Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
1998-06-04
2001-01-16
Picard, Leo P. (Department: 2835)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C361S689000, C312S223100, C381S300000, C381S303000, C381S304000, C381S305000, C381S306000, C381S307000, C381S332000, C381S333000, C381S386000, C381S388000, C381S087000
Reexamination Certificate
active
06175489
ABSTRACT:
BACKGROUND AND SUMMARY OF THE INVENTION
This application is related to portable computer speaker systems.
Background
Computer-Based Audio
The production of quality sound with computers has advanced significantly in recent years. Early personal computers typically had nothing more than a single, small speaker used to produce a beep or series of single-frequency beeps to indicate system status upon startup. However, consumers demanded more. With the significant advances in circuit miniaturization, improved sound quality electronics has been available for desktop systems for some time, and is now moving into the portable computer systems arena.
Today, there is a multimedia explosion that is adding a significant new dimension to the way people use computers. One of the biggest advantages is 16-bit, CD-quality sound. With the right speakers, this sound can be as impressive as the sound on a normal consumer's stereo system. More and more, computer applications include the capability to use and capture the full impact of 16-bit sound for multimedia. MIDI musical compositions become more inspiring, games more suspenseful, software more dramatic, and radio and television programs (obtained through the computer) can equal the quality of conventional reception systems.
In addition, computer and audio technologies are revolutionizing business. For example, in video conferencing, voices are reproduced with a natural quality that makes them seem as if the speaker were in the room. Providing a high-quality audio background during presentations greatly enhances their effectiveness, and portable computers provide the greatest opportunity for meeting this need. Furthermore, the work environment is becoming ever more mobile with employees traveling more, and perhaps even telecommuting (working from home). Use of increased travel time translates to work environments with higher ambient noise, such as airports, trains, or mass transit systems. Another factor in this trend is the user's need for more effective methods for communicating with potential customers, or even with the office when away on business.
Background
Spatial Impression
The design of sound reproduction systems is not only based on considerations of electrical and acoustical engineering and physics, but also requires knowledge of psychoacoustics, i.e. how sound is perceived by listeners.
One of the parameters of psychoacoustics is spatial impression. When a sound is generated in a room, the listener will first hear the sound via the direct path from the source. Shortly thereafter, the listener will hear the reflections of the sound off surfaces such as walls or ceilings. Human listeners will assess the size of the space they are in by listening to laterally reflected sound which accompanies a sound signal. Thus, in a loudspeaker system it is desirable to have some sound transmission paths which reach the ears of the listener with a certain amount of delay (e.g. 10-60 milliseconds) as compared with the direct transmission path. (This will give the impression of a spacious listening room by broadening the soundstage, and also by giving the illusion of pushing the sound beyond the physical location of the speakers, even if the listener is listening in a room which is very small.) Moreover, another peculiarity of this psychoacoustic parameter is that the low frequencies (below 500 Hz) dominate spatial impression. A more roomy spatial impression is welcome to many listeners. However, it is not easy to do this with a small speaker system, and particularly not with a small portable computer's speaker system.
To increase spatial impression, the ratio of laterally reflected energy to directly transmitted energy can be increased: the higher this ratio, the greater the spatial impression. (An extreme case of this is found in a symphony concert hall, where there is almost no direct sound.)
Whether the user is video-conferencing, playing a game, or just working with music in the background, spatial impression plays an important role in the computing experience. That role is growing ever more important as multimedia makes its way into even the most uncompromising of business applications.
Further background regarding spatial impression can be found in: J. Blauert, SPATIAL HEARING (2.ed. 1996); and in M. Barron, “Effects of Early Reflections on Subjective Acoustic Quality in Concert Halls” (thesis, University of Southampton, 1974); both of which are hereby incorporated by reference.
Background
Stereophonic and Surround Sound
Since its introduction in the 1950's, stereo has been regarded as an essential minimum requirement of quality sound reproduction. Stereo can convey a traditional soundstage in which the sound comes from the front, such as when one attends a play or concert. However, even stereo has shortcomings when required to convey the ambiance where the sound is heard from all around the listener. Stereo's lack of spatiality undermines sonic realism in, for example, a game where aircraft fly overhead from front to back, or footsteps come from off to the side. For this reason various “surround sound” schemes have been used, to provide at least some speaker output behind the listeners' positions.
Background
Portable Computer Audio Limitations
Two driving constraints on the development of portable computers are volume and power consumption. The form factor of portable computers cannot be expanded, so that volume is a key resource. Additional functions are continually sought to be added, and many of these place new demands on available volume. Moreover, as larger display sizes become available they require more area in the lid, and hence consume more volume. Similarly, users continually demand more battery lifetime, which implies a continuous struggle to minimize power consumption.
These two constraints bind especially tightly in the case of speakers: the low-frequency power-efficiency of a speaker is directly affected by its volume. Since low-frequency response is a significant limitation of portable speaker systems, this is a difficult constraint. Some attempts have been made to use external speakers with portable computers, but this is cumbersome.
As of 1997, the internal sound systems typically sold with portable computers produce marginal sound quality at best. Most multimedia computers sold today include a stereo sound card which is capable of reasonably good sound reproduction. However, the internal speakers are typically small and produce tinny sound with inadequate bass. As a result, millions of multimedia computer users suffer very poor sound fidelity from their computers.
However, poor sound quality in portable computers is undesirable. The experience of a game or multimedia presentation, with sound and video animation, can be astonishingly real when coupled with quality audio. Quality sound can make a significant difference in the enjoyment the user can get from a multimedia computer. Music while working is more enjoyable, training and “edutainment” titles are richer, and games become much more realistic and exciting.
Onboard Speaker System for Portable Computers which Maximizes Broad Spatial Impression
The present application discloses portable computers with improved spatial impression. This is realized by installing rearward-firing transducers in the plastic housing of a portable computer. The sound from these transducers reflects off external surfaces which may be present, to help provide the delayed lateral reflections which enhance spatial impression. In one class of embodiments, two small speakers (tweeters) are added in the front of the display, to make voice localization more natural.
The spatial impression of the resultant sound is significantly enhanced by the back radiation from the rearward-firing speakers. The direct sound path provides sound localization, while the back radiation provides sound ambience. Moreover, the rearward-firing speakers also increase the apparent front-back depth of the acoustic image. An advantage is that no external speakers are required to provide the level of
Ford Jeremy
Gough David E.
Markow Mitchell A.
Bui Tung Minh
Compaq Computer Corporation
Conley & Rose & Tayon P.C.
Picard Leo P.
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