Telephone network coupler

Claim 2

An analog coupling device for coupling a first circuit to at least one second circuit wherein said first circuit includes a DC carrier voltage and at least one AC signal, said device which comprises: said first circuit including a loading means for introducing a resistance in said first circuit so as to produce a DC current in said first circuit in response to a voltage applied to said first circuit; said first circuit further including at least one first circuit optical emitting means, said first circuit optical emitting means for transmitting an optical signal wherein said optical signal is indicative of both said DC current and said AC signal, said first circuit further including a first circuit forward biased optical receiving means, said first circuit forward biased optical receiving means for receiving an optical signal; said second circuit including second circuit optical emitting means for transmitting an optical signal, said second circuit emitting means located in operative association with said first circuit forward biased optical receiving means; said second circuit further including second circuit optical receiving means for receiving an optical signal, said second circuit optical receiving means located in operative association with said first circuit optical emitting means, said second circuit optical receiving means including a reverse biased photo sensitive pn junction.

Claim 3

The device of claim 1 wherein: said second circuits includes transmitter and receiving circuits, said second circuit emitting means located in sid second circuit transmitting circuit, said second circuit receiving means located in said second circuit receiving circuit.

Claim 4

The device of claim 1 wherein: said second circuit further includes an AC signal generating means, said AC generating means for generating an AC signal.

Claim 5

The device of claim 3 wherein: said generated AC signal is carried by said optical signal transmitted by said second circuit emitting means so as to be introduced into said first circuit.

Claim 6

The device of claim 1 wherein: said second circuit receiving circuit includes a reversed biased photovoltaic diode means.

Claim 7

The device of claim 1 wherein: said second circuit receiving means includes a reversed biased npn transistor.

Claim 8

The device of claim 6 wherein: said npn transistor has an open collector.

Claim 9

The device of claim 6 wherein: said npn transistor includes a resistor connected to the base of said npn transistor.

Claim 10

The device of claim 1 wherein: said first circuit includes a DC polarity reversing bridge means.

Claim 11

The device of claim 1 wherein: said loading means is further capable of introducing an impedance into said first circuit.

Claim 12

The device of claim 1 wherein: said first circuit optical emitting means includes a light emitting diode.

Claim 13

The device of claim 1 wherein: said second circuit optical emitting means includes a light emitting diode.

Claim 14

The device of claim 1 wherein: said reverse biased photo sensitive pn junction is located on a transistor having an open collector.

Claim 15

The device of claim 13 wherein: said transistor is an npn transistor.

Claim 16

The device of claim 14 wherein: said npn transistor has an open collector; said npn transistor includes a resistor connected to the base of said npn transistor.

Claim 17

The device of claim 13 wherein: said loading means is further capable of introducing an impedance into said first circuit.

Claim 18

The device of claim 16 wherein: said second circuits includes transmitter and receiving circuits, said second circuit emitting means located in said second circuit transmitting circuit, said second circuit receiving means located in said second circuit receiving circuit.

Claim 19

The device of claim 7 wherein: said loading means is further capable of introducing an impedance into said first circuit.

Claim 20

The device of claim 2 wherein: said second circuit receiving circuit includes a reversed biased photovoltaic diode means.

Claim 21

The device of claim 2 wherein: said second circuit receiving means includes an npn transistor; said npn transistor has an open collector.

Claim 22

An isolation device for use with a telephone network wherein said network includes tip and ring network lines, said device comprising; a first circuit, said first circuit connecting in series with said tip and ring network lines; said first circuit including a forward biased first circuit optical signal emitting means and a first circuit forward biased optical receiving means each connected in series in said first circuit; a second circuit, said second circuit electrically isolated from said first circuit and optically connected to said first circuit; said second circuit including a second circuit optical emitting means, said second circuit optical emitting means optically associated with said first circuit optical receiving means whereby said first circuit optical receiving means receives optical signals from said second circuit optical emitting means; said second circuit including a reversed biased photo sensitive second circuit optical receiving means, said second circuit optical receiving means optically coupled with said first circuit optical emitting means so as to receive optical signals from said first circuit optical emitting means.

Claim 23

An isolation device for use with a telephone network wherein said network includes tip and ring network lines, said device comprising; a first circuit, said first circuit connecting in series with said tip and ring network lines; said first circuit including a forward biased first circuit optical signal emitting means and a first circuit forward biased optical receiving means each connected in series in said first circuit; a second circuit, said second circuit electrically isolated from said first circuit and optically connected to said first circuit; said second circuit including a second circuit optical emitting means, said second circuit optical emitting means optically associated with said first circuit optical receiving means whereby said first circuit optical receiving means receives optical signals from said second circuit optical emitting means; said second circuit including a reversed biased photo sensitive second circuit optical receiving means, said second circuit optical receiving means optically coupled with said first circuit optical emitting means so as to receive optical signals from said first circuit optical emitting means.

Claim 24

A device of claim 21 wherein: said first circuit optical receiving means includes a forward biased bipolar transistor; said second circuit optical receiving means includes a reverse biased pn junction.

Claim 25

A circuit isolation device which comprises: a first circuit, said first circuit including a first circuit forward biased LED and a first circuit forward biased bipolar transistor connected together in series; a second circuit, said second circuit including a second circuit LED and a reverse biased photo sensitive pn junction; said second circuit LED optically connected with the base emitter junction of said first circuit bipolar transistor; said first circuit LED optically connected with said second circuit pn junction.

Claim 26

A circuit isolation device which comprises: a first circuit, said first circuit including a first circuit forward biased LED and a first circuit forward biased bipolar transistor connected together in series; a second circuit, said second circuit including a second circuit LED and a reverse biased photo sensitive pn junction; said second circuit LED optically connected with the base emitter junction of said first circuit bipolar transistor; said first circuit LED optically connected with said second circuit pn junction.

Claim 27

A circuit isolation device which comprises: a first circuit, said first circuit including a first circuit forward biased LED and a first circuit forward biased bipolar transistor connected together in series; a second circuit, said second circuit including a second circuit LED and a reverse biased photo sensitive pn junction; said second circuit LED optically connected with the base emitter junction of said first circuit bipolar transistor; said first circuit LED optically connected with said second circuit pn junction; and a first circuit buffer transistor and a resistor, one of the leads of said resistor connected to the emitter of said buffer transistor, the other of the leads of said resistor and the base of said buffer transistor connected to the emitter of said first circuit forward biased bipolar transistor, the collector of said first circuit forward biased bipolar transistor and the collector of said buffer transistor connected to the cathode of said first circuit LED.

Claim 28

A circuit isolation device which comprises: a first circuit, said first circuit including a first circuit forward biased LED and a first circuit forward biased bipolar transistor connected together in series; a second circuit, said second circuit including a second circuit LED and a reverse biased photo sensitive pn junction; said second circuit LED optically connected with the base emitter junction of said first circuit bipolar transistor; said first circuit LED optically connected with said second circuit pn junction; and a first circuit buffer transistor and a resistor, one of the leads of said resistor connected to the emitter of said buffer transistor, the other of the leads of said resistor and the base of said buffer transistor connected to the emitter of said first circuit forward biased bipolar transistor, the collector of said first circuit forward biased bipolar transistor and the collector of said buffer transistor connected to the cathode of said first circuit LED.

Claim 29

An isolation device for use with a telephone network wherein said network includes tip and ring network lines, said device comprising; a first circuit, said first circuit connecting in series with said tip and ring network lines; said first circuit including a forward biased first circuit optical signal emitting means and a first circuit forward biased optical receiving means each connected in series in said first circuit; a second circuit, said second circuit electrically isolated from said first circuit and optically connected to said first circuit; said second circuit including a second circuit optical emitting means, said second circuit optical emitting means optically associated with said first circuit optical receiving means whereby said first circuit optical receiving means receives optical signals from said second circuit optical emitting means; said second circuit including a reversed biased photo sensitive second circuit optical receiving means, said second circuit optical receiving means optically coupled with said first circuit optical emitting means so as to receive optical signals from said first circuit optical emitting means; said first circuit optical receiving means includes a forward biased bipolar transistor; and said second circuit optical receiving means includes a reverse biased photo sensitive base emitter pn junction.

Claim 30

An isolation device for use with a telephone network wherein said network includes tip and ring network lines, said device comprising; a first circuit, said first circuit connecting in series with said tip and ring network lines; said first circuit including a forward biased first circuit optical signal emitting means and a first circuit forward biased optical receiving means each connected in series in said first circuit; a second circuit, said second circuit electrically isolated from said first circuit and optically connected to said first circuit; said second circuit including a second circuit optical emitting means, said second circuit optical emitting means optically associated with said first circuit optical receiving means whereby said first circuit optical receiving means receives optical signals from said second circuit optical emitting means; said second circuit including a reversed biased photo sensitive second circuit optical receiving means, said second circuit optical receiving means optically coupled with said first circuit optical emitting means so as to receive optical signals from said first circuit optical emitting means; said first circuit optical receiving means includes a forward biased bipolar transistor; and said second circuit optical receiving means includes a reverse biased photo sensitive base emitter pn junction.

Claim 31

An analog coupling device for coupling a first circuit to at least one second circuit wherein said first circuit includes a DC carrier voltage and at least one AC signal, said device which comprises: said first circuit including a loading means for introducing a resistance in said first circuit so as to produce a DC current in said first circuit in response to a voltage applied to said first circuit; said first circuit further including at least one first circuit optical emitting means, said first circuit optical emitting means for transmitting an optical signal wherein said optical signal is indicative of both said DC current and said AC signal, said first circuit further including a first circuit forward biased optical receiving means, said first circuit forward biased optical receiving means for receiving an optical signal; said second circuit including second circuit optical emitting means for transmitting an optical signal, said second circuit emitting means located in operative association with said first circuit forward biased optical receiving means; and said second circuit further including second circuit optical receiving means for receiving an optical signal, said second circuit optical receiving means located in operative association with said first circuit optical emitting means, said second circuit optical receiving means including a reverse biased photo sensitive base emitter pn junction.

Claim 32

An analog coupling device for coupling a first circuit to at least one second circuit wherein said first circuit includes a DC carrier voltage and at least one AC signal, said device which comprises: said first circuit including a loading means for introducing a resistance in said first circuit so as to produce a DC current in said first circuit in response to a voltage applied to said first circuit; said first circuit further including at least one first circuit optical emitting means, said first circuit optical emitting means for transmitting an optical signal wherein said optical signal is indicative of both said DC current and said AC signal, said first circuit further including a first circuit forward biased optical receiving means, said first circuit forward biased optical receiving means for receiving an optical signal; said second circuit including second circuit optical emitting means for transmitting an optical signal, said second circuit emitting means located in operative association with said first circuit forward biased optical receiving means; and said second circuit further including second circuit optical receiving means for receiving an optical signal, said second circuit optical receiving means located in operative association with said first circuit optical emitting means, said second circuit optical receiving means including a reverse biased photo sensitive base emitter pn junction.

Claim 33

An analog coupling device for coupling a first circuit to at least one second circuit wherein said first circuit includes a DC carrier voltage and at least one AC signal, said device which comprises: said first circuit including a loading means for introducing a resistance in said first circuit so as to produce a DC current in said first circuit in response to a voltage applied to said first circuit; said first circuit further including at least one first circuit optical emitting means, said first circuit optical emitting means for transmitting an optical signal wherein said optical signal is indicative of both said DC current and said AC signal, said first circuit further including a first circuit forward biased optical receiving means, said first circuit forward biased optical receiving means for receiving an optical signal, and wherein the total DC resistance of said first circuit at 20 milliamps of current is less than 200 ohms; said second circuit including second circuit optical emitting means for transmitting an optical signal, said second circuit emitting means located in operative association with said first circuit forward biased optical receiving means; and said second circuit further including second circuit optical receiving means for receiving an optical signal, said second circuit optical receiving means located in operative association with said first circuit optical emitting means, said second circuit optical receiving means including a reverse biased photo sensitive pn junction.

Claim 34

An analog coupling device for coupling a first circuit to at least one second circuit wherein said first circuit includes a DC carrier voltage and at least one AC signal, said device which comprises: said first circuit including a loading means for introducing a resistance in said first circuit so as to produce a DC current in said first circuit in response to a voltage applied to said first circuit; said first circuit further including at least one first circuit optical emitting means, said first circuit optical emitting means for transmitting an optical signal wherein said optical signal is indicative of both said DC current and said AC signal, said first circuit further including a first circuit forward biased optical receiving means, said first circuit forward biased optical receiving means for receiving an optical signal, and wherein the total DC resistance of said first circuit at 20 milliamps of current is less than 200 ohms; said second circuit including second circuit optical emitting means for transmitting an optical signal, said second circuit emitting means located in operative association with said first circuit forward biased optical receiving means; and said second circuit further including second circuit optical receiving means for receiving an optical signal, said second circuit optical receiving means located in operative association with said first circuit optical emitting means, said second circuit optical receiving means including a reverse biased photo sensitive pn junction.

Claim 35

An analog coupling device for coupling a first circuit to at least one second circuit wherein said first circuit includes a DC carrier voltage and at least one AC signal, said device which comprises: said first circuit including a loading means for introducing a resistance in said first circuit so as to produce a DC current in said first circuit in response to a voltage applied to said first circuit; said first circuit further including at least one first circuit optical emitting means, said first circuit optical emitting means for transmitting an optical signal wherein said optical signal is indicative of both said DC current and said AC signal, said first circuit further including a first circuit forward biased optical receiving means, said first circuit forward biased optical receiving means for receiving an optical signal; said first circuit optical emitting means wired in series in said first circuit such that all current conducted in said first circuit passes through said first circuit optical emitting means; said second circuit including second circuit optical emitting means for transmitting an optical signal, said second circuit emitting means located in operative association with said first circuit forward biased optical receiving means; and said second circuit further including second circuit optical receiving means for receiving an optical signal, said second circuit optical receiving means located in operative association with said first circuit optical emitting means, said second circuit optical receiving means including a reverse biased photo sensitive pn junction.

Claim 36

An analog coupling device for coupling a first circuit to at least one second circuit wherein said first circuit includes a DC carrier voltage and at least one AC signal, said device which comprises: said first circuit including a loading means for introducing a resistance in said first circuit so as to produce a DC current in said first circuit in response to a voltage applied to said first circuit; said first circuit further including at least one first circuit optical emitting means, said first circuit optical emitting means for transmitting an optical signal wherein said optical signal is indicative of both said DC current and said AC signal, said first circuit further including a first circuit forward biased optical receiving means, said first circuit forward biased optical receiving means for receiving an optical signal; said first circuit optical emitting means wired in series in said first circuit such that all current conducted in said first circuit passes through said first circuit optical emitting means; said second circuit including second circuit optical emitting means for transmitting an optical signal, said second circuit emitting means located in operative association with said first circuit forward biased optical receiving means; and said second circuit further including second circuit optical receiving means for receiving an optical signal, said second circuit optical receiving means located in operative association with said first circuit optical emitting means, said second circuit optical receiving means including a reverse biased photo sensitive pn junction.

Claim 37

An isolation device for use with a telephone network wherein said network includes tip and ring network lines, said device comprising; a first circuit, said first circuit connecting in series with said tip and ring network lines; said first circuit including a forward biased first circuit optical signal emitting means and a first circuit forward biased optical receiving means each connected in series in said first circuit and wherein the total current conducted in said first circuit passes through said first circuit optical signal emitting means; a second circuit, said second circuit electrically isolated from said first circuit and optically connected to said first circuit; said second circuit including a second circuit optical emitting means, said second circuit optical emitting means optically associated with said first circuit optical receiving means whereby said first circuit optical receiving means receives optical signals from said second circuit optical emitting means; and said second circuit including a reversed biased photo sensitive second circuit optical receiving means, said second circuit optical receiving means optically coupled with said first circuit optical emitting means so as to receive optical signals from said first circuit optical emitting means.

Claim 38

An isolation device for use with a telephone network wherein said network includes tip and ring network lines, said device comprising; a first circuit, said first circuit connecting in series with said tip and ring network lines; said first circuit including a forward biased first circuit optical signal emitting means and a first circuit forward biased optical receiving means each connected in series in said first circuit and wherein the total current conducted in said first circuit passes through said first circuit optical signal emitting means; a second circuit, said second circuit electrically isolated from said first circuit and optically connected to said first circuit; said second circuit including a second circuit optical emitting means, said second circuit optical emitting means optically associated with said first circuit optical receiving means whereby said first circuit optical receiving means receives optical signals from said second circuit optical emitting means; and said second circuit including a reversed biased photo sensitive second circuit optical receiving means, said second circuit optical receiving means optically coupled with said first circuit optical emitting means so as to receive optical signals from said first circuit optical emitting means.

Claim 39

A circuit isolation device which comprises: a first circuit, said first circuit including first and second input junctions; said first circuit further including a first circuit forward biased LED connected in series with said first input junction and a first circuit forward biased bipolar transistor connected with said second input junction, said LED further connected to said forward biased bipolar transistor, said series connection between said LED and said first input junction comprising the only pathway in said first circuit between said first input junction and said LED; a second circuit, said second circuit including a second circuit LED and a reverse biased photo sensitive pn junction; said second circuit LED optically connected with the base emitter junction of said first circuit bipolar transistor; and said first circuit LED optically connected with said second circuit photo sensitive pn junction.

Claim 40

A circuit isolation device which comprises: a first circuit, said first circuit including first and second input junctions; said first circuit further including a first circuit forward biased LED connected in series with said first input junction and a first circuit forward biased bipolar transistor connected with said second input junction, said LED further connected to said forward biased bipolar transistor, said series connection between said LED and said first input junction comprising the only pathway in said first circuit between said first input junction and said LED; a second circuit, said second circuit including a second circuit LED and a reverse biased photo sensitive pn junction; said second circuit LED optically connected with the base emitter junction of said first circuit bipolar transistor; and said first circuit LED optically connected with said second circuit photo sensitive pn junction.

Claim 41

An analog coupling device for coupling a first circuit to at least one second circuit wherein said first circuit includes a DC carrier voltage and at least one AC signal, said device which comprises: said first circuit including a loading means for introducing a resistance in said first circuit so as to produce a DC current in said first circuit in response to a voltage applied to said first circuit; said first circuit further including at least one first circuit optical emitting means, said first circuit optical emitting means for transmitting an optical signal wherein said optical signal is indicative of both said DC current and said AC signal, said first circuit further including a first circuit forward biased optical receiving means, said first circuit forward biased optical receiving means for receiving an optical signal, together said first circuit optical emitting means and said first circuit forward biased optical receiving means containing not more than three forward biased junctions; said second circuit including second circuit optical emitting means for transmitting an optical signal, said second circuit emitting means located in operative association with said first circuit forward biased optical receiving mens; and said second circuit furthe rincluding second circuit optical receiving means for receiving an optical signal, said second circuit optical receiving means located in operative association with said first circuit optical emitting means, said second circuit optical receiving means including a reverse biased photo sensitive pn junction.

Claim 42

An analog coupling device for coupling a first circuit to at least one second circuit wherein said first circuit includes a DC carrier voltage and at least one AC signal, said device which comprises: said first circuit including a loading means for introducing a resistance in said first circuit so as to produce a DC current in said first circuit in response to a voltage applied to said first circuit; said first circuit further including at least one first circuit optical emitting means, said first circuit optical emitting means for transmitting an optical signal wherein said optical signal is indicative of both said DC current and said AC signal, said first circuit further including a first circuit forward biased optical receiving means, said first circuit forward biased optical receiving means for receiving an optical signal, together said first circuit optical emitting means and said first circuit forward biased optical receiving means containing not more than three forward biased junctions; said second circuit including second circuit optical emitting means for transmitting an optical signal, said second circuit emitting means located in operative association with said first circuit forward biased optical receiving mens; and said second circuit furthe rincluding second circuit optical receiving means for receiving an optical signal, said second circuit optical receiving means located in operative association with said first circuit optical emitting means, said second circuit optical receiving means including a reverse biased photo sensitive pn junction.

Claim 43

An isolation device for use with a telephone network wherein said network includes tip and ring network lines, said device comprising; a first circuit, said first circuit connecting in series with said tip and ring network lines; said first circuit including a forward biased first circuit optical signal emitting means and a first circuit forward biased optical receiving means each connected in series in said first circuit, together said first circuit optical signal emitting means and said first circuit optical receiving means containing not more than three forward biased junctions; a second circuit, said second circuit electrically isolated from said first circuit and optically connected to said first circuit; said second circuit including a second circuit optical emitting means, said second circuit optical emitting means optically associated with said first circuit optical receiving means whereby said first circuit optical receiving means receives optical signals from said second circuit optical emitting means; and said second circuit including a reversed biased photo sensitive second circuit optical receiving means, said second circuit optical receiving means optically coupled with said first circuit optical emitting means so as to receive optical signals from said first circuit optical emitting means.

Claim 44

An isolation device for use with a telephone network wherein said network includes tip and ring network lines, said device comprising; a first circuit, said first circuit connecting in series with said tip and ring network lines; said first circuit including a forward biased first circuit optical signal emitting means and a first circuit forward biased optical receiving means each connected in series in said first circuit, together said first circuit optical signal emitting means and said first circuit optical receiving means containing not more than three forward biased junctions; a second circuit, said second circuit electrically isolated from said first circuit and optically connected to said first circuit; said second circuit including a second circuit optical emitting means, said second circuit optical emitting means optically associated with said first circuit optical receiving means whereby said first circuit optical receiving means receives optical signals from said second circuit optical emitting means; and said second circuit including a reversed biased photo sensitive second circuit optical receiving means, said second circuit optical receiving means optically coupled with said first circuit optical emitting means so as to receive optical signals from said first circuit optical emitting means.

Claim 45

A circuit isolation device which comprises: a first circuit having not more than five forward biased devices, said forward biased devices including a first circuit forwrad biased LED and two first circuit forward biased bipolar transistors; a second circuit, said second circuit including a second circuit LED and a reverse biased photo sensitive pn junction; said second circuit LED optically connected with the base emitter junction of one of said first circuit bipolar transistors; and said first circuit LED optically connected with said second circuit pn junction.

Claim 46

A circuit isolation device which comprises: a first circuit having not more than five forward biased devices, said forward biased devices including a first circuit forwrad biased LED and two first circuit forward biased bipolar transistors; a second circuit, said second circuit including a second circuit LED and a reverse biased photo sensitive pn junction; said second circuit LED optically connected with the base emitter junction of one of said first circuit bipolar transistors; and said first circuit LED optically connected with said second circuit pn junction.

Claim 47

A circuit isolation device which comprises: a first circuit, said first circuit including a first circuit forward biased LED and a first circuit forward biased bipolar transistor connected together in series; a second circuit, said second circuit including a second circuit LED and a reverse biased photo sensitive base emitter pn junction; said second circuit LED optically connected with the base emitter junction of said first circuit bipolar transistor; and said first circuit LED optically connected with said second circuit pn junction.

Claim 48

A circuit isolation device which comprises: a first circuit, said first circuit including a first circuit forward biased LED and a first circuit forward biased bipolar transistor connected together in series; a second circuit, said second circuit including a second circuit LED and a reverse biased photo sensitive base emitter pn junction; said second circuit LED optically connected with the base emitter junction of said first circuit bipolar transistor; and said first circuit LED optically connected with said second circuit pn junction.

Claim 49

An isolation device for use with a telephone network wherein said network includes tip and ring network lines, said device comprising; a first circuit, said first circuit connecting in series with said tip and ring network lines; said first circuit including a forward biased first circuit optical signal emitting means and a first circuit forward biased optical receiving means each connected in series in said first circuit and wherein the total DC resistance of said first circuit with 20 milliamps of current is less than 200 ohms; a second circuit, said second circuit electrically isolated from said first circuit and optically connected to said first circuit; said second circuit including a second circuit optical emitting means, said second circuit optical emitting means optically associated with said first circuit optical receiving means whereby said first circuit optical receiving means receives optical signals from said second circuit optical emitting means; and said second circuit including a reversed biased photo sensitive second circuit optical receiving means, said second circuit optical receiving means optically coupled with said first circuit optical emitting means so as to receive optical signals from said first circuit optical emitting means.

Claim 50

An isolation device for use with a telephone network wherein said network includes tip and ring network lines, said device comprising; a first circuit, said first circuit connecting in series with said tip and ring network lines; said first circuit including a forward biased first circuit optical signal emitting means and a first circuit forward biased optical receiving means each connected in series in said first circuit and wherein the total DC resistance of said first circuit with 20 milliamps of current is less than 200 ohms; a second circuit, said second circuit electrically isolated from said first circuit and optically connected to said first circuit; said second circuit including a second circuit optical emitting means, said second circuit optical emitting means optically associated with said first circuit optical receiving means whereby said first circuit optical receiving means receives optical signals from said second circuit optical emitting means; and said second circuit including a reversed biased photo sensitive second circuit optical receiving means, said second circuit optical receiving means optically coupled with said first circuit optical emitting means so as to receive optical signals from said first circuit optical emitting means.