Image forming apparatus

Abstract

This invention provides an image forming apparatus that monitors the power switch even during sleep mode and also enables power saving. [Solution] The present invention provides an image forming apparatus that can switch between a normal power mode, a first power saving mode having lower power consumption than the normal power mode, and a second power saving mode having lower power consumption than the first power saving mode, comprising an image forming control unit used for controlling image processing, a power supply control unit used for controlling the supply and stopping of power, a power supply unit connected to an external power supply and supplying power to the image forming control unit and / or power supply control unit, a power switch for operating the power supply, and in the first power saving mode, the supply from the first power supply connected to the power supply control unit is stopped and the image forming control unit monitors the state based on the operation of the power switch, and in the second power saving mode, the supply from the second power supply connected to the image forming control unit is stopped and the power supply control unit monitors the state based on the operation of the power switch.

Description

Technical Field

[0001] The present disclosure relates to an image forming apparatus, and can be applied to, for example, an image forming apparatus such as a printer.

Background Art

[0002] Conventionally, in an image forming apparatus such as a printer, a configuration has been adopted in which detection (monitoring) of a power switch is performed using a small-scale microcomputer (power supply microcomputer) or the like (detecting a signal based on an operation of the power switch and performing power control) (Patent Document 1, etc.). The power switch is connected only to the power supply microcomputer, and the power supply microcomputer performs detection (monitoring) of the power switch even during the power saving mode (sleep).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in such a conventional power monitoring circuit, in order to detect the power switch, it is necessary to maintain power supply even when the apparatus is in sleep.

[0005] That is, the power of the power control unit such as the power supply microcomputer is consumed for detecting the power switch. As a result, the power consumption in the image forming apparatus such as a printer during sleep has been large.

[0006] Therefore, there is a demand for an image forming apparatus that can monitor the power switch even during sleep and also achieve power saving of the entire apparatus.

Means for Solving the Problems

[0007] The present invention relates to an image forming apparatus that can switch between a normal power mode, a first power saving mode having lower power consumption than the normal power mode, and a second power saving mode having lower power consumption than the first power saving mode, comprising an image forming control unit used for controlling image processing, a power supply control unit used for controlling the supply and stopping of power, a power cable connectable to an external power supply, a power supply unit that supplies power to the image forming control unit and / or the power supply control unit, a power switch for operating the power supply, and characterized in that in the first power saving mode, the supply from a first power supply connected to the power supply control unit is stopped and the image forming control unit monitors the state based on the operation of the power switch, and in the second power saving mode, the supply from a second power supply connected to the image forming control unit is stopped and the power supply control unit monitors the state based on the operation of the power switch. [Effects of the Invention]

[0008] According to this disclosure, it is possible to monitor the power switch even while the device is in sleep mode, and to reduce the overall power consumption of the device. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic cross-sectional view of an image forming apparatus according to an embodiment. [Figure 2] This is a schematic block diagram showing a circuit including the control unit (printer control CPU, power supply control CPU) of the image forming apparatus according to the embodiment. [Figure 3] This is an explanatory diagram showing the correspondence between the device states of each device in the printer according to the embodiment and the power supply of each device. [Figure 4] This is a state transition diagram showing the transitions between the device states of the printer according to the embodiment. [Figure 5] This flowchart shows the process when the device state of the printer according to this embodiment transitions from the power-off state to the OFF mode state. [Figure 6] This is a time chart showing the transition of the printer's device state from the power-off state to the OFF mode state according to the embodiment. [Figure 7]This flowchart shows the process when the device state of the printer according to this embodiment transitions from OFF mode to Sleep mode. [Figure 8] This is a time chart showing the transition of the printer's device state from OFF mode to Sleep mode according to the embodiment. [Figure 9] This flowchart shows the process when the device state of the printer according to this embodiment transitions from Sleep mode to ON mode. [Figure 10] This is a time chart showing the transition of the printer's device state from Sleep mode to ON mode according to the embodiment. [Figure 11] This flowchart shows the process when the device state of the printer according to this embodiment transitions from ON mode to Sleep mode. [Figure 12] This is a time chart showing the transition of the printer's device state from ON mode to Sleep mode according to the embodiment. [Figure 13] This flowchart shows the process when the device state of the printer according to the embodiment transitions from Sleep mode to OFF mode. [Figure 14] This is a time chart showing the transition of the printer's device state from Sleep mode to OFF mode according to the embodiment. [Modes for carrying out the invention]

[0010] (A) Main embodiment Hereinafter, one embodiment of the image forming apparatus according to this disclosure will be described in detail with reference to the drawings. Below, an example of applying the image forming apparatus according to this disclosure to a printer will be described.

[0011] (A-1) Configuration of the embodiment (A-1-1) Overall configuration Figure 1 is a schematic cross-sectional view showing the overall configuration of the printer 1 in this embodiment.

[0012] The printer 1 has an image forming unit 2 (2K, 2Y, 2M, 2C), a paper feed roller 11, a paper feed sensor 12, a conveyance roller 14, a conveyance roller 15, a writing sensor 16, a conveyance belt driven roller 17, a conveyance belt driving roller 18, a conveyance belt 19, a fixing unit 20, a discharge sensor 24, a discharge roller 25, and a discharge roller 26.

[0013] The image forming units 2K, 2Y, 2M, 2C each form a toner image. The image forming units 2K, 2Y, 2M, 2C each form a toner image of the toner colors black (K), yellow (Y), magenta (M), and cyan (C). The image forming units 2K, 2Y, 2M, 2C each include LED heads 3K, 3Y, 3M, 3C, and form a toner image on the paper M fed using transfer rollers 10K, 10Y, 10M, 10C installed opposite to each other.

[0014] The paper feed roller 11 is a roller that feeds the paper M one by one from a paper cassette (not shown). The paper feed sensor 12 is a sensor for detecting the paper M fed from a paper cassette (not shown).

[0015] The conveyance rollers 14 and 15 are rollers that convey the fed paper M to the conveyance belt 19. The writing sensor 16 is a sensor for determining the writing start timing of the fed paper M.

[0016] The conveyance belt 19 is formed in an endless shape and is a belt for conveying the fed paper M. The conveyance belt driving roller 18 is connected to a motor and gears (not shown) and is a roller for moving the conveyance belt 19. The conveyance belt driven roller 17 rotates in accordance with the rotation of the conveyance belt 19 and is a roller arranged to keep the tension of the conveyance belt 19 constant.

[0017] The fuser unit 20 incorporates a fuser roller 21 and a fuser backup roller 22. The fuser roller 21 is heated by an internal heater (a heating element such as a halogen lamp) (for example, heated to a temperature of approximately 170°C) to fix the toner image transferred to the paper surface. The fuser backup roller 22 is a roller that is pressed against the fuser roller 21 by a pressing means (not shown).

[0018] The ejection sensor 24 is a sensor for detecting the ejection status of the paper M (such as transport errors or paper jams).

[0019] The discharge roller 25 and discharge roller 26 are rollers for discharging the image-formed paper to the outside.

[0020] In addition, although not shown in the diagram, printer 1 also includes components such as motors for rotating each roller, rollers on the transport path laid at a distance less than or equal to the minimum media spacing, and clutches for switching power transmission to the rollers on the transport path ON / OFF.

[0021] (A-1-2) Schematic of Printer 1's Circuit Figure 2 is a schematic block diagram showing a circuit including the control unit (printer control CPU 203, power supply control CPU 202) of the image forming apparatus according to the embodiment.

[0022] As shown in Figure 2, the circuit E of printer 1 mainly consists of a power supply circuit 201, a power supply control CPU 202, a printer control CPU 203, an AC cord 204, a power switch SW 205, a Tr (Transistor) 206, a Tr (Transistor) 207, an FET (Field Effect Transistor) 208, a DCDC (DC-DC converter) 209, an SEL (selector) 210, a host IF control circuit 211, a host PC 212, a printer control circuit 213, and an LDO (Low Dropout) 214.

[0023] <Printer control CPU> The printer control CPU 203 has a general-purpose CPU that operates by reading a predetermined program written to a FLASHROM (not shown). The printer control CPU 203 has a large number of I / Os and centrally controls the ON / OFF of the motor and clutch of printer 1. The printer control CPU 203 also has a power saving control unit 2031 and a main control unit 2032.

[0024] During normal operation (hereinafter referred to as "ON mode"), the main control unit 2032 controls the motor and clutch of printer 1 and the host IF control circuit 211 to communicate with the host PC 212.

[0025] The power saving control unit 2031 monitors the status of the power switch 205 and also monitors the reception of data from the host PC 212 when in power saving mode (hereinafter referred to as "Sleep mode").

[0026] <Power Control CPU> The power control CPU 202 is a low-speed CPU that controls the main power supply of printer 1. In a low-power mode even lower than Sleep mode (hereinafter referred to as "OFF mode"), it monitors the power switch 205 and controls the power supply to the control board (circuit E), including the printer control CPU 203. During normal operation, it communicates with the printer control CPU 203 to monitor the operating status of the printer control CPU 203.

[0027] Furthermore, the power control CPU 202 has a built-in non-volatile memory 2021. When the power control CPU 202 is turned off, it writes its state during the transition to off mode, and when the power control CPU 202 is turned on, it reads the written state.

[0028] <Power supply circuit and power switch area> The power supply circuit 201 supplies power to the internal power supply of the printer 1 by connecting the AC cord 204 to a commercial AC power supply (not shown). When the AC cord 204 is connected to the commercial AC power supply, it supplies power 5VS0 and supplies power 24V according to instructions from the power control CPU 202.

[0029] Power switch SW205 is a standard switch (push-button switch) that is pressed by the user. The POWON signal indicates the status of power switch SW205; it is at a high level due to the pull-up resistor when power switch SW205 is not pressed, and at a low level when power switch SW205 is pressed.

[0030] Tr206 is a transistor that connects the POWON signal to the POWON_a signal when the power supply 3.3VS0 is on. The POWON_a signal is connected to the power control CPU 202, which can determine the pressed state of the power switch 205 by monitoring the POWON_a signal.

[0031] Tr207 is a transistor that connects the POWON signal to the POWON_b signal when the power supply 3.3VS is on. The POWON_b signal is connected to the printer control CPU 203, which can determine the pressed state of the power switch 205 by monitoring the POWON_b signal.

[0032] <Host interface peripherals and printer control circuits> The host IF control circuit 211 is a circuit that controls communication with the host PC 212 and includes interfaces such as LAN (Local Area Network) and USB (Universal Serial Bus).

[0033] The host PC212 is a general-purpose information processing device that issues print commands and other instructions to printer1.

[0034] The printer control circuit 213 is a circuit that has the necessary functions (such as printing on paper M) to operate printer 1.

[0035] <Each power source and its surroundings> As shown in Figure 2, printer 1 has five power supplies: 5VS0, 3.3VS0, 5VS, 3.3VS, and 24V.

[0036] Power supply 5VS0 is a 5V power supply provided by power supply circuit 201 when AC cord 204 is connected to a commercial AC power source, and it is always on as long as AC cord 204 is connected to a commercial AC power source.

[0037] Power supply 3.3VS0 is the power supply for the power control CPU 202, and 3.3V is generated from 5V via LDO214 according to the specifications of the power control CPU 202. The LDO214 is enabled and disabled by the 3VS0ON signal. When AC cord 204 is connected to the commercial AC power supply, the 3VS0ON signal is automatically enabled by the pull-up resistor, and in ON mode it is enabled by the printer control CPU 203, and disabled by the printer control CPU 203 in Sleep mode.

[0038] Power supply 5VS is a 5V power supply used to generate power supply 3.3VS, and is generated from power supply 5VS0 via FET208. FET208 is enabled and disabled by the 5VSON signal. The 5VSON signal is connected to either the 5VSON_a signal or the 5VSON_b signal by the 5VS_sel signal of the selector SEL210. If the 5VS_sel signal is high, the 5VSON_a signal is connected to the 5VSON signal; if the 5VS_sel signal is low, the 5VSON_b signal is connected to the 5VSON signal.

[0039] The 5VSON_a signal is controlled by the power control CPU 202, and the 5VSON_b signal is controlled by the printer control CPU 203. The 5VS_sel signal is controlled by the power control CPU 202 when the power control CPU 202 is powered on, and becomes low level due to the pull-down resistor when the power control CPU 202 is powered off.

[0040] Power supply 3.3VS is the power supply for the printer control CPU 203 and the host IF control circuit 211. It is generated from 5V to 3.3V via the DC-DC converter 209 according to the specifications of the printer control CPU 203. If power supply 5VS is on, power supply 3.3VS is on, and if power supply 5VS is off, power supply 3.3VS is off.

[0041] The 24V power supply is the power source for the printer control circuit 213 and is supplied by the power supply circuit 201. The power supply circuit 201 is enabled and disabled by the 24VON signal. The 24VON signal is controlled by the power supply control CPU 202. The power supply control CPU 202 controls the 24VON signal according to instructions from the printer control CPU 203.

[0042] (A-2) Operation of the embodiment Next, the operation of the printer 1 according to the embodiment having the above configuration will be described.

[0043] (A-2-1) Device status and state transitions of printer 1 First, before explaining the operation of printer 1, we will describe the device status of printer 1.

[0044] Figure 3 is an explanatory diagram showing the correspondence between the device states of the printer according to this embodiment and the power supply of each device.

[0045] Printer 1 has four possible device states: "Power OFF," "OFF mode," "Sleep mode," and "ON mode."

[0046] The power-off state means that the AC cord 204 is not plugged into printer 1, and the power to the entire device is turned off.

[0047] The OFF mode state is the standby state before printer 1 is started up, and the power AC is ON, power 5VS0 is ON, power 3.3VS0 is ON, power 5VS is OFF, power 3.3VS is OFF, and power 24V is OFF. At this time, only the power circuit 201 and power control CPU 202 are powered on, and the power control CPU 202 monitors whether the power switch 205 is pressed or not.

[0048] In Sleep mode, printer 1 is in a power-saving state, with the following configurations: AC power on, 5VS0 power on, 3.3VS0 power off, 5VS power on, 3.3VS power on, and 24V power off. At this time, the power control CPU 202 is powered off, and the printer control CPU 203 monitors whether the power switch 205 is pressed.

[0049] The ON mode state is when printer 1 is in normal operation and the power to the entire device is turned on. At this time, both the power control CPU 202 and the printer control CPU 203 are powered on, but the printer control CPU 203 monitors whether or not the power switch 205 is pressed.

[0050] Figure 4 is a state transition diagram showing the transitions between the device states of the printer according to the embodiment.

[0051] When the AC cord 204 is inserted into printer 1 while the power is OFF, printer 1 transitions to the OFF mode state.

[0052] When the power switch 205 is pressed while in OFF mode, printer 1 transitions to Sleep mode. After transitioning from OFF mode to Sleep mode, it transitions back to ON mode. Also, when the AC cord 204 is unplugged while in OFF mode, printer 1 turns OFF.

[0053] When a wake-up event occurs while in Sleep mode, printer 1 transitions to ON mode. Wake-up events include receiving a print job from host PC 212 or pressing a wake button (not shown). Additionally, if the AC cord 204 is unplugged while in Sleep mode, printer 1 will power off.

[0054] When a transition event occurs while in ON mode, printer 1 transitions to Sleep mode. Transition events include a certain period of time elapsed since the end of printing, pressing the power switch 205, or pressing a power-saving button (not shown). If the power switch 205 is pressed, the printer transitions to Sleep mode, and then to OFF mode. Additionally, if the AC cord 204 is unplugged while in ON mode, printer 1 will power off.

[0055] When the power switch SW205 is pressed while in Sleep mode, printer 1 transitions to OFF mode.

[0056] When the AC cord 204 is unplugged while in OFF mode, printer 1 will enter the power-off state.

[0057] (A-2-2) Transition from power-off state to OFF mode state Figure 5 is a flowchart illustrating the process when the printer according to the embodiment transitions from the power-off state to the OFF mode state. Figure 6 is a time chart showing the transition of the printer according to the embodiment from the power-off state to the OFF mode state. In Figure 6 (and similarly in Figures 8, 10, 12, and 14), the thick lines indicate a state where no integrated circuit (including the power switch SW205) is being driven.

[0058] Printer 1 waits for the AC cord 204 to be inserted into the device while the power is OFF (S51 No).

[0059] When AC cord 204 is inserted (S51 Yes), the AC power supply is turned on (tim61), and the power supply circuit 201 turns on power supply 5VS0 (tim62) (S52).

[0060] Additionally, when the 5VS0 power supply is turned on, the SEL210 drives the 5VSON signal to a low level (tim63), and the POWON signal becomes high level (tim64) due to the pull-up resistor.

[0061] When power supply 5VS0 is turned on, the 3.3VS0ON signal goes high (tim 65) due to the pull-up resistor, enabling LDO214 and turning on power supply 3.3VS0 (tim 66) (S53). Since power supplies 3.3VS0 and 5VS0 are on, the POWON_a signal is driven to high level (tim 67) by Tr206.

[0062] Since power supply 3.3VS0 is the power supply for the power control CPU 202, the power control CPU 202 is started up (S54), and the power control CPU 202 performs initial processing and waits for the initial processing to be completed (S55 No).

[0063] Once the initial processing of the power control CPU 202 is complete (S55 Yes), the power control CPU 202 drives the 5VSON_a signal to Low (tim68), the 5VS_sel signal to Low (tim69), and the 24VON signal to Low (tim70).

[0064] At this point, the device status of printer 1 will be set to OFF mode.

[0065] (A-2-3) Transition from OFF mode to Sleep mode Figure 7 is a flowchart illustrating the process when the printer's device state according to this embodiment transitions from OFF mode to Sleep mode. Figure 8 is a time chart illustrating the transition of the printer's device state from OFF mode to Sleep mode according to this embodiment.

[0066] In OFF mode, the power control CPU 202 waits for the power switch 205 to be pressed (S71 No).

[0067] When the power switch 205 is pressed (S71 Yes), the POWON signal goes to a low level (tim81), which causes the POWON_a signal to be driven to a low level (tim82) by the Tr206. The power control CPU 202 recognizes that the power switch 205 has been pressed when the POWON_a signal goes to a low level.

[0068] When the power control CPU 202 recognizes that the power switch 205 has been pressed, it waits for the power switch 205 to be released (S72 No).

[0069] When the power switch 205 is released (S72 Yes), the POWON signal goes to a high level (tim83), which drives the POWON_a signal to a high level (tim84) via Tr206. The power control CPU 202 recognizes that the power switch 205 has been released when the POWON_a signal goes to a high level.

[0070] When the power switch SW205 is released, the power control CPU 202 drives the 5VS_sel signal to a high level (tim85) and the 5VSON_a signal to a high level (tim86). As a result, the 5VSON signal is driven to a high level (tim87) by SEL210, and FET208 is enabled, turning on the 5VS power supply (tim88) (S73).

[0071] When power supply 5VS is turned on, DCDC209 turns on, and power supply 3.3VS turns on (tim89) (S74).

[0072] Since both power supplies 3.3VS and 5VS0 are on, the POWON_b signal is driven to a high level (tim90) by Tr207.

[0073] Since power supply 3.3VS is the power supply for the printer control CPU 203, the printer control CPU 203 is started up (S75).

[0074] The printer control CPU 203 performs initial processing and waits for the initial processing to complete (S76 No). Note that this initial processing is performed only by the power saving control unit 2031 of the printer control CPU 203.

[0075] Once the initial processing of the printer control CPU 203 is complete (S76 Yes), the printer control CPU 203 drives the 5VSON_b signal to High (tim91) and the 3VS0ON signal to Low level (tim92).

[0076] When the 3VS0ON signal goes low, the LDO214 is disabled, and the 3.3VS0 power supply is turned off (tim93) (S77).

[0077] When power supply 3.3VS0 is turned off, the power to power control CPU 202 is turned off, and power control CPU 202 stops (S78).

[0078] When the power control CPU 202 stops, the 5VSON_a signal goes to a low level (tim94) due to the pull-down resistor, and the 5VS_sel signal also goes to a low level (tim95) due to the pull-down resistor. Additionally, the 24VON signal becomes open and goes to a low level (tim96) due to the pull-down resistor, and the POWON_a signal also becomes open and goes to a low level (tim97) due to the pull-down resistor.

[0079] With the above steps, printer 1 will enter Sleep mode.

[0080] (A-2-4) Transition from Sleep mode to ON mode Figure 9 is a flowchart illustrating the process when the printer's device state according to this embodiment transitions from Sleep mode to ON mode. Figure 10 is a time chart illustrating the transition of the printer's device state from Sleep mode to ON mode according to this embodiment.

[0081] In Sleep mode, the power saving control unit 2031 of the printer control CPU 203 waits for a wake-up event to occur (S91 No).

[0082] If a recovery event occurs (S91 Yes), the power saving control unit 2031 of the printer control CPU 203 starts the main control unit 2032 of the printer control CPU 203 (S92) and waits for the initial processing of the main control unit 2032 of the printer control CPU 203 to be completed (S93 No).

[0083] Once the initial processing of the main control unit 2032 of the printer control CPU 203 is complete (S93 Yes), the power saving control unit 2031 of the printer control CPU 203 waits for it to be able to communicate with the power control CPU 202 (S94 No).

[0084] Furthermore, if a recovery event occurs (S91 Yes), the power saving control unit 2031 of the printer control CPU 203 opens the 3VS0ON signal and uses a pull-up resistor to bring the 3VS0ON signal to a high level (tim101), thereby enabling the LDO 214 and turning on the power supply 3.3VS0 (tim102) (S95).

[0085] Since power supply 3.3VS0 is the power supply for the power control CPU 202, the power control CPU 202 is started (S96). The power control CPU 202 performs the initial processing and waits for the initial processing to complete (S97 No).

[0086] Once the initial processing of the power control CPU 202 is complete (S97 Yes), the power control CPU 202 drives the 5VSON_a signal to High (tim104), the 5VS_sel signal to High level (tim105), and the 24VON signal to Low level (tim106). Also, because power supplies 3.3VS0 and 5VS0 are on, the POWON_a signal is driven to High level (tim103) by Tr206.

[0087] Once the initial processing of the power control CPU 202 is complete (S97 Yes), the power control CPU 202 waits for communication to become possible with the printer control CPU 203 (S98 No).

[0088] When the printer control CPU 203 becomes able to communicate with the power control CPU 202 (S94 Yes), and the power control CPU 202 becomes able to communicate with the printer control CPU 203 (S98 Yes), the printer control CPU 203 requests the power control CPU 202 to turn on the 24V power supply via the communication interface, and the power control CPU 202 sets the 24VON signal to a high level (tim107), causing the 24V power supply to be turned on from the power supply circuit 201 (tim108) (S99).

[0089] With the above steps, the device status of printer 1 will be in the ON mode state.

[0090] (A-2-5) Transition from ON mode to Sleep mode Figure 11 is a flowchart illustrating the process when the printer's device state according to the embodiment transitions from ON mode to Sleep mode. Figure 12 is a time chart illustrating the transition of the printer's device state from ON mode to Sleep mode according to the embodiment.

[0091] In ON mode, the power saving control unit 2031 of the printer control CPU 203 waits for the occurrence of a transition factor (S111 No).

[0092] When a transition event occurs (S111 Yes), the power saving control unit 2031 of the printer control CPU 203 instructs the main control unit 2032 of the printer control CPU 203 to transition to Sleep mode. The main control unit 2032 of the printer control CPU 203 performs the Sleep transition process (S112). Then, it waits for the transition process of the main control unit 2032 of the printer control CPU 203 to be completed (S113 No).

[0093] Once the transition process of the main control unit 2032 of the printer control CPU 203 is completed (S113 Yes), the power saving control unit 2031 of the printer control CPU 203 stops the operation of the main control unit 2032 and waits for the completion of the Sleep transition process of the power control CPU 202 (S114).

[0094] When a transition event occurs (S111 Yes), the printer control CPU 203 requests the power control CPU 202 via the communication interface to turn off the 24V power supply. The power control CPU 202 sets the 24VON signal to a low level (tim121), which turns off the 24V power supply from the power supply circuit 201 (tim122) (S116).

[0095] The power control CPU 202 performs the Sleep transition process (S117). Here, the power control CPU 202 writes information indicating the transition from ON mode to Sleep mode to the non-volatile memory 2021.

[0096] Wait for the power control CPU 202 to complete its sleep transition process (S118 No).

[0097] The power saving control unit 2031 of the printer control CPU 203 stops the operation of the main control unit 2032, and once the sleep transition process of the power control CPU 202 is completed (S115), the printer control CPU 203 sets the 3VSON signal to a low level (tim123), thereby disabling the LDO 214 and turning off the power supply 3.3VS0 (tim124) (S119).

[0098] When power supply 3.3VS0 is turned off, the power to power control CPU 202 is also turned off. Power control CPU 202 stops, and as a result of power control CPU 202 stopping, the 5VSON_a signal goes to a low level (tim125) due to the pull-down resistor, and the 5VS_sel signal also goes to a low level (tim126) due to the pull-down resistor. In addition, the 24VON signal becomes open and goes to a low level (tim127) due to the pull-down resistor, and the POWON_a signal also becomes open and goes to a low level (tim128) due to the pull-down resistor.

[0099] With the above steps, printer 1 will enter Sleep mode.

[0100] (A-2-6) Transition from Sleep mode to OFF mode Figure 13 is a flowchart illustrating the process when the printer's device state according to this embodiment transitions from Sleep mode to OFF mode. Figure 14 is a time chart illustrating the transition of the printer's device state from Sleep mode to OFF mode according to this embodiment.

[0101] In Sleep mode, the printer control CPU 203 waits for the power switch 205 to be pressed (S131 No).

[0102] When the power switch 205 is pressed (S131 Yes), the POWON signal goes to a low level (tim141), which causes the POWON_b signal to be driven to a low level (tim142) by Tr207. The printer control CPU 203 recognizes that the power switch 205 has been pressed when the POWON_b signal goes to a low level.

[0103] When the printer control CPU 203 recognizes that the power switch 205 has been pressed, it waits for the power switch 205 to be released (S132 No).

[0104] When the power switch 205 is released (S132 Yes), the POWON signal goes to high level (tim143), which drives the POWON_b signal to high level (tim144) via Tr207. The printer control CPU 203 recognizes that the power switch 205 has been released when the POWON_b signal goes to high level.

[0105] When the power switch SW205 is released, the printer control CPU 203 starts the OFF mode transition process (S133) and waits for the OFF mode transition process to complete (S134 No).

[0106] Once the printer control CPU 203 completes its transition to OFF mode (S134 Yes), the power saving control unit 2031 of the printer control CPU 203 opens the 3VS0ON signal and uses a pull-up resistor to bring the 3VS0ON signal to a high level (tim145), thereby enabling the LDO 214 and turning on the 3.3VS0 power supply (tim146) (S135).

[0107] Since power supply 3.3VS0 is the power supply for the power control CPU 202, the power control CPU 202 is started up (S136), and the power control CPU 202 performs initial processing and waits for the initial processing to be completed (S137 No).

[0108] Once the initial processing of the power control CPU 202 is complete (S137 Yes), the power control CPU 202 sets the 5VSON_a signal to a low level (tim147) and the 5VS_sel signal to a high level (tim148). As a result, the 5VSON signal goes to a low level (tim149), and the 5VS power supply is turned off (tim150) (S138).

[0109] When power supply 5VS is turned off, power supply 3.3VS is also turned off (tim151) (S139), which causes the 5VSON_b signal to become open and low level (tim152) due to the pull-down resistor.

[0110] Since power supply 3.3VS is the power supply for printer control CPU 203, turning it off stops printer control CPU 203 (S140), and power control CPU 202 sets the 5VS_sel signal to a low level (tim153).

[0111] At this point, the device status of printer 1 will be set to OFF mode.

[0112] When printer 1 is in the ON mode and power switch 205 is pressed, the printer control CPU 203 recognizes the pressing and releasing of power switch 205, and the device state of printer 1 transitions from ON mode to Sleep mode, and from Sleep mode to OFF mode, until it reaches OFF mode.

[0113] Furthermore, regardless of the state of printer 1, if the AC cord 204 is unplugged, it will transition to the power-off state.

[0114] (A-3) Effects of the Embodiment This embodiment provides the following effects.

[0115] Printer 1 is configured so that the power switch is detected by the power control CPU 202 when in OFF mode, and by the printer control CPU 203 when in Sleep mode. In Sleep mode, it is possible to turn off the power to the power control CPU 202, thereby reducing power consumption even in Sleep mode.

[0116] (B) Other embodiments This disclosure is not limited to the embodiments described above, and other modified embodiments, such as those exemplified below, may also be cited.

[0117] (B-1) In the above embodiment, a printer (color printer) was used as an example of an image forming apparatus, but other image forming apparatuses such as electrophotographic photocopiers or MFPs (Multi Function Peripherals) can also be applied.

[0118] (B-2) In the above embodiment, the power supply of the power control CPU 202 is turned on when in ON mode, but depending on the function required of the power control CPU 202, the power supply may be turned off when in ON mode. [Explanation of Symbols]

[0119] 1…Printer, 2…Image forming unit, 2C…Image forming unit, 2K…Image forming unit, 2M…Image forming unit, 2Y…Image forming unit, 3C…LED head, 3K…LED head, 3M…LED head, 3Y…LED head, 5VS…Power supply 5VS, 5VS0…Power supply 5VS0, 10C…Transfer roller, 10K…Transfer roller, 10M…Transfer roller, 10Y…Transfer roller, 11…Paper feed roller, 12…Paper feed sensor, 14…Conveyor roller, 15…Conveyor roller, 16…Write sensor, 17…Conveyor belt driven roller, 18…Conveyor belt driven roller, 19…Conveyor belt, 20… Fuser unit, 21…Fuser roller, 22…Fuser backup roller, 24…Ejection sensor, 24V…Power supply 24V, 25…Ejection roller, 26…Ejection roller, 201…Power supply circuit, 202…Power control CPU, 203…Printer control CPU, 204…AC cord, 205…Power switch, 206, 207…Tr, 208…FET, 209…DCDC, 210…SEL, 211…Host IF control circuit, 212…Host PC, 213…Printer control circuit, 2021…Non-volatile memory, 2031…Power saving control unit, 2032…Main control unit, E…Circuit E, M…Paper.

Claims

1. An image forming apparatus that can switch between a normal power mode, a first power saving mode having lower power consumption than the normal power mode, and a second power saving mode having lower power consumption than the first power saving mode, An image formation control unit used in the control of image processing, It includes a power control unit used for controlling the supply and shutdown of power, A power cable that can be connected to an external power supply is connected to a power supply unit that supplies power to the image forming control unit and / or the power supply control unit, A power switch to operate the power supply, In the first power saving mode, the power supply from the first power supply connected to the power control unit is stopped, and the image forming control unit monitors the state based on the operation of the power switch. In the second power-saving mode, the power supply from the second power supply connected to the image forming control unit is stopped, and the power control unit monitors the state based on the operation of the power switch. An image forming apparatus characterized by the following features.

2. When transitioning from the first power saving mode to the second power saving mode, based on a signal from the image forming control unit, the power supply from the first power supply connected to the power supply control unit, which is in a stopped state, is started, and then, based on a signal from the power supply control unit, the power supply from the second power supply connected to the image forming control unit is stopped, and the power supply control unit monitors the state based on the operation of the power switch, When transitioning from the second power saving mode to the first power saving mode, based on a signal from the power supply control unit, the power supply from the second power supply connected to the stopped image forming control unit is started, and then, based on a signal from the image forming control unit, the power supply from the first power supply connected to the power supply control unit is stopped, and the image forming control unit monitors the state based on the operation of the power switch. The image forming apparatus according to feature 1.

3. The power supply unit has power supplied to the image forming control unit, and the image forming control unit has a transistor that connects the first switch output signal of the power switch to the second switch output signal that connects to the image forming control unit. The image forming control unit monitors the pressed state of the power switch based on the second switch output signal. The image forming apparatus according to feature 1.

4. A switching means that controls the supply of power to the image forming control unit based on a first control signal, A selector that connects to the first control signal by selecting either a second control signal connected to the power control unit or a third control signal connected to the image forming control unit. The image forming apparatus according to claim 1, characterized by having the following features.

5. The image forming apparatus according to any one of claims 1 to 4, characterized in that it has a power generation means that generates power to be supplied to the power supply control unit based on a fourth control signal connected to the image forming control unit.

Images