Apple’s New Wind Patent for Cooling Electronic Devices

Last week, on November 6, 2012, Apple was granted a patent for what it calls a “method and apparatus for cooling electronic devices”: an “ionic wind generator.”

This patent (U.S. Patent No. 8,305,728, to be exact) details a cooling system in which an ionic wind pump uses magnets to redirect cool air to specific components of a machine. Basically, the system employs special sensors to determine which areas of a device are most in need of cooling. The ionic wind pump (a solid-state air moving device) moves air toward those areas via magnets.

Apple’s patent essentially describes a “smart” cooling system – a system that does not, like conventional computer fans, waste energy by cooling everything all at once, including components that are not in use.

The ‘728 Patent

Although it is the claims that define the rights ultimately granted by the Patent Office, the most straightforward description of what this patent covers is found in the first paragraph of the Summary, which in relevant part describes the invention in this way:

The present disclosure identifies as various embodiments of methods and apparatus for deflecting or redirecting a flow of ionized air, such as that generated by an ionic wind generator… [A] deflection field is generated proximate the path of the flow of ionized air, and is used to deflect at least some portion of the path of the flow of the ionized air to a different path. In some embodiments, the deflection field is established by a deflection field generator that is configured to generate an electric field and/or a magnetic field, sufficient to deflect at least a portion of the flow of ionized air to a different path. In some examples, the deflection field may be used essentially continuously to deflect at least a portion of the ionized airflow.

For the patent aficionados, claim 1, which is the broadest claim, covers:

1. A processing device comprising: an ionic wind generator configured to generate a flow of ionized air along a path; and a deflection field generator located proximate the path of the flow, the deflection field generator configured to generate an electromagnetic field that deflects at least a portion of the flow of the ionized air to a different path.

Figure 5B of U.S. Patent No. 8,305,728, “Method and apparatus for cooling electronic devices.”

What’s Wrong with Mechanical Fans?

The conventional mechanical fans used in most laptops are pretty bulky. Apple is constantly looking for ways to make its products smaller, sleeker, and more portable; a clunky mechanical fan doesn’t allow for much flexibility on this front.

Mechanical computer fans also waste a lot of energy due to inefficiency: their airflow significant but not usually directed toward the most high-temperature components. Also, the fan is always running.

Finally, mechanical fans are just loud. If your CPU is working hard, your laptop might sound like a commercial airliner preparing its jets for takeoff.

Improving on an Existing Design

Apple’s design improves upon an already-in-use version of the ionic wind generator. The problem with the current iteration is that it generates a very linear and fairly inefficient airflow: the air moves from one electrode toward a second electrode, and thus only the components in the space between receive any cooling benefits. Components that are peripheral to the path of the airflow are simply bypassed.

In 2010, inventors Jean Lee and Richard Blanco filed Apple’s original patent application for the revamped version. Apple wanted, with its device, to direct airflow to the specific components that needed cooling—but only when they needed cooling. And it wanted to be able to cool multiple areas simultaneously.

According to the company, Apple’s method utilizes a solid-state air mover using “corona discharge—an electrical discharge near a charged conductor caused by the ionization of the surrounding air.” This is made of one corona electrode, one collector electrode, and a high voltage power supply. An electric field is created when voltage is applied to electrodes; the electric field causes surrounding particles to become ionized (charged). The electric field “spreads” a charge toward the collector electrode, and the charge continues to spread and create air movement en masse.

Here’s how Apple is really changing things up: a magnet or electromagnet will act as a “deflection field generator” that alters the direction of the ionized air particles. The deflection field generator is able to change the magnitude of deflection.

Standard issue heat sensors will help the deflection field generator deflect or direct air to any of the high-temperature spots (like the CPU) it locates—so the air flow is sort of “made to order.”

Apple has also found a solution to a common problem with conventional mechanical fans: what is called the “no slip” condition at the “surface and the mean free stream velocity at the outer reaches from the surface” of an internal part. Basically, this condition creates a layer of air over a high-temperature part that acts as a barrier to cool air. Rather than a constant airstream, Apple has opted to release air to a component in different time intervals. This way, the ionic wind generator system creates multiple tiny streams of air that disturb that pesky barrier layer.

Whew. After all of that, a vent positioned in the path of the ionic wind pump’s normal flow allows the charged air particles to exit the machine.

The Future of the Ionic Wind Generator

Apple says the ionic wind generator can be used not only in larger desktop and laptop computers, but also in mobile devices like the iPhone and iPod. The company has accordingly released three different designs for different formats (though it neglected to specify which designs matched up to which devices).

The ionic wind generator system also means significant noise reduction and heat reduction, which iPad and iPhone users have been begging for over the past few years. Plus, Apple will be able to make its sleek devices even more compact by replacing bulky mechanical fans with the solid-state cooling device from its designs.

This kind of technology is already in use in highly specialized lab and industrial settings, but Apple is the first to appropriate it for commercial consumer devices.

We can definitely see this patent making it to the production and shipping stages, as consumers have been asking for quieter, more efficient cooling devices for years—and Apple won’t miss a chance to further reduce the size of its products.

Tip of the hat to Apple Insider for bringing this to our attention.



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Join the Discussion

4 comments so far.

  • [Avatar for Stan E. Delo]
    Stan E. Delo
    November 15, 2012 03:43 pm


    I think NASA has developed technology like that for use in either heating or cooling space suits during extra-vehicular excursions, and for other applications. In a very small application like this, a working fluid might be pumped by something as simple as a peizo actuator operating on demand to move the fluid through radiators of some kind. If the pump could be powered by heat alone, that would be ideal, but I am still puzzling over that one.

    I have been working on a solar collector now and then that transmits energy via a working fluid to a home for heat, and if I didn’t need electricity to pump the fluid, that would be a large bonus. Sterling motors would be Way too expensive, so the search continues. It needs to be very simple, with few or no moving parts, and very efficient would be very good. I have a few ideas in that regard, but I can’t really go into that here.

    Thanks for the very interesting article,

  • [Avatar for Matt Scyoc]
    Matt Scyoc
    November 15, 2012 01:01 pm

    Stan, do you know of any “circulatory” type designs floating around? Seems like a much better idea than classic fans that need to run constantly like you say.

  • [Avatar for Stan E. Delo]
    Stan E. Delo
    November 12, 2012 05:39 pm

    Thanks MIT-

    That is what I happened to be thinking as well. Inventions really need to be new and novel, instead of just being heavily funded. They really need to look into circulatory systems, instead of chasing magical solutions. I haven’t had a chance to look just yet, but it might actually work.

    Exterior coolers that take the heat out of the system, ideally without any pumps at all. Just a thermal convection circuit system. The *coolers* could just exchange heat, making the abode warmer, and the computer much cooler. A very small liquid pump used only on demand or need would seem to be Much smarter than relatively dumb auto-fans that need to run nearly constantly to keep the temperatures reasonably constant.

  • [Avatar for MIT PHD Attorney]
    MIT PHD Attorney
    November 12, 2012 02:00 pm

    This is well known prior art. Google on electric wind – been used for heat transfer for at least 60-70 years.