Equipment for Vehicle and Communication Interface Circuit for Use In this Equipment

• US 20100228433A1
• Filed: 11/17/2006
• Published: 09/09/2010
• Est. Priority Date: 02/17/2006
• Status: Active Grant

• Current Assignee: Mitsubishi Electric Corporation
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: Ohtsuka, Yasunori, Ohsawa, Takashi
• Granted Patent: US 8,180,526 B2
• Time in Patent Office: Days
• US Class Current: 701/36
• CPC Class Codes: H04B 2203/547 via DC power distribution
• CPC Class Codes: H04B 3/548 the power on the line being DC arrangements for feeding power H04L12/10; extracting feeding power from signals H04L25/02

Abstract

Equipment for vehicle in accordance with the present invention includes: a vehicle-mounted unit which runs with respect to a vehicle body ground on a side of a negative electrode of a battery; an impedance component having an end connected to the vehicle body ground, and another end connected to a circuit ground; a circuit to be controlled which runs with respect to the circuit ground; a control unit which runs with respect to the circuit ground, for controlling the circuit to be controlled and for outputting a communication signal in a digital form which is to be transmitted to the vehicle-mounted unit; and a communication interface circuit which runs with respect to both the vehicle body ground and the circuit ground, for cancelling a potential difference between the vehicle body ground and the circuit ground, and for carrying out bidirectional communications between the vehicle-mounted unit and the control unit.

Claims

1. Equipment for vehicle comprising:

a vehicle-mounted unit which runs with respect to a vehicle body ground to which a negative electrode of a battery power source is connected, for transmitting and receiving a communication signal in a digital form;

an impedance component having an end which is connected to said vehicle body ground, and another end which is connected to a circuit ground;

a circuit to be controlled which runs with respect to said circuit ground;

a control unit which runs with respect to said circuit ground, for controlling said circuit to be controlled, and for outputting a communication signal in a digital form which is to be transmitted to said vehicle-mounted unit;

a communication interface circuit which runs with respect to both said vehicle body ground and said circuit ground, for cancelling a potential difference which occurs between said vehicle body ground and said circuit ground due to a flow of a current which flows through said circuit to be controlled into said impedance component, and for carrying out bidirectional communications of said communication signal between said vehicle-mounted unit and said control unit.

2. The equipment for vehicle according to claim 1, characterized in comprising, as an input component of the communication interface circuit, a comparator which runs with respect to the circuit ground in such a way as to receive a communication signal which is generated with respect to the vehicle body ground from the vehicle-mounted unit, and a comparison reference signal which is generated with respect to said vehicle body ground, compare said communication signal with said comparison reference signal so as to determine whether said communication signal has a high level or a low level, and output a signal based on said determination to the control unit.

3. The equipment for vehicle according to claim 2, characterized in comprising a first constant current signal generation circuit when runs with respect to the circuit ground and which generates a constant current signal when the comparator outputs the signal, and a hysteresis circuit which runs with respect to the vehicle body ground and changes a level of the comparison reference signal inputted to the comparator when the constant current signal from said first constant current signal generation circuit flows thereinto.

4. The equipment for vehicle according to claim 1, characterized in comprising a second constant current signal generation circuit which runs with respect to the circuit ground and which generates a constant current signal from the communication signal outputted by the control unit, and a signal output circuit which runs with respect to the vehicle body ground and transmits a signal corresponding to the communication signal outputted by said control unit to the vehicle-mounted unit when the constant current signal from said second constant current signal generation circuit flows thereinto.

5. A communication interface circuit for use in equipment for vehicle including a vehicle-mounted unit which runs with respect to a vehicle body ground to which a negative electrode of a battery power source is connected, for transmitting and receiving a communication signal in a digital form, an impedance component having an end which is connected to said vehicle body ground, and another end which is connected to a circuit ground, and a control unit which runs with respect to said circuit ground, for controlling a circuit to be controlled, and for outputting a communication signal in a digital form which is to be transmitted to said vehicle-mounted unit, said communication interface circuit comprising:

a comparator which runs with respect to said circuit ground, which receives a communication signal which is generated with respect to said vehicle body ground which is transmitted from said vehicle-mounted unit at a noninverting input end thereof, and receives a comparison reference signal which is generated with respect to said vehicle body ground at an inverting input end thereof, which compares said communication signal with said comparison reference signal to determine whether said communication signal has a high level or a low level, and which outputs a signal based on this determination to said control unit;

a first constant current signal generation circuit which runs with respect to said circuit ground, and which generates a constant current signal when said comparator outputs a high-level signal;

a hysteresis circuit which runs with respect to said vehicle body ground and reduces a level of the comparison reference signal inputted to said comparator when the constant current signal from said first constant current signal generation circuit flows thereinto;

a second constant current signal generation circuit which runs with respect to said circuit ground and which generates a constant current signal from the communication signal outputted by said control unit; and

a signal output circuit which runs with respect to said vehicle body ground and transmits a same signal corresponding to the communication signal outputted by said control unit to the vehicle-mounted unit when the constant current signal from said second constant current signal generation circuit flows thereinto.