Telephonic communications – Terminal – Housing or housing component
Reexamination Certificate
1999-06-21
2001-06-12
Chiang, Jack (Department: 2642)
Telephonic communications
Terminal
Housing or housing component
C379S420040
Reexamination Certificate
active
06246763
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention concerns a casing for a mobile telephone usable in a public network or in a private installation. More generally, the invention concerns all casings that reproduce a sound message and that may need to be pressed against the ear.
2. Description of the Prior Art
Existing mobile telephones incorporate a loudspeaker to emit sound opposite a perforated area of a casing. The user places this area, and therefore the loudspeaker, near or against his or her ear in order to hear messages. To make it possible to use a casing of this type in “hands free” mode, it is possible to switch the mobile telephone to a mode in which the loudspeaker emits the message with sufficient power to be heard all around. These two modes of use have mutually contradictory constraints.
If the user has the casing pressed against his or her ear, for personal listening, low-frequency components of the message transmitted to the user are overamplified. Thus a standard requires the amplitude within an audible frequency band to be contained within specified limits. This makes it necessary to be able to filter the low-frequency components to reduce their amplitude. The electronic filtering usually employed requires the interpolation of a filter for processing the signal before it is converted into an audible message.
In hands free listening, on the other hand, low-frequency components are necessary for effective diffusion of the signal into a large space, for example an office. Accordingly, on changing from one mode of use to the other it is necessary to switch low-frequency filters into or out of service.
In practice, the cost of the filters adds to the price of the device.
Creating acoustic leakage in the perforated area of the casing to establish communication between the open air and a cavity formed between the loudspeaker and an inside face of the casing against which the loudspeaker is pressed, in order to damp low frequencies, is known per se. With a solution of this kind, compliance with the limits of the standard unfortunately cannot be obtained without adding a complementary electronic filter.
SUMMARY OF THE INVENTION
The aim of the invention is to remedy the above drawback by proposing a completely different way of damping low-frequency sound components, according to whether the casing is pressed against the listener's ear for private listening or held away from the ear for hands free listening. In accordance with the invention, a leakage passage is provided in a perforated area of the casing opposite the loudspeaker. A mouth of the leakage passage is in a cavity formed by the external part of the casing and the listener's ear (rather than one formed by an inside face of the casing and a loudspeaker diaphragm). An orifice at the other end of the passage is outside this area, in the open air. This creates acoustic leakage having the beneficial effect of damping low-frequency components. Furthermore, in accordance with the invention, the leakage occurs only if a cavity is formed between the casing and the listener's ear. This occurs only if the listener has the casing pressed against his or her ear, for private listening.
The invention therefore consists in mobile telephone casing having a perforated region to transmit sounds produced by the mobile telephone and in which this region includes an acoustic passage to connect a mouth on an outside face of the casing in this region to an orifice outside this region.
The invention will be better understood after reading the following description and examining the accompanying drawing. The drawing is given by way of example only and is in no way limiting on the invention.
REFERENCES:
patent: 5402486 (1995-03-01), Wang et al.
patent: 6104808 (2000-08-01), Alameh et al.
patent: 1 016 716 (1996-01-01), None
patent: 61-123388 (1986-06-01), None
patent: WO 97/47117 (1997-12-01), None
Alcatel
Chiang Jack
Sughrue Mion Zinn Macpeak & Seas, PLLC
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