A wireless power system includes a power source, power receiver, and components thereof. The system can also include a parasitic antenna that can improve the coupling to the power source in various modes. The antenna can have both a variable capacitor and a variable inductor, and both of those can be changed in order to change characteristics of the matching.

Packaging and details of a wireless power device

The present disclosure relates to a semiconductor light emitting device, comprising: a plurality of semiconductor layers, including a first semiconductor layer having a first conductivity, a second semiconductor layer having a second conductivity different from the first conductivity, and an active layer interposed between the first semiconductor layer and the second semiconductor layer, generating light via electron-hole recombination; a first electrode, supplying either electrons or holes to the plurality of semiconductor layers; a second electrode, supplying, to the plurality of semiconductor layers, electrons if the holes are supplied by the first electrode, or holes if the electrons are supplied by the first electrode; a non-conductive distributed bragg reflector coupled to the plurality of semiconductor layers, reflecting the light from the active layer; and a first light-transmitting film coupled to the distributed bragg reflector from a side opposite to the plurality of semiconductor layers with respect to the non-conductive distributed bragg reflector, with the first light-transmitting film having a refractive index lower than an effective refractive index of the distributed bragg reflector.

Semiconductor Light Emitting Device

Exemplary embodiments are directed to wireless power transfer. A transmit antenna generates an electromagnetic field having a region for wirelessly transferring power from the transmit antenna to a plurality of receiver devices. A controller is operably coupled to the transmit antenna. The controller determines a power allocation for a particular one of the plurality of receiver devices disposed within the region, and adjusts the power allocation based at least in part on a power requirement received from the particular one of the plurality of receiver devices.

Adaptive power control for wireless charging of devices

Exemplary embodiments are directed to wireless power transfer. A transmitter (202) generates an electromagnetic field at a resonant frequency with a transmit antenna to create a coupling -mode region within a near field of the transmit antenna (204). The transmitter defines a beginning of a recurring period by on-off keying the electromagnetic field during a synchronization portion of the recurring period. During a power transmission portion of the recurring period, the transmitter couples portions of the electromagnetic field to different receive antennas of various receiver devices within the coupling -mode region. The transmitter also determines a power allocation within the recurring period for the various receiver devices disposed within the coupling -mode region and adjusts a power level of the near field radiation responsive to power requirements received from the receiver devices.

Adaptive power control for wireless charging

Various radio frequency identification (RFID) tags are described that dynamically vary their resonant frequency to reduce or eliminate the potential effects of electromagnetic “tag-to-tag” coupling. An RFID tag, for example, includes a main antenna tuned to a first resonant frequency, and switching circuitry that dynamically changes the resonant frequency of the main antenna. The switching circuitry may selectively couple electrical elements, such as capacitive elements, inductive elements, or combinations thereof, to vary the resonant frequency of the RFID tag. The RFID tag may include a sensing circuit that determines when to selectively couple the electrical element to the main antenna to adjust the resonant frequency of the main antenna.

Variable frequency radio frequency identification (RFID) tags

A radio frequency identification tag having a step-tunable inductor for tuning a parallel resonant antenna circuit of the radio frequency identification tag to a desired frequency. The step-tunable inductor comprises a plurality of branches in which each branch is adapted for adjusting the step-tunable inductor to a desired inductance value for resonating the parallel antenna circuit to a carrier frequency of a tag interrogator/reader.

Inductively tunable antenna for a radio frequency identification tag

A radio frequency identification (RFID) tag device having a pulse position modulation (PPM) decoder circuit which calculates a relative frequency relationship between an internal clock-oscillator of the RFID tag device and an external PPM source such as a RFID tag reader, and then synchronizes the RFID tag device PPM decoder circuit to the required precision for reliable PPM symbol decoding. The PPM decoder is synchronized by measuring the “counts per pulse” (CPP) from a calibration cycle having a plurality of pulses in a single symbol frame.

Method, system and apparatus for initiating and maintaining synchronization of a pulse position modulation (ppm) decoder with a received ppm signal

A Radio Frequency Identification (RFID) security (10) uses an electronic key (12) for storing data. A reading mechanism (14) is provided and is used for reading a modulated signal having the data stored on the electronic key (12) when the electronic key (12) is coupled to the reading mechanism (14). An RF emulating circuit (16) is coupled to the reading mechanism (14) for emulating an RF energy signal to the electronic key (12) for allowing the reading mechanism (14) to read the data stored on the electronic key (12) when the electronic key (12) is coupled to the reading mechanism (14).

A radio frequency identification (rfid) security system having an rf emulating circuit

Radio frequency identification security system having RF emulating circuit

A universal programmer coil for programing tag coils of various configurations. The universal programmer coil has at least two programming coils coupled together for generating a signal which magnetically couples the universal programmer coil to tag coils of various configurations for programming the tag coils.

Lee Youbok

Papers

Inductively tunable antenna for a radio frequency identification tag

Method, system and apparatus for initiating and maintaining synchronization of a pulse position modulation (ppm) decoder with a received ppm signal

A radio frequency identification (rfid) security system having an rf emulating circuit

Radio frequency identification security system having RF emulating circuit

A universal coil for programming tag coils of various configurations