Telephonic communications – Substation or terminal circuitry – Amplifying
Reexamination Certificate
1998-05-29
2001-03-20
Woo, Stella (Department: 2743)
Telephonic communications
Substation or terminal circuitry
Amplifying
C379S387020, C455S570000
Reexamination Certificate
active
06205217
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a portable telephone set, and more particularly to a portable telephone set which has the function of magnifying the sound collected by its microphone and the sound output from its earphone.
BACKGROUND OF THE INVENTION
It is possible to arbitrarily set the amplification degree for the sound signals from the microphone of a conventional portable telephone set before the portable telephone set is delivered as a final product. Once this amplification degree is preset, however, the telephone set can be used only at the preset degree. The telephone set may move with the user to various places, and be used in various environments. Because the amplification degree is preset, however, the telephone set is not easily adaptable to various aural environments. If the preset amplification degree is relatively low, the user may speak louder naturally in a noisy environment, bothering or annoying other people.
In connection with such a problem, Japanese Patent Laid-Open No. H.6-6441 discloses a portable telephone set with which the user can speak lower in a public environment in order not to annoy the public. The portable telephone set is provided with a manual switch for setting a public environment mode, when the user uses it in a public environment. When the public environment is set by turning the manual switch on, transmitting and receiving sound amplifiers are increased in amplification degree, and a sidetone amplifier is turned on to provide the user with an amplified sidetone.
As a result, in the public environment mode, the sidetone is louder when the user is speaking. This naturally makes the user speak or vocalize lower in this mode. In this mode, the amplification degree of the other sound signal amplifier
9
is higher. Therefore, in this mode, the volume of the sound heard by the other party is not affected even if the user speaks low.
In the public environment mode, unconditionally, the amplification degree of the sound signal amplifier
9
connected to the microphone
11
is increased, and sidetone is output to be increased in level from the earphone
5
. This prompts the user to speak lower. Therefore, in a very noisy environment, the user speaks low and the amplification degree of the sound signal amplifier
9
is higher, and consequently the other party hears more noise.
In a digital portable telephone set or the like, high-or dense-compression sound coding technique is used. In this case, for simple coding of non-voice, when the noise level is high, the collected sound is coded as a sound signal of small volume. Consequently, if the user speaks low in a noisy place, the other party may hear a deteriorated voice. As a result, the party may ask the user to speak loud, or to cancel the public environment mode.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the invention to provide a portable telephone set with which the user's voice can be heard easily by the other party even if the noise around the user is loud while the set is used with the volume of sound increased.
A portable telephone set according to the invention comprises:
a demodulating circuit for demodulating a signal from a base station to output a demodulated signal;
a first signal processing unit for amplifying the demodulated signal to output a first amplified signal;
an earphone for converting the first amplified signal into a sound;
a microphone for converting a sound into a signal;
a second signal processing unit for amplifying the signal from the microphone to output a second amplified signal;
a modulating circuit for modulating the second amplified signal to output a modulated signal;
a volume control unit for increasing the amplification degrees of the first and second signal processing units to perform a volume increasing process in accordance with the user's selection;
a band limiting circuit for limiting to the voice band the sound input through the microphone; and
an S/N determining circuit for comparing the level of the signal from the microphone and the level of a signal from the band limiting circuit.
The volume control unit is rendered inoperative if the S/N determining circuit judges that the ratio of the level of the signal from the microphone to the level of the signal from the band limiting circuit has exceeded a predetermined range during the operation of the volume control unit.
Even while the volume increasing process is performed, the amplification degree of the first signal processing unit decreases automatically if the ambient noise is loud relatively to the user's voice. This inhibits the user from speaking excessively low. At the same time, the amplification degree of the second signal processing unit decreases. This prevents the ambient noise from being heard loudly by the other party.
The volume control unit may be rendered operative if the S/N determining circuit judges that the ratio of the level of the signal from the microphone to the level of the signal from the band limiting circuit has decreased to a predetermined range while the volume control unit is inoperative. In this case, the user does not need to switch the mode for the volume increasing process in each circumstance or environment.
REFERENCES:
patent: 4847897 (1989-07-01), Means
patent: 5379338 (1995-01-01), Umemoto et al.
patent: 0 682 437 A2 (1995-11-01), None
patent: 1406663 (1975-09-01), None
patent: 63-299434 (1988-12-01), None
patent: 5-103070 (1993-04-01), None
patent: 6-6441 (1994-01-01), None
patent: 406006441 (1994-01-01), None
patent: 408032484 (1994-01-01), None
patent: 3034658 (1996-12-01), None
patent: 409046154 (1997-02-01), None
NEC Corporation
Scully Scott Murphy & Presser
Woo Stella
LandOfFree
Portable telephone set does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Portable telephone set, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Portable telephone set will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2526988