Note: Descriptions are shown in the official language in which they were submitted.
2140679
The presant invention relates to a portable telephone
set and, more particularly, to a portable telephone set
having a ringing circuit and to be used in a portable mode
and mobile mode.
This application is a divisional application of '
C~n~ian patent application serial No. 2,035,411 filed on
January 31, 1991 claiming a convention date of January 31,
1990 . : ': ~. '' - ''~ '"'' ,
There has been .known a portable telephone set which
hzs two use-modes, i.e., a por~able mode in which the
telephone set is used by a use- while br nging it with
him and a mobile mode in which it is mounted on a vehicle.
In the portable mode, a compact and light-weight, built-in
'oudspeaker is used. In the mooile mode, a relatively
larse externaL loudspeaker is used because the loudspeaker
outputs not only a ringing tone but also a voice signal
and thus the voice quality therefrom ?lays an important
role.
In general, in the above-mentioned ringing circuit,
the built-in, i.e., internal louds?eaker is compact and
has a narrow frequency characteristics while the external
loudspeaker has a relatively wide recuency characteristics.
,:
In the conventional ringing circuit, however, a ringing
signal having a single frequency spectrum is used. Thus,
when the frequency characteristics of the internal and ;~
external loudspeakers are different, there may be a
problem that the energy of a ringing signal for driving
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the loucs?eaker cannot be used effectively. More
definitely, ~hen the ringing signal spectrum is broad
and the internal loudspeaker is used, a portion of the
frequency spectrum of the ringing signal which is not
S used increases and the powe_ consumption of a ringing
signal generating circuit is undesirablv increased.
On the other hand, when the ringing signal frequency
spectrum is narrowered to adjust it to the internal
loudspeaker, it is i~possi~le to supply enough power
to the external loudspeaker, so that an effective
ringing sound cannot be generated.
Furthermors, the switching between the internal
and external loudspeakers is manually carried out.
This manual switching is a troublesome operation for
the user.
SU~M~RY OF TXE INVENTION
An obje~t of the present invention is, therefore,
to provide a ringing circuit for use in a portable
telephone set which circuit is capable of producing
an effective ringing sound for ei.her an internal or
external loudspeaker thereof to be used
Another object of the present invenkion is to
provide a ringing circuit for use in a portable telephone ~
set which circuit automatically switches internal and ; ~ :i.i ' ~; .
25 external loudspeakers based on the use conditions of i~ i
the portable telephone set.
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_ 3 _ 2140679 :~ ~
Acco_ding to the present invention, there is provided
a portable telephone set havins two use-modes, portable ~ ;~
mode and mobile mode, and includes a mode detecting
circuit .or detec_ing the use-modes. Upon a call
S frcm a base station, a ringing circuit of the portable
teleonone set generates ringing sound from an internal
loudspe2ker thereof when the portable mode is detected -
or ~rom an extern21 loudspeaker when the mobile mode
is detected. In .he porta~le mode, the ringing circui.
produces a _i-st ringing signal having a .requency
spectrum adjusted to frequency charac.eristics of the
internal loudspea.cer and, in the mobile mode, produces
a second ringing signal h2vins a freauency spectrum
adjusted to freauency chzracteristics of the external
loudspeaker. The ringing circuit may include two
ringing sisnal generating circuits which generate
the first and second ringing sisnals, res?ectively.
Further, the rinsing circuit m2y include a single
rinsing sisnal generating circuit which generates -
the first or second ringir.g signal depending upon
use-mode detected. When the e~ternal loudspeaker is
connected to the telephone set, an input terminal of
the mode detecting circuit is grounded simultaneously
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and this grounding signal can be usPd as the detection ~--
signal of the moce detection circuit.
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~ 4 ~ 214067~
BRIEF DESCRIPTION OF THE DR~WINGS
The above-mentioned and other objects, features and
advantages of ~his invention will become more apparent
by reference to the following detalled description of
the invention taken in conjunction with the accompanying
drawings, wherein:
Fig. 1 is a schematic block diagram showing a
portable telephone set according to an embodiment of
the present invention;
Fis. 2 is a flowchart explaining the call reception
operation of the Fig. 1 portable telephone set;
Fig. 3 is a schematic block diagram showing a
specific construction of speaker/microphone of the
Fig. 1 embodiment;
Fig. 4 shows frequency charac~eristics of an
internal loudspeaker and an external loudspea.cer which
are used in the Fig. 3 embodiment;
Fig. 5 is a schematic block diagram showing a
ringing tone generator of the speaXer/microphone
portion shown in Fig. 3;
Fig. 6 is a schematic bloc.c diagram showing a mode :~
, detecting circuit used in the Fig. 3 embodiment; w
Fig. 7 is a schematic bloc.c diagram showing another
specific construction of speaker/micropnone portion of
the Fig. 1 embodiment; and
Fig. 8 is a schematic ~lock diagram showing a
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21~0679
s
ringing tone genera.or or the speaker/microphone portion
shown in Fig. 7.
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DETAILED DESCRIPTIO~ OF THE PREFERRED ~MBODIMENT
In Fig. 1, a portable telephone s~t 10 can be carried
S by the user or mounted on a vehicle. The telephone set 10
has an antenna 1 picking up a radio grequency (~ signal ~ ~-
and radiating an RF signal. The antenna 2 may ~e replaced
by or switched to a vehicle-mounted antenna when the
telepnone set 10 is mounted on tne vehicle. The picked- -~
up RF signal is supplied to a receiver portion 3 throush
an antenna duplexer 2. The receiver portion 3 demodulates
the received RF signal to produce an audio rrecuency (A~
signal which may include a voice signal and a data sig..al.
The voice signal is supplied to a speaker/microphone
portion 5 to be outputted from a speake circuit 12 or
a handset 14 therewithin. The handset 14 may include
an earpiece receiver and a mouthpiece microphone. The
data sisnal is supplied to both a call detector circuit 7
and a control circuit 9. ~ '
~0 The speaker/microphone i includes a microphone
circuit 13 as well as the speaker circuit 12 and the ~
handset 14. The microphone circuit 13 and speak~r ; -
circuit 12 are used for the so-called hands-rree
telephoning in which the user can make conversation
through these circuits 12, 13 without resorting to
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the handset 14. The hands-free telepnoning c~n be per,~ormed
only when the telephone set 10 is mounted on a vehicle. In
this case, ~he speaker circuit 12 is used for conversation
and 'or generating an audible rinsing tone. When the
; telephone set 10 is used as a portable one, .he handset 14
is used for conversation and the speaker circuit 12 is
dedicated to generating an audible ringing tone.
A voice signal is inputted througn the microphone
c~rcuit 13 or the handset 14 and supplied to a trznsmitter
portior. 4. The t_ansmitter portion 4 also supplied with
a data signal ~rom the cor.trol circuit 9 and various
signals from a signal generator 6. The transmitter
portion 4 trans~its the supplied signals to a base station
(not shown) of a mobile commll~ications svstem through the
1~ duplexer 2 and the antenna 1. The signa; generator 6
generates the various sisnals under the control of -~
control circuit 9. The control circuit 9 also cor.trols ,~
the receiver and transmitter portions 3, 4, especially, ;;
causes them to tune to a desired radio frequency channel '
20 in a well-known manner. ~-~
The call aetector circuit 7 detects '~rom the supplied
.: . ~,: ~ .;, ...
data signal a calling signal addressed to the telephone
set 10 and produces a call detection signal. The call
detection signal is led to both the control circuit 9 '-
and speaker/microphone circuit 5. In response, the
speaker/microphone circui~ 5 generates an audible
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2140679
.
-- 7 --
ringing tone through the spea.~er circuit 12 to alert the
user to a call.
The telepnone set 10 further includes a mode detect
circuit 8 which detects the use condition or the telephone
S set 10. More specifically, if the telephone set 10 is
used as a por.~ble set, the mode detect circuit 8 prcduces
a portable-mode signal. Ir the telephone set 10 is
mounted on a vehicle, the mode detect circuit 8 produces
a mobile-mode signal. Upon the mobile-mode signal, the
control circuit 9 may switch from the antenna 1 to the
vehicle-mount~ antenna.
In response to the portable-mode signal, the speaker ~;~
circuit 12 generates a firs. audible ringing tone whose -~'
frecuency is suitable to an internal speaker accommoda.ed
15 in the telephone set 10, which will be described later. 1~'
On the other hand, in response to the mobile-mode signal,
the speaker circuit 12 generates a second audible rinsing
tone whose frecuency is suitable to an external speaker
to be connected to the telephone set 10, which will also
be described later. Since the fresuencies or the ringing
tones are so selected, it is possible to produce an
audible ringing tone at the m~;ml-m level with the
m1 n~ mllm power consumption.
In Fig. 2, the portable telephone set 10 wa1ts at
step Sll for a call meant therefor on a so-called paging
channel which is one or control channels fo- broadcasting
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-- 8 --
calling sisnals and various control signals from a base
station to portable or mobile telephone sets. If the
telephone set 10 receives a calling signal addressed
thereto at step 512 and detects it with the call detect
i circuit 7, the control circuit 9 causes the signal
generator 6 to generate a response signal. The control
circuit 9 further causes the transmitter portion 4 to
transmit at step S13 the response signal to the base
station. Thereafter, the control circuit 9 checks at
steo S14 ~f it receives a channel designate signal
indicating a designated speech ch~nnel. If the control-; -
circuit 9 does not receive the channel designate signal
within a predetermined period or time, the operation
returns to step Sll. Otherwise, the ccntrol circuit 9
causes the receiver ard transmitte- portions 3, 4 to
tune to the designated speech channel a. step S15. ~ '
Step S15 is followed by step S16 at which the use~ ;
condi'ion of telephone set 10 is checXed using the mode
detect circuit 8. I~ the set 10 is used as a portable
20 set, the speaker circuit 12 generates a portable-mode ;
ringing tone whose fre~uency is suitabls to the internal
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loudspeaker at step 517. When the set 10 is mounted on
a vehicle, i.e., used as a mobile set, the speaker ~-~
circuit 12 generates a mobile-mode ringing tone whose
frequency is suitable to the external loudspeaker at
step S18. Steps S17 and S18 are followed by step Sl9
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at which the control circuit 9 monitors if it receives an
orf-hock signal indicating that the user goes of L -hook to
star. a telephone conversation. IL~ the ofr-hook signal
is not received within a pre~etermined ~eriod of time, the
S telephone set 10 returns to the waiting state (step Sll).
I- the o._-hook sisnal is received at s~ep Sl9, the
control circuit 9 perrorms at step S20 a connection process
in which the handset lg is connected to the receiver and
trans~itter portions 3, 4 in the portable mode while the
microphone circuit 13 and the speaker circuit 12 are
connected to the transmitter and receiver ?ortions 4 and 3, --:~
respectively, in the mobile mode. The completion or the
connection process allows the user to start a telephone
conversation at step S21.
15In Fis. 3, the speaker circuit 12 included in the
s?eaker/microphone portion 5 comprises z first ringing
tone gene ator 31 ror generating a firs. ringing tone
whose rre~uency is suitable to an internal loudspeaker 32 -
connected thereto. The speaker circuit 12 also comprises
a second ringing tone generator 33 ror generating a second
ringing tone whose freauency is suitable to an external
loudspeaker 35. Between the second ringing tone generator
33 and the external loudspeaker 35 is connected a signal
combining circuit 34 for combining the second ringing
tone and a voice signal rrom the receiver 3 (Fig. 1).
The external loudspeaker 35 is to be connected to the
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signal com~ining circui_ 3. through a t~m1 nal 36 attached
on a telephone set housing 37. While a voice signal is
outputted through the external speaker 35 together with
the ringing tone in the mobile mode, a voice signal is
5 outputted through the handset 14 (Fig. 1) in the portable -
mode. In ~he portable mode, only the ringing tone is
output,ed from the internal loudspeaker 32.
As mentioned above, the frequency spect.um of tne ;~
~irst ringing signal produced by the first ringing tone
generator 31 is set so that it substantially corrPsponds
to a relatively narrow fre~uency characteristics of the
internal loudspeaker 32. On the other hand, the frequency ;~-
spec-rum of the second ringing sisnal generated by th- -
second ringin.S tone generator 33 is set so that it -~
lS sub~tantially corresponds to a relatively wide frequency
ch2r2cteristics o' the external loucspeaker 35.
A connector 38 mounted on the housing 37 is connected -
to the mode detecting circuit 8. The connector 38 is
grounded when the telephone set, i.e.! the housing 37 -~
is mounted on a vehicle. Thus, when the connector 38
is not grounded, the mode detecting circuit 8 detects
that the telephone set is in the portable mode while ; -
when the connector 38 is grounded, the mode detecting
circuit 8 indicates that the telephone set is in the ~;
mobile mode. The connector 38 may be constructed such
that, when the external loudspeaker 35 is connected
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throush the connector 36 to the sisnal combining clrcui~
34, it is grounded simultaneousl~y. The mode detecting
circuit 8 provides a portable mode sisnal indicative of
the portable mode to the first ringing tone generator 31
and a mobile mode signal indicative of the mobile mode
to the second ringing signal generator 33. The call
detec~ing circui, 7 detects a calling signal rrom a data
signal from the receiving portion 3 and provides a call
detection signal indica.ive of the presence of calling ~;
signal rece?tion to both the ringing tone generators 31
ar.d 33.
With the Fig. 3 construction, when the telephone set
is in the portable mode and there is a calling signal
reception, the first rinsing tore generator 31 is oper~ted
lS to send the first ringing signal to the internal loud-
s?eaker 32. In this case, since the frequencv spectrum
of the first ringing s~gnal corresponds to the frequency
characteristics of the internal loudspeaker 32, the first
ringing tone generator 31 can operate the internal loud-
speaker 32 effectively with minimum power and thus theringing can be performec ef~ectively. On the other hand,
when the telephone set is in the mobile mode and there
is a calling signal reception, the second ringing tone
generator 33 operates to produce the second ringing
signal to the external loudspeaker 35. In this case,
since the frequency spectrum of the second ringing
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2140679
- 12 -
sisnal corres?onds to the fr-quency characteristics of
the external loudspeaker 35, the second ringing tone
generator 35 actuates the external loudspeaker 35 with
full ~ower, so that it is possible to call with mi~x;ml-m
volùme of the external loudspeaker 35.
Rererring to Fig. 4, an example of frequency
characteristics of ~he internal loudspeaker 32 is shown --;
by a curve A and that of the external loudspeaker 35 is - -
shown by a curve B. These data were obtained based on
10 the output voltages or a microphone circui. which oicks ' -
up sound from the respective loudspeakers under the same
measuring conditions. In general, the internal loudspeaker
32 is compact and thus its sound generating erficiency
is better in a narrow frequency band. On the other hand, - ;
15 the external loudspeake_ 35 does not provide high sound; ;~
generzting ef_iciency although it exhibits a good
frequency characteristics. The curve A indicates that'~
the internal loudspeaker has a sharp peak at 2.9 kHz
with its output level being about 5.2 dBV. The curve A
also shows that the internal loudspeaker outputs an
output level of about -1.5 d3V at 1.5 k~z and o~ about
-3.5 dBV at 1.3 k~z. On the other hand, the curve B
exhibits that the external loudspeaker has a relatively
wide frequency characteristics and its m~ximl~m output -~
point is at 1.3 kHz with level being about 0 dBV. Also,
the external loudspeaker outputs an output level of about
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-7.0 dBV at 1.5 kHz and o~ _a.0 dBV at 2.9 kHz.
Setting the ringing signal frequency to a single
frequency such as 1.5 kHz which is the frequency of ringer
.
of a cable telephone, there is no problem ~or the external ~ ~;
loudspeaker 35 since its ,requency at which a high output
level is prcduced is substantially coincident with the
ringer frequency. However, for the internal loudspeaker
32, its output level at the ringer requency is lower
than the m~i mllm output level by about 7 dB. When such
10 internal and external loudspea.~ers 32 and 35 are driven ~ -
by a ringing tone having such 2 single frequency, it is
impossible to operate the loudspeaker and the ringing
tone generator efîiciently in either the portable mode
or the mobile mode. However, when, as shown in Fig. 4,
the frequencies o. the first and second ringing tones
respectively senerated by the ringing tone generators
31 and 33 are set at around 2.9 kH2 and around 1.3 kHz,
respectively, it is possible to use the loudspeakers
32 and 35 and the ringing tone generators 31 and 33
e ficiently. ~oreover, each of the first and second
ringing tones need not have wide frequency spectra
and thus they can use a tone having a single frequency
spectrum.
In Fig. 5, each of the ringing tone generators 31
and 33 comprises an oscillator 51 for producing a ringing
tone, an oscillator power source 5~ for supplying power
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from a power source to the oscillator 51 and for on-orf
operating the ~ower source and an .~N~ gate 53 for on-off '
con.rolling the oscillator power source 52. To one input
of AND gate 53 a calling signal detection signal is
S supplied from the calling signal detection circuit 7
and to the o~her input thereof a portable mode or mobile
mode signal is supplied from ~he mode detecting circuit 8.
When .~ND gate 53 receives these inputs, the gate ;3 makes
the oscillator power source 52 turn on so that the
lO oscillator 51 produces the first or second ringing tone. -
More specifically, in the first ringing tone generator 31, '~ -
AND gate 53 makes the power source 52 turn on when the
gate 53 receives the calling signal detection signal and
the portable mode signal. In the second ringing tone
15 genera.or 33, ~ND gate 53 makes the power source 52 turn
on when the gate 53 receives the calling sisnal detection ~ ;
signal and the mobile mode signal.
In Fig. 6, the mode detecting circuit 8 comprises
a tarmtnAl 61 to which a positive voltage is applied.
To the term; n~l 61 is connected the one end or a pull-up
resister 62 the other end of which is connected to the
connector 38. To the connector 38 are connected the
inputs of inverters 63 and 6a. The output of inverter
63 is connected to the input of an inverter Ç5 whose
output is connected to the first ringing tone generator
31. The output of inverter 64 is connected to the second
ringing one generator 33.
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In ope_ation, when the connector 38 is grounded, i.e.,
the telephone set is moun.ed on a vehicle, the output of
inverter 64 becomes a high level indicative of the mobile
mode, while the output of inverter 6i becomes a low level.
S Thus, only the second ringing tone generator 33 is enabled
~o generate the second ringing tone. In contrast, when
the connecto~ 38 is not grounded, i.e., the telephone
set is removed from a vehible, the output of the in~erter
64 becomes a high level indicative of the portable mode,
while the output of inverter 64 becomes a low level.
Thus, only the irst ringing tone generator 31 is enabled
to generate the -irst ringing tcne.
Fig. 7 shows another example of the speaker circuit,
denoted by reference numeral 12A, comprising a ringing
tone generator 71 which produces the first or second
ringing tone according to the use mode or the telephone
set. The output of tone generator 71 is supplied to a
signal combining circuit 72 to be combined with a voice
signal from the receiving portion 3. The output of
combining circuit 72 is coupled to a speaker s-~itching
circuit 73 which connects the out?ut o~ signal combining
circuit 72 to one of the internal and external loudspeakers
32 and 35. The external loudspeaker 35 is to be connected
to the speaker switching circuit 73 through the connector 36.
Although the use mode signal outpu.ted by the mode
detecting circuit 8 may include the portable mode signal
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and the mobile mode signal as described wi~h reference to
Fig. 6, here, an output level variation of either of the
mode signals is utilized. The ringing tone generator 71
produces the first ringing tone when the use mode signal - -~
is the portable mode signal and the calling signal
detection signal is supplied. The generator 71 also
generates the second rlnging tone when the use mode
signal is the mobile mode signal and the calling signal
detection signal is supplied. The signal combining
circuit 72 combines the voice signal and the second
rinsing tone when the use mode signal is the mobile mode
signal wAile it merely passes therethrough the first ~
ringing tone when the use mode signal is the portable ~ '
mode signal. The output term;n~l of the speaker switching
lS circuit 73 is s-~itched to the internal loudspeaker 32 when
the use mode is the portable mode and to the external -
louds?eaker 35 when it is the mobile mcde. Therefore,
the ringing tone generator 71 of the speaker circuit 12
produces two kinds of ringing tone.
In Fig. 8, the ringing tone generator 71 is connected
through a bus 81 to the control circuit 9, which may
comprise a microprocessor, the calling signal detection ;
circuit 7 and the mode detecting circuit 8. The ringing
tone generator 71 comprises a clock generator 82 for
generating a clock signal. The clock signal is supplied
to a frequency divider 83 at which the clock signal is
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frequency divided. The divided clock signal is counted
by a counter 84 whose output is applied to a read-only
memory (ROM) 85. ROM 85 preliminarily stores patterns
corres?onding to the first and second ringing tone
S frequencies and provides one of the stored patterns -
accord~ng to the output of counter 84. The output
pattern of ROM 85 is supplied to a D/A converter 86
which converts the supplied patterns into a sinusoidal
wave signal containing high h~rmon;cs. A low-pass filter ~ -
(LPF) 87 el;m;n~tes the high harmonics contained in the
output of D/A converter 86 to provide a basic sinusoidal -~ -
wave signal and an amplirier 88 amplifies the basic
sinusoidal wave signal.
The frequency divider 83 divides the frequency of
the clock signal by a first frequency-dividing ratio
when .he portable mode signal is supplied from the mode
detec~ing circuit 8 and the calling signal detection
signal is supplied from the signal receive detecting
circuit 7. On the other hand, when the mobile mode
signal and the calling signal detection signal are
supplled, the frequency divider 83 divides the clock
signal by a second frequency-dividing ratio. The
counter 84 is used as a decoder for assigning addresses
for ROM 85 and the output of counter 84 when counted with
the first frequency-dividing ratio reads the pattern
corresponding to the first ringing tone frequency stored
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- 18 - -
in ROM 85. On the other hand, the output of counter 8a
when counted with the second ~requency-dividing ratio
reads the pattern corresponding to the second ringing -~
tone frequency stored in ROM 8~. In this manner, the ~ ;
5 two kinds OL ringing tone can be digitally produced. -
As described hereinbefore, the ringing circuit OL
the portable telephone set according to the present
invention includes the ringing tone generators for
generating the first and second ringing tones whose
frequencies are set to be suitable to frequency
characteris.ics of the internal loudspeaker to be used
in ~he portable mode and of the external loudspeaker to
be used in the mobile mode, respectively. The ringing
tone is selected according to the use mode of the
telephone set in which the associated loudspeaker is
actuated. Therefore, it is possible to~utilize the
ringing tone effectively in either mode and to provide
m~;mllm ringing with mlnimllm power consumption.
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