Wireless power transfer sheets using designated charging cradles have reached the stage of commercialization in the past few decades. Yet, it still requires a dedicated transmitter and perfectly aligned placement of a receiver. To achieve hassle-free integration of charging functions into daily objects, we propose a cuttable wireless power transfer sheet that allows users to modify their size and shape. (fig 1)
This intuitive manipulation allows users to easily add wireless power transmission capabilities to everyday objects.
The properties of the sheet such as thinness, flexibility, and lightness make our sheet highly compatible with various configurations.
Technology Features, Specifications and Advantages
We contribute a set of technical principles for the design of the circuitry, which integrates H-tree wiring and time division power supply techniques. H-tree wiring allows the sheet to remain functional even sheet is cut. The time-division power supply technique avoids the reduction in power transfer efficiency caused by the magnetic interference between adjacent transmitter coils.
When the wireless power transfer sheet adheres to another object, the sheet has to be re-shaped to fit the object. Existing technology often has problems regarding the re-shaping. The typical problem is a part of the coil of the sheet loses function after re-shaping. This technology copes with this problem by placing a power source in the center and laying H-tree wiring from the center out (fig2).
Even cutting off the sheet fig 3a (H), fig 3b (circle), fig 3c (star), it doesn't lose function due to the remaining power source. While fig 3d (I) and fig 3d (doughnut) won't work because of the lack of a power source.
Ideally we want to place each coil as close as possible to supply power to the sheet. However, placing coils too densely affects the power transfer efficiency. The time-division power supply technique solves such issues. This technique is making a group in accordance with the timing of on/off of each coil array and does not adjoin the group to other groups that have simultaneous on/off timing.
This method enables us to avoid magnetic interference between coils and contributes to power transfer efficiency (fig 4).
There are various applications for this sheet. If we apply this sheet into furniture, the furniture would become a piece of smart wireless charging furniture. The other examples are, bag, jacket, and craft. Some of these examples are already confirmed by the feasibility of our prototypes.
In other words, this sheet has the potential to transform various things into IoT devices easily.
There are various IoT devices in the world nowadays. However, one crucial point to manage an IoT device is how to charge it. This sheet can be a solution for that. If integrating these sheets into IoT devices such as mobile devices, sensors, and gadgets, it lets the IoT devices be charged easily and wirelessly. In addition, a wireless power transfer system is useful for moving device like a robot. (Wires can often be a hindrance for the device itself).
As this technology has a "novice-friendly" design procedure, this can be applied even in an emergency situation. Just bringing the sheet to where this sheet is needed and re-shaping it for the situation allows building a wireless power transfer environment.
In 2017, the scale of the wireless power transfer system market is estimated to be roughly US$1,120,000,000 in the world. The scale is estimated that will be reached roughly US$3,300,000,000 in 2023.