The late Steve Jobs famously hated cooling fan cacophony. The original 64k, 128k, and Mac Plus compact Macs had no internal fans and depended on natural convection for cooling. So did the second-generation form factor fanless “Earth Tones” variants of the teardrop iMac design in the early ’00s, and the G4 Cube Power Mac. In all these cases, it made for blessedly silent computing, but with definitely mixed success in terms of effective cooling.
Compact Macs got an internal fan with the Mac SE version in 1988. A fan was back in the iMac with the G4 “Luxo Jr.” model, and some third party hardware upgrades for the Cube incorporated cooling fans.
Apple laptops were fanless as well up until the PowerBook 3400c in 1997, but since then, and especially since the switch to hotter (in more ways than one) Intel processor silicon in 2006, thermostatically-regulated cooling fan racket has been a frequent accompaniment to Mac portable computing.
Thus far, iPads—with their ARM-based A-Series system-on-chip processors—have remained fanless, and the thermal profile of the full-size iPad has reportedly even improved somewhat with the switch to 32nm process A6X SoC’s in the fourth-generation iPad. The 32nm A5 SoC in the new iPad mini is also relatively cool-running.
However, it remains to be seen whether fanlessness can be maintained as tablet computers become more powerful, and all Mac systems currently have fans. The new Retina Display MacBooks have internal cooling fans with asymetrically-spaced blades designed to generate less noise than conventional symmetrically-bladed fans, but any small-diameter, high-revving, electric motor-driven fan is going to generate noise.
Which segues us to United States Patent 8,305,728, awarded to Apple by the U.S. Patent Office, for “Methods and apparatus for cooling electronic devices.”
The patent abstract describes “various apparatus and techniques for deflecting or redirecting a flow of ionized air generated from an ionic wind generator. In general, a deflection field generator can be located proximate to the path of the flow of ionized air. The deflection field generator is configured to generate an electromagnetic field, which deflects a least a portion of the flow of ionized air to a different path and may possibly increase local heat transfer.”
The inventors are cited as Jean L. Lee and Richard Lidio Blanco, Jr., presumably engineer employees of the patent assignee: Apple Inc.
Claimed in the patent application is 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 is configured to generate an electromagnetic field that deflects at least a portion of the flow of the ionized air to a different path, wherein the electromagnetic field exerts a Lorentz force on the at least the portion of the flow of the ionized air through an enclosure having vents located in the path of the flow. The first vent is located in the path of the flow and a second vent is located in the different path of the flow, with at least the portion of the flow deflected to cool the second component.
The processing device regulating this process would include a temperature sensor connected to a controller, configured to sense internal temperatures and configured to activate the deflection field generator if the temperature exceeds a threshold temperature, and also a power consumption sensor connected to the controller configured to activate the deflection field generator if the power exceeds a specified threshold.
Translation: a presumably silent means of cooling down internal components in electronic devices.
The patent application goes on to observe that modern electronic systems tend to generate large amounts of heat, with cooling devices currently in use today being primarily mechanically-based devices, such as electric fans and heat sinks.
The cooling device being proposed for use in such systems in the patent application is an ionic wind generator, which generates airflow based on the ionization of air molecules.
If Apple can make this work, it will be welcome relief to those of us who, like Steve Jobs, detest fan noise.
For full details of the patent application, see the United States Patent and Trademark Office.