Communication apparatus using telephone line

A communication apparatus using a telephone line for selectively transmitting and receiving a voice signal and an image signal via the telephone line, the communication apparatus comprising:

• a control circuit which selectively opens and closes the telephone line;
• at least one voice signal communications device connected to the control circuit, said voice signal communications device being operable to transmit and receive a voice signal via the telephone line, the voice signal communications device including a line length compensating circuit;
• at least one image signal communications device connected to the control circuit, said image signal communications device being operable to transmit and receive an image signal via the telephone line;
• a termination resistor connected between the image signal communications device and the control circuit, which said termination resistor servers as a termination for both the voice communication means and the image signal communication means;
• a transmission instruction circuit operable to instruct a transmission start for either the voice signal originated from the voice signal communications device or the image signal originated from the image signal communications device;
• a controller which responds to an output of the transmission instruction circuit, and causes the control circuit to close the telephone line and isolate the image signal communications device from the termination resistor when an instruction is given to start transmitting the voice signal from the voice signal communications device, or to close the telephone line and isolate the voice signal communications device when an instruction is given to start transmitting the image signal from the image signal communications device.

A communication apparatus using a telephone line for selectively transmitting and receiving a voice signal and an image signal via the telephone line, the communication apparatus comprising:

• a control circuit which selectively opens and closes the telephone line;
• a voice signal communications device connected to the control circuit, said voice signal communications device being operable to transmit and receive a voice signal via the telephone line;
• an image signal communications device connected to the control circuit, said image signal communications device being operable to transmit and receive an image signal via the telephone line;
• a termination circuit which serves as a termination for both the voice signal communications device and the image signal communications device, the termination circuit being connected to the telephone line;
• a CNG detector connected to the telephone line;
• a controller;
• a change-over switch which selectively connects the image signal communications device to one of the CNG detector and the termination circuit;
• wherein the controller operates the change-over switch so that the image signal communications device is connected to the termination circuit and thus to the telephone line upon detection of the presence of one of (1) a CNG signal on the telephone line, and (2) start of an image transmission;
• wherein the controller isolates a microphone and a speaker of the voice signal communications device upon detection of the presence of one of (1) a CNG signal on the telephone line, and (2) start of an image transmission.

A communication apparatus using a telephone line for selectively transmitting and receiving a voice signal and an image signal via the telephone line, the communication apparatus comprising:

• a voice signal communications device selectively connected to the telephone line, said voice signal communications device being operable to transmit and receive a voice signal via the telephone line, said voice signal using direct current supplied from the telephone line;
• an image signal communications device selectively connected to the telephone line, said image signal communications device being operable to transmit and receive an image signal via the telephone line;
• a termination circuit which serves as a termination for both the voice signal communications device and the image signal communications device, the termination circuit being connected to the telephone line;
• a controller which operates on a different power source than the voice signal communications device, wherein when image signal communications occurs the controller generates (1) signals to connect the image signal communications device to the telephone line via the termination circuit;
• and (2) signals to isolate an element of the voice signal communications device from the telephone line.

A communication apparatus using a telephone line for selectively transmitting and receiving a voice signal and an image signal via the telephone line, the communication apparatus comprising:

• a control circuit which selectively opens and closes the telephone line;
• at least one voice signal communications device connected to the control circuit, said voice signal communications device being operable to transmit and receive a voice signal via the telephone line via a telephone handset;
• at least one image signal communications device connected to the control circuit, said image signal communications device being operable to transmit and receive an image signal via the telephone line, a termination circuit connected between said image signal communication device and said control circuit, which said termination circuit servers as a termination for both the voice communication means and the image signal communication means;
• a controller which, at a time when the image signal communication device makes a call using DTMF signaling, keeps the handset connected to the telephone line whereby the handset can be utilized to confirm presence of a dial tone, and which when an instruction is given to start transmitting the image signal from the image signal communications device, isolates the voice signal communications device from the telephone line.