Transmission cable
A transmission cable that has three signal lines, and in which there is little unwanted radiation noise, is provided. In a section that is perpendicular to the longitudinal direction of the differential transmission cable, the distance between any two signal lines of the three signal lines is equal to a predetermined value. The differential transmission cable is twisted in its longitudinal direction. The differential transmission cable further includes a dielectric core line, and the signal lines are formed on the surface of the dielectric core line. In the differential transmission cable, the signal lines are formed in a helix in the longitudinal direction of the dielectric core line.
1. A transmission cable that is used in a multiple differential transmission system and that performs multiple transmission of a group of three differential signals,
the transmission system comprising:
a signal transmitter and a signal receiver;
wherein the signal transmitter is connected to a differential transmission path that has first, second, and third signal lines, and comprises:
a first differential driver that transmits a first output signal, and an inverted first output signal that is a phase inverted signal of the first output signal, in response to a first bit information signal;
a second differential driver that transmits a second output signal, and an inverted second output signal that is a phase inverted signal of the second output signal, in response to a second bit information signal; and
a third differential driver that transmits a third output signal, and an inverted third output signal that is a phase inverted signal of the third output signal, in response to a third bit information signal;
wherein the signal transmitter synthesizes the first output signal and the inverted third output signal and transmits the result to the first signal line, synthesizes the second output signal and the inverted first output signal and transmits the result to the second signal line, and synthesizes the third output signal and the inverted second output signal and transmits the result to the third signal line; and
wherein the absolute value of the binary signal voltage of the first output signal and the absolute value of the binary signal voltage of the second output signal are identical, and the absolute value of the binary signal voltage of the third output signal and absolute value of the binary signal voltage of the first output signal are different;
wherein the signal receiver is connected to the differential transmission path, which has the first, second, and third signal lines, and comprises:
a first differential receiver that detects a polarity of a terminal voltage that is generated in a first terminal resistor that is connected between the first signal line and the second signal line, and outputs the result of that detection as a first bit information signal;
a second differential receiver that detects a polarity of a terminal voltage that is generated in a second terminal resistor that is connected between the second signal line and the third signal line, and outputs the result of that detection as a second bit information signal;
a third differential receiver that detects a polarity of a terminal voltage that is generated in a third terminal resistor that is connected between the third signal line and the first signal line, and outputs the result of that detection as a third bit information signal;
a comparison unit of determining whether or not the absolute value of the third terminal voltage that is generated in the third terminal resistor exceeds a predetermined threshold voltage; and
a control unit of outputting the first, second, and third bit information signals that are output from the first, second, and third differential receivers, when the absolute value of the third terminal voltage exceeds the predetermined threshold voltage, and outputs a 0 or 1 for all of the first, second, and third bit information signals, depending on the third bit information signal that is output from the third differential receiver, when the absolute value of the third terminal voltage does not exceed the predetermined threshold voltage;
wherein the threshold voltage is set so that it is larger than the absolute value of the difference between the absolute value of the binary signal voltage of the first output signal and the absolute value of the binary signal voltage of the third output signal;
wherein said transmission cable comprises:
three signal lines; and
wherein in a cross section perpendicular to a longitudinal direction of the transmission cable, a distance between any pair of signal lines of the three signal lines is equal to a predetermined value.
2. The transmission cable according to claim 1 ,
wherein the three signal lines are twisted about one another in the longitudinal direction of the three signal lines.
3. The transmission cable according to claim 1 ,
wherein the three signal lines have 120-degree rotational symmetry about the center of the transmission cable, in a cross section perpendicular to the longitudinal direction of the transmission cable.
4. The transmission cable according to claim 1 ,
wherein the transmission cable has 120-degree rotational symmetry about the center of the transmission cable, in a cross section perpendicular to the longitudinal direction of the transmission cable.
5. A transmission cable comprising:
a core line made from a dielectric material; and
three signal lines that are formed on a surface of the core line;
wherein in a cross section perpendicular to a longitudinal direction of the transmission cable, a distance between any pair of signal lines of the three signal lines is equal to a predetermined value;
wherein the transmission cable is used in a multiple differential transmission system and performs multiple transmission of a group of three differential signals, and the transmission system comprises:
a signal transmitter and a signal receiver;
wherein the signal transmitter is connected to a differential transmission path that has first, second, and third signal lines, and comprises:
a first differential driver that transmits a first output signal, and an inverted first output signal that is a phase inverted signal of the first output signal, in response to a first bit information signal;
a second differential driver that transmits a second output signal, and an inverted second output signal that is a phase inverted signal of the second output signal, in response to a second bit information signal; and
a third differential driver that transmits a third output signal, and an inverted third output signal that is a phase inverted signal of the third output signal, in response to a third bit information signal;
wherein the signal transmitter synthesizes the first output signal and the inverted third output signal and transmits the result to the first signal line, synthesizes the second output signal and the inverted first output signal and transmits the result to the second signal line, and synthesizes the third output signal and the inverted second output signal and transmits the result to the third signal line; and
wherein the absolute value of the binary signal voltage of the first output signal and the absolute value of the binary signal voltage of the second output signal are identical, and the absolute value of the binary signal voltage of the third output signal and absolute value of the binary signal voltage of the first output signal are different;
wherein the signal receiver is connected to the differential transmission path, which has the first, second, and third signal lines and comprises:
a first differential receiver that detects a polarity of a terminal voltage that is generated in a first terminal resistor that is connected between the first signal line and the second signal line, and outputs the result of that detection as a first bit information signal;
a second differential receiver that detects a polarity of a terminal voltage that is generated in a second terminal resistor that is connected between the second signal line and the third signal line, and outputs the result of that detection as a second bit information signal;
a third differential receiver that detects a polarity of a terminal voltage that is generated in a third terminal resistor that is connected between the third signal line and the first signal line, and outputs the result of that detection as a third bit information signal;
a comparison unit for determining whether or not the absolute value of the third terminal voltage that is generated in the third terminal resistor exceeds a predetermined threshold voltage; and
a control unit for outputting the first, second, and third bit information signals that are output from the first, second, and third differential receivers, when the absolute value of the third terminal voltage exceeds the predetermined threshold voltage, and outputs a 0 or 1 for all of the first, second, and third bit information signals, depending on the third bit information signal that is output from the third differential receiver, when the absolute value of the third terminal voltage does not exceed the predetermined threshold voltage;
wherein the threshold voltage is set so that it is larger than the absolute value of the difference between the absolute value of the binary signal voltage of the first output signal and the absolute value of the binary signal voltage of the third output signal.
6. The transmission cable according to claim 5 ,
wherein the three signal lines are formed as a conductor pattern that is printed on a surface of the core line.
7. The transmission cable according to claim 5 ,
wherein the three signal lines are formed by etching a conductor layer that is formed on a surface of the core line.
8. The transmission cable according to claim 5 ,
wherein the three signal lines are formed in a helical shape in the longitudinal direction of the core line.