Image forming apparatus and control method for image forming apparatus for controlling a direct current to direct current converter to supply power to an USB device
AssigneeCanon Kabushiki Kaisha
InventorNaoto Sasahara
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Abstract
An apparatus, such as an image forming apparatus, includes a Universal Serial Bus (USB) host interface configured to connect to a USB device, a direct current to direct current (DC-DC) converter configured to supply power to the USB device connected to the USB host interface, and a control unit configured to switch the DC-DC converter from a pulse width modulation (PWM) mode to a pulse frequency modulation (PFM) mode based on a type of the USB device connected to the USB host interface.
Claims12
An apparatus having a standard power state and a power-saving state in which power consumption is lower than power consumption in the standard power state comprising:
- a Universal Serial Bus (USB) host interface configured to connect to a USB device;
- a direct current to direct current (DC-DC) converter configured to supply power to the USB device connected to the USB host interface;
- and
- at least one processor configured to operate as a control unit, the control unit being configured
- to maintain a mode of the DC-DC converter to a pulse width modulation (PWM) mode in a case where at least one USB device corresponding to the PWM mode in the power-saving state is connected to the USB host interface when shifting to the power-saving state from the standard power state, and
- to set the mode of the DC-DC converter to a pulse frequency modulation (PFM) mode in a case where no USB device corresponding to the PWM mode in the power-saving state is connected to the USB host interface when shifting to the power-saving state from the standard power state,
- wherein when a USB device corresponding to the PWM mode and a USB device corresponding to the PFM mode are each connected to the USB host interface, the control unit stops power supply from the DC-DC converter to the USB device corresponding to the PFM mode, and
- wherein the control unit sets the DC-DC converter to the PFM mode and stops power supply to all of the USB devices connected to the USB host interface if all of the USB devices connected to the USB host interface corresponds to the PFM mode.
A control method for an apparatus having a standard power state and a power-saving state in which power consumption is lower than power consumption in the standard power state, the apparatus including a USB host interface configured to connect to a USB device, and a DC-DC converter configured to supply power to the USB device connected to the USB host interface, the control method comprising:
- maintaining a mode of the DC-DC converter to a PWM mode in a case where at least one USB device corresponding to the PWM mode in the power-saving state is connected to the USB host interface when shifting to the power-saving state from the standard power state, and
- setting the mode of the DC-DC converter to a pulse frequency modulation (PFM) mode in a case where no USB device corresponding to the PWM mode in the power-saving state is connected to the USB host interface when shifting to the power-saving state from the standard power state,
- wherein when a USB device corresponding to the PWM mode and a USB device corresponding to the PFM mode are each connected to the USB host interface, the control unit stops power supply from the DC-DC converter to the USB device corresponding to the PFM mode, and
- wherein the control unit sets the DC-DC converter to the PFM mode and stops power supply to all of the USB devices connected to the USB host interface if all of the USB devices connected to the USB host interface corresponds to the PFM mode.
Dependencies are inferred from the claim text.