air conditioner

Abstract

To provide an air conditioning system capable of preventing reduction in power conversion efficiency after switched to an external power source and maintaining stable operation even with the external power source.SOLUTION: An air conditioning system 1A comprises an external power feeding unit 5 and an indoor unit 3A. The indoor unit has: a main control part 321 which operates using, as a power source, an internal voltage Vit or an external voltage Vex supplied from any one of an outdoor unit power supply part 31, an external power feeding unit 5 and an indoor unit power supply part 31; and a voltage monitoring part 322 that monitors a voltage level of the external voltage Vex outputted from the external power feeding unit 5 and a voltage level of the internal voltage Vit outputted from the indoor unit power supply part 31, and which outputs to the main control part 321 an internal monitoring signal Smi or an external monitoring signal Sme corresponding to either voltage of the external voltage Vex and the internal voltage Vit supplied to the main control part 321 as a stop signal Set for stopping the main control part 321.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an air conditioner.

Background Art

[0002] During normal operation, an air conditioner is powered by a commercial power supply. However, when the commercial power supply becomes unavailable for some reason, it may be powered by an external power supply for external power supply. When the power cable connecting the indoor unit provided in the air conditioner and the external power supply for external power supply is long, the voltage required for the operation of the indoor unit cannot be supplied due to the voltage drop caused by the power cable, and the possibility that the indoor unit cannot operate increases.

[0003] Patent Document 1 discloses an image display device that, when using a long-distance power extension cable, measures a part of an AC voltage transmission unit by voltage measuring means, and operates the current amount flowing through the AC voltage transmission unit according to the measured voltage measured by the voltage measuring means, thereby preventing shutdown (becoming inoperable) due to voltage drop in the power extension cable.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, the amount of current flowing in an air conditioner is very large compared to an image display device. Therefore, when, for example, a linear regulator is applied to the air conditioner as the current control means described in Patent Document 1, the power conversion efficiency becomes low because the flowing current is relatively large. As a result, since the current control means may generate heat, heat radiating means for radiating the heat is required.

[0006] In particular, in multi-split air conditioners where multiple indoor units are connected to a single outdoor unit, even after the power breaker of one indoor unit is switched off, it may be necessary to control communication between the multiple indoor units and the outdoor unit, including the indoor unit whose power breaker has been switched off. In this case, the indoor unit whose power breaker has been switched off should be supplied with a voltage lower than that during normal operation. However, if a current control means such as the one described in Patent Document 1 is used, it will convert high voltage to low voltage, resulting in low voltage conversion efficiency.

[0007] The objective of the present invention is to provide an air conditioner that can prevent power outages due to a drop in supply voltage without reducing power conversion efficiency after switching to an external power source with a long power cable, and that can maintain stable operation even with an external power source. [Means for solving the problem]

[0008] To achieve the above objective, an air conditioning system according to one aspect of the present invention comprises an external power supply unit, an internal power supply unit, a main control unit that operates using a voltage supplied from either the external power supply unit or the internal power supply unit as a power source, and an indoor unit having a voltage monitoring unit that monitors the voltage level of the external voltage output from the external power supply unit and the voltage level of the internal voltage output from the internal power supply unit, and outputs a monitoring signal corresponding to the voltage supplied to the main control unit from the external voltage and the internal voltage as a stop signal to stop the main control unit. [Effects of the Invention]

[0009] According to one aspect of the present invention, a decrease in power conversion efficiency after switching to an external power source can be prevented, and stable operation can be maintained even with an external power source. [Brief explanation of the drawing]

[0010] [Figure 1] This is a block diagram showing an example of a schematic configuration of an air conditioning system according to the first embodiment of the present invention. [Figure 2]This is a circuit diagram showing an example of the schematic configuration of an air conditioning system as a comparative example. [Figure 3] This is a block diagram showing an example of a schematic configuration of an air conditioning system according to a second embodiment of the present invention. [Figure 4] This is a block diagram showing an example of a schematic configuration of an air conditioning system according to a third embodiment of the present invention. [Figure 5] This is a block diagram showing an example of the schematic configuration of an indoor unit and an external power supply unit provided in an air conditioning system according to a third embodiment of the present invention. [Figure 6] This block diagram shows an example of the schematic configuration of a voltage monitoring unit provided in an air conditioning system according to a modification of the first to third embodiments of the present invention. [Modes for carrying out the invention]

[0011] [First Embodiment] An air conditioning system according to the first embodiment of the present invention will be described with reference to Figures 1 and 2. First, the schematic configuration of the air conditioning system according to this embodiment will be described with reference to Figure 1. Figure 1 is a diagram showing an example of the schematic configuration of the air conditioning system 1A according to this embodiment.

[0012] As shown in Figure 1, the air conditioning system 1A according to this embodiment includes an indoor unit 3A that adjusts and purifies the temperature of the air in the room where it is installed, and an external power supply unit (an example of an external power supply unit) 5 that supplies power to the indoor unit 3A as needed. The air conditioning system 1A includes an external power cable 7 that connects the indoor unit 3A and the external power supply unit 5. One end of the external power cable 7 is connected to a power terminal T5 provided on the external power supply unit 5, and the other end of the external power cable 7 is connected to a power terminal T3 provided on the indoor unit 3A. As a result, the external power supply unit 5 can supply the generated external voltage Vex to the indoor unit 3A.

[0013] The external power supply unit 5 is a power supply unit that supplies voltage to control peripheral devices such as an expansion valve (not shown) connected to the indoor unit 3A, even after the indoor unit 3A has stopped operating for heating or cooling and the circuit breaker has been tripped. The external power supply unit 5 has a voltage generation unit 51 that generates an external voltage Vex for the external power supply. The voltage generation unit 51 generates an external voltage Vex, for example, 5V. The voltage generation unit 51 monitors the internal voltage Vit for the internal power supply output from the indoor unit power supply unit 31 (details described later) provided in the indoor unit 3A, and outputs the external voltage Vex when the internal voltage Vit is not output. The voltage generation unit 51 may also be configured to monitor the voltage output from the circuit breaker.

[0014] The external power supply unit 5 has a reverse current prevention diode 52 that prevents the internal voltage Vit supplied to the indoor unit 3A from flowing back into the external power supply unit 5. The anode of the reverse current prevention diode 52 is connected to the voltage generation unit 51, and the cathode of the reverse current prevention diode 52 is connected to the power supply terminal T5.

[0015] The external power supply unit 5 has an indication signal generation unit 53 that generates an indication signal Ssu indicating whether or not an external voltage Vex is being output to the indoor unit 3A. The indication signal generation unit 53 monitors the external voltage Vex output from the voltage generation unit 51, and when the external voltage Vex is being output from the voltage generation unit 51, it generates an indication signal Ssu with a high signal level, for example, and outputs the generated indication signal Ssu to the indoor unit 3A. On the other hand, when the external voltage Vex is not being output from the voltage generation unit 51, the indication signal generation unit 53 generates an indication signal Ssu with a low signal level, for example, and outputs the generated indication signal Ssu to the indoor unit 3A.

[0016] As shown in Figure 1, the indoor unit 3A is connected to a commercial power supply (not shown) and has an indoor unit power supply unit (an example of an internal power supply unit) 31 that generates an internal voltage Vit, which is the power supply when the indoor unit 3A performs operations such as heating and cooling. The indoor unit power supply unit 31 has a voltage generation unit 311 that generates an internal voltage Vit for the internal power supply. The voltage generation unit 311 generates an internal voltage Vit voltage of, for example, 5V.

[0017] The indoor unit power supply unit 31 has a reverse current prevention diode 312 that prevents the external voltage Vex supplied to the indoor unit control unit 32A (details will be described later) provided in the indoor unit 3A from flowing back into the indoor unit power supply unit 31. The anode of the reverse current prevention diode 312 is connected to the voltage generation unit 311, and the cathode of the reverse current prevention diode 312 is connected to the power supply terminal T31 provided in the indoor unit power supply unit 31.

[0018] The indoor unit 3A has a main control unit 321 that operates using the voltage supplied from either the external power supply unit 5 or the indoor unit power supply unit 31 (i.e., the external voltage Vex or the internal voltage Vit) as a power source. The main control unit 321 is provided in the indoor unit control unit 32A provided in the indoor unit 3A. The indoor unit control unit 32A has a power supply terminal T32i connected to the indoor unit power supply unit 31 and a power supply terminal T32e connected to the external power supply unit 5. The power supply terminal T32i provided in the indoor unit control unit 32A and the power supply terminal T31 provided in the indoor unit power supply unit 31 are connected by a power cable 34i. The power supply terminal T32e provided in the indoor unit control unit 32A and the power supply terminal T3 provided in the indoor unit 3A are connected by a power cable 34e. Therefore, the power supply terminal T32e is connected to the external power supply unit 5 via the power cable 34e, the power supply terminal T3, the external power cable 7, and the power supply terminal T5. As a result, the internal voltage Vit generated by the indoor unit power supply unit 31 and the external voltage Vex generated by the external power supply unit 5 can be supplied to the indoor unit control unit 32A.

[0019] The indoor unit control unit 32A has, for example, a control circuit board. The main control unit 321, the power supply terminal T32i, and the power supply terminal T32e are provided on the control circuit board. The main control unit 321, the power supply terminal T32i, and the power supply terminal T32e are connected, for example, by a wiring pattern L32 formed on the control circuit board. One end of the wiring pattern L32 is connected to the power supply input terminal T321 provided on the main control unit 321, and the other end side of the wiring pattern L32 is bifurcated, and one of the other end sides is connected to the power supply terminal T32i, and the other of the other end sides is connected to the power supply terminal T32e. As described above, the external power supply unit 5 outputs the external voltage Vex when the internal voltage Vit is not output from the indoor unit power supply unit 31. Therefore, the internal voltage Vit or the external voltage Vex can be input to the power supply input terminal T321 of the main control unit 321.

[0020] Also, the wiring pattern L32 has a configuration in which the power supply terminal T32i and the power supply terminal T32e are directly connected to each other. Therefore, the internal voltage Vit input from the power supply terminal T32i is also input to the external power supply unit 5 via the wiring pattern L32, the power supply terminal T32e, the power cable 34e, the power supply terminal T3, the external power cable 7, and the power supply terminal T5 in addition to the main control unit 321. However, the external power supply unit 5 has a reverse current prevention diode 52 whose cathode is connected to the power supply terminal T5. Therefore, the internal voltage Vit input from the power supply terminal T5 is not input to the inside of the external power supply unit 5 more than the reverse current prevention diode 52.

[0021] Also, the external voltage Vex input from the power supply terminal T32e is also input to the indoor unit power supply unit 31 via the wiring pattern L32, the power supply terminal T32i, the power cable 34i, and the power supply terminal T31 in addition to the main control unit 321. However, the indoor unit power supply unit 31 has a reverse current prevention diode 312 whose cathode is connected to the power supply terminal T31. Therefore, the external voltage Vex input from the power supply terminal T31 is not input to the inside of the indoor unit power supply unit 31 more than the reverse current prevention diode 312.

[0022] Thus, even without a special circuit such as a power switching circuit in the indoor unit control unit 32A, the air conditioning system 1A can supply either the internal voltage Vit or the external voltage Vex to the main control unit 321 and prevent backflow to the external power supply unit 5 or the indoor unit power supply unit 31.

[0023] As shown in Figure 1, the air conditioning system 1A has a voltage monitoring unit 322 that monitors the voltage of the external voltage Vex output from the external power supply unit 5 and the voltage of the internal voltage Vit output from the indoor unit power supply unit 31, and outputs a monitoring signal corresponding to the voltage supplied to the main control unit 321 from the external voltage Vex and internal voltage Vit as a stop signal Sst to stop the main control unit 321. The voltage monitoring unit 322 is configured to monitor the magnitude (voltage level) of the voltage of the internal voltage Vit input from the indoor unit power supply unit 31 and the voltage of the external voltage Vex input from the external power supply unit 5 in order to prevent the main control unit 321 from operating at a voltage lower than the power supply voltage at which it can operate.

[0024] The voltage monitoring unit 322 outputs a monitoring signal corresponding to the internal voltage Vit as a stop signal Sst to the main control unit 321 when the internal voltage Vit is output from the indoor unit power supply unit 31. On the other hand, the voltage monitoring unit 322 outputs a monitoring signal corresponding to the external voltage Vex as a stop signal Sst to the main control unit 321 when the internal voltage Vit is not output from the indoor unit power supply unit 31. As will be described in detail later, the main control unit 321 operates the indoor unit 3A when the signal level of the stop signal Sst input from the voltage monitoring unit 322 is low, and stops the operation of the indoor unit 3A when the signal level of the stop signal Sst is high.

[0025] As described above, the external power supply unit 5 outputs an indication signal Ssu to the indoor unit 3A indicating whether or not it is outputting the external voltage Vex to the indoor unit 3A. When the voltage monitoring unit 322 receives the indication signal Ssu, which indicates that the external voltage Vex is being output, it switches the monitoring signal from the internal voltage Vit to the monitoring signal corresponding to the external voltage Vex.

[0026] To perform these functions, the voltage monitoring unit 322 has an external voltage monitoring unit 322b that monitors the external voltage Vex and outputs an external monitoring signal Sme as a monitoring signal corresponding to the external voltage Vex. The voltage monitoring unit 322 also has an internal voltage monitoring unit 322a that monitors the internal voltage Vit and outputs an internal monitoring signal Smi as a monitoring signal corresponding to the internal voltage Vit. Furthermore, the voltage monitoring unit 322 has a switching circuit 322c that sets the stop signal Sst input to the main control unit 321 as an external monitoring signal Sme when the voltage supplied to the main control unit 321 is the external voltage Vex, and as an internal monitoring signal Smi when the voltage supplied to the main control unit 321 is the internal voltage Vit.

[0027] The input terminal of the internal voltage monitoring unit 322a is connected to the wiring pattern L32, and the output terminal of the internal voltage monitoring unit 322a is connected to one input terminal of the switching circuit 322c. The input terminal of the external voltage monitoring unit 322b is connected to the wiring pattern L32, and the output terminal of the external voltage monitoring unit 322b is connected to the other input terminal of the switching circuit 322c. The output terminal of the switching circuit 322c is connected to the main control unit 321. The suggestion signal Ssu output from the external power supply unit 5 is input to the control signal input terminal of the switching circuit 322c.

[0028] The external voltage monitoring unit 322b outputs an external monitoring signal Sme to the switching circuit 322c when the external voltage Vex is lower than the external threshold voltage (details described later). The internal voltage monitoring unit 322a outputs an internal monitoring signal Smi to the switching circuit 322c when the internal voltage Vit is lower than the internal threshold voltage (details described later), which is set to a value higher than the external threshold voltage.

[0029] The external voltage monitoring unit 322b is set to an external threshold voltage that is compared with the voltage input from the wiring pattern L32. The external threshold voltage is set to a voltage lower than the minimum voltage of the external voltage Vex. However, the external voltage Vex input from the external power supply unit 5 to the indoor unit 3A may experience a voltage drop due to the length of the external power cable 7, etc. The external power supply unit 5 generates an external voltage Vex that has a voltage that allows the main control unit 321 to operate even if a voltage drop occurs. The minimum voltage of the external voltage Vex is the lowest voltage value that can occur when such a voltage drop occurs. For example, if the external voltage Vex generated by the voltage generation unit 51 is 5V and may drop to 3V due to a voltage drop caused by the length of the external power cable 7, etc., the external threshold voltage is set to 2.5V, which is the voltage at which the main control unit 321 can operate.

[0030] The external voltage monitoring unit 322b outputs a low-level external monitoring signal Sme to the switching circuit 322c if the voltage input from the wiring pattern L32 is higher than the external threshold voltage. On the other hand, the external voltage monitoring unit 322b outputs a high-level external monitoring signal Sme to the switching circuit 322c if the voltage input from the wiring pattern L32 is lower than the external threshold voltage. The switching circuit 322c outputs the external monitoring signal Sme as a stop signal Sst to the main control unit 321 if the signal level of the suggestion signal Ssu input from the external power supply unit 5 is high (i.e., the external voltage Vex is supplied from the external power supply unit 5 to the indoor unit control unit 32A).

[0031] The internal voltage monitoring unit 322a has an internal threshold voltage set to be compared with the voltage input from the wiring pattern L32. The internal threshold voltage is set to be lower than the internal voltage Vit and higher than the minimum voltage of the external voltage Vex input to the indoor unit 3A. Therefore, the internal threshold voltage is higher than the external threshold voltage. When the voltage input from the wiring pattern L32 is higher than the internal threshold voltage, the internal voltage monitoring unit 322a outputs a low-level internal monitoring signal Smi to the switching circuit 322c. On the other hand, when the voltage input from the wiring pattern L32 is lower than the internal threshold voltage, the internal voltage monitoring unit 322a outputs a high-level internal monitoring signal Smi to the switching circuit 322c. The switching circuit 322c outputs an internal monitoring signal Smi as a stop signal Sst to the main control unit 321 when the signal level of the suggestion signal Ssu input from the external power supply unit 5 is low (i.e., when the internal voltage Vit is supplied from the indoor unit power supply unit 31 to the indoor unit control unit 32A).

[0032] The main control unit 321 operates the indoor unit 3A when the signal level of the stop signal Sst input from the voltage monitoring unit 322 is low, and stops the operation of the indoor unit 3A when the signal level of the stop signal Sst is high. Therefore, the main control unit 321 stops operation when the internal voltage Vit supplied from the indoor unit power supply unit 31 to the indoor unit control unit 32A falls below the internal threshold voltage set in the internal voltage monitoring unit 322a, or when the external voltage Vex supplied from the external power supply unit 5 to the indoor unit control unit 32A falls below the external threshold voltage set in the external voltage monitoring unit 322b. The voltage monitoring unit 322 can individually monitor the voltage levels of the internal voltage Vit and the external voltage Vex, and can output a stop signal Sst to the main control unit 321 corresponding to the voltage of the indoor unit power supply unit 31 or the external power supply unit 5 that is supplying power to the indoor unit control unit 32A. This prevents malfunctions in the air conditioning system 1A, such as stopping operation based on an internal threshold voltage when operating on an external voltage Vex, or stopping operation at an external threshold voltage when operating on an internal voltage Vit.

[0033] As shown in Figure 1, the indoor unit 3A is equipped with an operating unit 33A that operates even when an external voltage Vex is supplied to the main control unit 321. The power terminal T33 of the operating unit 33A is connected to the wiring pattern L32. Therefore, the operating unit 33A operates using the internal voltage Vit as its power source when the internal voltage Vit is input to the indoor unit control unit 32A from the indoor unit power supply unit 31, and operates using the external voltage Vex as its power source when the external voltage Vex is input to the indoor unit control unit 32A from the external power supply unit 5.

[0034] The operating unit 33A has a temperature detection unit 331 that detects the temperature of the room in which the indoor unit 3A is installed. The temperature detection unit 331 has, for example, a thermistor (not shown) that converts temperature to voltage, and outputs the detected room temperature as a voltage to the main control unit 321.

[0035] As shown in Figure 1, the main control unit 321 has an analog-to-digital converter 321b connected to the temperature sensing unit 331. Hereinafter, the analog-to-digital converter may be referred to as the "AD converter". In Figure 1 and the later-described Figures 2, 3, and 5, the AD converter is represented as "ADC". The AD converter 321b converts the voltage of the analog signal input from the temperature sensing unit 331, which contains information about the detected temperature, into a digital signal. The AD converter 321b is connected to the wiring pattern L32 and uses the voltage supplied to the wiring pattern L32 as a reference voltage to perform AD conversion on the voltage input from the temperature sensing unit 331. The main control unit 321 adjusts the temperature of the room in which the indoor unit 3A is installed based on the temperature information contained in the digital signal converted by the AD converter 321b.

[0036] The main control unit 321 has an external operation determination unit 321a to which a suggestion signal Ssu is input. The external operation determination unit 321a determines whether the voltage currently supplied to the indoor unit control unit 32A is the external voltage Vex or the internal voltage Vit, based on the signal level of the suggestion signal Ssu input from the suggestion signal generation unit 53 provided in the external power supply unit 5. The external operation determination unit 321a determines that the internal voltage Vit is supplied to the indoor unit control unit 32A if the signal level of the suggestion signal Ssu input from the suggestion signal generation unit 53 is low. On the other hand, the external operation determination unit 321a determines that the external voltage Vex is supplied to the indoor unit control unit 32A if the signal level of the suggestion signal Ssu input from the suggestion signal generation unit 53 is high. If the external operation determination unit 321a determines that the internal voltage Vit is being supplied, the main control unit 321 operates the indoor unit 3A in an internal operation mode (i.e., normal heating and cooling) that performs temperature control in the room where the indoor unit 3A is installed. On the other hand, if the external operation determination unit 321a determines that the external voltage Vex is being supplied, the main control unit 321 operates in an external operation mode that performs control of the expansion valve and automatic cleaning of a filter (not shown) provided in the indoor unit 3A.

[0037] Thus, the main control unit 321 continues to operate the indoor unit regardless of whether the internal voltage Vit or the external voltage Vex is present, as long as a high-level stop signal Sst is not input from the voltage monitoring unit 322.

[0038] (Effects of the air conditioning system) Next, the effects of the air conditioning system 1A according to this embodiment will be explained using Figures 1 and 2. Figure 2 is a block diagram showing the schematic configuration of the air conditioning system 1X as a comparative example. In describing the air conditioning system 1X, components that perform the same actions and functions as the air conditioning system according to this embodiment are denoted by the same reference numerals, and their descriptions are omitted.

[0039] As shown in Figure 2, the comparative example air conditioning system 1X differs from the air conditioning system 1A according to this embodiment in the configuration of the voltage monitoring unit. The indoor unit control unit 32X provided in the indoor unit 3X of the air conditioning system 1X has a voltage monitoring unit 322X having one input terminal connected to the wiring pattern L32 and one output terminal connected to the main control unit 321. Furthermore, unlike the voltage monitoring unit 322 provided in the air conditioning system 1A according to this embodiment, the voltage monitoring unit 322X does not receive the suggestion signal Ssu output from the suggestion signal generation unit 53 provided in the external power supply unit 5.

[0040] Therefore, since the voltage monitoring unit 322X has a common threshold voltage set for the internal voltage Vit and the external voltage Vex, it is necessary to set the threshold voltage to the one with the smaller voltage drop between the internal voltage Vit and the external voltage Vex, considering that it is necessary to stop the operation of the main control unit 321 when noise or other interference occurs while the internal voltage Vit is output from the indoor unit power supply unit 31. The indoor unit 3X and the external power supply unit 5 are located in separate locations, while the indoor unit power supply unit 31 and the indoor unit control unit 32X are located inside the housing of the indoor unit 3X. Therefore, since the power cable 34i is shorter than the external power cable 7, the voltage drop in the wiring pattern L32 is smaller for the internal voltage Vit than for the external voltage Vex. If the internal voltage Vit generated by the voltage generation unit 311 in the indoor unit power supply unit 31 is, for example, 5V, and the external voltage Vex generated by the voltage generation unit 351 in the external power supply unit 5 is, for example, 5V, then the threshold voltage in the voltage monitoring unit 322X is set to, for example, 4.5V based on the voltage drop of the internal voltage Vit. Therefore, when the air conditioning system 1X is operating in external operation mode, even though the voltage is sufficient for the main control unit 321 to operate in external operation mode, the air conditioning system 1X will stop operating if the external voltage Vex falls below the threshold voltage.

[0041] Furthermore, the air conditioning system 1X can also be configured to include a linear regulator (not shown) between the wiring pattern L32 and the power terminal T32e, thereby increasing the voltage level of the external voltage Vex input to the power terminal T32e before inputting it to the wiring pattern L32. However, in such a configuration, in addition to the increased cost of providing the linear regulator, the power conversion efficiency of the linear regulator is low, which may cause the current control means to generate heat, thus requiring a heat dissipation means to dissipate the heat. This leads to problems such as an increase in circuit size and increased power consumption.

[0042] In contrast, the air conditioning system 1A according to this embodiment includes a voltage monitoring unit 322 that outputs a monitoring signal corresponding to the internal voltage Vit as a stop signal Sst to the main control unit 321 when the internal voltage Vit is output from the indoor unit power supply unit 31, and outputs a monitoring signal corresponding to the external voltage Vex as a stop signal Sst to the main control unit 321 when the internal voltage Vit is not output from the indoor unit power supply unit 31. As a result, the air conditioning system 1A can individually monitor the voltages of the internal voltage Vit and the external voltage Vex, and stop the operation of the main control unit 321 based on the stop signal Sst corresponding to the voltage input to the main control unit 321 from the internal voltage Vit and the external voltage Vex. Consequently, the air conditioning system 1A can prevent malfunctions in which the main control unit 321 stops operating even though the voltage is within the range at which it can operate in external operation mode. Furthermore, since the air conditioning system 1A does not require a linear regulator to convert the voltage of the external voltage Vex, it can prevent an increase in circuit size and power consumption.

[0043] As described above, the air conditioning system 1A according to this embodiment includes an external power supply unit 5, an indoor unit power supply unit 31, a main control unit 321 that operates using an internal voltage Vit or external voltage Vex supplied from either the external power supply unit 5 or the indoor unit power supply unit 31 as a power source, and an indoor unit 3A having a voltage monitoring unit 322 that monitors the voltage of the external voltage Vex output from the external power supply unit 5 and the voltage of the internal voltage Vit output from the indoor unit power supply unit 31, and outputs an internal monitoring signal Smi or an external monitoring signal Sme corresponding to the voltage supplied to the main control unit 321 from the external voltage Vex and the internal voltage Vit as a stop signal Sst to stop the main control unit 321.

[0044] As a result, the air conditioning system 1A does not use a linear regulator or the like after switching to the external voltage Vex, thus preventing a decrease in power conversion efficiency and maintaining stable operation even at the external voltage Vex.

[0045] [Second Embodiment] A second embodiment of the present invention will be described with reference to Figure 3. The schematic configuration of the air conditioning system according to this embodiment will be described with reference to Figure 3. Figure 3 is a block diagram showing an example of the schematic configuration of the air conditioning system 1B according to this embodiment. In describing the air conditioning system 1B according to this embodiment, components that perform the same actions and functions as the air conditioning system 1A according to the first embodiment will be denoted by the same reference numerals, and their descriptions will be omitted.

[0046] As shown in Figure 3, the air conditioning system 1B according to this embodiment includes an external power supply unit 5 and an indoor unit 3B connected to the external power supply unit 5. The indoor unit 3B has an indoor unit power supply unit 31 that generates an internal voltage Vit. The indoor unit 3B also has a main control unit 321 that operates using the internal voltage Vit or external voltage Vex supplied from either the external power supply unit 5 or the indoor unit power supply unit 31 as a power source. The indoor unit 3B also has a voltage monitoring unit 322 that monitors the voltage level of the external voltage Vex output from the external power supply unit 5 and the voltage level of the internal voltage Vit output from the indoor unit power supply unit 31, and outputs an internal monitoring signal Smi or an external monitoring signal Sme corresponding to the voltage supplied to the main control unit 321 from the external voltage Vex and internal voltage Vit as a stop signal Sst to stop the main control unit 321.

[0047] In this embodiment, the indoor unit 3B has an indoor unit control unit 32B. The indoor unit control unit 32B has the same configuration as the indoor unit control unit 32A in the first embodiment, except that it has a regulator 323 and a switching circuit 324 (details of which will be described later).

[0048] As shown in Figure 3, the indoor unit 3B includes an operating unit 33A that operates even when an external voltage Vex is supplied to the main control unit 321, and a regulator 323 (an example of a voltage generation unit) that generates an operating voltage Vdd for operating the operating unit 33A based on the external voltage Vex. The regulator 323 is, for example, a linear regulator and is provided in the indoor unit control unit 32B. Furthermore, the indoor unit 3B includes a switching circuit 324 (an example of a first switching unit) that switches the voltage level of the voltage that operates the operating unit 33A when an external voltage Vex is supplied to the main control unit 321 from the voltage level when an internal voltage Vit is supplied to the voltage level of the operating voltage Vdd. The switching circuit 324 is provided in the indoor unit control unit 32B.

[0049] More specifically, the input terminal of the regulator 323 is connected to the wiring pattern L32, and the output terminal of the regulator 323 is connected to one of the input terminals of the switching circuit 324. The other input terminal of the switching circuit 324 is connected to the wiring pattern L32. The output terminal of the switching circuit 324 is connected to the power supply terminal T33 of the operating unit 33A and the reference voltage input terminal (not shown) of the AD converter 321b provided in the main control unit 321. The control signal input terminal of the switching circuit 324 receives the suggestion signal Ssu output from the external power supply unit 5.

[0050] The regulator 323 converts an external voltage Vex, ranging from a voltage level generated by the voltage generation unit 51 in the external power supply unit 5 (e.g., 5V) to a voltage level where a voltage drop occurs due to the external power cable 7 or the like (e.g., 3V), into an operating voltage Vdd that is at the same voltage level as the external threshold voltage set in the external voltage monitoring unit 322b. Therefore, the operating voltage Vdd is the voltage at which the main control unit 321 can operate.

[0051] When the signal level of the suggestion signal Ssu input from the external power supply unit 5 is low, the switching circuit 324 outputs the internal voltage Vit supplied to the wiring pattern L32 input to the other input terminal from its output terminal to the operation unit 33A and the AD converter 321b. On the other hand, when the signal level of the suggestion signal Ssu input from the external power supply unit 5 is high, the switching circuit 324 outputs the operating voltage Vdd input to one of the input terminals from its output terminal to the operation unit 33A and the AD converter 321b. Thus, when the signal level of the suggestion signal Ssu input from the external power supply unit 5 is low, that is, when the internal voltage Vit is supplied from the indoor unit power supply unit 31 to the indoor unit control unit 32B, the switching circuit 324 outputs the internal voltage Vit, which has been switched from the operating voltage Vdd based on the external voltage Vex, to the operation unit 33A and the AD converter 321b. On the other hand, when the signal level of the suggestion signal Ssu input from the external power supply unit 5 is high, that is, when the external voltage Vex is supplied from the external power supply unit 5 to the indoor unit control unit 32B, the switching circuit 324 outputs the operating voltage Vdd, which is switched from the internal voltage Vit, to the operating unit 33A and the AD converter 321b.

[0052] The AD converter 321b provided in the main control unit 321 uses the voltage input from the switching circuit 324 as a reference voltage to perform AD conversion on the voltage input from the temperature detection unit 331. Both the internal voltage Vit input from the indoor unit power supply unit 31 to the wiring pattern L32 and the operating voltage Vdd output from the regulator 323 are voltages with stable voltage levels (i.e., voltages with almost no voltage drop) compared to the external voltage Vex. Therefore, the temperature detection unit 331 and AD converter 321b in this embodiment can improve the accuracy of temperature detection and AD conversion when operating with the external voltage Vex supplied from the external power supply unit 5 compared to the temperature detection unit 331 and AD converter 321b in the first embodiment.

[0053] As described above, in the air conditioning system 1B according to this embodiment, in addition to the configuration of the air conditioning system 1A according to the first embodiment, the indoor unit 3B includes an operating unit 33A that operates even when an external voltage Vex is supplied to the main control unit 321, a regulator 323 that generates an operating voltage Vdd for operating the operating unit 33A based on the external voltage Vex, and a switching circuit 324 that switches the voltage level of the voltage for operating the operating unit 33A when an external voltage Vex is supplied to the main control unit 321 from the voltage level when an internal voltage Vit is supplied to the voltage level of the operating voltage Vdd.

[0054] As a result, in addition to the effects of the air conditioning system 1A according to the first embodiment, the air conditioning system 1B can improve the accuracy of temperature detection and AD conversion when operating with the external voltage Vex supplied from the external power supply unit 5.

[0055] [Third Embodiment] A third embodiment of the present invention will be described with reference to Figures 4 and 5. Figure 4 is a block diagram showing an example of the schematic configuration of the air conditioning system 1C according to this embodiment. Figure 5 is a block diagram showing an example of the schematic configuration of indoor unit 3C-1, one of the multiple indoor units 3C-i, and one of the multiple external power supply units 5C-j, one external power supply unit 5C-1, provided in the air conditioning system 1C according to this embodiment. In describing the air conditioning system 1C according to this embodiment, components that perform the same operations and functions as the air conditioning system 1B according to the second embodiment will be denoted by the same reference numerals, and their descriptions will be omitted.

[0056] As shown in Figure 4, the air conditioning system 1C according to this embodiment includes an outdoor unit 8. The outdoor unit 8 is connected to a plurality of indoor units 3C-1, 3C-2, ..., 3C-i (where i is a natural number of 2 or more) and to each of the plurality of indoor units 3C-i, one external power supply unit (an example of an external power supply unit) 5C-1, 5C-2, ..., 5C-j (where j=2, 3, 4, ..., i-1, i (where "i" and "j" are the same number)). In other words, the air conditioning system 1C includes an outdoor unit 8, a plurality of indoor units 3C-1, 3C-2, ..., 3C-i connected to the outdoor unit 8, and one external power supply unit 5C-1, 5C-2, ..., 5C-j connected to each of the indoor units 3C-i.

[0057] Indoor units 3C-1, 3C-2, ..., 3C-i have similar configurations and perform similar functions. Therefore, the configurations of indoor units 3C-1, 3C-2, ..., 3C-i will be explained below using indoor unit 3C-1 as an example. Similarly, external power supply units 5C-1, 5C-2, ..., 5C-j have similar configurations and perform similar functions. Therefore, the configurations of external power supply units 5C-1, 5C-2, ..., 5C-j will be explained below using external power supply unit 5C-1 as an example.

[0058] As shown in Figure 5, the air conditioning system 1C according to this embodiment includes an external power supply unit 5C-1 and an indoor unit 3C-1 connected to the external power supply unit 5C-1. The external power supply unit 5C-1 has the same configuration as the external power supply unit 5 in the first embodiment and performs the same functions.

[0059] The indoor unit 3C-1 has an indoor unit power supply unit 31 that generates an internal voltage Vit. The indoor unit 3C-1 also has a main control unit 321 that operates using either the internal voltage Vit or the external voltage Vex supplied from either the external power supply unit 5C-1 or the indoor unit power supply unit 31 as a power source. The indoor unit 3C-1 also has a voltage monitoring unit 322 that monitors the voltage level of the external voltage Vex output from the external power supply unit 5C-1 and the voltage level of the internal voltage Vit output from the indoor unit power supply unit 31, and outputs an internal monitoring signal Smi or an external monitoring signal Sme corresponding to the voltage supplied to the main control unit 321 from the external voltage Vex and the internal voltage Vit as a stop signal Sst to stop the main control unit 321.

[0060] The operating unit 33C has a communication circuit (an example of a communication unit) 332 that generates operation information (an example of predetermined information) Vif to be transmitted to and received from the outdoor unit 8 at signal levels corresponding to the external voltage Vex and the internal voltage Vit, respectively. The operation information Vif includes information related to the operating state of the indoor unit 3C-1, such as whether the internal voltage Vit or the external voltage Vex is supplied to the main control unit 321 provided in the indoor unit 3C-1. The indoor unit 3C-1 has a switching circuit 325 that switches the voltage level of the operating voltage Vco that operates the communication circuit 332 to correspond to the voltage supplied to the main control unit 321. The indoor unit 3C-1 has a switching circuit 34 (an example of a second switching unit) that switches the signal level of the operation information Vif from the signal level of the operation information Vif corresponding to the internal voltage Vit to the signal level of the operation information Vif corresponding to the external voltage Vex when the external voltage Vex input from the external power supply unit 5C-1 is supplied to the main control unit 321. Furthermore, the indoor unit 3C-1 has a transformer 35 that converts the operation information Vif, which corresponds to the signal level of the external voltage Vex, and the operation information Vif, which corresponds to the signal level of the internal voltage Vit, into the same signal level operation information Vif, regardless of whether they are input from the switching circuit 34. The indoor unit communication circuit section is composed of the communication circuit 332, the switching circuit 34, and the transformer 35.

[0061] More specifically, one input terminal of the switching circuit 325 is connected to the output terminal of the regulator 323. The other input terminal of the switching circuit 325 is connected to the wiring pattern L32. The output terminal of the switching circuit 324 is connected to the power terminal T332 of the communication circuit 332. The control signal input terminal of the switching circuit 325 receives the suggestion signal Ssu output from the external power supply unit 5C-2.

[0062] When the signal level of the suggestion signal Ssu is low, the switching circuit 325 outputs the internal voltage Vit supplied to the wiring pattern L32 input to the other input terminal as the operating voltage Vco to the communication circuit 332 from its output terminal. On the other hand, when the signal level of the suggestion signal Ssu is high, the switching circuit 325 outputs the operating voltage Vdd (i.e., the voltage based on the external voltage Vex) input to one of the input terminals as the operating voltage Vco to the communication circuit 332 from its output terminal. Thus, when the signal level of the suggestion signal Ssu input from the external power supply unit 5C-1 is low, that is, when the internal voltage Vit is supplied from the indoor unit power supply unit 31 to the indoor unit control unit 32C, the switching circuit 325 outputs the internal voltage Vit, switched from the operating voltage Vdd based on the external voltage Vex, as the operating voltage Vco to the communication circuit 332. On the other hand, when the signal level of the suggestion signal Ssu input from the external power supply unit 5C-1 is high, that is, when the external voltage Vex is supplied from the external power supply unit 5C-1 to the indoor unit control unit 32C, the switching circuit 325 outputs the operating voltage Vdd, which is switched from the internal voltage Vit, as the operating voltage Vco to the communication circuit 332.

[0063] The communication circuit 332 operates using the operating voltage Vco input from the switching circuit 325 as its power source. Therefore, the communication circuit 332 can operate at the same voltage level as the voltage supplied to the wiring pattern L32 that operates the indoor unit control unit 32C.

[0064] One output terminal of the communication circuit 332, which outputs the operating voltage Vco, is connected to one input terminal of the switching circuit 34. The other output terminal of the communication circuit 332, which outputs the common voltage Vcom, is connected to the other input terminal of the switching circuit 34. The common voltage Vcom is a voltage that is input to one end of the primary winding of the transformer 35 (details will be described later) in common, regardless of whether the operating voltage Vco corresponds to the internal voltage Vit or the operating voltage Vdd.

[0065] The output terminal of the switching circuit 34 is connected to the primary winding (not shown) of the transformer 35. The control signal input terminal of the switching circuit 34 receives the suggestion signal Ssu output from the external power supply unit 5C-2. The switching circuit 34 has three output terminals. One of these three output terminals is connected to one end of the primary winding of the transformer 35, one of the remaining three output terminals is connected to the other end of the primary winding of the transformer 35, and the other of the remaining three output terminals is connected to an intermediate terminal connected between one end and the other end of the primary winding of the transformer 35.

[0066] The switching circuit 34 outputs the common voltage Vcom input from the communication circuit 332 to one end of the primary winding of the transformer 35, regardless of whether the operating voltage Vco corresponds to the internal voltage Vit or the operating voltage Vdd. When the signal level of the suggestion signal Ssu output from the external power supply unit 5C-2 is high (i.e., the external voltage Vex is supplied to the indoor unit control unit 32C), the switching circuit 34 outputs the operating voltage Vco input from the communication circuit 332 to the other end of the primary winding of the transformer 35. When the signal level of the suggestion signal Ssu output from the external power supply unit 5C-2 is low (i.e., the internal voltage Vit is supplied to the indoor unit control unit 32C), the switching circuit 34 outputs the operating voltage Vco input from the communication circuit 332 to the middle terminal of the primary winding of the transformer 35. In this way, the switching circuit 34 switches the output destination of the operating voltage Vco input from the communication circuit 332 according to the signal level of the suggestion signal Ssu output from the external power supply unit 5C-2.

[0067] The turns ratio between the number of turns from one end to the other of the primary winding of the transformer 35 and the number of turns from one end to the intermediate terminal of the primary winding of the transformer 35 is set based on the voltage ratio between the operating voltage Vdd and the internal voltage Vit input to the switching circuit 325. In this embodiment, the turns ratio and the voltage ratio are set to match. As a result, regardless of whether the operating voltage Vco applied to the primary winding of the transformer 35 corresponds to the internal voltage Vit or the operating voltage Vdd, the voltage output from the secondary winding (not shown) of the transformer 35 will be the voltage corresponding to the operating voltage Vdd.

[0068] The secondary winding of transformer 35 is connected to the outdoor unit 8. Transformer 35 outputs operational information Vif, which is the voltage level output from the secondary winding, to the outdoor unit 8. Therefore, the air conditioning system 1C can stabilize the signal level of the signal, including the operational information Vif, transmitted and received between the indoor unit 3C-1 and the outdoor unit 8, by making the voltage amplitude of the signal the same regardless of whether the internal voltage Vit or the external voltage Vex is supplied to the indoor unit control unit 32C.

[0069] As shown in Figure 5, the outdoor unit 8 has a monitoring system 81. Operation information Vif output from the transformer 35 installed in the indoor unit 3C-1 is input to the monitoring system 81. Based on the operation information Vif input to the transformer 35, the monitoring system 81 determines the operating status of the indoor unit 3C-1, such as whether it is operating on the internal voltage Vit or the external voltage Vex. If the monitoring system 81 determines that the external voltage Vex is supplied to the indoor unit 3C-1, it controls, for example, the main control unit 321 installed in the indoor unit 3C-1 to control the expansion valve (not shown) connected to the indoor unit 3C-1.

[0070] In this way, the air conditioning system 1C can control the expansion valve and other devices of the indoor units 3C-1, 3C-2, ..., 3C-i when the operation switches from the operation of the internal voltage Vit to the operation of the external voltage Vex, thereby preventing the monitoring system 81 installed on the outdoor unit 8 from mistakenly determining that an abnormality has occurred in the air conditioning system 1C.

[0071] As described above, the air conditioning system 1C according to this embodiment includes an outdoor unit 8, a plurality of indoor units 3C-i connected to the outdoor unit 8, and an external power supply unit 5C-j. Each of the plurality of indoor units 3C-i has, in addition to the configuration of the indoor unit 3B in the second embodiment, a communication circuit 332 that generates operation information Vif to be transmitted and received with the outdoor unit 8 at signal levels corresponding to the external voltage Vex and the internal voltage Vit, respectively; a switching circuit 34 that switches the signal level of the operation information Vif from the signal level of the operation information Vif corresponding to the internal voltage Vit to the signal level of the operation information Vif corresponding to the external voltage Vex when the external voltage Vex input from the external power supply unit 5C-j is supplied to the main control unit 321; and a transformer 35 that converts the operation information Vif to the same signal level regardless of whether the operation information Vif at the signal level corresponding to the external voltage Vex or the operation information Vif at the signal level corresponding to the internal voltage Vit is input from the switching circuit 34.

[0072] As a result, in addition to the effects of the air conditioning system 1B according to the second embodiment, the air conditioning system 1C can stabilize the signal level of the signal by making the voltage amplitude of the signal, including the operation information Vif transmitted and received between the indoor unit 3C-i and the outdoor unit 8, the same regardless of whether the internal voltage Vit or the external voltage Vex is supplied to the indoor unit control unit.

[0073] [Variation] An air conditioning system according to a modification of the first to third embodiments of the present invention will be described with reference to Figure 6. This modified air conditioning system has the same configuration as the air conditioning systems of the first to third embodiments, except that the configuration of the voltage monitoring unit is different. In other words, the voltage monitoring unit in this modified system can be applied to the voltage monitoring unit 322 provided in the air conditioning systems of the first to third embodiments. Hereinafter, only the configuration of the voltage monitoring unit of this modified air conditioning system will be described.

[0074] Figure 6 is a block diagram showing an example of the schematic configuration of a voltage monitoring unit 326 provided in the air conditioning system according to this modified example. For ease of understanding, the main control unit 321 provided in the air conditioning system according to this modified example is also shown in Figure 6.

[0075] As shown in Figure 6, the voltage monitoring unit 326 provided in the air conditioning system according to this modified example has a switching circuit 326c that switches the threshold voltage VT to an external threshold voltage VTe for monitoring the voltage level of the external voltage Vex when an external voltage Vex is input to the main control unit 321, and switches the threshold voltage VT to an internal threshold voltage VTi, which is set to a higher value than the external threshold voltage VTe, for monitoring the voltage level of the internal voltage Vit when an internal voltage Vit is input to the main control unit 321. The voltage monitoring unit 326 also has a voltage monitoring circuit 326d that outputs a monitoring signal as a stop signal Sst to the main control unit 321 when the input voltage of either the external voltage Vex or the internal voltage Vit is lower than the threshold voltage VT input from the switching circuit 326c.

[0076] More specifically, the voltage monitoring unit 326 has an internal threshold voltage generation unit 326a that generates an internal threshold voltage VTi. The internal threshold voltage generation unit 326a has a DC power supply (not shown) that outputs a DC voltage at the voltage level of the internal threshold voltage VTi. The voltage level of the internal threshold voltage VTi is set to the same voltage level as the internal threshold voltage in the first to third embodiments described above. The output terminal of the internal threshold voltage generation unit 326a is connected to one of the input terminals of the switching circuit 326c. As a result, the internal threshold voltage VTi generated by the internal threshold voltage generation unit 326a is input to the switching circuit 326c.

[0077] The voltage monitoring unit 326 includes an external threshold voltage generation unit 326b that generates an external threshold voltage VTe. The external threshold voltage generation unit 326b includes a DC power supply (not shown) that outputs a DC voltage at the voltage level of the external threshold voltage VTe. The voltage level of the external threshold voltage VTe is set to the same voltage level as the external threshold voltage in the first to third embodiments described above. The output terminal of the external threshold voltage generation unit 326b is connected to the other input terminal of the switching circuit 326c. As a result, the external threshold voltage VTe generated by the external threshold voltage generation unit 326b is input to the switching circuit 326c.

[0078] The output terminal of the switching circuit 326c is connected to one of the input terminals of the voltage monitoring circuit 326d. The control signal input terminal of the switching circuit 326c receives an indication signal Ssu output from the external power supply unit 5 (not shown in Figure 6; see Figures 1, 3, and 5). When the signal level of the indication signal Ssu input from the external power supply unit 5 is low, the switching circuit 326c outputs the internal threshold voltage VTi input to one input terminal as the threshold voltage VT to the voltage monitoring circuit 326d from its output terminal. On the other hand, when the signal level of the indication signal Ssu input from the external power supply unit 5 is high, the switching circuit 326c outputs the external threshold voltage VTe input to the other input terminal as the threshold voltage VT to the voltage monitoring circuit 326d from its output terminal.

[0079] Thus, when the signal level of the suggestion signal Ssu input from the external power supply unit 5 is low, that is, when the internal voltage Vit is supplied from the indoor unit power supply unit 31 to the main control unit 321, the switching circuit 326c outputs an internal threshold voltage VTi as a threshold voltage VT for comparison with the internal voltage Vit to the voltage monitoring circuit 326d. On the other hand, when the signal level of the suggestion signal Ssu input from the external power supply unit 5 is high, that is, when the external voltage Vex is supplied from the external power supply unit 5 to the main control unit 321, the switching circuit 326c outputs an external threshold voltage VTe as a threshold voltage VT for comparison with the external voltage Vex to the voltage monitoring circuit 326d.

[0080] The other input terminal of the voltage monitoring circuit 326d is connected to the wiring pattern L32. The output terminal of the voltage monitoring circuit 326d is connected to the main control unit 321. The voltage monitoring circuit 326d compares the voltage input via the wiring pattern L32 with the threshold voltage VT input from the switching circuit 326c.

[0081] If the signal level of the suggestion signal Ssu input from the external power supply unit 5 is low, the voltage monitoring circuit 326d compares the internal threshold voltage VTi input from one input terminal with the internal voltage Vit input from the other input terminal. If the voltage monitoring circuit 326d determines that the internal voltage Vit is higher than the internal threshold voltage VTi, it does not output a monitoring signal to stop the main control unit 321. On the other hand, if the voltage monitoring circuit 326d determines that the internal voltage Vit is lower than the internal threshold voltage VTi, it outputs a monitoring signal to stop the main control unit 321.

[0082] If the signal level of the suggestion signal Ssu input from the external power supply unit 5 is high, the voltage monitoring circuit 326d compares the external threshold voltage VTe input from one input terminal with the external voltage Vex input from the other input terminal. If the voltage monitoring circuit 326d determines that the external voltage Vex is higher than the external threshold voltage VTe, it does not output a monitoring signal to stop the main control unit 321. On the other hand, if the voltage monitoring circuit 326d determines that the external voltage Vex is lower than the external threshold voltage VTe, it outputs a monitoring signal to stop the main control unit 321.

[0083] Thus, the air conditioning system according to this modified configuration, like the air conditioning systems according to the first to third embodiments described above, can individually monitor the voltage levels of the internal voltage Vit and the external voltage Vex, and can output a stop signal Sst to the main control unit 321 corresponding to the voltage of the indoor unit power supply unit 31 or the external power supply unit 5 that supplies power to the indoor unit control unit. This prevents malfunctions in the air conditioning system according to this modified configuration, such as stopping operation based on the internal threshold voltage VTi when operating on the external voltage Vex, or stopping operation based on the external threshold voltage VTe when operating on the internal voltage Vit. [Explanation of symbols]

[0084] 1A, 1B, 1C, 1X Air Conditioning System 3A,3B,3C-1,3C-2,3C-i,3X Indoor unit 5,5C-1,5C-2,5C-j External Power Supply Unit 7. External power cable 8 Outdoor unit 31 Indoor unit power supply section 32A, 32B, 32C, 32X Indoor Unit Control Unit 33A,33C Operating part 34,322c,324,325,326c switching circuit 34e, 34i power cable 35 transformers 51,311,351 Voltage generation unit 52,312 Reverse current protection diodes 53 Suggestion signal generation unit 81 Monitoring System 321 Main Control Unit 321a External operation determination section 321b Analog-to-Digital Converter 322,322X Voltage Monitoring Unit 322a Internal voltage monitoring unit 322b External voltage monitoring unit 323 Regulator 326 Voltage Monitoring Unit 326a Internal threshold voltage generation unit 326b External threshold voltage generation unit 326d Voltage Monitoring Circuit 331 Temperature detection unit 332 Communication Circuit L32 Wiring Pattern SME external monitoring signal SMI internal monitoring signal Sst stop signal SSU suggestive signal T3, T5, T31, T32e, T32i, T33, T332 Power terminals T321 Power Input Terminal Vco, Vdd operating voltage Vcom Common Voltage Vex External Voltage Vif operation information Vit Internal Voltage VT threshold voltage VTe External threshold voltage VTi internal threshold voltage

Claims

1. External power supply unit, An indoor unit having an internal power supply unit, a main control unit that operates using a voltage supplied from either the external power supply unit or the internal power supply unit as a power source, and a voltage monitoring unit that monitors the voltage level of the external voltage output from the external power supply unit and the voltage level of the internal voltage output from the internal power supply unit, and outputs a monitoring signal corresponding to the voltage supplied to the main control unit from the external voltage and the internal voltage to the main control unit as a stop signal to stop the main control unit. An air conditioning system equipped with [specific features / features].

2. The voltage monitoring unit outputs the monitoring signal corresponding to the internal voltage as a stop signal to the main control unit when the internal voltage is output from the internal power supply unit, and outputs the monitoring signal corresponding to the external voltage as a stop signal to the main control unit when the internal voltage is not output from the internal power supply unit. The air conditioning system according to claim 1.

3. The external power supply unit outputs an indication signal to the indoor unit indicating whether or not it is outputting the external voltage to the indoor unit. When the voltage monitoring unit receives the indication signal indicating that the external voltage is being output, it switches the monitoring signal from the internal voltage to the monitoring signal corresponding to the external voltage. The air conditioning system according to claim 1 or 2.

4. The aforementioned indoor unit is An operating unit that also operates when the aforementioned external voltage is supplied to the main control unit, A voltage generation unit that generates an operating voltage for operating the aforementioned operating unit based on the external voltage, A first switching unit that switches the voltage level of the voltage that operates the operating unit when the external voltage is supplied to the main control unit from the voltage level when the internal voltage is supplied to the operating voltage level. has An air conditioning system according to any one of claims 1 to 3.

5. The operating unit has a temperature detection unit that detects the temperature of the room in which the indoor unit is installed. The air conditioning system according to claim 4.

6. The outdoor unit is connected to the indoor unit, The operating unit has a communication unit that generates predetermined information to be transmitted and received with the outdoor unit at signal levels corresponding to the external voltage and the internal voltage, respectively. The aforementioned indoor unit is A second switching unit that, when the external voltage is supplied to the main control unit, switches the signal level of the predetermined information from the signal level of the predetermined information corresponding to the internal voltage to the signal level of the predetermined information corresponding to the external voltage, A transformer that converts the predetermined information of the signal level corresponding to the external voltage and the predetermined information of the signal level corresponding to the internal voltage, whichever is input from the second switching unit, into the predetermined information of the same signal level. It has, The outdoor unit is connected to a plurality of indoor units, and to each of the plurality of indoor units, one external power supply unit is connected. The air conditioning system according to claim 4 or 5.

7. The aforementioned voltage monitoring unit, An external voltage monitoring unit that monitors the external voltage and outputs an external monitoring signal as the monitoring signal corresponding to the external voltage, An internal voltage monitoring unit that monitors the internal voltage and outputs an internal monitoring signal as the monitoring signal corresponding to the internal voltage, A switching circuit that converts the stop signal input to the main control unit into an external monitoring signal when the voltage supplied to the main control unit is the external voltage, and into an internal monitoring signal when the voltage supplied to the main control unit is the internal voltage. has An air conditioning system according to any one of claims 1 to 6.

8. The external voltage monitoring unit outputs the external monitoring signal to the switching circuit when the external voltage is lower than the external threshold voltage. The internal voltage monitoring unit outputs the internal monitoring signal to the switching circuit when the internal voltage is lower than the internal threshold voltage, which is set to a value higher than the external threshold voltage. The air conditioning system according to claim 7.

9. The aforementioned voltage monitoring unit, A switching circuit that switches the threshold voltage to an external threshold voltage for monitoring the voltage level of the external voltage when the external voltage is input to the main control unit, and switches the threshold voltage to an internal threshold voltage set to a value higher than the external threshold voltage for monitoring the voltage level of the internal voltage when the internal voltage is input to the main control unit, A voltage monitoring circuit that outputs the monitoring signal as a stop signal to the main control unit when the input voltage among the external voltage and the internal voltage is lower than the threshold voltage input from the switching circuit. has An air conditioning system according to any one of claims 1 to 6.

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