Abstract: An image forming apparatus according to the present general inventive concept includes a transfer unit configured to transfer an image formed on a photoreceptor to a transfer medium, a power supply unit configured to supply transfer power to the transfer unit, a density sensor unit configured to sense a density of the image transferred to the transfer medium, and a control unit configured to control the power supply unit so that the transfer power supplied to the transfer unit is adjusted, wherein the density sensor unit is allowed to move from a first position for sensing a density of sample patches formed on the transfer medium to a second position for sensing a density of a reference reflective plate, and the control unit performs a sensor compensation mode and a density compensation mode.

Abstract: A resonance power transmission system, and a method of controlling transmission and reception of a resonance power are provided. According to one embodiment, a method of controlling resonance power transmission in a resonance power transmitter may include: transmitting resonance power to a resonance power receiver, the resonance power having resonance frequencies which vary with respect to a plurality of time intervals; and receiving, from the resonance power receiver, information regarding the resonance frequency having the highest power transmission efficiency among the resonance frequencies used in the time intervals.

Abstract: A method of fabricating a multi-band filter module is provided. The method includes forming a Film Bulk Acoustic Resonator (FBAR) on a piezoelectric substrate by forming a resonant part on the piezoelectric substrate and then an air gap recessed on a surface of the piezoelectric substrate and positioned under the resonant part; and forming a Surface Acoustic Wave (SAW) device on the piezoelectric substrate in which the steps of forming the FBAR and the SAW are concurrently performed.

Abstract: A wireless power transmission system, and an apparatus and method for controlling power in the wireless power transmission system are provided. The method includes determining a resonance frequency of the wireless power transmission system in which a wireless power transmission efficiency is greater than or equal to a predetermined value. The method further includes generating an operation power based on the wireless power transmission efficiency, the operation power being used to operate a target device. The method further includes transmitting the operation power to the target device. The method further includes controlling an amount of the operation power received by the target device to be within a predetermined range.

Abstract: A source device and a method for controlling a magnetic field using two source resonators in a wireless power transmission system are provided. A device configured to control a magnetic field, includes resonators configured to form the magnetic field to transmit power to another device. The device further includes a magnetic field shape determining unit configured to determine a shape of the magnetic field. The device further includes a phase changing unit configured to change a phase of at least one of the resonators to form the magnetic field in the determined shape.

Abstract: Provided is a source-target structure matching controlling apparatus and method that may perform matching control of a source-target structure while resonance power is transmitted and received through the source-target structure. The source-target structure matching controlling apparatus may include a target resonator to receive, from a resonance power transmitter, the resonance power through a magnetic-coupling, and a rectifier to rectify the resonance power to generate a DC voltage, and provide the DC voltage to a load. The source-target structure matching controlling apparatus may detect an impedance of the load and a variance in the impedance, and may transmit, to the resonance power transmitter, information associated with the variance in the impedance of the load.

Abstract: A power converter for transmitting a resonance power is provided that includes: an input end that receives a direct current (DC) voltage of a predetermined level; a first power converter that converts the DC voltage of a predetermined level to an alternating current (AC) signal using a first switching pulse signal having substantially the same frequency as a resonant frequency; a second power converter that converts the DC voltage of a predetermined level to an AC signal using a second switching pulse signal having an opposite phase to the first switching pulse signal; a first short circuit that reduces or eliminates an odd harmonic of the AC signal outputted from the first power converter, and provides the AC signal; and a second short circuit that reduces or eliminates an odd harmonic of the AC signal outputted from the second power converter, and provides the AC signal.

Abstract: A resonance power transmission system, and a method of controlling transmission and reception of a resonance power are provided. According to one embodiment, a method of controlling resonance power transmission in a resonance power transmitter may include: transmitting resonance power to a resonance power receiver, the resonance power having resonance frequencies which vary with respect to a plurality of time intervals; and receiving, from the resonance power receiver, information regarding the resonance frequency having the highest power transmission efficiency among the resonance frequencies used in the time intervals.

Abstract: An apparatus and method for efficiently, wirelessly transmitting a power to a plurality of target devices are provided. A wireless power transmitter may include: a source resonator configured to wirelessly transmit energy to a target device with at least one target resonator, the energy being stored in a capacitor; and a feeding unit configured to generate an induced current flowing in the source resonator in the same direction as a direction of an input current flowing in a transmission line, the feeding unit being electrically connected to the capacitor and forming a closed loop with the source resonator.

Abstract: A wireless power transmission system based on cell division is provided. A communication and power control method of the wireless power transmission system, includes setting a magnetic coupling zone. The method further includes detecting a target device in the magnetic coupling zone. The method further includes transmitting a power to the target device. The method further includes adjusting an amount of the power based on a transmission efficiency of the power.

Abstract: A source device and a method for controlling a magnetic field using two source resonators in a wireless power transmission system are provided. A device configured to control a magnetic field, includes resonators configured to form the magnetic field to transmit power to another device. The device further includes a magnetic field shape determining unit configured to determine a shape of the magnetic field. The device further includes a phase changing unit configured to change a phase of at least one of the resonators to form the magnetic field in the determined shape.

Abstract: A protector that protects a rectifier, and a wireless power receiver including the protector are provided. In one embodiment, a protector for an electronic device may include: a switch configured to control current flow to a rectifier of the electronic device; and a switch controller configured to: compare, with a predetermined threshold value, a voltage difference between an output voltage of the rectifier and a voltage of the electronic device; and transmit a control signal to the switch (i) to discontinue current flow to the rectifier when the voltage difference is greater than the predetermined threshold value, and (ii) to enable current flow to rectifier when the voltage difference is less than or equal to the predetermined threshold value.

Abstract: An apparatus and method are described that may enable a target device to communicate with a source device using a wireless power. The communication apparatus receives a wireless power from a source resonator through a magnetic coupling between the source resonator and a target resonator. The communication apparatus transmits a message, and modulates the message based on the received wireless power and impedance mismatch between the source device and the target device. The communication apparatus controls the impedance mismatch by changing an impedance of the target device.

Abstract: An apparatus and method of protecting a power receiver of a wireless power transmission system are provided. A wireless power receiver includes a rectifier comprising an input and an output, and configured to receive a signal through the input, to rectify the signal to produce a rectified signal, and to output the rectified signal through the output, and a capacitor connected to the output of the rectifier and to ground. The wireless power receiver further includes a direct current-to-direct current (DC/DC) converter connected to the output of the rectifier and to a load, and configured to convert the rectified signal to a power, and to provide the power to the load, and a device configured to create a short circuit to protect the rectifier and/or the capacitor when a voltage greater than a threshold voltage is applied to the input of the rectifier and/or the output of the rectifier.

Abstract: Provided are a wirelessly charged robot cleaner in a robot cleaning system and a controlling method thereof. The wirelessly charged robot may include a target resonator to receive a resonance power through energy-coupling with a source resonator of a wireless power transmitter, a wireless power receiving unit to convert the received resonance power into a rated voltage, and a battery controller to check a remaining capacity of the battery based on a scope of a predetermined area to be cleaned, and to charge, using the rated voltage, the battery based on the remaining capacity of the battery.

Abstract: An apparatus and method for controlling a magnetic field when power is wirelessly transmitted are provided. According to one general aspect, a wireless power transmitter may include: a source resonator configured to wirelessly transmit power to a target device including at least one sub-resonator located there within; and a magnetic field distribution controller configured to control the distribution of the magnetic field within the resonator based the resonance frequency of the at least one sub-resonator and the resonance frequency of the source resonator.

Abstract: A source resonator for wirelessly transmitting power to a target device may include a magnetic field distribution adjusting unit that is configured to adjust the magnetic field generated by the source resonator. In one or more embodiments, the magnetic field distribution adjusting unit may adjust the magnetic field to be substantially uniform in a predetermined vicinity of the source resonator. For example, the magnetic field distribution adjusting unit may adjust the intensity of the magnetic field near the center of the source resonator to be substantially the same as the intensity of the magnetic field near an edge area of the source resonator.

Abstract: An active rectifier and a wireless power receiver including the active rectifier are provided. According to an aspect, an active rectifier may include: a first loop configured to provide voltage when the phase of an input signal is positive; and a second loop configured to provide voltage when the phase of the input signal is negative, wherein the first loop and the second loop include a delay locked loop configured to compensate for reverse current leakage due to a delay of a switch included therein.

Abstract: The present description relates to a polymerizable liquid crystal compound, a polymerizable liquid crystal composition including the same, and an optically anisotropic body.

Abstract: A wireless power transmission system with an enhanced magnetic field strength is provided. A wireless power transmitter includes a generator configured to generate a power. The wireless power transmitter further includes a resonator configured to generate a magnetic field to transmit the power to a target device. The wireless power transmitter further includes a slab unit configured to enhance the magnetic field.