power is output by the power supply unit 12, the third power control module 14C may also selectively control whether or not the second DC power is output. Generate a control signal.

3B is a circuit diagram showing an example of a specific configuration of the power supply control unit 14 shown in FIG. 3A. The power control unit 14 is configured to selectively supply DC power output from the power supply unit 12 applied to the input terminal 5V_SMPS to the image forming unit 11 or the like through the output terminal 5V on the side of the FET U31. do.

The power supply control unit 14 may further include a resistor R37 provided on the output side of the second DC power supply 5V and a plurality of capacitors C34, C35, and C36 for noise removal. The power control unit 14 may further include a capacitor C31 and a resistor R31 provided at the input terminal 5V_SMPS. The power supply control unit 14 includes a source S connected to the input terminal 5V_SMPS, and drains D1, D2, D3, and D4 connected to the output terminal 5V on the side of the FET U31. And a FET U31 that switches so that the second DC power source is selectively output to the output terminal 5V on the side of the FET U31 according to Vg). The FET U31 is an n-channel type. The FET U31 is turned off when the gate voltage Vg is high and turned on when it is low. When the FET U31 is turned off, the second DC power is not normally supplied through the output terminal 5V on the side of the FET U31. When the FET U31 is turned on, the second DC power is normally supplied.

The power control unit 14 may further include a capacitor C32 and a resistor R32 connecting the input terminal 5V_SMPS to the gate G of the FET U31. In the gate G of the FET U31, the collector C of the transistor Q31 with the resistor R35 interposed therebetween, and the output terminal nPOWER_SW of the switch circuit unit 19 with the resistor R36 interposed therebetween. Are each connected. The level of the gate voltage Vg is determined by whether the transistor Q31 is turned on and the level of the output terminal nPOWER_SW of the switch circuit unit 19 (hereinafter also referred to as a "switch signal"). The emitter E of the transistor Q31 is grounded, the base B has the resistors R33 and R34, the capacitor C33 and the diode D31 interposed therebetween, and the output terminal of the control signal of the control unit 18 ( Vc).

4 is a circuit diagram illustrating an example of the configuration of the switch circuit unit 19. The switch circuit unit 19 may be provided in the panel unit for manipulating the user, as described above. The soft power switch 191 is a soft switch, and is turned on when the user presses it, and returns to the turn-off state when the user releases it. One end of the soft power switch 191 is connected to the operating power source 3.3V with the diode D41 and the resistor R41 interposed therebetween, and the other end is grounded. The operating power source 3.3V is not shown, but may be supplied from the power supply unit 12 or other power supply means. The switch circuit unit 19 may further include a capacitor C41 connected to both ends of the soft power switch 191. The connection point nPOWER_SW of the diode D5 and the resistor R4 becomes an output terminal of the switch signal of the switch circuit unit 19. The switch circuit unit 19 outputs a switch signal nPOWER_SW corresponding to the state of the soft power switch 191 according to the user's operation. The switch signal nPOWER_SW is high when the soft power switch 191 is turned off and low when the soft power switch 191 is turned on.

First, the soft power off state will be described. In the soft power-off state in this embodiment, the mechanical power switch 13 is turned on, and the first DC power supply from the power supply unit 12 is applied to the input terminal 5V_SMPS of the power supply control unit 14. However, the controller 18 may be turned off and may not operate normally. In this case, referring again to FIG. 3, the control signal Vc of the control unit 18 is Low, and the transistor Q31 is turned off. In addition, the soft power switch 191 of the switch circuit unit 19 is turned off, and the switch signal nPOWER_SW is high. The gate voltage Vg of the FET U31 becomes High, and the FET U31 is turned off. As a result, the second DC power supply is not normally supplied through the output terminal 5V on the side of the FET U31 of the power supply control unit 14.

Next, a process of switching from the soft power off state to the power on state will be described. The power-on state in this embodiment is a state in which the control unit 18 is turned on to normally control the image forming unit 11 and the like. In the soft power-off state, in order to turn on the power, the user presses the soft power switch 191 of the switch circuit unit 19 for a predetermined time. The switch signal nPOWER_SW goes low while the soft power switch 191 is pressed. When the switch signal nPOWER_SW goes low, the gate voltage Vg of the FET U31 goes low. As a result, the FET U31 is turned on, and the second DC power is normally supplied through the output terminal (5V on the side of the FET U31) of the power supply control unit 14.

As shown in FIG. 3, the output terminal (5V on the side of the FET U31) of the power control unit 14 is connected to the power input terminal (5V on the side of the control unit 18) of the control unit 18. When the second DC power is normally supplied through the output terminal (5V on the side of the FET U31) of the power control unit 14, the control unit 18 is turned on and starts to operate, and outputs a control signal Vc that is High. When the control signal Vc becomes high, the transistor Q31 is turned on. When the transistor Q31 is turned on, the collector C of the transistor Q31 goes low, and the gate voltage Vg of the FET U31 is kept low. Accordingly, the second DC power supply is continuously supplied through the output terminal (5V on the side of the FET U31) of the power supply control unit 14. That is, even if the user releases the soft power switch 191 of the switch circuit unit 19 and the switch signal nPOWER_SW is switched from low to high, the gate voltage Vg continues to be low by the transistor Q31. Is maintained. In the present embodiment, the resistance value of each of the resistor R35 and the resistor R36 has the gate voltage Vg when the switch signal nPOWER_SW is high and the collector C of the transistor Q31 is low. The FET U31 is designed to be at a level low enough to turn on.

Next, a state in which the power-on state is switched to the soft-off state will be described. In the power-on state, as described above, the control signal Vc output from the controller 18 is high, the transistor Q31 is turned on, the gate voltage Vg of the FET U31 is low, and the FET U31 is Turned on, the second DC power is normally supplied through the output terminal (5V on the side of the FET U31) of the power control unit 14. In the power-on state, in order to turn off the power, the user presses the soft power switch 191 of the switch circuit unit 19 for a predetermined time and then releases it. At this time, the soft power switch 191 is turned on for a predetermined time, and then returns to the turned off state. When the soft power switch 191 is returned from the turn on state to the turn off state, the switch signal nPOWER_SW is switched from low to high. Referring again to FIG. 3, the switch signal nPOWER_SW is transmitted to the control unit 18 (see nPOWER_SW on the control unit 18 side). When the switch signal nPOWER_SW is switched from low to high, the control unit 18 determines to command the switching from the power on state to the soft power off state. The control part 18 complete | finishes the operation | movement currently in process, and outputs the control signal Vc which is Low. When the control signal Vc goes low, the transistor Q31 is turned off. When the transistor Q31 is turned off, the collector C of the transistor Q31 becomes High. As a result, the gate voltage Vg of the FET U31 becomes High, and the FET U31 is turned off. As a result, the second DC power supply is switched to the soft power-off state in which the second DC power supply is not normally supplied through the output terminal (5V on the side of the FET U31) of the power supply control unit 14.

The switching between the soft power off state and the power on state is not limited to the case by the soft power switch 191. For example, the controller 18 can switch the control signal Vc from high to low in accordance with a certain result of determination in the power-on state even without the operation of the soft power switch 191. For example, the user may enter the standby mode without operating the image forming apparatus 1 for a predetermined time. As a result, it can be switched from the power on state to the soft power off state. On the contrary, the soft power switch 191 may be switched from the soft power off state to the power on state without using the soft power switch 191. For example, in the standby mode, there may be a user's operation or another wakeup event. In this case, the controller 18 may switch the control signal Vc from Low to High, and as a result, may be switched from the soft power off state to the power on state.

Hereinafter, a process of switching from the hard power off state to the power on state will be described. The hard power off state in this embodiment refers to a case where AC power is not normally input to the power supply unit 12. As a result, the first DC power supply 5V_SMPS is not normally output from the power supply unit 12. Examples of the hard power-off state include a case in which AC power is not input from the outside, such as a power failure or a power cord being disconnected, or a case in which the mechanical power switch 13 is turned off by a user's operation or the like.

Referring back to FIG. 3, the power supply control unit 14 includes the collector C at the gate G of the FET U31 with the resistor R36 therebetween in order to switch from the hard power-off state to the power-on state. It further comprises a transistor Q32 to be connected. The emitter E of the transistor Q32 is grounded, and the base B is connected to the output terminal 5V_SMPS of the power supply 12 through the resistor R39 and the capacitor C37. The emitter E of the transistor Q32 and the base B are connected by a resistor R38. Diode D32 connects capacitor C37 to ground.

In the hard power-off state, since the first DC power supply is not normally supplied from the output terminal 5V_SMPS of the power supply unit 12, the base B of the transistor Q32 is turned low, and the transistor Q32 is turned off.

In the hard power-off state, when the first DC power is normally supplied from the output terminal 5V_SMPS of the power supply unit 12 due to the AC power being input again, the current flows instantaneously through the capacitor C37. As a result, the base B of the transistor Q32 becomes temporarily high, and the transistor Q32 is turned on. When the transistor Q32 is turned on, the collector C becomes low, and the gate voltage Vg of the FET U31 becomes low. As a result, the FET U31 is turned on and is switched to the power-on state where the second DC power is normally supplied through the output terminal (5V on the side of the FET U31) of the power supply controller 14. After the transistor Q32 is turned on, when the time enough for the capacitor C37 is sufficiently charged, the base B of the transistor Q32 is switched to Low, and as a result, the transistor Q32 is turned off. However, as described above, when the second DC power source 5V is normally supplied, the transistor Q31 is turned on by the control unit 18 before the transistor Q32 is turned off, and the turn-on of the FET U31 continues. Can be maintained.

FIG. 5 shows another embodiment of the power control unit 14 shown in FIG. The power control unit 14 shown in FIG. 5 includes a switching unit 142 and a microcomputer 142. Similar to the FET U31 shown in FIG. 3, the switching unit 142 has a DC power output from the power supply unit 12 applied to the input terminal 5V_SMPS to the image forming unit 11 or the like through the output terminal 5V. Allow for optional supply. The microcomputer 142 is a control IC provided separately from the control unit 18, and outputs a switch control signal EN_5V to the switching unit 142 to control the turning on / off of the switching unit 142. The microcomputer 142 controls the switching unit 142 based on the switch signal nPOWER_SW from the switch circuit unit 19. The microcomputer 142 operates by receiving the DC power (5V_SMPS) output from the power supply unit 12.

In the soft power-off state, the switch signal nPOWER_SW is high and the switching unit 142 is turned off, so that DC power is not supplied through the output terminal 5V. In the soft power-off state, when the switch signal nPOWER_SW is changed from high to low, the microcomputer 142 outputs the switch control signal EN_5V so that the switching unit 142 is turned on. Accordingly, DC power is normally supplied through the output terminal 5V. At the same time, the microcomputer 142 may output the reset signal RST_CPU to the controller 18 so that the controller 18 can normally operate.

On the contrary, in the power-on state, when the switch signal nPOWER_SW is changed from low to high (when the soft power switch 191 is pressed and dropped), the switch control signal EN_5V is turned on so that the switching unit 142 is turned off. Output Accordingly, DC power is not normally supplied through the output terminal 5V. At the same time, the microcomputer 142 may output the reset signal RST_CPU to the controller 18 to finish the operation that the controller 18 is processing.

On the other hand, in the hard power-off state, since the DC power supply 5V_SMPS of the power supply unit 12 is not input to the microcomputer 142, the microcomputer 142 is turned off. In the hard power-off state, when the DC power is normally supplied from the output terminal 5V_SMPS of the power supply unit 12 due to the input of the AC power again, etc., the microcomputer 142 is turned on to start operation. Subsequently, the microcomputer 142 outputs the switch control signal EN_5V such that the microcomputer 142 turns on the switching unit 142, and outputs the reset signal RST_CPU to the control unit 18 so that the control unit 18 outputs the reset signal RST_CPU. You can make the operation work normally. Thus, the transition from the hard power off state to the power on state is achieved.

Hereinafter, the discharge circuit unit 15 according to an embodiment of the present invention will be described in detail. As described with reference to FIGS. 3 to 5, the power supply control unit 14 switches depending on whether the DC power is normally output from the output terminal 5V_SMPS of the power supply unit 12 when switching from the hard power-off state to the power-on state. Start the operation. More specifically, the power supply control unit 14 shown in Figs. 3 and 5, in any of the embodiments, the DC power supply 5V_SMPS should not be output from the power supply unit 12 before being output normally, that is, the DC power supply 5V_SMPS The transition operation does not begin until the level transitions from low to high.

By the way, as shown in FIG. 2, the capacitor C21 of considerable capacity is provided in the output terminal 5V_SMPS of the power supply part 12. As shown in FIG. Therefore, when the hard power-off state lasts for a considerable time until the capacitor C21 is sufficiently discharged, the output terminal 5V_SMPS of the power supply unit 12 may drop to Low. In this state, when the AC power is input again, such as when the mechanical power switch 13 is turned on, the output terminal 5V_SMPS of the power supply unit 12 may be switched from low to high, so that the power control unit 14 performs a normal switching operation. do. However, if the power-on state of the output terminal 5V_SMPS of the power supply unit 12 does not fall low due to the residual power remaining in the capacitor C21 if the power-on state is immediately switched to the power-on state soon after entering the hard power-off state. There is a fear that a state in which the power supply control unit 14 cannot switch to the power-on state normally may occur. For example, in a situation where the soft power switch 191 or the like is in the soft power-off state, the user turns off the mechanical power switch 13 as a pre-operation to turn on the power, and then immediately turns it on. have. In this case, the capacitor C21 starts discharging from the time when the mechanical power switch 13 is turned off, but the capacitor C21 does not sufficiently discharge until the mechanical power switch 13 is turned on again, so that the power supply unit 12 is discharged. If the output terminal 5V_SMPS is kept high, the power supply controller 14 cannot perform the switching operation from the hard power off state to the power on state.

In order to prevent such a concern, the discharge circuit unit 15 remains in the hard power-off state, that is, when the AC power is cut off, the remaining power remaining in the capacitor C21 provided in the output terminal 5V_SMPS of the power supply unit 12. Discharge quickly. Accordingly, even when the mechanical power switch 13 is turned off immediately after being turned on in the soft power-off state, the output terminal 5V_SMPS of the power supply unit 12 is rapidly turned low by the discharge circuit unit 15. Since it is switched to High, the power supply controller 14 can normally perform the switching operation from the hard power off state to the power on state.

The image forming apparatus 1 may further include a zero crossing detecting unit 16 that detects whether the AC power is cut off so that the discharge circuit unit 15 may operate according to whether the AC power is cut off. 6 is a circuit diagram showing a zero crossing detecting unit 16 according to the present embodiment. The zero crossing detecting unit 16 includes a photocoupler PD that emits light as a current flows, and a photocoupler composed of a transistor Q61 that switches according to the emission of the photodiode PD. The photodiode PD is connected to the mechanical power switch 13 through a resistor R61. Transistor Q61 is of npn type, the emitter is grounded and the collector is connected to resistor R62.

If the AC power is input and the mechanical power switch 13 is turned on, a current of varying magnitude in a sinusoidal waveform flows through the photodiode PD. When the current flows through the photodiode PD, the photodiode PD emits light. When the current does not flow through the photodiode PD, the photodiode PD does not emit light. That is, when the AC power source is in the positive or negative section, the photodiode PD emits light, and the photodiode PD emits light at the point where the AC power source becomes zero, that is, at the zero point of the waveform of the AC power source. I never do that. When the photodiode PD emits light, the transistor Q61 is turned on to output a detection signal Zerocross that is High. When the photodiode PD does not emit light, the transistor Q61 is turned off to output a low detection signal Zerocross. Fig. 7 shows an example of the waveform of the sense signal Zerocross according to the present embodiment. Reference numeral 71 in FIG. 7 denotes a section in which the detection signal Zerocross is high, and reference numeral 72 denotes a point in which the detection signal Zerocross is low. If the AC power is not input from the outside or the mechanical power switch 13 is turned off, no current flows in the photodiode PD, and thus the detection signal Zerocross is low for a predetermined time (symbol of FIG. 7). 73). When the detection signal Zerocross is low for a predetermined time or more, the discharge circuit unit 15 determines that the AC power is interrupted, and quickly discharges the remaining power remaining in the capacitor C21 provided at the output terminal 5V_SMPS of the power supply unit 12. To discharge.

8 is a circuit diagram showing an example of the configuration of the discharge circuit section 15 according to the embodiment of the present invention. The discharge circuit unit 15 includes a pnp type transistor Q81 that switches based on a sensing signal Zerocross. The emitter of transistor Q81 is connected to output terminal 5V_SMPS of power supply 12 through resistor R84, and the collector of transistor Q81 is grounded via diode D81. When the base of the transistor Q81 is High, the transistor Q81 is turned off. When the base is Low, the transistor Q81 is turned off, and the remaining power remaining in the capacitor C21 is discharged.

The image forming apparatus 1 may further include a delay circuit 17 that receives a detection signal Zerocross and delays the predetermined time and outputs the delayed signal. The delay circuit 17 may be implemented as a low pass filter and may include resistors R81 and R82 and capacitors C81 and C82. A resistor R83 may be provided between the delay circuit 17 and the base of the transistor Q81. The delay time Tdelay of the delay circuit 17 may be determined as follows.

[Equation 1]

Tdelay = R * C

(Where R is the series resistance value of resistors R81 and R82, C is the parallel capacitance value of capacitors C81 and C82).

When the AC power is input, the signal passing through the delay circuit 17 is continuously kept high (see reference numeral 91 in FIG. 9) and becomes low at the moment when the AC power is cut off (see reference numeral 92 in FIG. 9). . Accordingly, when the AC power is input, the transistor Q81 remains turned off. When the AC power is cut off, the transistor Q81 is immediately turned off, and the remaining power remaining in the capacitor C21 is discharged. do.

10 is a flowchart illustrating a control method of the image forming apparatus 1 according to an embodiment of the present invention. First, in operation 1001, an image is formed by receiving DC power of a predetermined level converted from AC power. In this case, the power is turned on. Next, in operation 1002, when the user presses the soft power switch 191 to turn off the power in the power-on state, the supply of the DC power is cut off to switch to the soft power-off state. Next, in operation 1003, it is checked whether the AC power is cut off in the soft power-off state. When the user turns off the mechanical power switch 13 as a pre-operation for turning on the power using the mechanical power switch 13, the AC power is cut off. Next, in operation 1004, when the AC power is cut off, the remaining power remaining in the capacitor C21 provided at the output terminal 5V_SMPS of the power supply 12 is discharged. Next, in operation 1005, it is checked whether the user turns on the mechanical power switch 13 as a subsequent operation for turning on the power using the mechanical power switch 13. In operation 1006, when the mechanical power switch 13 is turned on, the input of the AC power is resumed, and the conversion is resumed to supply the DC power.

As mentioned above, the present invention has been described in detail through preferred embodiments, but the present invention is not limited thereto and may be variously implemented within the scope of the claims.

1: image forming apparatus
11: Image forming unit
12: power supply
13: mechanical power switch
14: power control unit
19: switch circuit
191: soft power switch

Claims (21)

In the image forming apparatus,
An image forming unit for forming an image;
A power supply unit converting the input AC power to output a DC power of a predetermined level for the operation of the image forming unit;
A mechanical power switch for inputting or cutting off the AC power;
A switch circuit unit including a soft power switch to be turned on or off according to a user's operation, and outputting a switch signal corresponding to a state of the soft power switch;
A power control unit for selectively supplying the DC power output from the power supply unit to the image forming unit according to the switch signal;
And a discharge circuit unit configured to discharge residual power of the power supply unit when the AC power is cut off by the mechanical power switch. The method of claim 1,
The power control unit cuts off the DC power supplied to the image forming unit according to the switch signal before the AC power is cut off,
And the power supply unit receives the AC power again by the mechanical power switch after the remaining power is discharged, and resumes the supply of the DC power. The method of claim 1,
A zero crossing detection unit for detecting the zero point of the waveform of the AC power and outputs a detection signal,
And the discharge circuit unit discharges the remaining power of the power supply unit based on the detection signal. The method of claim 3,
And a delay circuit unit configured to delay a detection signal of the zero crossing detection unit and output the delayed signal to the discharge circuit unit. The method of claim 3,
The discharge circuit unit,
A resistor unit having one end connected to an output terminal of the DC power source of the power supply unit;
And a switching device unit connected between the other end of the resistor unit and the ground to switch on / off according to the level of the detection signal. An image forming unit for forming an image, a power source for converting input AC power to output a predetermined level of DC power for the operation of the image forming unit, a mechanical power switch for inputting or blocking the AC power, and A switch power circuit including a soft power switch to be turned on or off according to an operation, and outputting a switch signal corresponding to a state of the soft power switch; and the DC power output from the power supply unit according to the switch signal. In the control method of the image forming apparatus comprising a power supply control unit for selectively supplying to the image forming unit,
Supplying the DC power to the image forming unit to form an image;
And discharging the remaining power of the power supply unit when the AC power is cut off by the mechanical power switch. The method of claim 6,
Cutting off the DC power supplied to the image forming unit according to the switch signal before the AC power is cut off;
And after the remaining power is discharged, resuming the input of the AC power and the supply of the DC power by the mechanical power switch. The method of claim 6,
Detecting a zero point of the waveform of the AC power and outputting a detection signal,
The discharging step includes discharging the remaining power of the power supply unit based on the detection signal. The method of claim 8,
Delaying the detection signal by a predetermined amount;
The discharging step includes discharging the remaining power of the power supply unit based on the delayed detection signal. A power supply control system for driving an image forming unit of an image forming apparatus,
A mechanical power switch for switching supply and interruption of AC power;
A switch control unit which selects one of a turn-on state and a turn-off state and outputs a switch signal in response to the turn-on state;
A power control unit for detecting whether the AC power is supplied or cut off, and for supplying DC power to the image forming unit based on the switch signal;
And a discharge unit for discharging the residual power when the AC power is cut off. A power supply control system comprising an image forming unit and controlling a power supply of an image forming apparatus operable in a soft power off state and a power on state,
A power supply unit for inputting a first power source to convert the first power source to a second power source and outputting the second power source to the image forming unit;
And a control unit for controlling the power supply unit to output the second power when the first power is input when the power-on state is entered from the soft power-off state. The method of claim 11,
And a discharge unit configured to selectively output the second power source to the image forming unit. The method of claim 12,
And the discharge unit selectively discharges the remaining power remaining in the power supply unit. The method of claim 13,
And the discharge unit discharges the remaining power remaining in the power supply unit when the input of the first power source is interrupted when the discharge unit is in the power-on state from the soft power-off state. The method of claim 13,
And the discharge unit does not discharge residual power remaining in the power supply unit when a predetermined time elapses after the first power is input from the soft power-off state to the power-on state. The method of claim 12,
Further comprising a detection unit for detecting whether or not the first power cut off,
And the discharge unit selectively discharges the residual power according to a detection result of the detection unit. The method of claim 16,
The detection unit includes a zero crossing detection unit for detecting whether the first power is cut off based on the zero crossing of the first power supply. The method of claim 11,
And the controller detects whether the power is on from the soft power-off state and controls the power unit to output the second power. The method of claim 13,
And the control unit controls the power supply unit not to output the second power supply to the image forming unit when the power-on state becomes the soft power-off state. The method of claim 11,
And said first power source is an AC power source, and said second power source is a DC power source. A power control method of an image forming apparatus operable in a soft power off state and a power on state,
Detecting whether the image forming apparatus is in the power on state from the soft power off state;
Determining whether AC power is input to the image forming apparatus when the image forming apparatus is brought into the power on state from the soft power off state;
Discharging the remaining power remaining in the power supply section of the image forming apparatus when the image forming apparatus is turned into the power-on state in the soft power-off state and the input of the AC power is cut off. Way.

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