Telephonic communications – Telephone line or system combined with diverse electrical... – To produce visual-graphic copy
Reexamination Certificate
1999-04-13
2002-08-27
Chan, Wing F. (Department: 2743)
Telephonic communications
Telephone line or system combined with diverse electrical...
To produce visual-graphic copy
C379S100050, C358S400000
Reexamination Certificate
active
06442253
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ISDN (integrated services digital network) terminal apparatus which is connected to the ISDN line for use and allows a facsimile apparatus which is designed to be connected to the public switched telephone network line for use, to be connected to the ISDN line for use.
2. Description of the Related Art
Recently, the number of ISDN subscribers has been increased as the Internet is popularized and the transmission speed increases.
FIG. 4
shows a use condition of an ISDN line
1
. An ISDN subscriber's telephone apparatus
2
, facsimile apparatus
3
or personal computer
4
can be connected to the ISDN line
1
through a terminal adapter (hereinafter referred to as “TA”)
5
and a digital service unit (hereinafter referred to as “DSU”)
6
. A TA in which the function of the DSU
6
is incorporated has been commercialized. An apparatus has also been commercialized that is provided with an analog port for allowing a facsimile apparatus and a cordless telephone apparatus which have been used for the public switched telephone network line, to be connected to the ISDN line
1
. A G
4
facsimile apparatus which is developed specifically for the ISDN line is available. However, the G
4
facsimile apparatus has not widely penetrated in the home consumer market because the G
4
facsimile apparatus is large in size and expensive.
The G
3
facsimile apparatus
3
as shown in
FIG. 4
has an interface for connecting the facsimile apparatus
3
to the public switched telephone network line. The facsimile apparatus
3
cannot directly be connected to the ISDN line
1
because the interface for the ISDN line
1
is different, and accordingly the TA
5
and the DSU
6
are necessary. To the TA provided with a terminal called an analog port, conventional apparatuses designed for the public switched telephone network line can be connected. The analog port is provided with the function of an exchange and is capable of operating conventional apparatuses designed for the public switched telephone network line.
FIG. 5
shows a schematic configuration of an analog port
10
. The analog port
10
has the function of an exchange for the public switched telephone network line. An exchange for the public switched telephone network line comprises a call signal generating circuit, an off-hook detecting circuit for detecting that the handset is lifted, an office voltage supplying circuit and a polarity-reversing circuit. When the calling party's handset is lifted, the line thereof is closed and current flows through the line, so that the exchange detects that the handset is lifted and sends out a dial tone. The calling party sends out a dial number by means of tones or pulses. Recognizing this, the exchange specifies the called party's line. The exchange then checks the line and when the line is not busy, outputs a call signal of a voltage of 75 V. By the call signal, the called party's telephone rings. The exchange sends a ringback tone to the calling party to inform the calling party that the called party's telephone apparatus is ringing. When the called party's handset is lifted, the line is closed, whereby the exchange recognizes that the handset is lifted. This recognition stops the transmission of the call signal to the called party and the transmission of the ringback tone to the calling party, and the telephone line is connected, so that a telephone conversation can be performed.
The exchange has other various functions and the facsimile apparatus is designed to operate in accordance with the functions. Therefore, the analog port
10
is designed to provide these functions. The analog port
10
of
FIG. 5
has a call signal generating circuit
11
for generating a call signal having an amplitude of a voltage of as high as 75 V and issues a signal in a cycle of 16 Hz. A codec/tone generating circuit
12
performs a codec operation of converting analog signals such as voice into digital signals to transmit the digital signals to the ISDN line
1
and converting digital signals received from the ISDN line
1
into analog signals, and an operation of generating a tone signal of a specific frequency in response to a specific digital signal received through the ISDN line
1
. A line current supplying/polarity-reversing circuit
13
performs the functions of the office voltage supplying circuit and the polarity-reversing circuit for the telephone apparatus
2
and the facsimile apparatus
3
for the public switched telephone network line. A line current detecting circuit
14
determines whether the handset is lifted off the hook or not by detecting that an off-hook operation of lifting the handset of the telephone apparatus
2
closes the line to increase the current supplied from the line current supplying/polarity-reversing circuit
13
. The office voltage supplied from the line current supplying/polarity-reversing circuit
13
through the line current detecting circuit
14
is directed out through an analog port output terminal
15
. By connecting the telephone apparatus
2
or the facsimile apparatus
3
designed for the public switched telephone network line to the analog port output terminal
15
, the telephone apparatus
2
or the facsimile apparatus
3
can be operated similarly to the case in which a conventional apparatus is connected to the exchange.
As shown in
FIG. 4
, in order for a subscriber of the ISDN line
1
to connect the telephone apparatus
2
, facsimile apparatus
3
or personal computer
4
designed for the public switched telephone network line to the ISDN line
1
, it is necessary to use a TA or DSU having the analog port
10
. Therefore, extra parts are necessary, extra power is consumed and as well the advantage of the function of the ISDN line
1
cannot be fully taken, so that the ISDN line is an inconvenient and expensive item for the ISDN subscriber. When the telephone apparatus
2
, the facsimile apparatus
3
or the personal computer
4
is the calling party, a dial number is sent out by means of tones or pulses. It is necessary for the analog port
10
to recognize the dial number by means of tones or pulses and to specify the called party's line. Since the exchange has functions other than this and the facsimile apparatus
3
is designed to operate in accordance with these functions, it is necessary to design the analog port
10
so as to provide the functions of the exchange. Moreover, the G
3
facsimile apparatus operates while monitoring the occurrence of abnormal conditions of the apparatus and the line with an incorporated CPU. For example, on the called party's side, reception is performed while monitoring the signal level of the reception signal, and when the signal terminates, it is determined whether the signal terminates normally or due to an instantaneous chopping. When it is determined that the signal terminates normally, the apparatus performs the next operation. When it is determined that the signal terminates due to an instantaneous chopping, the monitoring of the signal is continued, and when the signal comes again, the reception is continued. When the signal absence is continued, a processing to be performed when an abnormal condition occurs in the line is performed.
In the case of the ISDN line
1
, the line condition is normally monitored by a different block and cannot be monitored by the signal output to the analog port
10
. Therefore, when an abnormal condition occurs, a processing similar to that performed in the case of the public switched telephone network line must be performed through the analog port output terminal
15
to stop the operation. For example, the signal is stopped or the polarity of the line voltage is reversed to stop the operation of the facsimile apparatus
3
. Since the output condition of the analog port output terminal
15
is changed after the occurrence of an abnormal condition is detected and a processing to handle the abnormal condition is performed as described above, a delay is caused in
Chan Wing F.
Nixon & Vanderhye P.C.
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