Acoustics – Anatomic or prosthetic relation – Ear and mouth
Patent
1981-07-09
1983-06-07
Rubinson, G. Z.
Acoustics
Anatomic or prosthetic relation
Ear and mouth
1791155PC, 179116, 1791155VC, 181166, H04R 716
Patent
active
043872751
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a speaker provided with a mechanical filter and more particularly a speaker in which the filter frequency remains unchanged even after a long time interval of operation and the problems such as the rolling phenomenon and the bottoming of a voice coil bobbin are eliminated and a speaker system which uses the speaker of the type described.
BACKGROUND OF THE INVENTION
In order to limit the acoustic frequencies reproduced by a speaker within a desired range, there has been a universal practice to insert a low-pass filter or a bandpass filter comprising an electronic circuit into the input stage of the speaker, but there has been also devised and demonstrated a speaker of the type in which a mechanical filter is incorporated into the speaker so that the range of reproduced acoustic frequencies may be limited and the characteristics substantially similar to those attained by the insertion of a low-pass filter or a bandpass filter comprising an electronic circuit may be realized. In the latter type speakers, used in general as a mechanical filter is a center holder or retainer made of a phenol-impregnated and corrugated fabric and interposed between a voice coil bobbin and a diaphragm.
When the center holder or retainer has been used for a long time, it is subjected to fatigue so that phenol is broken and consequently the compliance is increased. As a result, the filter characteristics are varied and subsequently the range of reproduced acoustic frequencies is changed.
There has been also devised and demonstrated a speaker of the type which is mounted on a partition wall disposed within a speaker box or cabinet; an air-tight chamber is defined between the speaker box or cabinet and a front plate of the speaker box; and a passive cone is mounted on the front plate, whereby the vibrations of a diaphragm cause the vibrations of the air trapped in the air-tight chamber which in turn cause the passive cone to drive. In this case, the air-tight chamber acts as a mechanical filter, so that a desired range of reproduced acoustic frequencies may be determined by suitably determining the volume of the air-tight chamber.
However, the box of the speaker system of the type described above becomes large in size and the partition plate or wall and the passive cone must be provided in addition to the speaker. As a consequence, there arises the problem that the costs increase.
DISCLOSURE OF THE INVENTION
According to the present invention, an air-tight chamber is defined within a speaker itself and used as a mechanical filter. Therefore, the compliance of the mechanical filter can be made independent on the fatigue of a suspension which constitutes a mechanical filter. It follows, therefore, that even when the fatigue of the suspension should occur, the filter characteristics remain unchanged and consequently the range of reproduced acoustic frequencies remains unchanged. Since the air-tight chamber or space is defined within the speaker itself not in the speaker box or cabinet, the overall system can be made into compact in size and the cost savings can be attained.
The present invention will become more apparent from the following description of embodiments thereof taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a sectional view of a first embodiment of the present invention;
FIG. 2 is a sectional view of a second embodiment of the present invention;
FIGS. 3 through 6, inclusive, are sectional views used for the explanation of the rolling phenomenon;
FIG. 7 is a schematic view showing the dynamic correlation among the parts of the speakers shown in FIGS. 5 and 6;
FIG. 8 is a sectional view of a third embodiment of the present invention;
FIG. 9 is a sectional view of a fourth embodiment of the present invention;
FIGS. 10 and 11 are sectional views used for the explanation of the assembly of the speakers shown in FIGS. 5 and 8;
FIG. 12 is a sectional view of a fifth embodiment of the present invention;
FIG. 13 is a s
REFERENCES:
patent: 2318517 (1943-05-01), Olson
patent: 3772466 (1973-11-01), Hossbach
patent: 4147899 (1979-04-01), Mori et al.
patent: 4235302 (1980-11-01), Tsukamoto
patent: 4239090 (1980-12-01), Dahlquist
patent: 4239943 (1980-12-01), Czerwinski
Fukuyama Tatsuo
Mizutani Toshiyuki
Shimada Yasuomi
Matsushita Electric - Industrial Co., Ltd.
Rubinson G. Z.
Schroeder L.
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