Acoustics – Plural diaphragm sound sources
Reexamination Certificate
2000-01-28
2001-10-09
Dang, Khanh (Department: 2837)
Acoustics
Plural diaphragm sound sources
C181S199000, C181S141000
Reexamination Certificate
active
06298942
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a housing having a loudspeaker system which includes two elongate loudspeaker enclosures which are situated near a front side of the housing and which extend at a distance from one another, which enclosures each have a longitudinal axis, the two longitudinal axes extending at least substantially parallel to one another and to the front side, each loudspeaker enclosure comprising near its longitudinal axis a first loudspeaker unit for radiating tones which are at least substantially related to a first frequency range, and a second loudspeaker unit for radiating tones which are at least substantially related to a second frequency range lower than the first frequency range, the first loudspeaker units both being situated on one and the same imaginary connecting line which extends transversely to the longitudinal axes of the loudspeaker enclosures, and both second loudspeaker units being situated at a substantially equal distance from this connecting line.
Such a housing is known from DE-A 38 35 539. The known housing forms part of a television set having a vertically disposed loudspeaker enclosure secured to the housing at opposite sides of a display screen. The two respective loudspeaker enclosures have been given a mirror-symmetrical design for acoustic and esthetic reasons. Each loudspeaker enclosure has an active loudspeaker for radiating lower mid-range tones in its central part and this loudspeaker further has two openings in its upper part and its lower part. These openings can be used both for mounting tweeters and as bass-reflex openings. The function of the openings depends on whether the enclosure is a right-hand or a left-hand enclosure and during assembly care is taken that tweeters are mounted in the upper openings of each associated pair of loudspeaker enclosures; the lower openings of such a pair of enclosures serving as bass-reflex openings.
A drawback of the known housing is that two mutually different loudspeaker enclosures are used, which is impractical, leads to additional manufacturing and assembly costs, and increases the risk of an incorrect assembly.
OBJECTS AND SUMMARY OF THE INVENTION
It is an object of the invention to improve the housing of the type defined in the opening paragraph, in such a manner that a practical and low-cost realization of the loudspeaker system is possible while the acoustic performance of the loudspeaker system is maintained.
In order to achieve said object the housing in accordance with the invention is characterized in that one of the two loudspeaker units is situated in an area which extends at one side of the connecting line which extends transversely to the longitudinal axes of the loudspeaker enclosures, and the other one of the second loudspeaker units is situated in an opposite area which extends at the other side of said connecting line.
The invention is based on the recognition of the fact that the human ear is directionally insensitive to bass tones. Loudspeaker units which emit only or mainly bass tones may therefore be arranged at various locations without causing any audible acoustic effects. The invention utilizes this fact with the advantage that the two loudspeaker enclosures which are used can be identical to one another. As is common practice, the front sides of the loudspeaker enclosures may be covered with a grille, a fabric covering or the like, inter alia for esthetic reasons. A further advantage of the housing in accordance with the invention is that the possibility of using two mutually identical loudspeaker enclosures provides more scope for the construction and styling of the housing.
As is also apparent from the foregoing, the housing is preferably equipped with two basically identical loudspeaker enclosures. The styling and/or the construction of the loudspeaker enclosures and of the parts of the housing which cooperate therewith is preferably such that during mounting of the loudspeaker enclosures in or on the housing these enclosures can be secured at the appropriate locations in only one position and orientation. A loudspeaker system having two identical loudspeaker enclosures has considerable advantages in production. Only loudspeaker enclosures of one type have to be manufactured, which is a cost-reducing factor. Moreover, there are logistic and administrative advantages.
An embodiment of the housing in accordance with the invention is characterized in that the loudspeaker enclosures each extend at least substantially vertically with their longitudinal axes. This is an arrangement which is known per se. With this arrangement the two loudspeaker units are disposed at the same level, while the second loudspeaker units are each situated at a different level, i.e. one second loudspeaker unit at a higher level and the other second loudspeaker unit at a lower level with respect to the first-mentioned level. Furthermore, in this embodiment the loudspeaker enclosures are preferably situated each near one side of the housing. The space between the loudspeaker enclosures can be used for accommodating audio, video and/or data equipment.
An embodiment of the housing in accordance with is characterized in that the first loudspeaker units each comprise an active loudspeaker, which is also referred to as a woofer. Such a loudspeaker unit has an operating range which extends roughly between 40 Hz and 3000 Hz.
An embodiment of the housing in accordance with the invention is characterized in that the first loudspeaker units each comprise a tweeter. Such a loudspeaker unit has an operating range which extends roughly between 3 kHz and 20 kHz. In many versions the first loudspeaker units will comprise both an active loudspeaker and a tweeter and will consequently have an operating range which extends roughly between 40 Hz and 20,000 Hz.
An embodiment of the invention is characterized in that the second loudspeaker units each comprise a passive radiator. Such a loudspeaker unit has an operating range which extends roughly between 40 Hz and 150 Hz. For a correct performance of the passive radiators the loudspeaker enclosures in the present embodiment are wholly closed. Alternatively, the second loudspeaker units may have bass-reflex openings.
The invention further relates to an apparatus including a display screen and a housing with a loudspeaker system.
Such an apparatus is known from the afore-mentioned DE-A 38 35 539. The known apparatus is a conventional television set, which has a loudspeaker enclosure secured to the housing of the television set at opposite sides for the purpose of stereophonic reproduction of sound. These loudspeaker enclosures are constructed in a manner as already stated in the introductory part of this description.
It is an object of the invention to improve the known apparatus by utilizing the advantages which can be attained by means of the housing in accordance with the invention.
To achieve this object, in accordance with the invention, the apparatus including a display screen includes the housing in accordance with the invention, the display screen extending between the two loudspeaker enclosures and the connecting line which extends transversely to the longitudinal axes of the loudspeaker enclosures extending through a central area of the display screen. The central area is to be understood to mean a zone which extends through or in the proximity of the middle or center of the display screen. In general, the loudspeaker enclosures are disposed vertically and are situated at opposite sides of the display screen. During use, but this depends on the construction of the loudspeaker enclosures, tones in the entire audible frequency range can be radiated. Anyway, it is guaranteed that in the apparatus in accordance with the invention tones to which the human ear is directionally sensitive are radiated from the same level, particularly the level related to the center of the screen, while the other tones, i.e. the bass tones, to which the ear is not directionally sensitive, are emitted from two different levels. This yields a constructiona
Schlatmann Paul H. M.
Tiessens Michel J. H.
Dang Khanh
U.S. Philips Corporation
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