One of the most eagerly anticipated mobile device innovations is widespread application of wire-free inductive charging. Nobody will miss lugging power bricks around, looking for outlets to plug them in, and fumbling with cable connectors with attendant potential for port damage through extended or rough use. Along with the obvious convenience and non-mechanical connectivity’s durability are the minimal likelihood of corrosion with all electronics enclosed and protected from water or oxygen in the atmosphere, enhanced safety for medical implants enabling recharging/powering through the skin rather than penetrating wires creating opportunity for infection, and non radiative energy transfer.
There are some downsides, however. Inductive charging is less efficient, and it produces waste heat. Charging is slower than with a more electrically efficient hard-wired connection, and the technology is more expensive to manufacture. However, the technology is young, and advances are constantly improving performance on all of these negative counts.
For example, JVIS USA, LLC, of Shelby, Michigan—a wire-free power technology developer—is announcing formation of Open Dots Alliance—a non-profit organization to further oversee and promote the world’s first and only open standard for wire-free power, currently in use on 12 vehicle models across five major automobile brands (albeit three of which are Fiat Chrysler Automobiles nameplates).
The new standard is called Open Dots; “Open” because it is an open platform free of royalties or license fees, and “Dots” because it employs a distinctive pattern of four contacts (or dots) to receive wire-free power. The standard has been in use and is currently available in more cars and trucks than all other wire-free power technologies combined.
JVIS notes that wire-free charging is gaining greater acceptance among automotive manufacturers because vehicle owners want a hassle-free “drop and charge” means to charge phones while they drive. However, the Open Dots platform expands this ecosystem to include, tablets, laptop computers, power tools and other commonly used electronic devices as well.
“The standard employs a conductive technology that is fundamentally different than other technologies based on induction,” explains Mitch Randall, a director of Open Dots Alliance. “Consequently, the technology offers benefits that are not achievable by other standards.” These are:
- Safety – No electromagnetic fields are used. Zero risk of cancer claimed.
- Random Placement – Devices receive power at any position or orientation on a pad.
- High Power – The technology can deliver up to 160 Watts
- Power Diversity – High and low power devices can operate side-by-side on a pad
- Bulk Charging – A pad will charge as many devices as will fit on its surface
- High Efficiency – Efficiency is nearly 100%
- Low Cost – The technology is inherently low-cost.
The basic principle of operation of the Open Dots standard is illustrated in figure 1. A pattern of connection points on the bottom of an Open Dots device makes contact randomly with metal strips on the Open Dots pad.
The Open Dots pad’s contact strips are alternately connected to plus and minus. By the nature of the device’s contact point geometry, at least one contact will be connected to plus, and at least one contact will be connected to minus no matter where the device rests on the charging pad.
Because it isn’t possible to know which contact(s) will land on a positive strip and which contact(s) will land on a negative strip, a four-way bridge rectifier is used to right the random polarity. The contact points connect to the signals A, B, C, and D in the diagram at right, and the output of the rectifier is labeled “+” and “-“.
The Open Dots standard calls for a potential of 15V to 19V on the pad electrodes. Thus, the output of the four-way bridge rectifier is approximately 15V to 19V. For many applications, such as for cell phones, the rectifier output is dropped to 5V with a switching regulator.
The entire signal path is shown in figure 3. A power supply provides power for the system. The power is conditioned by a sensing circuit and brought to the pad electrodes. The contact points make direct electrical connection to the pad electrodes. The contact signals are brought through a rectifier to provide a positive and negative power signal into the device-side regulator. Finally, the regulated output powers a device.
The pad voltage is 15V for pads that can supply up to 20W, and 19V for pads that can supply up to 160W. Thus, a device resting on the pad can determine if it is on a low-power pad or a high-power pad.
Incidentally, given popular perception that wireless an emerging cutting-edge technology, many will be surprised to learn that wire-free power is over 85 years old, originally conceived in 1928 in Frank Rich’s patent # 1,668,249 for “Automobile Riding Amusement Device”—a precursor of slot car racing, but life-sized and technically much farther advanced than the miniature slot car standards developed in the 1960s.
Mr. Rich’s invention involved a large track with alternately polarized electric strips upon which rideable electric cars would pick up their power by dragging four electrical pickups. This is a little trickier than it seems at first, JVIS explains, because a way of preventing the pickups from shorting out the energized strips on the track had to be implemented. Rich accomplished that in two ways. First, the strips were narrow and widely separated, and second, a clever relay was used to prevent shorting by forming a connection of the contacts into the circuit only when needed. Rich’s invention was best suited to application cars that followed a track, and it also only worked with AC power, because otherwise the car would change direction depending on where it was on the track. However, the conceptual groundwork was laid for inductive charging technology to be advanced as an emerging mainstream technology some 85 years later.
On May 13 in Detroit at the Ward’s Auto Interiors Conference, the Open Dots Alliance will announce its first user consortium: the Open Dots Alliance Membership Program. Randall believes this will help ensure Open Dots products from various brands will work together seamlessly for a positive customer experience. The membership program is open to all interested companies with no fees to join.
“Members simply pledge not to make, sell, or resell ‘counterfeit’ conductive wireless products,” he said, “so consumers are never disappointed.” The Open Dots Alliance defines “counterfeit” wire-free products as those products that use a similar conductive technology but do not adhere to the standard.
The Open Dots Alliance’s new website, www.opendotsalliance.org, provides design guides, schematics, application notes, history, frequently asked questions, and more data. This will aid manufacturers in assessing the Open Dots technology, while decreasing their design learning curve.
A compliance logo is displayed on consumer packaging to show the product meets Open Dots’ certification standards. These standards and test protocols are provided in full online so that manufactures can self-certify their products to the standard.
“The Open Dots Alliance wants to make joining the consortium as easy as possible,” Mr. Randall says. “Thus, membership requires no fee or financial commitment, nor does it expose members to any liability.” To join the consortium, potential members simply submit a signed copy of the membership agreement. It can be downloaded from www.opendotsalliance.org (pdf).
Auto brands providing Open Dots compatible products include: Ford, Chrysler, RAM, Dodge, and Scion, along with phone case maker INCIPIO. The Open Dots Alliance welcomes additional companies to join the consortium.
Open Dots Alliance will hold a media briefing to announce its first user consortium at 2:15 p.m., Wednesday, May 13, at Ward’s Auto Interiors Conference, at Cobo Center in Detroit.
Open Dots Alliance is a 501(c)(6) non-profit organization, based in Shelby, Michigan, founded in 2015 as the custodian of the world’s first and only open standard for wire-free power: Open Dots. Open Dots Alliance maintains an industry consortium of member companies with the common goal of providing products that are inter-operable across brands for the public good.
Open Dots Alliance also maintains a website that provides essential technical design and certification information as well as historical and educational information. The Open Dots Alliance is funded by donations from wireless charging industry visionaries who share the goal of creating a ubiquitous open standard for wire-free power. For more information, visit www.opendotsalliance.org.
JVIS USA, LLC