Apple's Patent Background
Many electronic devices, such as computers, smart phones, and the like are becoming smaller and more compact. As these electronic devices become smaller the internal space available for audio speakers becomes smaller as well. This is especially true as space within the device enclosure for audio speakers may compete with the space required for circuit boards, hard drives, and the like. Generally, as a speaker decreases in size it is able to move less mass and thus sound quality (or at least loudness) may decrease. This may be especially noticeable for sounds in the lower end of the audio spectrum, e.g., beneath 1 kHz. Furthermore, the available volume within an electronic device shrinks which in turn provides less air for a speaker to vibrate and thus limits the audible response. Similarly, the volume level and frequencies able to be produced by a speaker may also decrease as the size of the speaker decreases. Thus, as electronic devices continue to decrease in size, detrimental effects may be experienced for audio produced by the devices.
Apple's Solution
Apples invention generally relates to a MacBook Pro including an audio transducer in electrical communication with the processor. The audio transducer includes a magnetic coil, and a magnet in communication with the magnetic coil. The enclosure includes a top panel, a bottom panel and the enclosure substantially surrounds the processor, the memory, and the audio transducer. The audio transducer is operably connected to the at least one of the top panel or the bottom panel of the enclosure.
Yikes, Surround Sound on MacBook Pros!
Leaping to Apple's patent FIG. 8 below, we see that the audio transducers (26) may be combined with multiple speakers 20, 72 and 74 to produce either a 3.1 or 4.1 surround sound configuration. For example, for a 3.1 surround sound configuration two top enclosure speakers 72, in combination with the bottom enclosure speaker (20) and the audio transducer (26) may each cover an audio range. The top enclosure speakers may be high range, the bottom enclosure speaker may be mid-range and the audio transducer may be the low range or bass sound. Similarly, to achieve a 4.1 surround sound configuration an additionally bottom enclosure speaker may be added.
Apple further states that the audio transducer may operate in such a fashion that it effectively provides a near full-range response frequency instead of acting like a subwoofer. That is, the transducer may output both low and mid-range frequencies, essentially performing as a "subtweeter." In such embodiments, the speaker may output not only bass range frequencies (e.g., about 20-500 Hz), but also mid-frequencies (e.g., about 500-1500 Hz or higher).
The audio transducer may be combined with other speakers in an electronic device such as a laptop, tablet or handheld computing device 10. For example, in one embodiment, two tweeters and one woofer may be combined with the audio transducer. The transducer may output the bass channel and, optionally, the middle ranges, while the tweeters handle high frequency outputs. The woofer may output its standard range of frequencies. Through the combination of the woofer and the audio transducer, more decibels per watt may be outputted, especially in bass frequencies.
Future Home Theater System & Beyond
Thinking far ahead, Apple states that an audio transducer of the type disclosed in their invention may be incorporated into a seat or chair as part of a home theater experience. The audio transducer may vibrate not only the chair but the person sitting in the chair under certain circumstances, thereby providing not only audible but also tactile feedback if desired. Further, the motion of the person may serve to displace yet more air and thus create an even louder sound.
Another example that Apple provides, is that the audio transducer may be combined with a capacitive or touch-based input so that motions of a user's hands on a device enclosure may act to increase or decrease the output of the audio transducer.
Alternative Audio Transducer as Gel Speaker
Apple's patent FIGS. 4 and FIG. 5 illustrate alternative embodiments of the audio transducer 26. In either embodiment, the audio transducer may be a gel speaker, a surface transducer or other device that produces sound by vibrating a surface. In operation, the audio transducer typically receives electrical signals from the processor and translates those electrical signals into vibrations, which in turn may be perceived as audible sound. The audio transducer may include a bracket 62, a transmission material 56, a coil 54 and a magnet 60.
The transmission material in some embodiments may be an audio gel, as is known to those of ordinary skill in the art. In other embodiments, the transmission material may be a foamed or reticulated material, or a dense flexible material capable of efficiently transmitting vibration from either the coil or magnet to another surface.
Some of the Transducer Detailing
Apple's patent FIGS. 4 and 5 below illustrate the transducer 26 including a coil 54 and made of an electrically conductive material. When an electrical signal is transmitted through the coil it acts as an electromagnet. If an alternating current is passed through the coil, the coil may alternate between being magnetically active and inactive, or polarized a non-polarized depending on the nature of the coil.
The audio transducer typically also includes a magnet that is biased into a rest position by a spring, plate or the like. The magnet has a set polarization and, depending on the audio signal, either is forced towards the coil or away from the coil when the coil is energized.
The magnet may be any type of material with magnetic properties, for example, iron or another ferrous material. Thus, as current is passed through the coil, the magnet is forced away from the coil (or drawn towards the coil, depending on the relative polarization of coil and magnet). Generally, the coil forces the magnet away when energized. When the coil is not energized, the magnet returns to its rest state, which is relatively nearer the coil than the magnet's position when the coil is energized.
Further, the distance the magnet travels from the coil may be varied by varying the electrical charge to which the coil is subjected. In this manner, the magnet may be driven by the coil in precise motions depending on the strength and duration of electrical current applied to the coil. These motions may vibrate not only air near the magnet, but also any surface to which the magnet is attached. In this manner, the audio transducer may induce vibrations in a surface (such as an enclosure of the electronic device) to which the transducer is affixed by the bracket 62. The motion of the surface may produce audible sound waves in much the same manner as the diaphragm of a conventional speaker moves air to produce a similar effect.
Patent Credits
Apple's patent application was originally filed in Q3 2010 by inventors Aleksandar Pance, Paul Puskarich, Craig Leong, Ronald Isaac, Ruchi Goel, Jim Tenneboe, Daniel Culbert, Neil Warren and Nathan Johanningsmeier.
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