초록 ▼

A communication device includes: an oscillating circuit for generating a single including a signal potential that is based on a reference potential; a first terminal for communicating with a vehicle; and a first resistance circuit connected between an output of the oscillating circuit and the first

A communication device includes: an oscillating circuit for generating a single including a signal potential that is based on a reference potential; a first terminal for communicating with a vehicle; and a first resistance circuit connected between an output of the oscillating circuit and the first terminal and having a resistance value variable according to a first input signal. Preferably, the vehicle includes: a second terminal connected to the first terminal; and a second resistance circuit connected between a ground node fed with the reference potential and the second terminal. The vehicle is provided with a first signal extraction node on a path connecting the second terminal and the second resistance circuit to each other.

대표청구항 ▼

1. A communication device communicating with a vehicle, comprising: a signal generating unit for generating a signal including a signal potential that is based on a reference potential;a first terminal for performing two-way communication with said vehicle;a first resistance circuit connected betwee

1. A communication device communicating with a vehicle, comprising: a signal generating unit for generating a signal including a signal potential that is based on a reference potential;a first terminal for performing two-way communication with said vehicle;a first resistance circuit connected between an output of said signal generating unit and said first terminal and having a resistance value varying according to a first input signal; anda detecting unit detecting a signal at a signal extraction node on a path connecting said first terminal and said first resistance circuit to each other. 2. The communication device according to claim 1, wherein said vehicle includesa second terminal connected to said first terminal, anda second resistance circuit connected between a node fed with said reference potential and said second terminal, andsaid vehicle is provided with a first signal extraction node on a path connecting said second terminal and said second resistance circuit to each other. 3. The communication device according to claim 2, wherein said second resistance circuit has a resistance value varying according to a second input signal. 4. The communication device according to claim 2, wherein said vehicle further includes a rectifying circuit connected between said second terminal and said second resistance circuit, andsaid rectifying circuit includesa rectifying element having a forward direction set at a direction from said second terminal toward said second resistance circuit, anda switching element becoming conductive in accordance with a control signal to allow a current to flow such that the current is able to flow from said second terminal in a direction opposite to the forward direction of said rectifying element. 5. The communication device according to claim 4, wherein said second resistance circuit includesa first resistance element connected between said rectifying element and the node fed with said reference potential, anda second resistance element connected between said switching element and the node fed with said reference potential. 6. The communication device according to claim 3, wherein when said signal potential is 12 V while said reference potential is 0 V, said first and second resistance circuits are configured to be capable of switchably outputting a plurality of electric potentials from said signal extraction node or said first signal extraction node, said plurality of electric potentials including a first electric potential between 4 V and 5V and a second electric potential between 7 V and 8 V. 7. A communication system comprising: a vehicle; anda communication device communicating with said vehicle,said communication device includinga signal generating unit for generating a signal including a signal potential that is based on a reference potential,a first terminal for performing two-way communication with said vehicle;a first resistance circuit connected between an output of said signal generating unit and said first terminal and having a resistance value varying according to a first input signal, anda detecting unit detecting a signal at a signal extraction node on a path connecting said first terminal and said first resistance circuit to each other. 8. The communication system according to claim 7, wherein said vehicle includesa second terminal connected to said first terminal, anda second resistance circuit connected between a node fed with said reference potential and said second terminal, andsaid vehicle is provided with a first signal extraction node on a path connecting said second terminal and said second resistance circuit to each other. 9. The communication system according to claim 8, wherein said second resistance circuit has a resistance value varying according to a second input signal. 10. The communication system according to claim 8, wherein said vehicle further includes a rectifying circuit connected between said second terminal and said second resistance circuit, andsaid rectifying circuit includesa rectifying element having a forward direction set at a direction from said second terminal toward said second resistance circuit, anda switching element becoming conductive in accordance with a control signal to allow a current to flow such that the current is able to flow from said second terminal in a direction opposite to the forward direction of said rectifying element. 11. The communication system according to claim 10, wherein said second resistance circuit includesa first resistance element connected between said rectifying element and the node fed with said reference potential, anda second resistance element connected between said switching element and the node fed with said reference potential. 12. The communication system according to claim 9, wherein when said signal potential is 12 V while said reference potential is 0 V, said first and second resistance circuits are configured to be capable of switchably outputting a plurality of electric potentials from said signal extraction node or said first signal extraction node, said plurality of electric potentials including a first electric potential between 4 V and 5 V and a second electric potential between 7 V and 8 V. 13. A vehicle communicating with a communication device, said communication device includinga signal generating unit for generating a signal including a signal potential that is based on a reference potential,a first terminal performing two-way communication with said vehicle;a first resistance circuit connected between an output of said signal generating unit and said first terminal and having a resistance value varying according to a first input signal, anda detecting unit detecting a signal at a signal extraction node on a path connecting said first terminal and said first resistance circuit to each other,said vehicle comprising:a second terminal connected to said first terminal; anda second resistance circuit connected between a node fed with said reference potential and said second terminal,said vehicle being provided with a first signal extraction node on a path connecting said second terminal and said second resistance circuit to each other. 14. The vehicle according to claim 13, wherein said second resistance circuit has a resistance value varying according to a second input signal. 15. The vehicle according to claim 14, wherein when said signal potential is 12 V while said reference potential is 0 V, said first and second resistance circuits are configured to be capable of switchably outputting a plurality of electric potentials from said signal extraction node or said first signal extraction node, said plurality of electric potentials including a first electric potential between 4 V and 5 V and a second electric potential between 7 V and 8 V.