JPH0519011U - LAN device for vehicle - Google Patents

Abstract

(57) [Summary] [Object] To provide a vehicle LAN device which is inexpensive and requires a small number of terminals of a switch unit. [Configuration] A vehicle LAN device includes a plurality of switch units 1, 2, and 3, two signal lines 4 and 5, and a control circuit 6. The switch units 1, 2 and 3 have switches S1, S2 and S3 and resistors R1, R2 and R3 built therein, and end portions O1, O2 and O3 in which the switches S1, S2 and S3 and resistors R1, R2 and R3 are connected in series. , O4, O
5 and O6. The signal lines 4 and 5 connect the respective ends O1 to O6 of the switch units 1, 2 and 3. The control circuit 6 is connected to the two signal lines 4 and 5 and controls the loads 7, 8 and 9 according to the resistance value between the signal lines 4 and 5.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an improvement of a vehicle local area network (LOCAL AREA NETWORK / hereinafter simply referred to as "LAN") device for controlling various loads mounted on a vehicle by using a shared transmission line.

[0002]

[Prior Art]

 The LAN device is generally known as a network in which each terminal device and computers are connected by a shared transmission line. This LAN device had the feature that it was possible to freely add and remove local units. In addition, when LAN devices were used in vehicles, we were able to contribute to the reduction of harnesses and the quantification of vehicles. Conventionally, this kind of technique is disclosed in, for example, Japanese Utility Model Laid-Open No. 59-73863 and Japanese Patent Laid-Open No. 2-197444.

[0003]

[Problems to be solved by the device]

 However, the LAN device of the vehicle is expensive. For example, the switch units arranged at various places in the vehicle need to incorporate a circuit such as a multiple interface as disclosed in Japanese Patent Laid-Open No. 2-197444 in order to generate a coded signal indicating the operation state of the switch. It was Further, the switch unit requires a power supply line and a ground line in order to supply power to the internal circuit in addition to the signal line, and has the disadvantage that the number of terminals of the switch unit and the number of electric wires connected to the switch unit are large. It was.

[0004]

[Means for Solving the Problems]

 The present invention solves the above-mentioned drawbacks of the prior art, and an object of the present invention is to provide a vehicle LAN device which is inexpensive and requires a small number of terminals of the switch unit. In order to achieve the above object, a plurality of switch units each having a switch and a resistor built-in, having an end portion in which the switch and the resistor are connected in series, and arranged at various places of the vehicle, and the plurality of switches are provided. It is provided with two signal lines connecting each end of the unit, and a control circuit connected to the two signal lines and controlling a load according to a resistance value between the two signal lines. There is provided a vehicular LAN device characterized by the above.

[0005]

【Example】

 FIG. 1 is an electric circuit diagram showing a preferred embodiment of the present invention. In FIG. 1, reference numerals 1, 2 and 3 incorporate switches S1, S2 and S3 and resistors R1, R2 and R3, and the switches S1, S2 and S3 and resistors R1, R2 and R3 are connected in series. And a plurality of switch units arranged at various places of the vehicle, having the end portions O1, O2, O3, O4, O5 and O6. Further, 4 and 5 are two signal lines connecting the respective ends O1, O2, O3, O4, O5 and O6 of the plurality of switch units 1, 2 and 3. A control circuit 6 is connected to the two signal lines 4 and 5 and controls the loads 7, 8 and 9 according to the resistance value between the two signal lines 4 and 5. The control circuit 6 includes a resistor Ri, a reference voltage generator 6a, an AD converter 6b, a central processing unit 6c, and an output unit 6d. More specifically, the resistor Ri divides the reference voltage V0 output by the reference voltage generator 6a together with the resistors R1, R2 and R3 of the switch units 1, 2 and 3 described above, and the divided voltage Vi is supplied to the A-D converter 6b. Is to be entered as. The A-D converter 6b converts the divided voltage Vi, which is an analog signal, into a digital signal and inputs the digital signal to the central processing unit 6c. The central processing unit 6c is composed of a microcomputer, collates the value of the divided voltage Vi with previously stored data, and operates the switches S1, S2 and S3 in the switch units 1, 2 and 3, respectively. The state is judged and the corresponding loads 7, 8 and 9 are controlled via the output section 6d. The output section 6d is composed of a power MOSFET and a relay.

Next, the operation will be described. As shown in FIG. 2, the divided voltage Vi is determined according to the operating states of the switches S1, S2 and S3. For example, when the switch S1 is turned on, the divided voltage Vi = reference voltage V0.resistor Ri / (resistor Ri + resistor R1) [volt]. Similarly, when the switch S2 is turned on, the divided voltage Vi = V0.Ri / (Ri + R2) [volt], and when the switch S3 is turned on, the divided voltage Vi = V0.Ri / (Ri + R3) [volt]. Becomes Further, when the switches S1 and S2 are both turned ON, the divided voltage Vi = V0.Ri / {Ri + R1.R2 / (R1 + R2)} [volts], and when the switches S1 and S3 are both turned ON, the divided voltage is obtained. Vi = V0.Ri / {Ri + R1.R3 / (R1 + R3)} [volt], and when the switches S2 and S3 are both turned on, the divided voltage Vi = V0.Ri / {Ri + R2.R3 / (R 2 + R3)} [volt]. When all the switches S1, S2 and S3 are turned on, the divided voltage Vi = V0.Ri / {Ri + R1.R2.R3 / (R1.R2 + R1.R3 + R2.R3)} [volt].

For example, assuming that the reference voltage V0 = 5 [volts], the resistors Ri = 10 [KΩ], R1 = 10 [KΩ], R2 = 20 [KΩ], and R3 = 30 [KΩ], the switch S1 is When the switch S2 is turned on, the divided voltage Vi = 2.5 [volts], when the switch S2 is turned on, the divided voltage Vi≈1.7 [volts], and when the switch S3 is turned on, the divided voltage Vi≈1.3 [volts] , Divided voltage Vi = 3 [volt] when switches S1 and S2 are turned on, divided voltage ≈2.9 [volt] when switches S1 and S3 are turned on, and divided voltage when switches S2 and S3 are turned on The voltage Vi is about 2.3 [volt], and the divided voltage Vi is about 3.2 [volt] when the switches S1, S2 and S3 are turned on. The data of the divided voltage Vi is stored in advance in the central processing unit 6c, and this data is collated with the divided voltage Vi input through the A / D conversion unit 6b to switch the switch S1. , S2 and S3 are determined. For example, if the input divided voltage Vi is 3 [volts], it is determined that the switches S1 and S2 are in the ON operation state. Then, for example, the loads 7 and 8 are controlled based on this determination. Similarly, when another divided voltage Vi is input, the operating states of the switches S1, S2, and S3 are determined by the value of the divided voltage Vi, and the corresponding loads 7, 8 and 9 are controlled. Although three switch units are used in the above-described embodiment, the number of switch units is not limited to this, and it is possible to use n switch units.

[0008]

[Effect of the device]

 The vehicle LAN device of the present invention having the above-described configuration and operation is inexpensive because it does not need to incorporate a high-priced circuit such as a multiple interface in the switch unit, and the number of terminals of the switch unit and the connection to the switch unit are low. This has the advantage that the number of wires is small.

[Brief description of drawings]

FIG. 1 is an electric circuit diagram showing a preferred embodiment of the present invention.

FIG. 2 is an operation explanatory view of what is shown in FIG.

[Explanation of symbols]

 1,2,3 Switch unit 4,5 Signal line 6 Control circuit 7,8,9 Load

Claims (1)

[Scope of utility model registration request] 1. A plurality of switch units, each of which has a switch and a resistor built-in, has an end portion in which the switch and the resistor are connected in series, and is arranged at each position of a vehicle, and an end portion of each of the plurality of switch units. A vehicle including two connected signal lines and a control circuit connected to the two signal lines and controlling a load according to a resistance value between the two signal lines. LAN device for use.