Ventilation device

Abstract

To solve the problem in which inrush current and pulse-like current generated from an environment sensor become a variable factor in power supply voltage, and may affect stable operation of another electric circuit in a ventilation device.SOLUTION: A ventilation device comprises: an environment sensor 18 or an environment sensor 19 for measuring the concentration of a measurement object contained in air, and outputting measurement information; a microcontroller 31 for acquiring the measurement information outputted by the environment sensor 18 or the environment sensor 19; a first power supply circuit 29 connected to the microcontroller 31, and for supplying electric power to the microcontroller 31; and a second power supply circuit 30 provided separately from the first power supply circuit 29, and for supplying electric power to the environment sensor 18 or the environment sensor 19 via a switch circuit 44 connected to the environment sensor 18 or the environment sensor 19.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to ventilation devices. [Background technology]

[0002] Patent Document 1 discloses a ventilation device equipped with a CO2 sensor. In particular, the document discloses a ventilation device that incorporates a CO2 sensor provided in an exhaust air duct to measure the concentration of CO2 contained in indoor air, and a CO2 sensor provided in an intake air duct to measure the concentration of CO2 contained in outdoor air. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7237177 Summary of the Invention [Problem to be solved by the invention]

[0004] The ventilation device described in Patent Document 1 uses a CO2 sensor as an environmental sensor that detects the air condition. However, in many cases, an inrush current and a pulse current flow when the power supply that supplies power to the CO2 sensor is turned on and when the CO2 sensor measures the CO2 concentration in the air.

[0005] Therefore, inrush currents and pulsed currents generated by environmental sensors such as CO2 sensors can cause fluctuations in the power supply voltage, which may affect the stable operation of other electrical circuits within the ventilation device.

[0006] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a ventilation device that can operate stably even when equipped with an environmental sensor. [Means for solving the problem]

[0007] The ventilation device according to the present disclosure comprises an environmental sensor that measures the concentration of a measurement target substance contained in the air and outputs the measurement information, a microcontroller that acquires the measurement information output by the environmental sensor, a first power supply circuit that is connected to the microcontroller and supplies power to the microcontroller, and a second power supply circuit that is provided separately from the first power supply circuit and supplies power to the environmental sensor via a switch circuit that is connected to the environmental sensor. [Effects of the Invention]

[0008] The ventilation device of the present disclosure includes a second power supply circuit that is provided separately from the first power supply circuit that supplies power to the microcontroller and that supplies power to the environmental sensor via a switch circuit connected to the environmental sensor.This makes it less likely that inrush current and pulsed current generated by the environmental sensor will cause fluctuations in the power supply voltage of the first power supply circuit, thereby achieving the effect of obtaining a ventilation device that can operate stably even when equipped with an environmental sensor. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram showing the configuration of a ventilation device according to a first embodiment. [Figure 2] 1 is a functional configuration diagram showing the functional configuration of a ventilation device according to Embodiment 1. FIG. [Figure 3] 2 is an explanatory diagram showing a schematic diagram of details of an isolated switching power supply, a first power supply circuit, a second power supply circuit, and a switch circuit in the ventilation device according to the first embodiment. FIG. [Figure 4] 3 is an explanatory diagram schematically illustrating the details of connections between a switch circuit and an environmental sensor in the ventilation device according to the first embodiment. FIG. [Figure 5] FIG. 2 is a schematic diagram for explaining the circulation operation in the ventilation device according to the first embodiment. [Figure 6] 10 is an explanatory diagram for explaining an example of a current waveform when the environment sensor 18 (CO 2 sensor) used in the ventilation device according to the first embodiment is operating. FIG. [Figure 7]4 is an explanatory diagram for explaining an example of a current waveform when the environment sensor 19 (PM2.5 sensor) used in the ventilation device according to the first embodiment is operating. FIG. [Figure 8] 5 is an explanatory diagram for explaining fluctuations in power supply voltage in response to a sudden change in load current of the linear regulator in the ventilation device according to the first embodiment. FIG. [Figure 9] 3 is an explanatory diagram for explaining power supply from a power supply device in the ventilation device according to the first embodiment. FIG. [Figure 10] 4 is an explanatory diagram for explaining the operating time of the environment sensor in the ventilation device according to the first embodiment. FIG. [Figure 11] 4 is an explanatory diagram for explaining the output voltage and output current in the power supply circuit when the environmental sensor in the ventilation device according to the first embodiment is in operation. FIG. [Figure 12] 2 is an explanatory diagram illustrating an example of the hardware configuration of a control circuit included in the ventilation device according to the first embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments for carrying out the present disclosure will be described in detail with reference to the accompanying drawings. In each drawing, the same or corresponding parts are designated by the same reference numerals. Duplicate descriptions of such parts will be appropriately simplified or omitted. In addition, the size relationships between the components in each drawing may differ from the actual size relationships. Furthermore, the present invention is not limited to the embodiments for carrying out the present disclosure.

[0011] Embodiment 1 FIG. 1 is a schematic diagram showing the configuration of a ventilation device according to a first embodiment. In FIG. 1, the symbol OA (Outdoor Air) refers to outside air, which represents air drawn into the ventilation device 1 from outdoors (hereinafter, this may be referred to as outdoor air OA). Similarly, the symbol SA (Supply Air) refers to supply air, which represents air blown indoors from the ventilation device 1 (hereinafter, this may be referred to as supply air SA). Furthermore, the symbol RA (Return Air) refers to return air, which represents air drawn into the ventilation device 1 from indoors (hereinafter, this may be referred to as return air RA). Furthermore, the symbol EA (Exhaust Air) refers to exhaust air, which represents air blown outdoors from the ventilation device 1 (hereinafter, this may be referred to as exhaust air EA).

[0012] The outer shell of the ventilation device 1 is made up of a metal housing 2. When the ventilation device 1 is a ceiling-mounted type (also called a ceiling-embedded type), the ventilation device 1 is installed above the ceiling. An outside air intake port 3 and an exhaust outlet 4 are formed on one side of the housing 2 of the ventilation device 1. An intake air outlet 5 and an indoor air intake port 6 are formed on the other side of the housing 2 of the ventilation device 1 opposite the one side. Duct piping (not shown) is connected to each of the outside air intake port 3, exhaust outlet 4, intake air outlet 5, and indoor air intake port 6.

[0013] In the ventilation device shown in FIG. 1, a heat exchanger 7 is provided in the middle of the ventilation device 1. In addition, an intake air blower 8 for supplying outside air OA into the room is installed between the heat exchanger 7 and the intake air outlet 5, and an intake air passage 9 passing through the heat exchanger 7 is formed. The intake fan 8 has built-in blades (not shown) for sending air, and the blades built into the intake fan 8 are rotated by a motor 10a to move the air. This generates an airflow as the intake air passage 9.

[0014] An exhaust fan 11 for exhausting the air returned indoors from the indoors to the outdoors is installed between the heat exchanger 7 and the exhaust outlet 4, and an exhaust air passage 12 passing through the heat exchanger 7 is formed. The exhaust fan 11 has built-in blades (not shown) for sending air, and the blades built into the exhaust fan 11 are rotated by a motor 10b to move the air. This generates an airflow in the exhaust air passage 12. It should be noted that the motor 10a of the air supply fan 8 and the motor 10b of the exhaust fan 11 are often DC motors that consume little power.

[0015] The outside air inlet 3 is connected to the outdoors by a duct pipe (not shown) connected to the outside air inlet 3. The supply air outlet 5 is connected to the indoors by a duct pipe (not shown) connected to the supply air outlet 5. The outdoor air inlet 3 draws outdoor air OA from outdoors into the ventilation device 1 via a duct pipe connected to the outdoor air inlet 3. The drawn outdoor air OA passes through the heat exchanger 7 and flows through a duct pipe connected to the supply air outlet 5, and is supplied indoors as supply air SA from the supply air outlet 5. Through this series of steps, the outdoor outdoor air OA is supplied indoors as supply air SA.

[0016] The indoor air intake 6 is connected to the indoors via a duct pipe (not shown) connected to the indoor air intake 6. The exhaust air outlet 4 is connected to the outdoors via a duct pipe (not shown) connected to the exhaust air outlet 4. The indoor air intake 6 draws return air RA that has been recirculated indoors into the ventilation device 1 via a duct pipe connected to the indoor air intake 6. The drawn-in return air RA passes through the heat exchanger 7 and flows through a duct pipe connected to the exhaust air outlet 4, and is discharged to the outdoors as exhaust air EA from the exhaust air outlet 4. Through this series of flows, the indoor return air RA is discharged to the outdoors as exhaust air EA.

[0017] Outside air OA taken in from outdoors passes through heat exchanger 7 and is supplied indoors as supply air SA. This series of paths is supply air duct 9. In addition, return air RA that has been circulated indoors passes through heat exchanger 7 and is discharged outdoors as exhaust air EA. This series of paths is exhaust air duct 12. The heat exchanger 7 has a heat exchange section made of sheet materials stacked in a grid pattern, and heat is exchanged between the intake air passage 9 and the exhaust air passage 12 in this heat exchange section.

[0018] That is, the supply air duct 9 and the exhaust air duct 12 intersect three-dimensionally in the heat exchange section of the heat exchanger 7, and heat exchange occurs between the outside air OA passing through the supply air duct 9 and the return air RA passing through the exhaust air duct 12. Due to this heat exchange, supply air SA at a temperature close to that of the return air RA is supplied indoors, and exhaust air EA is exhausted at a temperature close to that of the outside air OA.

[0019] A filter 13a for removing dust and other particles contained in the outside air OA is attached to each inlet side of the heat exchanger 7 in the supply air duct 9. Similarly, a filter 13b for removing dust and other particles contained in the return air RA is attached to each inlet side of the heat exchanger 7 in the exhaust air duct 12.

[0020] A control circuit storage case 14 is provided on the outer surface of the housing 2, and stores a control circuit 15 for controlling the operation of the ventilation device 1. A remote controller 16 is also installed indoors for setting and operating the operating state of the ventilation device 1. The remote controller 16 is connected to the control circuit 15 by a communication line 17.

[0021] Fig. 2 is a functional configuration diagram showing the functional configuration of the ventilation device according to the first embodiment. As shown in Fig. 2, the ventilation device 1 has a blower control circuit 26 for driving the motor 10a of the intake air blower 8 and the motor 10b of the exhaust air blower 11. The ventilation device 1 also has a control circuit 15. The ventilation device 1 also has a stepping motor (not shown) for opening and closing the damper 22. The ventilation device 1 also has a remote controller 16 for transmitting and receiving control signals for controlling each functional component of the ventilation device 1 and status signals indicating the status of each functional component of the ventilation device 1 via a communication line 17 between the ventilation device 1 and a microcontroller 31.

[0022] 2 shows an example in which the remote controller 16 receives power from the first power supply circuit 29 via a wired connection and is connected to the microcontroller 31 via a wired connection. That is, the remote controller 16 and the microcontroller 31 exchange signals via a wired connection. However, the remote controller 16 may be powered by a battery built into the remote controller 16 itself, and the remote controller 16 and the microcontroller 31 may be connected wirelessly. That is, the remote controller 16 and the microcontroller 31 may exchange signals wirelessly.

[0023] Ventilation device 1 also has environment sensors 18, 19, and 20. In this first embodiment, environment sensors 18 and 19 are each provided with a switch circuit 44 in front of the environment sensor, so that the timing of starting power supply from second power supply circuit 30 can be adjusted. As shown in FIG. 4, switch circuit 44 is provided with a plurality of switch circuits, and a separate switch circuit is connected to each environment sensor. Details will be described later.

[0024] An environmental sensor is a sensor used to measure the concentration of a specific substance contained in the air. An example of the environmental sensor 18 is a CO2 sensor that measures the concentration of carbon dioxide (hereinafter also referred to as CO2) contained in the air. An example of the environmental sensor 19 is a PM2.5 sensor that measures the concentration of fine particulate matter (hereinafter also referred to as PM2.5) contained in the air. PM2.5 (Particulate Matter 2.5) is a particle suspended in the air with a diameter of 2.5 micrometers or less, and the PM2.5 sensor is a sensor that measures the concentration of PM2.5 in the air.

[0025] In many CO2 sensors, which are examples of environmental sensors 18, an inrush current and a pulse current flow when the power supply that supplies electric power is turned on and when the concentration of CO2 in the air is measured. Similarly, in many PM2.5 sensors, which are examples of environmental sensors 19, an inrush current and a pulse current flow when the power supply that supplies electric power is turned on and when the concentration of PM2.5 in the air is measured.

[0026] An example of the environmental sensor 20 is a formaldehyde sensor that measures the concentration of formaldehyde in the air (the environmental sensor 20 may also be referred to as an organic compound environmental sensor). Formaldehyde is a highly volatile organic compound contained in building materials, furniture, etc. placed indoors, and is often found in indoor air and is known to be a major cause of sick house symptoms. In a formaldehyde sensor, which is an example of the environmental sensor 20, unlike a CO2 sensor, which is an example of the environmental sensor 18, and a PM2.5 sensor, which is an example of the environmental sensor 19, no inrush current or pulse-like current flows when the power supply that supplies electric power is turned on or when the concentration of formaldehyde in the air is being measured.

[0027] Some or all of the environmental sensors, which measure the target substance in the indoor air, such as a CO2 sensor as environmental sensor 18, an indoor PM2.5 sensor as environmental sensor 19a (described later), and a formaldehyde sensor as environmental sensor 20, may be installed outside the housing 2 of the ventilation device 1 (provided that they are installed in a location where the target substance in the indoor air can be measured), and may be able to communicate with the control circuit 15.

[0028] In addition, in the formaldehyde sensor, which is an example of environmental sensor 20, no switch circuit is provided in front of environmental sensor 20, and power is supplied continuously from the time environmental data is measured by environmental sensor 20. In addition, ventilation device 1 has switch circuit 44 for turning ON (i.e., electrically "on") or OFF (i.e., electrically "off") the supply of voltage from second power supply circuit 30 given to a CO2 sensor, which is an example of environmental sensor 18, and a PM2.5 sensor, which is an example of environmental sensor 19.

[0029] Rectifier circuit 24 is connected to commercial power supply 23 having an AC voltage of, for example, 200 V, and outputs a DC voltage of 282 V. This DC voltage from rectifier circuit 24 is used to drive motor 10 a of intake fan 8 and motor 10 b of exhaust fan 11. The DC voltage output from rectifier circuit 24 is also supplied to non-insulated switching power supply 25 and isolated switching power supply 27.

[0030] Non-insulated switching power supply 25 outputs a DC voltage of, for example, 15 V. The 15 V DC voltage output from non-insulated switching power supply 25 is output to fan control circuit 26. Here, 0 V, which is the reference potential in rectifier circuit 24 and the reference potential in fan control circuit 26, is a potential common to rectifier circuit 24 and fan control circuit 26 (sometimes referred to as a common potential). Isolated switching power supply 27 outputs a DC voltage of, for example, 12 V. The 12 V DC voltage output from isolated switching power supply 27 is output to first power supply circuit 29 and second power supply circuit 30.

[0031] The 12V DC voltage output from the isolated switching power supply 27 is mainly used to drive a stepping motor (not shown) suitable for opening and closing the damper 22 via a damper control circuit .

[0032] A DC voltage of, for example, 5 V is output from the first power supply circuit 29, which receives the DC voltage of 12 V output from the isolated switching power supply 27. The DC voltage of 5 V output from the first power supply circuit 29 is supplied to the microcontroller 31. The DC voltage of 5 V is also supplied from the first power supply circuit 29 to the remote controller 16.

[0033] The second power supply circuit 30, which receives the 12 V DC voltage output from the isolated switching power supply 27, outputs a 5 V DC voltage, for example. The 5 V DC voltage output from the second power supply circuit 30 is supplied to the environment sensors 18 and 19 via the switch circuit 44. The 5 V DC voltage output from the second power supply circuit 30 is also supplied to the environment sensor 20 without passing through the switch circuit 44.

[0034] The fan control circuit 26 mainly exchanges control signals with the microcontroller 31 via an isolation circuit 32. Examples of the isolation circuit 32 include a photocoupler that exchanges signals using light, and an isolator IC that exchanges signals using magnetism.

[0035] The control circuit 15 is composed of a rectifier circuit 24, a non-isolated switching power supply 25, a blower control circuit 26, an isolation circuit 32, an isolated switching power supply 27, a first power supply circuit 29, a microcontroller 31, a damper control circuit 28 and a second power supply circuit 30.

[0036] Microcontroller 31 issues commands for measuring the concentration at each environmental sensor and commands for transferring the concentration information measured by each environmental sensor to microcontroller 31 by exchanging communication signals between environmental sensors 18, 19, and 20. Communication methods conforming to standards such as UART (Universal Asynchronous Receiver / Transmitter) and I2C (Inter-Integrated Circuit) are used for exchanging communication signals here.

[0037] When UART is used for exchanging communication signals, if the microcontroller 31 does not have enough ports for UART communication, a multiplexer IC is used that has a switch function that can switch communication signals from a pair of ports of the microcontroller 31 for each of multiple communication signals. In this case, controlling the multiplexer for each communication signal makes it possible to communicate with multiple environmental sensors.

[0038] Furthermore, the microcontroller 31 outputs a motor driving pulse signal as a command signal to the damper control circuit 28 in order to excite the motor windings that rotate the damper 22 .

[0039] The reference voltage of 0V is common (also referred to as a common potential) for first power supply circuit 29, which is the power supply for microcontroller 31 and outputs a DC voltage of 5V, second power supply circuit 30, which is the power supply for environmental sensors 18, 19, and 20 and outputs a DC voltage of 5V, and isolated switching power supply 27, which is the power supply for damper control circuit 28 and outputs a DC voltage of 12V. Therefore, there is no need to insulate communication signals input and output via communication line 21 between environmental sensors 18, 19, and 20 and microcontroller 31, and signals such as command signals from microcontroller 31 to damper control circuit 28.

[0040] Since the operation of the remote controller 16 controls the operating state of the ventilator 1 based on communication with the microcontroller 31, the operation of the remote controller 16 will be described below as being included in the functions of the microcontroller 31.

[0041] Microcontroller 31 controls the airflow rates of air supply fan 8 and exhaust fan 11 in response to the concentration information obtained from environmental sensors 18, 19, and 20. Specifically, microcontroller 31 outputs pulse signals to fan control circuit 26 for setting the rotation speeds of motor 10a of air supply fan 8 and motor 10b of exhaust fan 11. Fan control circuit 26, to which the pulse signals for setting the rotation speeds have been input, outputs drive signals to motor 10a of air supply fan 8 and motor 10b of exhaust fan 11.

[0042] In addition, rotation information output from each of the motor 10a of the intake air blower 8 and the motor 10b of the exhaust air blower 11 (for example, rotation speed information and rotation phase information of each of the motors 10a and 10b) is output as a pulse signal to the microcontroller 31 via the blower control circuit 26.

[0043] Note that there is insulation between first power supply circuit 29, which is the power supply for microcontroller 31 and outputs a DC voltage of 5 V, and non-isolated switching power supply 25, which is the power supply for fan control circuit 26 and outputs a DC voltage of 15 V. Therefore, the reference voltage of 0 V that is the first power supply circuit 29 and non-isolated switching power supply 25 is not the same. Therefore, signals must be exchanged between microcontroller 31 and fan control circuit 26 via isolation circuit 32, which has a built-in isolation element such as a photocoupler.

[0044] 3 is an explanatory diagram showing the details of an isolated switching power supply, a first power supply circuit, a second power supply circuit, and a switch circuit in a ventilation device according to embodiment 1. As shown in FIG. 3, in isolated switching power supply 27, a primary winding 34 and a secondary winding 36 of high-frequency isolation transformer 33 are insulated from each other. An input of first power supply circuit 29 and an input of second power supply circuit 30 are connected in parallel to secondary winding 36 of high-frequency isolation transformer 33. Secondary winding 36 of high-frequency isolation transformer 33 functions as a DC power supply for first power supply circuit 29 and second power supply circuit 30.

[0045] A rectifier diode 37 for rectifying AC to DC is connected to the high-voltage side of the secondary winding 36. The primary winding 34 side includes a switching semiconductor element 35 and a control IC 40 that controls the switching semiconductor element 35, and the control IC 40 controls the switching semiconductor element 35 so that the DC voltage on the secondary winding 36 side is stabilized at, for example, 12 V.

[0046] Furthermore, in order to stabilize the DC voltage on the secondary winding 36 side of the isolated switching power supply 27 and remove noise, an electrolytic capacitor 38 is connected between, for example, DC 12V (i.e., a DC voltage of 12V) and GND on the secondary winding 36 side. Note that, in order to ensure the stability of the DC voltage on the secondary winding 36 side, a feedback loop is formed by feeding back the output of a voltage feedback circuit 39 to a control IC 40, and the operation of the control IC 40 is negative feedback controlled.

[0047] Specifically, isolated switching power supply 27 operates as follows. Rectifier circuit 24, to which 200V commercial power supply 23 is connected, outputs a DC voltage of 282V (DC 282V in FIG. 3 ). The high-potential side of this DC voltage 282V output from rectifier circuit 24 is input to one end of primary winding 34 of high-frequency isolation transformer 33. Meanwhile, one end of switching semiconductor element 35, such as a MOSFET, is connected to the other end of primary winding 34. The other end of switching semiconductor element 35 is connected to the low-potential side of DC voltage 282V output from rectifier circuit 24.

[0048] When switching semiconductor element 35 switches at a frequency of several tens of kHz, the DC voltage of 282 V output from rectifier circuit 24 is pulsed, generating a pulse voltage in secondary winding 36 of high-frequency isolation transformer 33. The pulse voltage generated in secondary winding 36 of high-frequency isolation transformer 33 is smoothed by rectifier diode 37 and electrolytic capacitor 38, generating a DC voltage of 12 V (DC12 V in FIG. 3). The DC voltage of 12 V is maintained by controlling the on / off state of switching semiconductor element 35 using voltage feedback circuit 39 and control IC 40.

[0049] Here, the input of the first power supply circuit 29 connected to the secondary winding 36 of the high-frequency isolation transformer 33 is also the input of the linear regulator 41a. Moreover, the input of the second power supply circuit 30 connected to the secondary winding 36 of the high-frequency isolation transformer 33 is also the input of the linear regulator 41b. That is, the secondary winding 36 of the high-frequency isolation transformer 33 supplies DC power to the linear regulator 41a in the first power supply circuit 29 and also supplies DC power to the linear regulator 41b in the second power supply circuit 30.

[0050] A bypass diode 43a, which functions as a protective diode, is connected in parallel to linear regulator 41a. Similarly, a bypass diode 43b, which functions as a protective diode, is connected in parallel to linear regulator 41b. Furthermore, in order to stabilize the voltage and remove noise, an output capacitor 42a is connected in first power supply circuit 29 between DC5V (i.e., a direct current voltage of 5V) and GND. Similarly, an output capacitor 42b is connected in second power supply circuit 30 between DC5V and GND.

[0051] The linear regulators 41a and 41b are used here because they generate little noise, are expected to operate stably, and are relatively inexpensive. Furthermore, the linear regulators 41a and 41b are mainly composed of a reference power supply, an error detection amplifier, and an output transistor. Furthermore, because the linear regulators 41a and 41b operate linearly using analog circuits, they generate little switching noise, unlike switching regulators.

[0052] When a phenomenon occurs in which the output voltage becomes higher than the input voltage of 12 V DC, it is necessary to prevent current from flowing inside linear regulator 41 a and linear regulator 41 b. To prevent this, bypass diodes 43 a and 43 b are connected to the input and output terminals of linear regulator 41 a and linear regulator 41 b, respectively, for protection.

[0053] Linear regulators 41a and 41b perform continuous feedback loop control, resulting in better response than switching regulators. However, as shown in Figure 8, if the feedback loop response cannot keep up, the current to the load increases suddenly, causing the power supply voltage to drop (i.e., Figure 8 schematically shows the drop in output voltage at the timing of the sudden increase in load current at time ta). Conversely, when the power supply voltage is at normal levels, the power supply voltage rises when the current to the load is suddenly cut off (i.e., Figure 8 schematically shows the rise in output voltage at the timing of the sudden decrease in load current at time tb).

[0054] Continuing with the explanation regarding the configuration shown in Figure 3, the output of the first power supply circuit 29 is connected to the power supply input terminal VDD of the microcontroller 31 to supply power to the microcontroller 31.

[0055] Furthermore, the output of the second power supply circuit 30 is connected to the power supply input terminal VDD of the environmental sensor 18 (or the environmental sensor 19) via the switch circuit 44. That is, the environmental sensor 18 (or the environmental sensor 19) is supplied with power from the second power supply circuit 30 via the switch circuit 44.

[0056] An example of the switch circuit 44 is a configuration that combines an NPN transistor 45 and a PNP transistor 46. A control signal output from the output port P of the microcontroller 31 is connected to the base of the NPN transistor 45, and controls the ON or OFF state (i.e., the switching state) of the NPN transistor 45. The collector of the NPN transistor 45 is connected to the base of the PNP transistor 46, and the ON or OFF state of the PNP transistor 46 (i.e., the switching state) is controlled by the ON or OFF state of the collector of the NPN transistor 45.

[0057] That is, the control signal output from the output port P of the microcontroller 31 controls the ON or OFF state of the PNP transistor 46 via the NPN transistor 45. The collector of the PNP transistor 46 is connected to the power supply input terminal VDD of the environmental sensor 18 (or environmental sensor 19).

[0058] 3, when the PNP transistor 46 is turned ON by the control signal output from the output port P of the microcontroller 31, DC 5V (i.e., a direct current voltage of 5V) from the emitter of the PNP transistor 46 is applied to the power supply input terminal VDD of the environmental sensor 18 (or environmental sensor 19) through the collector of the PNP transistor 46, thereby supplying power to the environmental sensor 18 (or environmental sensor 19). Therefore, a transistor having a rating capable of passing a sufficient current through the environmental sensor 18 (or environmental sensor 19) is used for the PNP transistor 46.

[0059] If there are multiple types of environmental sensors, a separate switch circuit is connected to each of the multiple environmental sensors. For example, if environmental sensor 18 is a CO2 sensor and environmental sensor 19 is a PM2.5 sensor, a switch circuit is connected to environmental sensor 18, and another switch circuit is connected to environmental sensor 19. This allows the ON or OFF state of environmental sensor 18 and environmental sensor 19 to be set individually for each environmental sensor by a control signal from microcontroller 31.

[0060] Furthermore, even when multiple CO2 sensors are used as the environmental sensor 18, a separate switch circuit is connected to each of the multiple environmental sensors (i.e., each of the multiple CO2 sensors). This allows the ON or OFF state of each of the multiple CO2 sensors serving as the environmental sensor 18 to be set individually for each CO2 sensor by a control signal from the microcontroller 31. The same applies when multiple PM2.5 sensors are used as the environmental sensor 19, and when one or more CO2 sensors and PM2.5 sensors are combined.

[0061] Fig. 4 is an explanatory diagram showing in schematic form the details of the connections between the switch circuits and the environmental sensors in the ventilation device according to embodiment 1. Below, with reference to the configuration example shown in Fig. 4, we will specifically explain how each environmental sensor is set by the control signal of the microcontroller 31.

[0062] 4, the second power supply circuit 30 is a DC power supply of DC 5V (i.e., a DC voltage of 5V). In the second power supply circuit 30, one end of each of the switch circuits 44a, 44b, and 44c is connected to the DC 5V side of the second power supply circuit 30 (i.e., the high voltage side as viewed from 0V, which is the ground level).

[0063] The other end of switch circuit 44a is connected to a power supply input terminal VDD of a CO2 sensor, which is an example of environmental sensor 18. The other end of switch circuit 44b is connected to a power supply input terminal VDD of an indoor PM2.5 sensor, which is an example of environmental sensor 19a. The other end of switch circuit 44c is connected to a power supply input terminal VDD of an outdoor PM2.5 sensor, which is an example of environmental sensor 19b.

[0064] 4, the power supply input terminal VDD of a formaldehyde sensor, which is yet another example of the environmental sensor 20, is connected to the second power supply circuit 30. However, the formaldehyde sensor, which is another example of the environmental sensor 20, does not have a switch circuit between the power supply input terminal VDD of the formaldehyde sensor and the second power supply circuit 30.

[0065] This is because the power consumption of the formaldehyde sensor, which is an example of environmental sensor 20, is much less than the power consumption of environmental sensors 18, 19a, and 19b (the power consumption of the formaldehyde sensor, which is an example of environmental sensor 20, can be, for example, not more than 1 / 10 of the power consumption of environmental sensors 18, 19a, and 19b). Therefore, the formaldehyde sensor, which is an example of environmental sensor 20, is not affected by the generation of inrush current or a drop in power supply voltage caused by environmental sensors 18, 19a, and 19b, as will be described later. Therefore, the formaldehyde sensor, which is an example of environmental sensor 20, hardly causes fluctuations in the output voltage of second power supply circuit 30.

[0066] 4, microcontroller 31 communicates with environmental sensors 18, 19a, 19b, and 20. Microcontroller 31 has a transmission port TxD and a reception port RxD for each connected environmental sensor. Furthermore, each of environmental sensors 18, 19a, 19b, and 20 also has a transmission port TxD and a reception port RxD of a microcontroller (not shown) connected to it corresponding to each environmental sensor (in the following description, these will be simply referred to as the transmission port TxD of the environmental sensor and the reception port RxD of the environmental sensor).

[0067] As shown in Figure 4, in microcontroller 31, the transmitting port TxD provided in each environmental sensor connected to microcontroller 31 is connected to the receiving port RxD in each environmental sensor of environmental sensor 18, environmental sensor 19a, environmental sensor 19b, and environmental sensor 20, and communication is carried out between each connected port.

[0068] Also, as shown in Figure 4, in microcontroller 31, the receiving port RxD provided in each environmental sensor connected to microcontroller 31 is connected to the transmitting port TxD in each environmental sensor of environmental sensor 18, environmental sensor 19a, environmental sensor 19b, and environmental sensor 20, and communication is carried out between each connected port.

[0069] 4, when microcontroller 31 controls the supply of power from second power supply circuit 30 to environmental sensor 18 and environmental sensors 19a and 19b, it controls the timing at which the power supply starts so that they do not overlap in time. That is, microcontroller 31 controls the timing at which switch circuit 44a to which environmental sensor 18 is connected, switch circuit 44b to which environmental sensor 19a is connected, and switch circuit 44c to which environmental sensor 19b is connected, turn ON so that they do not overlap in time. Note that environmental sensors 19a and 19b may be collectively referred to as environmental sensor 19.

[0070] If the environmental sensor 18 is a CO2 sensor, the microcontroller 31 controls the timing at which the CO2 sensor is powered on. The microcontroller 31 then controls the timing at which the CO2 sensor measures the concentration of CO2 in the air. Specifically, the microcontroller 31 controls the timing at which the CO2 sensor starts measuring the concentration of CO2 in the air and the timing at which the CO2 sensor transfers the concentration information obtained by the measurement to the microcontroller 31. If the environmental sensor 19 is a PM2.5 sensor, the microcontroller 31 then controls the timing at which the PM2.5 sensor is powered on. The microcontroller 31 then controls the timing at which the PM2.5 sensor measures the concentration of PM2.5 in the air. Specifically, the microcontroller 31 controls the timing at which the PM2.5 sensor starts measuring the concentration of PM2.5 in the air and the timing at which the PM2.5 sensor transfers the concentration information obtained by the measurement to the microcontroller 31.

[0071] Environmental sensors 18 and 19 are each controlled by microcontroller 31 so that the timing at which each environmental sensor is powered on and the timing at which each environmental sensor measures the concentration of a specific substance corresponding to that environmental sensor do not overlap in time. That is, when there are multiple environmental sensors, such as environmental sensors 18 and 19, microcontroller 31 outputs a control signal to each environmental sensor so that the measurement times of the respective environmental sensors do not overlap. Note that when there are multiple environmental sensors 18, microcontroller 31 outputs a control signal to each environmental sensor so that the measurement times of the respective environmental sensors 18 do not overlap. Similarly, when there are multiple environmental sensors 19, microcontroller 31 outputs a control signal to each environmental sensor so that the measurement times of the respective environmental sensors 19 do not overlap.

[0072] Microcontroller 31 sends control signals to each of environmental sensors 18 and 19, where microcontroller 31 controls when power is applied to each of environmental sensors 18 and 19 and when each environmental sensor measures the concentration of a particular substance corresponding to each environmental sensor.

[0073] The isolated switching power supply 27 is connected to a first power supply circuit 29 and a second power supply circuit 30, and is also connected to a damper control circuit .

[0074] Therefore, when the damper 22, which is supplied with a drive voltage from the damper control circuit 28, operates, the power consumption increases, and the startup and measurement operations of at least one of the environmental sensors 18 and 19 may affect the isolated switching power supply 27.

[0075] Conversely, if the damper 22 is operated while the environmental sensors 18 and 19 are performing their startup and measurement operations, the operation of the damper 22 may affect the isolated switching power supply 27 due to increased power consumption.

[0076] Therefore, when the damper 22 operates, it is desirable to control the microcontroller 31 so that the activation and measurement operations of the environmental sensors 18 and 19 are not performed. Also, when the activation and measurement operations of at least one of the environmental sensors 18 and 19 are being performed, it is desirable to control the microcontroller 31 so that the damper 22 does not operate.

[0077] In this way, by the microcontroller 31 controlling the timing of power supply to the damper 22, the environmental sensor 18, and the environmental sensor 19, it is possible to operate each of them stably while avoiding effects on the isolated switching power supply 27 such as the occurrence of inrush current or a drop in the power supply voltage from the damper 22, the environmental sensor 18, or the environmental sensor 19.

[0078] The operation of each will be described in detail below with reference to Figure 1. In the following, an example will be described in which a CO2 sensor is used as environmental sensor 18, a PM2.5 sensor is used as environmental sensor 19, and a formaldehyde sensor is used as environmental sensor 20. Here, when distinguishing between multiple PM2.5 sensors according to their installation locations, the indoor PM2.5 sensor will be described as environmental sensor 19a, and the outdoor PM2.5 sensor will be described as environmental sensor 19b.

[0079] Environmental sensors 18, 19a, and 20 are installed in exhaust air duct 12 between indoor air inlet 6 and heat exchanger 7. These sensors measure indoor air quality (i.e., the density of measurement targets such as carbon dioxide CO2, fine particulate matter PM2.5, and the organic compound formaldehyde in the indoor air). Environmental sensors 18, 19a, and 20 are connected to control circuit 15 via communication line 21a. Control circuit 15 then issues commands to environmental sensors 18, 19a, and 20 to power on and measure concentrations. The concentration information acquired by environmental sensors 18, 19a, and 20 is sent to control circuit 15 when control circuit 15 commands each environmental sensor to transmit information.

[0080] An environmental sensor 19b is installed in the intake air duct 9 between the outside air inlet 3 and the heat exchanger 7. The environmental sensor 19b measures the outdoor air quality (i.e., the density of measurement targets such as carbon dioxide CO2, fine particulate matter PM2.5, and the organic compound formaldehyde in the outdoor air). The environmental sensor 19b is connected to the control circuit 15 via a communication line 21b. This allows the control circuit 15 to instruct the environmental sensor 19b to turn on the power and measure the concentration. The concentration information acquired by the environmental sensor 19b is sent to the control circuit 15 when the control circuit 15 instructs the environmental sensor 19b to transmit information.

[0081] Note that the CO2 concentration in outdoor air is typically lower than the CO2 concentration in indoor air. Furthermore, the concentration of formaldehyde, a highly volatile organic compound that is generated from indoor building materials, furniture, and the like, is negligibly low in outdoor air. Therefore, an example will be described in which no environmental sensors similar to environmental sensors 18 and 20 are installed in air supply duct 9, and only environmental sensor 19b, which measures the concentration of PM2.5 in the air flowing in from outdoors, is installed.

[0082] Control circuit 15 controls the ventilation operation of ventilation device 1. Specifically, environmental sensors 18, 19a, and 20 installed in exhaust air duct 12 measure the concentrations of CO2, PM2.5, and formaldehyde contained in the indoor air returned through the indoor space. Control circuit 15 determines whether the concentrations of the substances (in this example, CO2, PM2.5, and formaldehyde) that environmental sensors 18, 19a, and 20 measure are higher than the preset concentrations set in advance for the respective substances.

[0083] If control circuit 15 determines that the concentration is higher than a specified value, control circuit 15 controls ventilation device 1 so that the ventilation air volume increases according to the concentration. Specifically, control circuit 15 controls ventilation device 1 so that both the volume of air supplied by supply air blower 8 and the volume of air exhausted by exhaust blower 11 increase.

[0084] Environmental sensor 19b installed in intake air duct 9 detects the concentration of PM2.5, a pollutant, in the outdoor air. If the concentration of PM2.5 in the outdoor air is higher than normal, control circuit 15 stops the air supply from outdoors and starts circulating indoor air. Examples of when the concentration of PM2.5 in the outdoor air is higher than normal include when the concentration of pollen in the air is higher than normal during pollen season, and when the concentration of yellow sand in the air is higher than normal during yellow sand season.

[0085] In the ventilation device 1, the filter 13a attached to the heat exchanger 7 may lose its ability to remove dust and pollutants from the air flowing in from outdoors. In such cases, the PM2.5 concentration in the air flowing in from outdoors is not improved compared to the PM2.5 concentration in the indoor air measured by the environmental sensor 19a installed in the exhaust air duct 12. Therefore, in such cases, as when the PM2.5 concentration is higher than normal, the control circuit 15 stops supplying air from outdoors and starts circulating indoor air.

[0086] Fig. 5 is a schematic diagram illustrating the circulation operation of the ventilation device according to embodiment 1. One example of a method for circulating indoor air is to switch the air path inside ventilation device 1, as shown in Fig. 5. That is, control circuit 15 first closes outside air inlet 3 and exhaust outlet 4 using dampers (not shown) provided before outside air inlet 3 and exhaust outlet 4, respectively, and stops exhaust fan 11.

[0087] Thereafter, damper 22 is opened so that the air passage between supply air outlet 5 and heat exchanger 7 communicates with the air passage between indoor air inlet 6 and heat exchanger 7. In this way, the air flow generated by supply air blower 8 allows indoor air drawn in through indoor air inlet 6 to be blown out into the room from supply air outlet 5. In other words, indoor air can be circulated.

[0088] Here, we will briefly explain the features of each environmental sensor installed in the ventilation device 1 of this embodiment. The CO2 sensor exemplified as environmental sensor 18 is an optical CO2 detection device recommended in the Ministry of Economy, Trade and Industry's "Guidelines for the Selection of Carbon Dioxide Concentration Measuring Devices," and is actually used as an environmental sensor in ventilation devices.

[0089] Such optical CO2 detection (or optical CO2 detection devices) utilizes the infrared absorption properties of carbon dioxide (CO2). Methods that utilize the infrared absorption properties of CO2 include the NDIR (Non-Dispersive InfraRed) method, which measures the CO2 concentration from the amount of infrared light absorbed, and the photoacoustic method, which uses a microphone to detect acoustic waves generated when infrared light is absorbed and measures the CO2 concentration based on the acoustic waves detected by the microphone.

[0090] However, optical CO2 detection (or optical CO2 detection devices) causes a large current to flow when measuring the concentration of CO2, which is the object to be measured. FIG. 6 is an explanatory diagram illustrating an example of a current waveform when the environment sensor 18 (here, a CO2 sensor) used in the ventilation device according to the first embodiment is operating. In particular, when a photoacoustic system is used for the environment sensor 18, as illustrated in FIG. 6, a pulsed current with an amplitude of 300 mA flows in the environment sensor 18.

[0091] 6, an inrush current of nearly 1 A also occurs when power is applied to the environmental sensor 18 and the environmental sensor 18 starts up. The pulsed current generated in the environmental sensor 18 when measuring the CO2 concentration and the inrush current generated when power is applied can affect the power supply from the second power supply circuit 30, as will be described later.

[0092] The PM2.5 sensor exemplified in environmental sensor 19 (i.e., environmental sensor 19a, environmental sensor 19b) detects the concentration of fine particles with a diameter of 2.5 micrometers or less contained in the air. The PM2.5 sensor has a built-in fan for generating an airflow inside the PM2.5 sensor. A laser beam is irradiated onto the fine particles in the air carried into the sensor by the airflow generated by the fan. The irradiated laser beam is scattered by the fine particles, and environmental sensor 19 detects the amount of scattered light by the fine particles using a photodiode. Environmental sensor 19 measures the concentration of PM2.5 in the air based on the amount of scattered light detected.

[0093] That is, in principle, environmental sensor 19 needs to drive a fan and irradiate laser light, so a large current flows when measuring the concentration of PM2.5, which is the object to be measured. Fig. 7 is an explanatory diagram for explaining an example of a current waveform when environmental sensor 19 (here, a PM2.5 sensor) used in the ventilation device according to embodiment 1 operates. As shown in Fig. 7, when measuring the concentration of PM2.5, a pulsed current with an amplitude of 100 mA flows in environmental sensor 19.

[0094] 7, an inrush current of nearly 1 A also occurs when power is applied to the environmental sensor 19 and the environmental sensor 19 starts up. These pulsed currents generated in the environmental sensor 19 when measuring the PM2.5 concentration and the inrush current generated when power is applied can affect the power supply from the second power supply circuit 30, as will be described later.

[0095] In the environmental sensors 18 and 19 (i.e., environmental sensors 19a and 19b) used in the ventilation device 1, a pulsed current flows when the environmental sensors 18 and 19 measure the concentration, as shown in Figures 6 and 7.

[0096] If direct current 5V (DC5V) as a power supply voltage is supplied to the microcontroller 31 and at least one of the environmental sensors 18 and 19 from only the first power supply circuit 29, the voltage output by the first power supply circuit 29 may decrease due to the pulsed current generated from at least one of the environmental sensors 18 and 19.

[0097] When the voltage output from the first power supply circuit 29 drops in this way, the voltage supplied to the microcontroller 31 drops, causing the operation of the microcontroller 31 to become unstable, and in the worst case scenario, the microcontroller 31 enters an initial state (sometimes referred to as a reset state). If the microcontroller 31 enters the initial state, there is a possibility that control of the entire ventilator 1 and ventilation operation will stop.

[0098] Therefore, in the first embodiment, the power supply to the environmental sensors 18 and 19 is separated from the power supply to the microcontroller 31. Specifically, the power supply to the microcontroller 31 is performed by a first power supply circuit 29, and the power supply to the environmental sensors 18 and 19 is performed by a second power supply circuit 30.

[0099] In this way, by separating at least the power supply to microcontroller 31 from the power supply to environmental sensors 18 and 19, it is possible to supply power to microcontroller 31 without being affected by the pulsed current in the power supply to environmental sensors 18 and 19. This makes it possible to suppress a drop in the voltage supplied to microcontroller 31, allowing microcontroller 31 to operate stably.

[0100] In addition, an inrush current flows through environmental sensors 18 and 19 when they are turned on. This will be explained with reference to the functional configuration shown in Fig. 3. If switch circuit 44 as shown in Fig. 3 is not provided, when isolated switching power supply 27 starts up, isolated switching power supply 27 outputs a 12V DC voltage (DC12V in Fig. 3) to first power supply circuit 29 and second power supply circuit 30, respectively. In response to the output of this 12V DC voltage, first power supply circuit 29 and second power supply circuit 30 each simultaneously output a 5V DC voltage (DC5V in Fig. 3).

[0101] Since the microcontroller 31 is connected to the first power supply circuit 29 and the environmental sensors 18 and 19 are connected to the second power supply circuit 30, current flows simultaneously through the microcontroller 31 and each environmental sensor (i.e., the environmental sensors 18 and 19). Therefore, if the switch circuit 44 shown in FIG. 3 were not provided, the isolated switching power supply 27 would be overloaded, potentially causing the 12V DC voltage output from the isolated switching power supply 27 to become unstable. If the voltage output from the isolated switching power supply 27 becomes unstable in this way, the protection function of the control IC 40 may be activated, potentially preventing the isolated switching power supply 27 of the ventilator 1 from starting.

[0102] Therefore, as shown in FIG. 3, a switch circuit 44 is provided between the second power supply circuit 30 and the environmental sensors (i.e., the environmental sensors 18 and 19), and the voltage supply to the environmental sensors (i.e., the environmental sensors 18 and 19) is controlled by controlling the ON / OFF state of the switch circuit 44.

[0103] Specifically, as shown in Fig. 4, a switch circuit 44 (switch circuits 44a, 44b, and 44c in Fig. 4) is provided between the output of second power supply circuit 30 and the power supply terminals of environmental sensor 18 and environmental sensor 19 (environmental sensors 19a and 19b in Fig. 4). Switch circuit 44a is connected to environmental sensor 18. Switch circuit 44b is connected to environmental sensor 19a. Switch circuit 44c is connected to environmental sensor 19b.

[0104] The switch circuits connected to the environmental sensors can be individually controlled to be turned on or off by the microcontroller 31. This will be described in detail with reference to Figures 3 and 4. The output port P1 of the microcontroller 31 is connected to the base of the NPN transistor 45 in the switch circuit 44a.

[0105] When the output signal from the output port P1 of the microcontroller 31 is a high-level signal, the NPN transistor 45 in the switch circuit 44a is turned ON, causing the PNP transistor 46 in the switch circuit 44a to be in a conductive state. When the output signal from the output port P1 of the microcontroller 31 is a low-level signal, the NPN transistor 45 in the switch circuit 44a is turned OFF, causing the PNP transistor 46 in the switch circuit 44a to be in a cut-off state.

[0106] Similarly, the output port P2 of the microcontroller 31 is connected to the base of the NPN transistor 45 in the switch circuit 44b. When the output signal from the output port P2 of the microcontroller 31 is a high-level signal, the NPN transistor 45 in the switch circuit 44b is turned ON, causing the PNP transistor 46 in the switch circuit 44b to be in a conductive state. When the output signal from the output port P2 of the microcontroller 31 is a low-level signal, the NPN transistor 45 in the switch circuit 44b is turned OFF, causing the PNP transistor 46 in the switch circuit 44b to be in a cut-off state.

[0107] Similarly, the output port P3 of the microcontroller 31 is connected to the base of the NPN transistor 45 in the switch circuit 44c. When the output signal from the output port P3 of the microcontroller 31 is a high-level signal, the NPN transistor 45 in the switch circuit 44c is turned ON, causing the PNP transistor 46 in the switch circuit 44c to be in a conductive state. When the output signal from the output port P3 of the microcontroller 31 is a low-level signal, the NPN transistor 45 in the switch circuit 44c is turned OFF, causing the PNP transistor 46 in the switch circuit 44c to be in a cut-off state.

[0108] As described above, when the PNP transistor 46 in the switch circuit 44a is in a conducting state, a voltage of 5V is supplied from the second power supply circuit 30 to the environmental sensor 18, and when the PNP transistor 46 in the switch circuit 44a is in a cut-off state, the DC voltage of 5V from the second power supply circuit 30 is not supplied to the environmental sensor 18.

[0109] Similarly, when the PNP transistor 46 in the switch circuit 44b is in a conducting state, a voltage of 5V is supplied from the second power supply circuit 30 to the environmental sensor 19a, and when the PNP transistor 46 in the switch circuit 44b is in a blocking state, the DC voltage of 5V from the second power supply circuit 30 is not supplied to the environmental sensor 19a.

[0110] Similarly, when the PNP transistor 46 in the switch circuit 44c is in a conducting state, a voltage of 5V is supplied from the second power supply circuit 30 to the environmental sensor 19b, and when the PNP transistor 46 in the switch circuit 44c is in a blocking state, the DC voltage of 5V from the second power supply circuit 30 is not supplied to the environmental sensor 19b.

[0111] That is, the voltage supply from the second power supply circuit 30 to each environmental sensor (that is, each of the environmental sensors 18, 19a, and 19b) can be individually controlled by the output signal output from the output port of the microcontroller 31.

[0112] When microcontroller 31 controls the ON / OFF of each switch circuit, it controls the timing of supplying voltage to each environmental sensor so that it does not overlap. This prevents voltage from being supplied to environmental sensor 18 and environmental sensor 19 (environmental sensor 19a and environmental sensor 19b in FIG. 4) at the same time. In other words, it prevents the effects of inrush currents generated by environmental sensor 18 and environmental sensor 19 from overlapping.

[0113] As an example of the switch circuit 44, it is configured by combining an NPN transistor 45 and a PNP transistor 46, and can individually control the supply of voltage to the environmental sensors 18 and 19 (environmental sensors 19a and 19b in FIG. 4) based on each control signal from the output port P of the microcontroller 31 (output port P1, output port P2, and output port P3 in FIG. 4), as described in detail with reference to FIGS. 3 and 4.

[0114] Note that the microcontroller 31, which has a small inrush current at startup, can be directly supplied with the output of the first power supply circuit 29 without going through the switch circuit 44. It goes without saying that the PNP transistor 46 shown in Fig. 3 should be an element rated to allow a sufficient current to flow when the environmental sensor is started up and when making measurements.

[0115] The formaldehyde sensor exemplified as the environmental sensor 20 detects the concentration using an electrochemical gas sensor. There are several methods for detecting the concentration, but a simple example will be described below. Air is induced between two electrodes maintained at a certain potential, and the formaldehyde contained in the induced air causes electrolysis at one of the two electrodes. The current generated by this electrolysis is proportional to the concentration of formaldehyde, and this is utilized to measure the concentration of formaldehyde in the air.

[0116] Incidentally, the current consumption of such environmental sensor 20 when measuring the concentration of formaldehyde, which is the measurement target, is extremely small compared to the current consumption of environmental sensors 18 and 19 (this current consumption can be approximately 3 mA, for example, although it depends on environmental sensors 18 and 19 used). Furthermore, even when powering on environmental sensor 20 and starting up environmental sensor 20, the current consumption is extremely small compared to the inrush current of environmental sensors 18 and 19 (this inrush current at startup can be approximately 20 mA, for example, although it depends on environmental sensor 20 used). Therefore, compared to environmental sensors 18 and 19, the possibility that environmental sensor 20 will affect the power supply from second power supply circuit 30 is extremely low.

[0117] Below, the relationship between the inrush current and the pulse current when each environmental sensor 18 and environmental sensor 19 in this embodiment is started up and when each environmental sensor measures the concentration of the substance to be measured will be described together with the operation of each environmental sensor, with reference to Figures 9 and 10. The action and effect of the configuration of this embodiment will also be described.

[0118] 9 is an explanatory diagram illustrating power supply from the power supply device in the ventilation device according to Embodiment 1. At time t0 when commercial power supply 23 is turned on, isolated switching power supply 27 is started up. As a result, the power supply voltage of microcontroller 31, which receives the voltage output of first power supply circuit 29 as its power input, and the power supply voltage of environment sensor 20, which receives the voltage output of second power supply circuit 30 as its power input, are supplied almost simultaneously, as shown by the voltage changes in FIGS. 9(a) and 9(b), respectively.

[0119] At time ta1 after the microcontroller 31 has completed its initial processing operation after power-on, the microcontroller 31 outputs a high-level signal from the output port P1 to turn on the switch circuit 44a. As a result, a direct current voltage of 5V (DC5V) is supplied from the second power supply circuit 30 to the environment sensor 18 (i.e., the CO2 sensor), as shown by the voltage change in Figure 9(c).

[0120] Next, at time ta2, when the inrush current of at least the environmental sensor 18 (i.e., the CO2 sensor) has subsided, a high-level signal is output from output port P2, turning on switch circuit 44b. As a result, a direct current voltage of 5V (DC5V) is supplied from second power supply circuit 30 to environmental sensor 19a (i.e., the indoor PM2.5 sensor), as shown by the voltage change in Figure 9(d).

[0121] Subsequently, at time ta3, when the inrush current of at least the environmental sensor 19a (i.e., the indoor PM2.5 sensor) has subsided, a high-level signal is output from the output port P3, turning on the switch circuit 44c. As a result, a direct current voltage of 5V (DC5V) is supplied from the second power supply circuit 30 to the environmental sensor 19b (i.e., the outdoor PM2.5 sensor), as shown by the voltage change in Figure 9(e).

[0122] The time between time ta1 and time ta2 shown in Fig. 9 is at least the time until the voltage drop at time ta shown in Fig. 8(a) subsides and a stable supply of 5V DC voltage is achieved. As a specific example of setting the time between time ta1 and time ta2 shown in Fig. 9, the second power supply circuit 30 may be monitored and set to a state where the voltage drop has settled to within 1 / 20 of 5V (i.e., 0.25V). (In this case, for example, the number of times the power is turned on may be counted, and the time between time ta1 and time ta2 shown in Fig. 9 may be measured and stored in memory every 20 power-on times, and the measured time between time ta1 and time ta2 stored in memory may be used the next time the power is turned on.) Alternatively, the time between time ta1 and time ta2 may be set to a predetermined time.

[0123] Similarly, the time between time ta2 and time ta3 shown in Figure 9 is at least the time until the voltage drop at time ta shown in Figure 8(a) subsides and a stable supply of 5V DC voltage is achieved. As a specific example of setting the time between time ta2 and time ta3 shown in Figure 9, the second power supply circuit 30 may be monitored and set to a state where the voltage drop has stabilized within 1 / 20 of 5V (i.e., 0.25V). (In this case, for example, the number of times the power is turned on may be counted, and the time between time ta2 and time ta3 shown in Figure 9 may be measured and stored in memory every 20 power-on times, and the measured time between time ta2 and time ta3 stored in memory may be used the next time the power is turned on.) Alternatively, the time between time ta2 and time ta3 may be set to a predetermined time.

[0124] As described above, the timing of the inrush current generation of the environmental sensor 18 (i.e., the CO2 sensor) and the environmental sensor 19 (i.e., the indoor PM2.5 sensor as the environmental sensor 19a and the outdoor PM2.5 sensor as the environmental sensor 19b), which have a larger inrush current when power is supplied than the microcontroller 31 and the environmental sensor 20 (i.e., the formaldehyde sensor), is controlled so that they do not overlap.

[0125] This control prevents an overload state from occurring in the isolated switching power supply 27 that outputs the 12 V DC voltage that is input to the first power supply circuit 29 and the second power supply circuit 30. This also prevents the control power supply of the ventilator 1 from being unable to start up.

[0126] Next, an explanation will be given with reference to FIG. 10, which is an explanatory diagram for explaining the operating time of the environmental sensor in the ventilation device according to the first embodiment. Before the explanation, a brief explanation will be given of an actual specific example. The CO2 sensor used as the environmental sensor 18 in the first embodiment requires 5 seconds to obtain a stable concentration measurement result. Furthermore, the PM2.5 sensors used as the environmental sensors 19a and 19b in the first embodiment require time for the rotation speed of the built-in fan to stabilize, and therefore require 30 seconds to obtain a stable concentration measurement result.

[0127] The formaldehyde sensor used as environmental sensor 20 in the first embodiment utilizes a chemical reaction, and therefore requires time for the reaction time to stabilize in response to changes in concentration, so it takes one minute to obtain a stable measurement result. The following describes the actual time it takes for environmental sensors 18, 19a, 19b, and 20 to obtain a stable measurement result.

[0128] 10, the symbol S in Fig. 10 indicates the timing at which a "command to start concentration measurement" is output from the microcontroller 31. Similarly, the symbol T in Fig. 10 indicates the timing at which a "command to transfer concentration information" is output from the microcontroller 31. During the operation of each environmental sensor, concentration measurement is performed during high level times (i.e., when "H" is shown in Fig. 10), and concentration measurement is not performed during low level times (i.e., when "L" is shown in Fig. 10).

[0129] 10(a) is an example of the concentration measurement time of environmental sensor 20 (i.e., the formaldehyde sensor). As described above, it takes longer for environmental sensor 20 to obtain a stable concentration measurement result than the other environmental sensors (i.e., environmental sensors 18 and 19). However, because the current that flows when environmental sensor 20 measures the concentration is smaller than the other environmental sensors (i.e., environmental sensors 18 and 19), there is no problem even if the concentration measurement time overlaps with the concentration measurement time of the other environmental sensors (i.e., environmental sensors 18 and 19).

[0130] Specifically, the microcontroller 31 commands the environmental sensor 20 (i.e., the formaldehyde sensor) to start concentration measurement at time t1, which is the timing indicated by symbol S in Fig. 10(a). After that, when one minute required for measuring the concentration in the environmental sensor 20 has elapsed, the microcontroller 31 acquires the concentration information measured by the environmental sensor 20 at time t4, which is the timing indicated by symbol T in Fig. 10(a), during a time when the microcontroller 31 is not communicating with other environmental sensors (i.e., the microcontroller 31 commands the environmental sensor 20 to transmit the concentration information measured by the environmental sensor 20 to the microcontroller 31).

[0131] Subsequently, the microcontroller 31 issues a command to start the next concentration measurement at time t40, which is the timing indicated by symbol S in FIG. 10(a).

[0132] The microcontroller 31 commands the environmental sensor 20 (i.e., the formaldehyde sensor) to start concentration measurement at time t1, which is the timing indicated by symbol S in Fig. 10(a), and then commands the environmental sensor 18 (i.e., the CO2 sensor) to start concentration measurement at time t10, which is the timing indicated by symbol S in Fig. 10(b). After that, when the 5 seconds required for the environmental sensor 18 to measure the concentration have elapsed, the concentration information measured by the environmental sensor 18 is acquired at time t2, which is the timing indicated by symbol T in Fig. 10(b) (i.e., the microcontroller 31 commands the environmental sensor 18 to transmit the concentration information measured by the environmental sensor 18 to the microcontroller 31).

[0133] At time t2, which is the timing indicated by symbol T in Fig. 10(b), the microcontroller 31 acquires concentration information measured by the environmental sensor 18, and then at time t20, which is the timing indicated by symbol S in Fig. 10(c), the microcontroller 31 commands the environmental sensor 19a (i.e., the indoor PM2.5 sensor) to start concentration measurement. After that, when the 30 seconds required for the environmental sensor 19a to measure the concentration have elapsed, the microcontroller 31 acquires the concentration information measured by the environmental sensor 19a at time t3, which is the timing indicated by symbol T in Fig. 10(c) (i.e., the microcontroller 31 commands the environmental sensor 19a to transmit the concentration information measured by the environmental sensor 19a to the microcontroller 31).

[0134] At time t3, which is the timing indicated by symbol T in Fig. 10(c), the microcontroller 31 acquires concentration information measured by the environmental sensor 19a, and then at time t30, which is the timing indicated by symbol S in Fig. 10(d), the microcontroller 31 commands the environmental sensor 19b (i.e., the outdoor PM2.5 sensor) to start concentration measurement. After that, when the 30 seconds required for the environmental sensor 19b to measure the concentration have elapsed, the microcontroller 31 acquires the concentration information measured by the environmental sensor 19b at time t4, which is the timing indicated by symbol T in Fig. 10(d) (i.e., the microcontroller 31 commands the environmental sensor 19b to transmit the concentration information measured by the environmental sensor 19b to the microcontroller 31).

[0135] At this point, more than one minute required for measurement by the environmental sensor 20 (i.e., the formaldehyde sensor) has passed since time t1, when the command to start concentration measurement was issued. Therefore, as described above for the environmental sensor 20, the microcontroller 31 commands the environmental sensor 20 (i.e., the formaldehyde sensor) to start concentration measurement at time t40, which is the timing indicated by symbol S in FIG. 10(a). Along with this command, the microcontroller 31 also commands the environmental sensor 18 (i.e., the CO2 sensor) to start concentration measurement at time t40, which is the timing indicated by symbol S in FIG. 10(b).

[0136] By repeating commands from the microcontroller 31 according to this series of mechanisms from time t1 to time t40, the microcontroller 31 repeatedly causes each environmental sensor to start concentration measurement and acquires concentration information from each environmental sensor.

[0137] As described above, the microcontroller 31 can prevent electrical influences on other functional components by controlling the overlap of the periods during which environmental sensors, such as the environmental sensors 18 and 19 (i.e., the environmental sensors 19a and 19b), measure concentrations, which electrically influence other functional components due to the flow of pulsed current when measuring concentrations. The electrical influences on other functional components referred to here specifically include a startup failure of the isolated switching power supply 27, malfunctions of the environmental sensors caused by a simultaneous drop in the power supply voltages supplied to the environmental sensors 18, 19, and 20 (for example, a loss of communication from the environmental sensors, which prevents the microcontroller 31 from acquiring concentration information), and the like.

[0138] Fig. 11 shows an example of actual measurements when this embodiment is applied, showing an example of voltage and current measured when a concentration is measured using an actual CO2 sensor as the environmental sensor 18. Fig. 11(a) shows the voltage (DC 5V) output from the first power supply circuit 29, Fig. 11(b) shows the voltage (DC 5V) output from the second power supply circuit 30, and Fig. 11(c) shows the current (also referred to as inflow current) flowing through the CO2 sensor as the environmental sensor 18.

[0139] When the CO2 sensor serving as the environmental sensor 18 measures the CO2 concentration in the air, a maximum current of 820 mA flows, as shown in Figure 11(c). Accordingly, as shown in Figure 11(b), the voltage output from the second power supply circuit 30 drops to 4.01 V. However, as shown in Figure 11(a), the voltage output from the first power supply circuit 29, which is the power supply for the microcontroller 31, drops only to 4.93 V, confirming that the drop in the voltage output from the first power supply circuit 29 can be suppressed.

[0140] The lower limit of the supply voltage range for the CO2 sensor used in the actual measurements was 2.4 V according to the specifications, and the voltage drop to the CO2 sensor was approximately 1 V, which fully satisfied the lower limit of the supply voltage range. However, if multiple other environmental sensors were to simultaneously measure concentrations, it is easy to predict that the voltage output from the second power supply circuit 30 would drop more than the actual measurement. If this were to happen, the voltage supplied to the environmental sensor would fall below the lower limit of the supply voltage range, potentially rendering the environmental sensor inoperable.

[0141] Therefore, according to the first embodiment, by controlling the timing at which each environmental sensor measures the concentration so that it does not overlap, it is possible to prevent a drop in the output voltage of the second power supply circuit 30 due to current flowing simultaneously through multiple environmental sensors. Also, by separating the first power supply circuit 29, which serves as the power source for the microcontroller 31, which also controls the entire ventilation device 1, from the second power supply circuit 30, the microcontroller 31 is not affected by a voltage drop in the second power supply circuit 30 due to current flowing through the environmental sensors. This allows a stable voltage to be supplied to the microcontroller 31.

[0142] Fig. 12 is an explanatory diagram illustrating an example of the hardware configuration of control circuit 15 provided in a ventilation device. Fig. 12 illustrates the hardware configuration when the functions of control circuit 15 are realized using hardware that executes a program. Control circuit 15 has processor 151 and memory 152.

[0143] The processor 151 is a CPU (Central Processing Unit). The processor 151 may be a processing device, an arithmetic unit, a microprocessor, a microcomputer, or a DSP (Digital Signal Processor). Each function of the control circuit 15 is realized by the processor 151, software, firmware, or a combination of software and firmware. The software or firmware is written as a program and stored in the memory 152, which is an internal memory. The memory 152 is a non-volatile or volatile semiconductor memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable Read Only Memory), or an EEPROM (registered trademark) (Electrically Erasable Programmable Read Only Memory).

[0144] The configurations described in the above embodiments are merely examples, and may be combined with other known technologies. Furthermore, parts of the configurations may be omitted or modified without departing from the spirit of the invention.

[0145] Various aspects of the present disclosure are summarized below as appendices.

[0146] (Appendix 1) an environmental sensor that measures the concentration of a measurement target substance contained in the air and outputs measurement information; a microcontroller that acquires the measurement information output by the environmental sensor; a first power supply circuit coupled to the microcontroller for supplying power to the microcontroller; a second power supply circuit provided separately from the first power supply circuit and supplying power to the environmental sensor via a switch circuit connected to the environmental sensor. (Appendix 2) The ventilation device described in Appendix 1, wherein the switch circuit is controlled to be turned ON or OFF based on a control signal output from the microcontroller, and the supply of voltage to the environmental sensor is controlled to be turned ON or OFF by the switch circuit being turned ON or OFF. (Appendix 3) 3. The ventilation device of claim 2, wherein when there are multiple environmental sensors, a switch circuit is connected to each of the environmental sensors, and the control signal is output from the microcontroller to the switch circuit so that the timing at which each of the switch circuits turns on does not overlap. (Appendix 4) an organic compound environment sensor connected to the second power supply circuit without passing through the switch circuit; A ventilation device described in any one of Appendix 2 to Appendix 3, wherein the control signal is output from the microcontroller to the switch circuit so that the timing of turning on the supply of voltage to the organic compound environment sensor does not overlap in time with the timing of turning on the supply of voltage to the environment sensor. (Appendix 5) 5. A ventilation device according to any one of claims 2 to 4, wherein, when there are multiple environmental sensors, the control signal from the microcontroller is output to each of the environmental sensors so that the measurement times of each of the environmental sensors do not overlap. (Appendix 6) 6. The ventilation device according to claim 1, wherein the object to be measured is at least one of carbon dioxide and dust. (Appendix 7) an isolated switching power supply having a primary input and a secondary output; an AC voltage is input to the primary side input of the isolated switching power supply, and an AC voltage is output from the secondary side output of the isolated switching power supply; 6. The ventilation device according to claim 1, wherein a DC voltage generated from an AC voltage output from the secondary output is input to a linear regulator included in each of the first power supply circuit and the second power supply circuit. (Appendix 8) 8. The ventilation device according to any one of claims 1 to 7, further comprising a housing and a damper inside the housing that opens and closes to switch from a preset airway inside the housing to another airway, wherein while the damper is opening and closing, a control signal output from the microcontroller is output to the switch circuit to stop the supply of voltage output from the second power supply circuit to the environmental sensor. [Explanation of symbols]

[0147] 1 ventilation device, 2 housing, 3 outdoor air intake port, 4 exhaust air outlet, 5 supply air outlet, 6 indoor air intake port, 7 heat exchanger, 8 supply air blower, 9 supply air duct, 10a, 10b motor, 11 exhaust air blower, 12 exhaust air duct, 13a, 13b filter, 14 control circuit storage case, 15 control circuit, 16 remote controller, 17 communication line, 18 environmental sensor (CO2 sensor), 19 environmental sensor (PM2.5 sensor), 19a environmental sensor (indoor PM2.5 sensor), 19b environmental sensor (outdoor PM2.5 sensor), 20 environmental sensor (formaldehyde sensor), 21a, 21b communication line, 22 damper (air path switching means), 23 commercial power supply, 24 rectifier circuit, 25 non-isolated switching power supply, 26 Blower control circuit, 27 isolated switching power supply, 28 damper control circuit, 29 first power supply circuit, 30 second power supply circuit, 31 microcontroller, 32 isolation circuit, 33 high-frequency isolation transformer, 34 primary winding, 35 switching semiconductor element, 36 secondary winding, 37 rectifier diode, 38 electrolytic capacitor, 39 voltage feedback circuit, 40 control IC, 41a, 41b linear regulator, 42a, 42b output capacitor, 43a, 43b bypass diode, 44, 44a, 44b, 44c switch circuit, 45 NPN transistor, 46 PNP transistor.

Claims

1. an environmental sensor that measures the concentration of a measurement target substance contained in the air and outputs measurement information; a microcontroller that acquires the measurement information output by the environmental sensor; a first power supply circuit coupled to the microcontroller for supplying power to the microcontroller; a second power supply circuit provided separately from the first power supply circuit and supplying power to the environmental sensor via a switch circuit connected to the environmental sensor.

2. 2. The ventilation device of claim 1, wherein the switch circuit is controlled to be turned on or off based on a control signal output from the microcontroller, and the supply of voltage to the environmental sensor is controlled to be turned on or off by turning the switch circuit on or off.

3. 3. The ventilation device according to claim 2, wherein when there are a plurality of environmental sensors, a switch circuit is connected to each of the environmental sensors, and the control signal is output from the microcontroller to the switch circuit so that the timing at which each of the switch circuits turns on does not overlap in time.

4. an organic compound environment sensor connected to the second power supply circuit without passing through the switch circuit; 3. The ventilation device of claim 2, wherein the control signal is output from the microcontroller to the switch circuit so that the timing of turning on the supply of voltage to the organic compound environment sensor does not overlap in time with the timing of turning on the supply of voltage to the environment sensor.

5. 3. The ventilation device according to claim 2, wherein when there are a plurality of environmental sensors, the control signal from the microcontroller is output to each of the environmental sensors so that the measurement times of the environmental sensors do not overlap.

6. 2. The ventilation device according to claim 1, wherein the measurement object is at least one of carbon dioxide and dust.

7. an isolated switching power supply having a primary input and a secondary output; an AC voltage is input to the primary side input of the isolated switching power supply, and an AC voltage is output from the secondary side output of the isolated switching power supply; 2. The ventilation device according to claim 1, wherein a DC voltage generated from an AC voltage output from the secondary output is input to a linear regulator included in each of the first power supply circuit and the second power supply circuit.

8. 2. The ventilation device of claim 1, further comprising a housing and a damper inside the housing that opens and closes to switch from a preset air path inside the housing to another air path, and while the damper is opening and closing, a control signal output from the microcontroller is output to the switch circuit to stop the supply of voltage output from the second power supply circuit to the environmental sensor.

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