Communication device for air conditioner

Abstract

The invention provides a communication device of an air conditioner, which can stabilize communication. A communication device of an air conditioner according to an embodiment includes a plurality of devices connected by two AC power lines and one communication line. A communication device for an air conditioner has a power supply circuit and a transmission circuit. The power supply circuit generates a DC voltage based on the phase of one of the two AC power supply lines. The transmission circuit varies the voltage of the communication line on the basis of a signal transmitted by a control device that controls the air conditioner. A capacitor is connected between the transmission circuit and the communication line. When the reference potential of the communication line increases, the voltage of the communication signal flowing through the communication line is boosted using the charge of the capacitor.

Description

Technical Field

[0001] An embodiment of the present invention relates to a communication device for an air conditioner. Background Art

[0002] As a communication device of the air conditioner, there is a device that uses two switches to suppress poor communication caused by the charge accumulated in the parasitic capacitance of the communication line. In this method, one switch is used to increase the voltage of the communication line, and the other switch is used to discharge the parasitic capacitance. Among them, in the former switch, the voltage is increased by short-circuiting the power supply of the communication circuit and the communication line. However, when the voltage of the communication line is higher than the power supply voltage of the communication circuit, sometimes the voltage cannot be increased, the communication content is missing or the communication is not connected, and the communication becomes unstable.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent No. 3578134 Summary of the invention

[0006] Technical problem to be solved by the invention

[0007] The technical problem to be solved by the present invention is to provide a communication device for an air conditioner capable of stabilizing communication.

[0008] Solutions for solving the above technical problems

[0009] The communication device of the air conditioner of the embodiment is composed of a plurality of devices connected to one communication line through two AC power lines. The communication device of the air conditioner includes a power supply circuit and a transmission circuit. The power supply circuit generates a DC voltage based on the phase of any one of the two AC power lines. The transmission circuit changes the voltage of the communication line based on a signal sent by a control device that controls the air conditioner. A capacitor is connected between the transmission circuit and the communication line. When the reference potential of the communication line rises, the charge of the capacitor is used to boost the voltage of the communication signal.

[0010] In addition, the communication device of the air conditioner in other embodiments is composed of a plurality of devices connected to one communication line via two AC power lines. The communication device of the air conditioner includes a power supply circuit and a transmission circuit. The power supply circuit generates a DC voltage based on the phase of any one of the two AC power lines. The transmission circuit changes the voltage of the communication line based on a signal sent by a control device that controls the air conditioner. A circuit in which a diode and a capacitor are connected in parallel is provided between the transmission circuit and the communication line. The diode is connected in a direction so that current flows from the transmission circuit to the communication line. When the reference potential of the communication line rises, the charge of the capacitor is used to boost the voltage of the communication signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a block diagram showing an example of the configuration of the air conditioner according to the first embodiment.

[0012] Figure 2 This is a block diagram showing the circuit and function of the communication device of the air conditioner according to the first embodiment.

[0013] Figure 3 1 is a diagram showing an example of various parasitic components generated in the wiring portion 80 .

[0014] Figure 4 This is a diagram showing an example of a communication waveform on the transmission side and a communication waveform on the reception side when interference occurs in a conventional communication circuit.

[0015] Figure 5 This is a diagram showing an example of a communication waveform on the transmission side and a communication waveform on the reception side when interference occurs in the communication circuit of the air conditioner according to the first embodiment.

[0016] Figure 6 This is a block diagram showing the circuit and function of the communication device of the air conditioner according to the second embodiment.

[0017] Figure 7 This is a block diagram showing the circuit and function of the communication device of the air conditioner according to the third embodiment.

[0018] Figure 8 This is a block diagram showing the circuit and function of the communication device of the air conditioner according to the fifth embodiment. DETAILED DESCRIPTION

[0019] Hereinafter, a communication device for an air conditioner according to an embodiment will be described with reference to the drawings.

[0020] (First embodiment)

[0021] Figure 11 is a block diagram showing an example of the structure of the air conditioner 1 of the first embodiment. The air conditioner 1, for example, includes an outdoor unit 10 and a plurality of indoor units 20 (20A, 20B, ..., 20M). The outdoor unit 10 and the plurality of indoor units 20 are connected to a commercial AC power supply 31 via two AC power lines (a first AC power line 32 and a second AC power line 33), and are connected to each other via a communication line 34. In addition, the commercial AC power supply 31 is exemplified as a single-phase power supply, but a three-phase AC power supply may be used as a power supply in the outdoor unit 10 having a compressor and consuming a large amount of power, and any two phases thereof may be connected to the indoor unit 20 as AC power lines 32 and 33. Furthermore, in the case of using a four-wire three-phase AC power supply having N phases as a neutral point, the 1st phase and the N phases in the three-phase AC may be used as AC power lines 32 and 33, respectively, to supply the indoor unit 20 with operating power for the indoor unit 20.

[0022] The plurality of indoor units 20A, 20B, ..., 20M have the same configuration. In the following description, when the indoor units are described without distinguishing them, they are referred to as the indoor units 20. The first AC power line 32, the second AC power line 33, and the communication line 34 are generally contained in one cable called a jumper. In this case, one wire in the three-wire cable is used as the communication line 34. In the first embodiment, a plurality of indoor units 20 are provided, but the indoor unit 20 may be a single one (one).

[0023] exist Figure 2 In the embodiment, the communication device 2 is composed of a first communication device 40 of the outdoor unit 10 and a second communication device 50 of the indoor unit 20. A first air conditioning circuit 60 is further provided in the outdoor unit 10, and a second air conditioning circuit 70 is provided in the indoor unit 20. The first air conditioning circuit 60 and the second air conditioning circuit 70 are examples of control devices, and they operate in association with each other to perform a predetermined air conditioning operation.

[0024] The first communication device 40 and the second communication device 50 are connected via the above-mentioned three-wire cable, i.e., the wiring portion 80, through the first AC power line 32, the second AC power line 33, and the communication line 34. The wiring portion 80 is connected to the first AC power line 32 on the first communication device 40 side through the connection terminal L, connected to the second AC power line 33 through the connection terminal N, and connected to the communication line 34 through the connection terminal S. The wiring portion 80 is connected to the first AC power line 32 on the second communication device 50 side through the connection terminal L', connected to the second AC power line 33 through the connection terminal N', and connected to the communication line 34 through the connection terminal S'.

[0025] The first communication device 40 includes, for example, a power supply circuit 41, a transmission circuit 42, a reception circuit 43, a reverse voltage protection diode 44, and a capacitor 45. The second communication device 50 includes, for example, a power supply circuit 51, a transmission circuit 52, a reception circuit 53, a reverse voltage protection diode 54, and a capacitor 55. The first communication device 40 and the second communication device 50 have the same configuration. Hereinafter, these configurations will be described using the first communication device 40.

[0026] The power supply circuit 41 is connected to two AC power supply lines 32 and 33 connected to the commercial AC power supply 31, and generates a DC voltage based on one phase, here, the phase of the second AC power supply line 33. The transmission circuit 42 varies the voltage of the communication line 34 based on a signal generated by the first air conditioning circuit 60 that controls the outdoor unit 10 of the air conditioner 1, that is, a transmission signal for the indoor unit 20. For example, the following communication method is used as the voltage variation of the communication line 34: in a carrier cycle in a certain period, if the transmission signal is "1", a high potential is maintained for a predetermined period, and on the other hand, if the transmission signal is "0", a low potential state is continued during the carrier cycle.

[0027] The transmission circuit 42 includes a series circuit of a first switch 42A and a second switch 42B connected to the power supply circuit 41. The first switch 42A and the second switch 42B are both formed of, for example, low-on-resistance components. The first switch 42A and the second switch 42B may be formed of components other than low-on-resistance components.

[0028] The first switch 42A located on the high potential side of the power circuit 41 is a switch for increasing the voltage of the communication line 34, and the second switch 42B connected to the reference potential side of the power circuit 41, that is, the second AC power line 33, is a switch for decreasing the voltage of the communication line 34. The communication line 34 is connected to the mutual connection point of the two switches 42A and 42B. Through this connection, the first switch 42A or the second switch 42B is turned on (becomes conductive), so that a rectangular wave voltage is generated in the communication line 34. At this time, the upper limit value of the voltage of the communication line 34 is limited by the voltage of the power circuit 41.

[0029] The receiving circuit 43 has, for example, a function as a voltage sensor for reading voltage, a function for generating a signal corresponding to a voltage change, and a function for transmitting the generated signal to the first air conditioning circuit 60. The receiving circuit 43 is connected between the communication line 34 and the second AC power line 33 as the low potential side of the power supply circuit 41, reads the voltage change generated in the communication line 34, and transmits a signal corresponding to the read voltage change to the first air conditioning circuit 60. Although not shown in the figure, a general receiving circuit is used as the receiving circuit 43, which includes: an RC filter for extracting a voltage change of a communication signal; and an insulating circuit for insulating the signal in response to the rising edge and the falling edge of the signal output from the RC filter and outputting it as a Hi / Lo signal.

[0030] The reverse voltage protection diode 44 is provided in parallel with the receiving circuit 43. The reverse voltage protection diode 44 protects the receiving circuit 43 from a reverse voltage which is opposite to the direction designed for the voltage applied to the receiving circuit 43.

[0031] The capacitor 45 is inserted between the transmission circuit 42 and the communication line 34 and is included in the communication circuit. When current flows through the communication line 34, it stores electricity. When the reference potential of the communication line 34 rises, the capacitor 45 releases the stored charge to increase the voltage of the communication signal flowing through the communication line 34.

[0032] The first air conditioning circuit 60 receives the signal corresponding to the voltage change transmitted by the receiving circuit 43. The first air conditioning circuit 60 generates a control signal for controlling the opening and closing of the first switch 42A and the second switch 42B in the transmitting circuit 42 based on the setting content of the air conditioner 1, the operating status of the outdoor unit 10, and the received signal. The first air conditioning circuit 60 transmits the generated control signal to the transmitting circuit 42.

[0033] The second air conditioning circuit 70 receives the signal corresponding to the voltage change transmitted by the receiving circuit 53. The second air conditioning circuit 70 generates a control signal for controlling the opening and closing of the first switch 52A and the second switch 52B in the transmitting circuit 52 according to the setting content of the air conditioner 1, the operating status of the indoor unit 20, and the received signal. The second air conditioning circuit 70 transmits the generated control signal to the transmitting circuit 52. In addition, the setting content of the air conditioner 1 includes, but is not limited to, operation modes such as operation / stop, cooling and heating, and indoor set temperature.

[0034] In the communication device of the air conditioner of the first embodiment, one wire of the three-wire cable is used as the communication line 34. If the communication line 34 and the AC power lines 32 and 33 are connected to the same cable, the communication line 34 will be affected by the AC power lines 32 and 33 compared to the case where the communication line is independent. Therefore, in the communication line 34, the communication waveform may be disturbed due to parasitic inductance, parasitic resistance, parasitic capacitance, or a combination thereof.

[0035] exist Figure 3 In the wiring portion 80, the wiring 81 is connected to the connection terminal L, the wiring 82 is connected to the connection terminal N, and the wiring 83 is connected to the connection terminal S. In addition, the wiring 84 is connected to the connection terminal L', the wiring 85 is connected to the connection terminal N', and the wiring 86 is connected to the connection terminal S'. The wiring 81 and the wiring 84 are connected to the first AC power line 32, and the wiring 82 and the wiring 85 are connected to the second AC power line 33. Parasitic reactance 87 (parasitic inductance) and parasitic resistance 88 are generated between the connection terminals L-L', between the connection terminals N-N', and between the connection terminals S-S', respectively. In addition, parasitic capacitance 89 (parasitic capacitance) is generated between the wirings connecting the terminals.

[0036] Here, the reference potentials of the transmission side (e.g., the outdoor unit 10 side) and the reception side (e.g., the indoor unit 20 side) of the communication are equal when no current flows through the AC power lines 32 and 33, but become unequal when current flows through the AC power lines 32 and 33. The reason for the unequal reference potentials is that the parasitic inductance in the parasitic reactance 87 and the parasitic resistance in the parasitic resistance 88 in the wiring portion 80 have a large influence, and at commercial frequencies, the parasitic resistance plays a dominant role in this influence. In addition, the voltage generated by the flow of this current may have an adverse effect on the communication operation.

[0037] For example, when no capacitor 45 is provided between the transmitting circuit 42 and the communication line 34, when the equipment in the outdoor unit 10 and / or the indoor unit 20 operates and current flows through the AC power lines 32 and 33, a voltage (interference voltage) is generated in the wiring due to the presence of the parasitic reactance 87, the parasitic resistance 88, and the parasitic capacitance 89 of the wiring portion 80. The interference voltage changes the reference potential of the communication line. For example, when the current flowing through the AC power lines 32 and 33 is set to I and the parasitic resistance is set to R, the voltage (interference voltage) V generated by the parasitic resistance 88 is V=IR. In this way, if the current I flowing through the outdoor unit 10 and / or the indoor unit 20 increases, the interference voltage V increases. In particular, the large current generated by the operation of the compressor of the outdoor unit 10 increases the interference voltage V. Therefore, relative to the Figure 4The upper part shows the output voltage of the power supply circuit 41 on the sending side of the communication waveform, and the lower part shows the rise of the reference potential BV on the receiving side of the communication waveform, which relatively reduces the voltage of the communication waveform. As a result, the amplitude (voltage) of the rectangular wave waveform as the communication signal is suppressed and becomes smaller, and the correct waveform cannot be read on the receiving side (here, the power supply circuit 51 side), and normal communication cannot be performed. In particular, when the interference voltage exceeds the power supply voltage of the communication circuit, that is, the output voltage of the power supply circuits 41 and 51, the receiving circuit 43 cannot read the voltage change, and communication becomes invalid.

[0038] In contrast, in the communication device 2 of the first embodiment, a circuit is provided on the transmission side in which a capacitor 45 is connected between the transmission circuit 42 and the communication line 34. When the reference potential of the communication line 34 rises on the receiving side due to the aforementioned interference, the capacitor 45 releases the accumulated charge to boost the voltage of the communication signal flowing in the communication line 34.

[0039] Therefore, even if Figure 5 The envelope of the lower end of the pulse signal shown, i.e., the reference potential BV of the communication line 34 on the receiving side, rises, and the amplitude of the rectangular wave communication signal flowing through the communication line 34 is also maintained at approximately the same magnitude as when the voltage of the communication line 34 is normal. Therefore, the correct signal can be received on the receiving side (here, the power supply circuit 51 side), and communication obstruction can be suppressed. In addition, Figure 5 and Figure 4 Similarly, the upper section shows the communication waveform of the transmitting side, and the lower section shows the communication waveform of the receiving side. Figure 5 , for reference, shows the case where all transmission signals are "1". Here, when the transmission signal is "0", the high voltage (pulse) section disappears during the predetermined communication duty cycle, and the minimum voltage is maintained.

[0040] In addition, it is also possible to consider suppressing the influence of parasitic resistance and parasitic inductance by setting the DC voltage output from the transmission circuit 42 to a higher value than the interference voltage, but this requires that the power supply circuits 41 and 51 be configured as DC power supply circuits with high voltage output, which becomes the main reason for the large-scale and complicated device. In this regard, in the communication device 2 of the first embodiment, only by connecting the capacitor 45 between the transmission circuit 42 and the communication line 34, the output of the power supply circuits 41 and 51 is low voltage and smooth communication can be performed, which can be expected to achieve the miniaturization and simplification of the power supply circuit. Cost reduction. Similarly, on the receiving side, a capacitor 55 is also connected between the transmission circuit 52 and the communication line 34, so it has the same effect. In addition, it can be set to a simpler structure than the communication device of other embodiments described later.

[0041] (Second embodiment)

[0042] Next, use Figure 6 The second embodiment is described. The communication device 2 of the second embodiment is different from the first embodiment in the following aspects: in the communication circuits provided with capacitors 45 and 55, respectively, resistors 46 and 56 are inserted in series on the downstream side observed from the power supply circuits 41 and 51. That is, a capacitor 45 and a resistor 46 are connected in series on the communication line 34 of the transmission circuit 42 connected to the output of the power supply circuit 41 of the outdoor unit 10. Similarly, a capacitor 55 and a resistor 56 are connected in series in sequence on the communication line 34 of the transmission circuit 52 connected to the output of the power supply circuit 51 of the indoor unit 20. Other aspects have the same structure as the communication device of the first embodiment. In addition, the connection order of each resistor 46 and 56 and the capacitor 45 and 55 is not limited. It is also possible to connect resistors 46 and 56 to the output of the power supply circuits 41 and 51, and connect capacitors 45 and 55 before them.

[0043] The communication device 2 of the second embodiment is provided with the capacitors 45 and 55 similarly to the first embodiment. Therefore, even when the voltage of the communication line 34 rises due to noise, the influence of the parasitic resistance and the parasitic inductance can be suppressed.

[0044] Furthermore, in the communication device 2 of the second embodiment, resistors 46 and 56 are inserted in series in the capacitors 45 and 55 on the downstream side observed from the power supply circuits 41 and 51. The first switch 42A and 52A and the second switch 42B and 52B in the transmitting circuits 42 and 52 are components with low on-resistance, so sometimes a large current flows instantaneously. Since the capacitors 45 and 55 are charging currents, the resistance of the charging path is significantly reduced, thereby generating a large current. Such a large current may be the cause of shortening the life of the capacitors 45 and 55. Therefore, resistors 46 and 56 are respectively inserted to suppress the peak value of the current flowing in the receiving circuits 43 and 53 or the wiring portion 80, and suppress the generation of the instantaneous large current flowing in the communication line 34, thereby extending the life of the capacitors 45 and 55.

[0045] In addition, when the impedance of the communication line 34 and the receiving circuits 43 and 53 is low, a pulse current flows in the communication line. Due to the flow of the pulse current, the frequency component above the communication frequency is propagated as noise, sometimes hindering other devices. In this regard, by inserting the resistors 46 and 56 in series to the capacitors 45 and 55, the outflow of the pulse current can also be prevented.

[0046] (Third embodiment)

[0047] Next, use Figure 7The third embodiment is described. The communication device 2 of the third embodiment is different from the first embodiment in that it has a circuit in which diodes 47 and 57 are provided in parallel with the capacitors 45 and 55 in the first embodiment to flow current from the transmission circuit 42 to the downstream side. The other aspects have the same structure as the communication device of the first embodiment.

[0048] The communication device 2 of the third embodiment is provided with the capacitors 45 and 55 similarly to the first embodiment. Therefore, even when the voltage of the communication line 34 increases due to noise, it is possible to suppress interference with communication via the communication line 34 .

[0049] Furthermore, in the communication device 2 of the third embodiment, diodes 47 and 57 are provided in parallel with the capacitors 45 and 55 to allow current to flow from the transmission circuit 42 to the downstream side. Therefore, when the first switch 42A is turned on and the voltage of the communication line 34 rises due to the DC voltage generated by the power supply circuit 41 on the receiving side, the charge stored in the capacitors 45 and 55 is released, and the voltage of the communication signal flowing through the communication line 34 is increased. Therefore, the timing of the capacitors 45 and 55 releasing the charge can be made appropriate.

[0050] (Fourth embodiment)

[0051] Next, the fourth embodiment will be described. The communication device 2 of the fourth embodiment is different from the third embodiment in that the same resistors as those of the second embodiment are respectively provided on the downstream side of the circuit in which capacitors 45 and 55 and diodes 47 and 57 are provided in parallel as viewed from the transmission circuit 42. The other aspects have the same configuration as the communication device of the third embodiment.

[0052] The communication device 2 of the fourth embodiment is similar to the third embodiment. Even when the voltage of the communication line 34 rises due to interference, it is possible to suppress the obstruction of communication via the communication line 34 and to make the timing of the discharge of the charge of the capacitors 45 and 55 appropriate. Furthermore, in the communication device 2 of the fourth embodiment, since the resistor is provided, it is possible to suppress the peak value of the current flowing in the receiving circuits 43 and 53 and the wiring unit 80, and suppress the generation of the large current flowing in the communication line 34.

[0053] (Fifth embodiment)

[0054] Next, through Figure 8The fifth embodiment is described. The communication device 2 of the fifth embodiment is different from the first embodiment in the following aspects: a filter, such as a low-pass filter 90, is provided between the communication line 34 and the capacitors 45 and 55 in the first embodiment to suppress changes in the voltage of the communication line 34. Other aspects have the same structure as the communication device of the first embodiment.

[0055] The low pass filter 90 includes a resistor 91 and a capacitor 92. The resistor 91 is provided in series with the communication line 34 between the transmission circuits 42 and 52 and the capacitors 45 and 55. The capacitor 92 is provided in parallel with the reception circuits 43 and 53. The low pass filter 90 suppresses changes in the voltage of the communication line 34 of a frequency component higher than the communication signal.

[0056] The communication device 2 according to the fifth embodiment can suppress the hindrance of communication through the communication line 34 by the capacitors 45 and 55 , similarly to the first embodiment.

[0057] Furthermore, by providing the low-pass filter 90 between the transmission circuits 42 and 52 and the capacitors 45 and 55, it is possible to suppress leakage of high-frequency noise to the outside. Furthermore, by providing the low-pass filter 90, it is possible to omit a resistor.

[0058] According to at least one embodiment described above, the communication device of an air conditioner comprises an outdoor unit 10 and one or more indoor units 20 connected via one communication line and two AC power lines, the communication device of the air conditioner comprises: a power circuit for generating a DC voltage based on the phase of any one of the two AC power lines; and a transmitting circuit for changing the voltage of the communication line based on a signal sent by a control device for controlling the air conditioner, a circuit in which a diode and a capacitor are connected in parallel is provided between the transmitting circuit and the communication line, the diode being connected in a direction so that current flows from the transmitting circuit to the communication line, and when the reference potential of the communication line rises, the charge of the capacitor is used to boost the voltage of the communication signal flowing through the communication line, thereby stabilizing the communication.

[0059] In each of the above embodiments, the communication device is applied as a communication device between an outdoor unit 10 and a plurality of indoor units 20, but it can also be applied as a communication device between other multiple devices. For example, the communication device can also be applied as a communication device between an indoor unit 20 and other indoor units 20. In addition, the communication device is configured so that both the sending side and the communication side can perform transmission and reception respectively, but it can also be set to other configurations. For example, one side can only have a transmission function and the other side can only have a receiving function. In addition, one side can only have a transmission function and the other side can have a transmission and reception function, or one side can have a transmission and reception function and the other side can only have a reception function.

[0060] Several embodiments of the present invention have been described, but these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other ways, and various omissions, substitutions, and changes can be made without departing from the scope of the subject matter of the invention. These embodiments and their variations are included in the scope and subject matter of the invention, and are also included in the invention described in the claims and the scope equivalent thereto.

[0061] Description of Reference Numerals

[0062] 1 Air conditioner

[0063] 2 communication device

[0064] 10Outdoor unit

[0065] 20Indoor unit

[0066] 31 Commercial AC power supply

[0067] 32 1st AC power cord

[0068] 33 2nd AC power cord

[0069] 34 communication lines

[0070] 40 No. 1 communication device

[0071] 41, 51 power supply circuit

[0072] 42, 52 transmission circuit

[0073] 42A, 52A 1st switch

[0074] 42B, 52B 2nd switch

[0075] 43, 53 receiving circuit

[0076] 45, 55, 92 capacitors

[0077] 46, 56, 91 resistors

[0078] 47, 57 diodes

[0079] 50 second communication device

[0080] 60 1st air conditioning circuit

[0081] 70 2nd air conditioning circuit

[0082] 80 Wiring Department

[0083] 81~86 wiring

[0084] 90 Low pass filter

[0085] L, L', N, N', S, S' connection terminals.

Claims

1. A communication device for an air conditioner, the air conditioner comprising a plurality of devices connected via two AC power lines and one communication line, characterized in that: have: a power supply circuit that generates a DC voltage based on a phase of any one of the two AC power supply lines; and a transmitting circuit that varies the voltage of the communication line based on a signal transmitted by a control device that controls the air conditioner, A capacitor is connected between the transmitting circuit and the communication line. When the reference potential of the communication line rises, the voltage of the communication signal flowing through the communication line is boosted using the charge of the capacitor.

2. The communication device for an air conditioner according to claim 1, wherein: A resistor is inserted in series with the capacitor. A terminal of the capacitor or a terminal of the resistor is connected to the communication line.

3. A communication device for an air conditioner, the air conditioner comprising an outdoor unit and one or more indoor units connected via two AC power lines and one communication line, characterized in that: have: a power supply circuit that generates a DC voltage based on a phase of any one of the two AC power supply lines; and a transmitting circuit that varies the voltage of the communication line based on a signal transmitted by a control device that controls the air conditioner, A circuit formed by connecting a diode and a capacitor in parallel is provided between the transmitting circuit and the communication line. The diode is connected in a direction that allows current to flow from the transmission circuit to the communication line. When the reference potential of the communication line rises, the voltage of the communication signal flowing through the communication line is boosted using the charge of the capacitor.

4. The communication device for an air conditioner according to claim 1 or 3, characterized in that: The control device further includes a receiving circuit that reads a voltage variation of the communication line and transmits a signal corresponding to the voltage variation to the control device.

5. The communication device for an air conditioner according to claim 3, wherein: A resistor is inserted in series with the circuit in which the diode and the capacitor are connected in parallel.

6. The communication device for an air conditioner according to claim 1, wherein: A filter that suppresses changes in voltage of the communication line is inserted between the communication line and the capacitor.

7. The communication device for an air conditioner according to claim 1, wherein: The plurality of devices are an outdoor unit and one or more indoor units.

8. The communication device for an air conditioner according to claim 1, wherein: The plurality of devices are a plurality of indoor units.

Images