Air conditioning system master/slave control unit determination
First Claim
1. An air conditioning device in which a plurality of air conditioning control units (11-C, 11-C, . . . ) are connected to each other through a communication line (20) composed of two signal lines (2a,2b) having either positive polarity or negative polarity and a control signal for controlling air conditioning is bidirectionally transmitted at a proper polarity between the control units (11-C, 11-C, . . . ), one out of the control units (11-C, 11-C . . . ) functioning to apply a direct-current voltage to the communication line (20) in order to automatically determine each polarity of the signal lines (2a,2b),said air conditioning control units (11-C, 11-C, . . . ) each comprising:
- power superposition means (50) for applying a specific direct-current voltage from a power source to the communication line (20);
polarity select means (60) which has a negative-polarity resistance characteristic that current increasingly flows as the applied voltage is lowered to reduce the internal resistance and is connected in series to the power source while being applied with the direct-current voltage, wherein the voltage Vn corresponding to the minimum current value based on the negative-polarity resistance characteristic is set larger than the power source voltage, the maximum current value Id based on the negative-polarity resistance characteristic is set smaller than the minimum overcurrent value Is of the communication line (20), the terminal voltage drops when the power source has the same polarity as in the communication line (20), and the terminal voltage rises to vary the terminal voltage for determining the polarity of the communication line (20) when the power source is different in polarity from the communication line (20)number output means (41) for controlling the power superposition means (50) such that the power superposition means (50) outputs to the communication line (20) a bit signal based on a unit number preassigned to each of the control units (11-C, 11-C, . . . ), by using a power-source voltage to be superposed on the voltage of the communication line (20);
voltage discriminating means (70) for detecting the terminal voltage of the polarity select means (60) and outputting a low-voltage signal when the terminal voltage is a set voltage or less and a high-voltage signal when the terminal voltage is above the set voltage, respectively, andmaster/slave unit determining means (42) for observing the voltage of the communication line (20),determining the control unit to be a slave unit whose power superposition means (50) applies no direct-current voltage to the communication line (20) and disconnecting the power source and the communication line (20) from each other, when detecting a high-level voltage of the communication line (20) at the time of outputting a "0" bit of the unit number of the control unit, or when the voltage discriminating means (70) outputs a high-voltage signal at the time of outputting a "1" bit of the unit number of the control unit, whiledetermining the control unit to be a master unit whose power superposition means (50) applies a direct-current voltage to the communication line (20) and establishing a connection between the power source and the communication line (20) when the voltage discriminating means (70) outputs a low-voltage signal and the entire unit number of the control unit is outputtedand then deactivating the number output means (41) to complete the operation of determining to be a master unit or a slave unit.
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Accused Products
Abstract
A plurality of air conditioning system control units are connected to each other through a communication line (20). Discharge resistors (R1, R2) are provided for discharging residual charges of the communication line (20). The control unit has a power superposition circuit (50) for applying a direct-current voltage and outputs an identification number signal from the power superposition circuit (50) to the communication line (20). The control unit further has a polarity select circuit (60) having a negative-polarity resistance characteristic that current increasingly flows as an applied voltage is lowered, and a voltage discriminating circuit (70) for detecting the terminal voltage of the polarity select circuit (60). When detecting the voltage of the communication line (20), the control unit determines whether its own control unit is a master unit or a slave unit according to output signals from the voltage discriminating circuit (70) and a polarity discriminating circuit (3C).
19 Citations
12 Claims
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1. An air conditioning device in which a plurality of air conditioning control units (11-C, 11-C, . . . ) are connected to each other through a communication line (20) composed of two signal lines (2a,2b) having either positive polarity or negative polarity and a control signal for controlling air conditioning is bidirectionally transmitted at a proper polarity between the control units (11-C, 11-C, . . . ), one out of the control units (11-C, 11-C . . . ) functioning to apply a direct-current voltage to the communication line (20) in order to automatically determine each polarity of the signal lines (2a,2b),
said air conditioning control units (11-C, 11-C, . . . ) each comprising: -
power superposition means (50) for applying a specific direct-current voltage from a power source to the communication line (20); polarity select means (60) which has a negative-polarity resistance characteristic that current increasingly flows as the applied voltage is lowered to reduce the internal resistance and is connected in series to the power source while being applied with the direct-current voltage, wherein the voltage Vn corresponding to the minimum current value based on the negative-polarity resistance characteristic is set larger than the power source voltage, the maximum current value Id based on the negative-polarity resistance characteristic is set smaller than the minimum overcurrent value Is of the communication line (20), the terminal voltage drops when the power source has the same polarity as in the communication line (20), and the terminal voltage rises to vary the terminal voltage for determining the polarity of the communication line (20) when the power source is different in polarity from the communication line (20) number output means (41) for controlling the power superposition means (50) such that the power superposition means (50) outputs to the communication line (20) a bit signal based on a unit number preassigned to each of the control units (11-C, 11-C, . . . ), by using a power-source voltage to be superposed on the voltage of the communication line (20); voltage discriminating means (70) for detecting the terminal voltage of the polarity select means (60) and outputting a low-voltage signal when the terminal voltage is a set voltage or less and a high-voltage signal when the terminal voltage is above the set voltage, respectively, and master/slave unit determining means (42) for observing the voltage of the communication line (20), determining the control unit to be a slave unit whose power superposition means (50) applies no direct-current voltage to the communication line (20) and disconnecting the power source and the communication line (20) from each other, when detecting a high-level voltage of the communication line (20) at the time of outputting a "0" bit of the unit number of the control unit, or when the voltage discriminating means (70) outputs a high-voltage signal at the time of outputting a "1" bit of the unit number of the control unit, while determining the control unit to be a master unit whose power superposition means (50) applies a direct-current voltage to the communication line (20) and establishing a connection between the power source and the communication line (20) when the voltage discriminating means (70) outputs a low-voltage signal and the entire unit number of the control unit is outputted and then deactivating the number output means (41) to complete the operation of determining to be a master unit or a slave unit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification