Vapor pressure deficit control device

Abstract

To provide a less expensive saturation deficit control apparatus, in which the saturation deficit detection sensor is configured by a simpler and less expensive temperature sensor and a control method corresponding to the characteristics of the sensor is performed for controlling a saturation deficit.SOLUTION: When a thermoelectromotive force difference which is a difference between the thermoelectromotive force of a dry-bulb thermocouple TD and the thermoelectromotive force of a wet-bulb thermocouple TW is larger than a relatively large first set value and smaller than a relatively small second set value, a control part 3 outputs an ON or OFF operation signal to a mist 6 to humidify a target space or stop the humidification. The thermocouples used for the dry bulb and the wet bulb are inexpensive among various temperature sensors, and in order to obtain the thermoelectromotive force difference between the two thermocouples, a simple wire structure in which the thermocouples are connected in series and connected to the control unit is sufficient, and thus it is possible to realize a less expensive saturation deficit control device.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a vapor pressure deficit control device that operates a humidifier to control the vapor pressure deficit of a target space to a value favorable for plant growth, and more particularly to a vapor pressure deficit control device with a simple structure and low cost. [Background technology]

[0002] Patent Document 1 below discloses an invention of a vapor pressure deficit control device. According to this vapor pressure deficit control device, a seasonal pattern is determined from the amount of solar radiation and temperature (Figure 3a), a threshold is determined based on the difference between the current vapor pressure deficit and the set vapor pressure deficit and the determined seasonal pattern (Figure 3b, S2), and humidification can be performed by operating the mist 7 for a specified time only when the output value exceeds the threshold (S3, S4). After humidification for the specified time, additional humidification is performed by operating the mist for a time corresponding to the newly acquired output value (S5, S6). In this way, the current vapor pressure deficit can be precisely controlled in a manner that is appropriate for the season (Figure 2), and plant photosynthesis can be performed appropriately. The reference numerals and figure numbers used in this section are the same as those used in Patent Document 1. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2021-103967 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] This invention was made in view of the needs of the industry, which require a vapor pressure deficit control device that can be manufactured at a lower cost than conventional devices and can perform vapor pressure deficit control with sufficient accuracy. The objective is to provide a vapor pressure deficit control device that uses a simpler and less expensive device to detect the vapor pressure deficit of a target space, and performs vapor pressure deficit control using a control method corresponding to the characteristics of the device. [Means for solving the problem]

[0005] The vapor pressure deficit control device described in claim 1 is A vapor pressure deficit control device that operates a humidifier to control the vapor pressure deficit of a target space, A dry-bulb temperature sensor that outputs a physical quantity corresponding to the dry-bulb temperature, A wet-bulb temperature sensor that outputs a physical quantity corresponding to the wet-bulb temperature, A control unit that outputs an operation signal to activate the humidifier based on the physical quantity output by the dry-bulb temperature sensor and the physical quantity output by the wet-bulb temperature sensor, It is equipped with getting tired of Difference control device In, The dry-bulb temperature sensor is a dry-bulb thermocouple. The wet-bulb temperature sensor is a wet-bulb thermocouple. The control output is the thermoelectric difference, which is the difference between the thermoelectric power of the dry-bulb thermocouple and the thermoelectric power of the wet-bulb thermocouple. It is characterized by the following.

[0007] Claim 2 The vapor pressure deficit control device described in claim 1 In the vapor pressure deficit control device described above, The control unit, The aforementioned thermoelectric voltage difference has a relatively large first setting value and a relatively small second setting value. The device is characterized by outputting the operation signal when the thermoelectric power difference is greater than the first set value and when the thermoelectric power difference is less than the second set value.

[0008] Claim 3 The vapor pressure deficit control device described in claim 2 In the vapor pressure deficit control device described above, The control unit, In the relationship between the thermoelectric voltage difference, dry-bulb temperature, and vapor pressure deficit, when a target vapor pressure deficit range and a target temperature range are defined, the thermoelectric voltage difference is selected such that a vapor pressure deficit within the target vapor pressure deficit range is achieved throughout the entire target temperature range, and this value is used as the set value.

[0009] Claim 4The saturation difference control device described in 3 In the saturation difference control device described in The control unit is provided with switching means for allowing the output of the operation signal only when the target space is within the target temperature range.

[0010] Claim 5 The saturation difference control device described in 、 A vapor pressure deficit control device that operates a humidifier to control the vapor pressure deficit of a target space, A dry-bulb temperature sensor that outputs a physical quantity corresponding to the dry-bulb temperature, A wet-bulb temperature sensor that outputs a physical quantity corresponding to the wet-bulb temperature, A control unit that outputs an operation signal to activate the humidifier based on the physical quantity output by the dry-bulb temperature sensor and the physical quantity output by the wet-bulb temperature sensor, In a vapor pressure deficit control device equipped with, The dry bulb temperature sensor is a dry bulb temperature measuring resistor, The wet bulb temperature sensor is a wet bulb temperature measuring resistor, The control output is a voltage difference which is the difference between the voltage of the dry bulb temperature measuring resistor and the voltage of the wet bulb temperature measuring resistor.

Advantages of the Invention

[0012] According to the saturation difference control device described in claim 1 By using a dry bulb thermocouple and a wet bulb thermocouple to obtain a thermoelectromotive force difference proportional to the saturation difference of the target space, and controlling the saturation difference by operating the humidifying device based on this thermoelectromotive force difference. The thermocouples used for the dry bulb and the wet bulb are particularly inexpensive among various temperature sensors, and in order to obtain the thermoelectromotive force difference between the two thermocouples, a simple wiring structure in which they are serially connected and connected to the control unit is sufficient, so a low-cost saturation difference control device can be realized.

[0013] Claim 2According to the vapor pressure deficit control device described herein, the control unit uses a first set value, which is the upper limit, and a second set value, which is the lower limit, as references. When the thermoelectric voltage difference is greater than the first set value, it outputs an operation signal (ON signal) to the humidifier to humidify the target space. When the thermoelectric voltage difference is less than the second set value, it outputs an operation signal (OFF signal) to the humidifier to stop humidifying the target space. In this way, the vapor pressure deficit of the target space can be maintained at a desirable value corresponding to the thermoelectric voltage difference between the two set values.

[0014] Claim 3 According to the vapor pressure deficit control device described herein, the control unit can achieve a vapor pressure deficit within a range favorable for plant growth throughout the entire temperature range favorable for plant growth.

[0015] Claim 4 According to the vapor pressure deficit control device described, when the temperature of the target space is within a predetermined temperature range, the humidifier can be operated to perform the necessary humidification. However, when the temperature of the target space is outside the predetermined temperature range, no operation signal is output to the humidifier, thus avoiding unnecessary humidification.

[0016] Claim 5 According to the vapor pressure deficit control device described, a voltage difference proportional to the vapor pressure deficit of the target space is obtained using a dry-bulb resistance thermometer and a wet-bulb resistance thermometer, and the vapor pressure deficit is controlled by operating the humidifier based on this voltage difference. Even when the dry-bulb and wet-bulb resistance thermometers are installed at a distance from the control unit, there is no need to use special wires such as compensation wires to connect the dry-bulb and wet-bulb resistance thermometers to the control unit, thus reducing installation costs. [Brief explanation of the drawing]

[0017] [Figure 1] This is an overall configuration diagram of the vapor pressure deficit control device of the first embodiment. [Figure 2]This figure shows, in tabular form, the values ​​of the thermoelectric power difference, which is the control output obtained by the vapor pressure deficit control device of the first embodiment, calculated for 15 combinations of preferred dry-bulb temperature (15~35 [°C]) and preferred vapor pressure deficit (3~9 [g / m3]). [Figure 3] Figure 2 is a graph showing the relationship between the dry-bulb thermoelectric power difference (vertical axis) and temperature (horizontal axis) for three different vapor pressure deficit values ​​(3, 6, and 9 [g / m3]) for each of the three values ​​shown in the table. The graph shows a dashed line indicating the range in which a desirable vapor pressure deficit (3 to 9 [g / m3]) can be achieved at a given dry-bulb temperature (15 to 35 [°C]), and also displays the upper limit of the dry-bulb thermoelectric power difference, set value 1, and the lower limit, set value 2, for the dry-bulb thermoelectric power difference within that range. [Figure 4] This flowchart shows an example of a control procedure (1) in the vapor pressure deficit control device of the first embodiment. [Figure 5] Figure 2 is a graph showing the relationship between the dry-bulb thermoelectric power difference (vertical axis) and temperature (horizontal axis) for three different vapor pressure deficit values ​​(3, 6, and 9 [g / m3]) for each of the three values ​​shown in the table. The graph shows a dashed line indicating the range in which a desirable vapor pressure deficit (3 to 9 [g / m3]) can be achieved at a given dry-bulb temperature (15 to 35 [°C]), and the median value of the dry-bulb thermoelectric power difference within that range is shown as a set value of the electromotive force difference with a range of ±α. [Figure 6] This is a flowchart showing an example of a control procedure (2) in the vapor pressure deficit control device of the first embodiment. [Figure 7] This figure shows a bridge circuit for obtaining the voltage difference between a dry-bulb resistance thermometer and a wet-bulb resistance thermometer in the vapor pressure deficit control device of the second embodiment. [Figure 8] This figure shows a vapor pressure deficit table indicating vapor pressure deficit [g / m3] for temperature [°C] and humidity [%]. [Modes for carrying out the invention]

[0018] Regarding the vapor pressure deficit control device of the first embodiment, see Figures 1 to 6 and Figure 8. of I will explain by referring to it. First, with reference to Figure 1, the configuration of the vapor pressure deficit control device 1 of the first embodiment will be described. The vapor pressure deficit control device 1 has a sensor unit 2 equipped with a dry-bulb thermocouple TD as a dry-bulb temperature sensor and a wet-bulb thermocouple TW as a wet-bulb temperature sensor. A thermocouple is a temperature measuring element that connects two metal wires made of different materials and utilizes the Seebeck effect, a phenomenon in which a thermoelectric voltage is generated when a temperature difference is applied to two contacts. In the dry-bulb thermocouple TD, one of the two contacts, the temperature-measuring junction, is kept dry, while in the wet-bulb thermocouple TW, one of the two contacts, the temperature-measuring junction, is kept wet, such as by being wrapped in a damp cloth. The dry-bulb thermocouple TD and the wet-bulb thermocouple TW are connected in series, and the difference in thermoelectric voltage between the thermoelectric voltage of the dry-bulb thermocouple TD and the thermoelectric voltage of the wet-bulb thermocouple TW is output between the ends of the metal wires opposite to the respective temperature-measuring junctions of the dry-bulb thermocouple TD and the wet-bulb thermocouple TW.

[0019] In the first embodiment, a T-type thermocouple according to JIS standards was used as the thermocouple in the sensor section, but K-type and E-type thermocouples can also be used. If the temperature range to be measured is around room temperature or slightly below freezing, a T-type thermocouple is preferable due to its high accuracy and low cost. However, if a wide temperature range is important, a K-type thermocouple, which has slightly better linearity of thermoelectric power than a T-type thermocouple, may be selected. Furthermore, if there are circumstances where a higher thermoelectric power value (voltage) is desirable, an E-type thermocouple can also be used.

[0020] The vapor pressure deficit control device 1 has a control unit 3 to which the aforementioned sensor unit 2 is connected. The control unit 3 has a digital indicating controller 4, an operation switch, and a relay 5. The ends opposite to the temperature measuring junctions of the dry-bulb thermocouple TD and the wet-bulb thermocouple TW, which are connected in series, are connected to the digital indicating controller 4. The digital indicating controller 4 measures and acquires the thermoelectric voltage difference as a control output from the sensor unit 2, compares this thermoelectric voltage difference with a preset reference value, and outputs an ON / OFF signal to the operation switch and relay 5 according to the control method described later. The operation switch and relay 5, upon receiving an ON signal from the digital indicating controller 4, output an ON signal as an operation signal to the outside, operating the mist 6, which is a humidifier in the target space, to humidify the target space. When the output from the digital indicating controller 4 is an OFF signal, the operation signal output from the operation switch and relay 5 is an OFF signal, and the mist 6 is not operated.

[0021] Next, with reference to Figures 2, 3, and 8, the set value, which is the reference value for vapor pressure deficit control by the control unit 3, will be explained. Figure 8 is a vapor pressure deficit table. The vapor pressure deficit table shows the calculated vapor pressure deficit [g / m³] for each intersection of the temperature [°C] displayed in each column of the top horizontal row and the humidity [%] displayed in each column of the left vertical column. 3 This is shown. In the vapor pressure deficit table, the area enclosed by the solid line is the vapor pressure deficit value of 3-6 [g / m³] which is generally the most suitable for plant (crop) growth. 3 The range is defined as ], but the area enclosed by the dashed line with the number indicating the vapor pressure deficit in italics, i.e., the vapor pressure deficit value is 6~9 [g / m³]. 3 There is also the view that the range of ] is acceptable, and in the first embodiment, the vapor pressure deficit of these two regions, i.e., 3 to 9 [g / m³], is used. 3Let [[ID=]] be the preferred value, and consider the air temperature (i.e., dry-bulb temperature) in these two regions, which is 15 to 35 [°C], as the air temperature at which the mist 6 should be controlled. Since the dry-bulb temperature may be the ambient air temperature (environmental temperature) around the control device, such as the temperature measurement value measured in the target space (e.g., greenhouse), in the control in the control unit 3, the control of the mist 6 is performed on the condition that the ambient air temperature (environmental temperature) is within the range of 15 to 35 [°C]. The details of the specific configuration for this will be described at the end of the description of the embodiment.

[0022] FIG. 2 is a diagram showing in tabular form the values of the thermoelectric power difference as the control output obtained by the saturation difference control device 1 of the first embodiment, calculated for each combination of the dry-bulb temperature (15 to 35 [°C]) to be controlled and the preferred saturation difference (3 to 9 [g / m 3 ).

[0023] Specifically, at each value of the saturation difference of 3 [g / m 3 , 6 [g / m 3 , and 9 [g / m 3 , when the temperature (air temperature, i.e., dry-bulb temperature) takes on the values of 15 [°C], 20 [°C], 25 [°C], 30 [°C], and 35 [°C], the value of the thermoelectric power difference output by the sensor unit 2 is calculated.

[0024] For example, the calculation procedure when the saturation difference is 3 [g / m 3 and the temperature is 15 [°C] will be described. First, the saturated absolute humidity [g / m 3 is obtained from the temperature using the formula defined in JIS Z8806, and this is used as the relative humidity [g / m 3 at the saturation difference of 3 [g / m 3Convert to ]. Also, use the psychrometer formula (Sprung's formula) specified in JIS Z 8806 to determine the wet-bulb temperature [°C], and then determine the wet-bulb temperature difference [°C]. Then, using the thermoelectric power table and approximation formula specified in JIS C 1602, determine the thermoelectric power [μV] of the dry-bulb thermocouple TD and the thermoelectric power [μV] of the wet-bulb thermocouple TW, and from these values, determine the thermoelectric power difference [μV], which is the difference between the thermoelectric power of the dry-bulb thermocouple TD and the thermoelectric power of the wet-bulb temperature sensor. Perform the above calculations for each temperature of 20 [°C], 25 [°C], 30 [°C], and 35 [°C]. Then, perform the above calculations for 6 [g / m 3 ], 9[g / m 3 The same procedure is performed for each of the vapor pressure deficits. This yields the values ​​shown in the table in Figure 2.

[0025] Figure 3 plots the values ​​shown in the table in Figure 2 on a coordinate system with the difference between the wet and dry bulb thermoelectric power on the vertical axis and temperature (i.e., dry bulb temperature) on the horizontal axis, showing three different values ​​of vapor pressure deficit (3, 6, 9 [g / m³]). 3 This graph shows the relationship between the dry-bulb thermoelectric power difference and temperature, represented by three lines connecting points at each interval. In this graph, the preferred dry-bulb temperature (15~35[°C]) and vapor pressure deficit (3~9[g / m³]) are shown. 3 The range in which the desired result can be achieved is shown by a rectangular dashed line. Within this range, the upper limit of the dry-bulb / wet-bulb thermoelectric power difference, electromotive force difference setting value 1, is 150 [μV], and the lower limit, electromotive force difference setting value 2, is 93 [μV]. Therefore, as will be explained below, the control unit 3 can control the mist 6 to fall within a desirable range by appropriately operating it using the two electromotive force difference setting values ​​1 and 2 provided for the dry-bulb / wet-bulb thermoelectric power difference.

[0026] Figure 4 is a flowchart showing an example of the control procedure (1) in the vapor pressure deficit control device 1 of the first embodiment. When control is started (START), it is determined whether the dry-bulb / wet-bulb thermoelectric power difference sent from the sensor unit 2 is greater than the electromotive force difference setting value 1 (S1). If the dry-bulb / wet-bulb thermoelectric power difference is less than the electromotive force difference setting value 1 (S1, NO), the target space is considered to be sufficiently humid, and the determination based on the electromotive force difference setting value 1 (S1) is repeated at appropriate time intervals without outputting an operation signal to the mist 6.

[0027] In the determination using the electromotive force difference setting value 1 (S1), if the difference between dry and wet bulb thermoelectric power is greater than the electromotive force difference setting value 1 (S1, YES), the target space is considered dry. Therefore, the digital indicating controller 4 outputs an ON signal to the operation switch and relay 5, and the operation switch and relay 5 output an ON signal to the mist 6 for a predetermined period of time (S2), activating the mist 6 and humidifying the target space. Humidification by the mist 6 will continue for a predetermined period of time (for example, 30 seconds) after the operation switch and relay 5 have given the ON signal to the mist 6 for a predetermined period of time, and then automatically stop.

[0028] Next, it is determined whether the dry-bulb / wet-bulb thermoelectric power difference sent from the sensor unit 2 is less than the set value of 2 (S3). If it is not less than 2 (S2, NO), the target space is not considered sufficiently humid, and the digital indicator controller 4 outputs an ON signal to the operation switch and relay 5. The operation switch and relay 5 then provide a signal to the mist 6 to turn ON for a predetermined time (S2) to humidify the target space.

[0029] In the determination using the electromotive force difference set value 2 (S2), if the dry-bulb / wet-bulb thermoelectric force difference is less than the electromotive force difference set value 2 (S3, YES), the target space is considered to be sufficiently humid. Therefore, the digital indicating controller 4 outputs an OFF signal to the operation switch and relay 5, and the operation switch and relay 5 provide a signal to the mist 6 to turn OFF for a predetermined period of time (S4). The mist 6 does not operate for the predetermined period of time, and the control returns to the determination using the set value 1 (S1).

[0030] Next, an example of the control procedure (2) in the vapor pressure deficit control device 1 of the first embodiment will be described. Figure 5 is similar to Figure 3, showing the preferred dry-bulb temperature (15-35°C) and vapor pressure deficit (3-9 g / m³). 3 The range in which the above can be achieved is shown by a rectangular dashed line in the graph. Here, the electromotive force difference setting value for example (2), which serves as the control reference, is set to 125 [μV], which is the intermediate value between electromotive force difference setting value 1 and electromotive force difference setting value 2 in example (1). There is only one electromotive force difference setting value, but a small tolerance range of ±a is added to this electromotive force difference setting value. The numerical value a that determines the added range can be set arbitrarily, but for example, in the numerical example in the first embodiment, a value of approximately ±3 [μV] is preferred for the numerical value a.

[0031] Figure 6 is a flowchart showing an example (2) of the control procedure in the vapor pressure deficit control device 1 of the first embodiment. When control is started (START), it is determined whether the difference between the dry and wet bulb thermoelectric power sent from the sensor unit 2 is greater than the set value of the electromotive force difference + a (S21). If the difference between the dry and wet bulb thermoelectric power is less than the set value of the electromotive force difference + a (S21, NO), the target space is considered to be sufficiently humid, and the determination based on the set value of the electromotive force difference + a (S21) is repeated at appropriate time intervals without outputting an operation signal to the mist 6.

[0032] In the determination using the electromotive force difference set value + a (S21), if the difference between dry and wet bulb thermoelectric power is greater than the electromotive force difference set value + a (S1, YES), the target space is considered dry. Therefore, the digital indicating controller 4 outputs an ON signal to the operation switch and relay 5, and the operation switch and relay 5 output an ON signal to the mist 6 for a predetermined time (S22), activating the mist 6 and humidifying the target space. The humidification time by the mist 6 is the same as in example (1).

[0033] Next, it is determined whether the dry-bulb / wet-bulb thermoelectric power difference sent from the sensor unit 2 is less than the set value -a (S23). If it is not less than a set value (S23, NO), the target space is not considered sufficiently humid, and the digital indicator controller 4 outputs an ON signal to the operation switch and relay 5. The operation switch and relay 5 then provide a signal to the mist 6 to turn ON for a predetermined time (S22) to humidify the target space.

[0034] In the determination using the electromotive force difference set value -a (S23), if the dry-bulb / wet-bulb thermoelectric force difference is less than the electromotive force difference set value -a (S23, YES), the target space is considered to be sufficiently humid. Therefore, the digital indicating controller 4 outputs an OFF signal to the operation switch and relay 5, and the operation switch and relay 5 give the mist 6 an OFF signal for a predetermined time (S24). The mist 6 does not operate for the predetermined time, and the control returns to the determination using the electromotive force difference set value +a (S21).

[0035] As described above, the vapor pressure deficit control device 1 of the first embodiment employs a simple configuration in which thermocouples are connected in series, and a simple control method that switches the operation of the mist 6 using a thermoelectric voltage difference setting value that realizes a temperature range and vapor pressure deficit range favorable for plant growth. Therefore, it is possible to achieve vapor pressure deficit control with sufficient accuracy at a low cost.

[0036] In particular, according to example control procedure (1), the mist 6 is operated based on the upper limit (set value 1) and lower limit (set value 2) of the dry-bulb thermoelectric power difference, thereby ensuring that a temperature range and vapor pressure deficit range favorable for plant growth can be reliably achieved.

[0037] Furthermore, according to the control procedure example (2), the operation of Mist 6 is performed based on an electromotive force difference setting value that has a small range of ±a between the upper limit (setting value 1) and lower limit (setting value 2) of the wet-bulb thermoelectric force difference. Therefore, chattering, which can occur when the electromotive force difference setting value is a single numerical value without a range, does not occur.

[0038] Next, the vapor pressure deficit control device 10 of the second embodiment will be described with reference to Figure 7. Figure 7 shows the basic structure of the vapor pressure deficit control device 10 of the second embodiment, and shows a sensor unit 20 consisting of two dry and wet resistance thermometers, and a bridge circuit 40 provided in the control unit 30 to obtain a voltage difference, which is the control output, from the two voltages output by the two dry and wet resistance thermometers.

[0039] In Figure 7, the sensor unit 20 includes a dry-bulb temperature thermistor or a dry-bulb platinum resistance thermometer Rd (hereinafter referred to as the dry-bulb resistance thermometer Rd) and a wet-bulb temperature thermistor or a wet-bulb platinum resistance thermometer Rw (hereinafter referred to as the wet-bulb resistance thermometer Rw).

[0040] In Figure 7, the bridge circuit 40 of the control unit 30 is composed of the dry-bulb resistance thermometer Rd and the wet-bulb resistance thermometer Rw of the sensor unit 2, and fixed resistors R1 and R2. A power supply is connected between the connection point F of the dry-bulb resistance thermometer Rd and the wet-bulb resistance thermometer Rw, and the connection point E of the fixed resistors R1 and R2, providing a power supply voltage Ep. The control output of the bridge circuit 40 is the signal voltage Es obtained between the connection point C of the dry-bulb resistance thermometer Rd and the fixed resistor R1, and the connection point D of the wet-bulb resistance thermometer Rw and the fixed resistor R2. The signal voltage Es is obtained as the voltage difference between the potential drop across fixed resistor R1, i.e., the voltage between connection points C and E, and the potential drop across fixed resistor R2, i.e., the voltage between connection points D and E.

[0041] According to the vapor pressure deficit control device 10 of the second embodiment, even when the dry-bulb resistance thermometer Rd and the wet-bulb resistance thermometer Rw are installed at a location away from the control unit 3, there is no need to use special wires such as compensation wires for connecting the dry-bulb resistance thermometer Rd and the wet-bulb resistance thermometer Rw to the control unit 3, thus reducing installation costs.

[0042] In the first and second embodiments described above, thermocouples, thermistors, and platinum resistance thermometers were used as examples of dry-bulb and wet-bulb temperature sensors, but other temperature sensors based on different principles can also be used as the dry-bulb and wet-bulb temperature sensors of the present invention.

[0043] Furthermore, in the first and second embodiments described above, the temperature range for vapor pressure deficit control was set to 15 to 35°C, and the mist 6 was controlled on the condition that the ambient temperature was within this temperature range. However, as a specific configuration, the control units 3 and 30 may be provided with a switching means that prevents them from outputting an operation signal to the mist 6 outside of this temperature range. For example, in Figure 1, a bimetal can be provided at the output of the operation switch and relay 5 as a switching means that allows the operation signal to be output externally only when the temperature range is 15 to 35°C. Alternatively, a temperature sensor (not shown) may be provided outside the control unit 3, and a signal indicating whether the ambient temperature measurement result from this temperature sensor is within the 15 to 35°C temperature range may be input to the control unit 3. The operation switch and relay 5 may be configured to operate only when the ambient temperature measurement result is within the 15 to 35°C temperature range. This configuration prevents the vapor pressure deficit control device 10 from operating at temperatures outside the temperature range in which vapor pressure deficit control is not intended. [Explanation of symbols]

[0044] 1,10...Vascular pressure deficit control device 2.20...Sensor section 3,30…Control Unit 6…Mist as a humidifier TD... Dry-bulb thermocouple as a dry-bulb temperature sensor TW... Wet-bulb thermocouple as a wet-bulb temperature sensor Rd... Dry-bulb temperature thermistor or dry-bulb platinum resistance thermometer (dry-bulb resistance thermometer) as a dry-bulb temperature sensor. Rw...Wet-bulb temperature thermistor or wet-bulb platinum resistance thermometer (wet-bulb resistance thermometer) as a wet-bulb temperature sensor.

Claims

1. A vapor pressure deficit control device that operates a humidifier to control the vapor pressure deficit of a target space, A dry-bulb temperature sensor that outputs a physical quantity corresponding to the dry-bulb temperature, A wet-bulb temperature sensor that outputs a physical quantity corresponding to the wet-bulb temperature, A control unit that outputs an operation signal to activate the humidifier based on the physical quantity output by the dry-bulb temperature sensor and the physical quantity output by the wet-bulb temperature sensor, In a vapor pressure deficit control device equipped with, The dry-bulb temperature sensor is a dry-bulb thermocouple. The wet-bulb temperature sensor is a wet-bulb thermocouple. The vapor pressure deficit control device is characterized in that the control output is a thermoelectric voltage difference, which is the difference between the thermoelectric voltage of the dry-bulb thermocouple and the thermoelectric voltage of the wet-bulb thermocouple.

2. The control unit, The aforementioned thermoelectric voltage difference has a relatively large first setting value and a relatively small second setting value. The vapor pressure deficit control device according to claim 1, characterized in that it outputs the operation signal when the thermoelectric power difference is greater than the first set value and when the thermoelectric power difference is less than the second set value.

3. The control unit, The vapor pressure deficit control device according to claim 2, characterized in that, in the relationship between the thermoelectric voltage difference, the dry-bulb temperature, and the vapor pressure deficit, when a target vapor pressure deficit range and a target temperature range are defined, a value of the thermoelectric voltage difference is selected such that a vapor pressure deficit within the target vapor pressure deficit range is realized throughout the entire target temperature range, and this value is used as the set value.

4. The vapor pressure deficit control device according to claim 3, characterized in that the control unit is provided with a switching means that allows the output of the operation signal only when the target space is within the target temperature range.

5. A vapor pressure deficit control device for operating a humidifier to control the vapor pressure deficit of a target space, A dry-bulb temperature sensor that outputs a physical quantity corresponding to the dry-bulb temperature, A wet-bulb temperature sensor that outputs a physical quantity corresponding to the wet-bulb temperature, A control unit that outputs an operation signal to activate the humidifier based on the physical quantity output by the dry-bulb temperature sensor and the physical quantity output by the wet-bulb temperature sensor, In a vapor pressure deficit control device equipped with, The dry-bulb temperature sensor is a dry-bulb resistance thermometer. The wet-bulb temperature sensor is a wet-bulb resistance thermometer. The vapor pressure deficit control device is characterized in that the control output is a voltage difference, which is the difference between the voltage of the dry-bulb resistance thermometer and the voltage of the wet-bulb resistance thermometer.

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