Telephonic communications – Private or single line system – Having transducer circuitry
Reexamination Certificate
2001-09-24
2003-12-30
Kuntz, Curtis (Department: 2643)
Telephonic communications
Private or single line system
Having transducer circuitry
C379S167010, C379S167140, C379S171000
Reexamination Certificate
active
06671360
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims, under 35 USC 119, priority of Japanese Application No. 2001-154386 filed May 23, 2001.
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to an intercom system for a building or an apartment house, and more particularly to an intercom system for a building or an apartment house which can achieve power saving by suppressing current consumption and, at the same time, can ensure favorable talking quality by preventing the occurrence of howling.
(2) Description of the Related Art
A conventional intercom system for a building or an apartment house has a structure as shown in a block diagram of FIG.
3
.
The intercom system for a building or an apartment house shown in the drawing has at least one main entrance station
101
, a plurality of residential master stations
102
,
102
, . . . which are respectively installed inside of a plurality of residences in a building or an apartment house, a common line
103
connecting the main entrance station
101
and respective residential master stations
102
,
102
, . . . in parallel, a line power supply
104
for supplying a direct current power supply (DC power supply) to the main entrance station
101
and respective residential master stations
102
,
102
, . . . in parallel through the common line
103
, an electronic door lock
105
which is connected to the main entrance station
101
for locking and releasing an entrance door of a the building or apartment house, and a plurality of call switches
106
,
106
, . . . which are connected to respective residential master stations
102
,
102
, . . . and are mounted on front doors of respective residences (hereinafter referred to as “residential front doors”) for operation by a visitor to the residence.
In the drawing, the main entrance station
101
comprises a talk module
110
which includes a control circuit
120
, a line impedance and voltage regulating circuit
121
, a multiplex/separation circuit
122
, a speech circuit
123
, a data transmission/reception circuit
124
, an electric door lock circuit
125
, an electric door drive circuit
126
and a power supply circuit
127
, and at least one switch module
111
which includes a control circuit
130
, a call switch
131
, and a lighting circuit
132
.
Further, each residential master station
102
,
102
, . . . includes a control circuit
140
, a line impedance and voltage regulating circuit
141
, a multiplex/separation circuit
142
, a speech circuit
143
, an electric door lock releasing button
144
, a data transmission/reception circuit
145
and a power supply circuit
146
.
Further, the line power supply
104
includes a power supply circuit
150
and a choke circuit
151
.
In the intercom system for a building or an apartment house having such a structure, the choke circuit
151
of the line power supply
104
supplies stabilized direct current power such as DC 24 V, for example, to the common line
103
from the power supply circuit
150
. This direct current power is supplied as standby operational power to the power supply circuit
127
through the line impedance and voltage regulating circuit
121
of the talk module
110
of the main entrance station
101
and to the power supply circuits
146
through the line impedance and voltage. regulating circuits
141
of respective residential master stations
102
,
102
When a visitor standing at the entrance of the building or apartment house operates the call switch
131
of the switch module
111
of the main entrance station
101
to call a resident living in a specified residence, a calling data signal is output from the control circuit
130
in response to operation of the call switch and is transmitted to respective residential master stations
102
,
102
, . . . through the control circuit
120
, the data transmission/reception circuit
124
, the multiplex/separation circuit
122
of the talk module
110
and the common line
103
.
In respective residential master stations
102
,
102
, . . . , the control circuit
140
compares an address which forms the calling data signal which is received through the common line
103
, the multiplex/separation circuit
142
and the data transmission/reception circuit
145
with a preset address at its own terminal. If these addresses agree with each other, the control circuit
140
generates a calling tone by means of a speaker (not shown in the drawing) in the speech circuit
143
so that the resident in the called residence is informed of the call from the visitor standing at the entrance of the building or apartment house.
Upon hearing the calling tone generated by the speaker (not shown in the drawing) in the speech circuit
143
of the residential master station
102
, the resident living in the called residence of the building or apartment house picks up a handset (not shown in the drawing) in the speech circuit
143
. The control circuit
140
detects this pick up of the handset to activate the speech function (detailed explanation thereof being omitted) of the speech circuit
143
and to transmit a response data signal to the talk module
110
of the main entrance station
101
through the data transmission/reception circuit
145
, the multiplex/separation circuit
142
and the common line
103
.
In the speech module
110
of the main entrance station
101
, the control circuit
120
detects the response data signal which is received through the common line
103
, the multiplex/separation circuit
122
and the data transmission/reception circuit
124
and activates the speech function (detailed explanation thereof being omitted) of the speech circuit
123
. Accordingly, a speech path (detailed explanation being omitted) is established between a microphone and a speaker (not shown in the drawing) which form the speech circuit
123
and the handset (not shown in the drawing) of the speech circuit
143
of the residential master station
102
to enable transmitting and receiving speech signals through this speech path.
Subsequently, when the resident living in the called residence operates the electric door lock releasing button
144
of the residential master station
102
for releasing the electric door lock
105
mounted on the front door at the main entrance, a release data signal is output from the control circuit
140
and is transmitted to the control circuit
120
of the talk module
110
of the main entrance station
101
through a path similar to the path for the above-mentioned response data signal.
Further, the control circuit
120
of the talk module
110
of the main entrance station
101
detects the lock release data signal transmitted from the residential master station
102
and controls the electric door lock drive circuit
126
so as to drive the electric door lock circuit
125
to release the electric door lock
105
.
However, in the conventional intercom system for a building or an apartment house, the choke circuit
151
of the line power supply
104
has given frequency characteristics and hence, when the speech signals for establishing the talk are transmitted to the common line
103
, the frequency characteristics of the choke circuit
151
cause feedback of the speech signals so that it is difficult to cancel the feedback speech signals at the speech circuit
123
of the talk module
110
in the main entrance station
101
and at the speech circuit
143
of the called residential master station
102
whereby there exists a drawback that howling can be generated.
Further, in the line impedance and voltage regulating circuit
121
of the talk module
110
which forms the main entrance station
101
and in the line impedance and voltage regulating circuits
141
of respective residential master stations
102
,
102
, . . . , the power supply voltage from the line power supply
104
is set to a high value to ensure a dynamic range with a standby current value. At the same time, the electric door lock circuit
125
of the talk module
110
in the main entrance station
101
is driven at a stabilized low
Nakata Kengo
Shinozaki Tatsuru
Sumiya Hiroshi
Aiphone Co., Ltd.
Kuntz Curtis
Lorusso, Loud & Kelly
Taylor Barry W.
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