Samsung's world's first magnetic resonance 3D glasses, the frame acts as a coil?

The editorial department of Nikkei Electronics disassembled Samsung Electronics' 3D glasses "SSG-3700CR" and its wireless charger "CY-SWC1000A". Samsung Electronics exhibited the product at the "2011 International CES" held in January 2011 and launched it in South Korea in the same month. Samsung said that this is the world's first home appliance product that adopts the "Magnetic Resonance" charging method.

The wireless charger is in the shape of a top hat and can hold up to 4 pairs of 3D glasses. The inside is hollow, and a paper clip-shaped aluminum plate is wound along the inner diameter (Figure A-1). The aluminum plate is a non-concentric coil, and from the direction of the magnetic field lines, it is estimated that it has the same effect as a coil wound about 6 times.

Figure A-1: ​​Paperclip-shaped coil inside the power supply
Disassembling the "Wireless Charger" 3D glasses charger from Samsung Electronics, a large aluminum power supply coil is attached to the inside of the top hat-shaped shell (a). The coil reciprocates in a size of 311mm×71mm (b). Eight ceramic capacitors are installed in the middle. The power control board uses a product from ON Semiconductor (c).

On the power circuit board connected to the aluminum plate, the air-core coil, inductor and electrolytic capacitor are very eye-catching. The resonant frequency when supplying power is 13.56MHz, and the frequency of the crystal oscillator is the same. Although the instruction manual says "Complies with Part 18 of FCC regulations", it also indicates precautions, namely, "When charging, keep a distance of more than 20cm from the housing."

The 3D glasses were jointly developed by Samsung Electronics and Silhouette, a famous Austrian eyeglass frame company (Figure A-2). They weigh 27g, the lightest among 3D glasses. When the glasses are hung on the housing, they will automatically charge without a switch. However, the glasses and charger are sold separately, and can also be charged via a USB cable.

Figure A-2: No power receiving coil was found
3D glasses hooked to a power supply for charging before (a, b) and after (c) disassembly. The lithium polymer rechargeable battery on the left end of the frame is used to transmit power through the frame to drive the LCD panel and the Bluetooth transceiver module on the right end of the frame. The flexible substrate inside the frame seems to directly play the role of the power receiving coil.

Unlike other companies' 3D glasses, this model uses Bluetooth wireless communication specifications instead of infrared communication to exchange synchronization signals with the TV and control the LCD screen. These functions are realized by the lithium polymer rechargeable battery and Bluetooth transceiver module stored in the end of the glasses frame. There is a thin flexible substrate in the frame, which seems to be used to power the LCD panel and Bluetooth module through the battery.

However, no power receiving coil was found that corresponds to the large power supply coil on the charger side. In addition, if only the Bluetooth module part is close to the housing, it cannot be charged. The frame must be hung on the charger housing to start charging. As long as the glasses are hung on the housing, they can be charged even if the module part is several centimeters away. Wireless power supply technicians speculate that "the frame of the glasses acts as a coil."