JP2008233047A - Stalk liquid flow measuring sensor, stalk liquid flow measuring device, and stalk liquid flow measurement method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stalk liquid flow measuring sensor, a stalk liquid flow measuring device, and a stalk liquid flow measurement method capable of measuring stalk liquid flow of plants with stalks of small diameter, with high sensitivity and at low cost. <P>SOLUTION: The stalk liquid flow measuring sensor 1 comprises a substrate 2 comprising insulating synthetic-resin films or sheets, or insulating sheets or thin plates of inorganic material, such as insulating ceramic wafers, a pair of thin-film metal temperature sensing resistors 3 and 5 prepared on its surface, a thin-film metal heater 4 formed in parallel between a pair of temperature sensing resistors 3 and 5, also a pair of conductive materials 6 extracting electrical signal from the thin-film metal temperature sensing resistors 3 and 5, respectively, and a conductive material 7 supplying current to the thin-film metal heater 4. Surface of the substrate 2 is coated by insulating material 8, after arranging the thin-film metal temperature sensing resistors 3 and 5 as well as the thin-film metal heater 4. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a sensor for measuring stem fluid flow, a stem fluid flow measuring device, and a stem fluid flow measuring method for measuring the flow rate of plant stem fluid by a heat pulse method.

As a method for measuring the sap flow flowing in a plant conduit, for example, there is a method disclosed in Patent Document 1. In this example, a sensor device is used that includes two temperature sensors that protrude from the mounting seat at a predetermined interval and a heater disposed between the two temperature sensors. A pulsatile current is passed through the heater, a temperature change is detected by a temperature sensor, and the flow rate of the heat pulse is measured to indirectly measure the stem fluid flow.
Japanese Patent Laid-Open No. 5-188070

  However, since the conventional sensor device is large, it has been difficult to apply to a plant having a small stem diameter. Moreover, the thermocouple was used as a temperature sensor, and the sensitivity with respect to a temperature change was bad. Furthermore, the temperature sensor and the heater are different, and two types of devices are required, leading to an increase in cost.

  The present invention has been made in view of such circumstances, and is a low-cost, sensitive and easy-to-handle sensor for measuring stem fluid flow of a plant having a small stem diameter, and stem fluid. An object of the present invention is to provide a flow measuring device and a stem fluid flow measuring method.

  In order to achieve the object, the stem fluid flow measurement sensor of the present invention is formed in parallel between a pair of thin film metal resistance thermometers formed on an insulating base material and the pair of resistors. A configuration including a thin film metal heater, a pair of conductive materials that respectively extract electric signals of the pair of thin film metal resistance thermometers, and a conductive material that supplies current to the thin film metal heater was adopted.

  Since the temperature sensor can be a thin film metal resistance thermometer, the sensitivity is higher than the thermocouple and the accuracy is high. Also, a reference junction such as a thermocouple is not necessary. In addition, the structure is suitable for mass production and can be made inexpensive. Furthermore, since the sensor can be miniaturized, the stem fluid flow of a plant having a small stem diameter can be measured.

  The sensor for measuring stem fluid flow according to the present invention is suitable for mass production and can be inexpensive because the thin film metal temperature measuring resistor and the thin film metal heater are the same shape and the same metal resistor.

  Moreover, the stem fluid flow measurement sensor of the present invention is preferably a platinum resistor having the same shape as the thin-film metal resistance thermometer and the thin-film metal heater. Suitable and inexpensive.

  Since the base material is an insulating synthetic resin film or sheet, for example, a plastic film or sheet, or a sheet or thin plate made of an insulating inorganic material such as a ceramic wafer, a thin film resistor is formed on the surface of the thin base material. A sensor can be manufactured by providing a body, and the sensor can be thinned.

  Further, the stem fluid flow measuring sensor of the present invention includes a distance between the centers of the one thin film metal resistance thermometer and the thin film metal heater, and a distance between the other thin film metal resistance thermometer and the center of the thin film metal heater. The distance can be not equal, and in this case, the flow rate of the stem fluid can be measured by the heat pulse method.

  In addition, the stem fluid flow measuring sensor of the present invention can be used by winding the stem, the thin film metal resistance temperature detector, and the thin film metal heater around the stem of a small plant.

  In the stem fluid flow measurement sensor according to the present invention, the base material is made of an insulating synthetic resin film, for example, an insulating plastic film, and the thin film metal resistance thermometer and the thin film metal heater are sandwiched between the thin film metal temperature measuring resistor and the thin film metal heater. In this case, it can be formed using a commercially available thin film metal resistance temperature detector and thin film metal heater and an insulating synthetic resin film, for example, an insulating plastic film, and can be made inexpensive.

  Further, the stem fluid flow measuring device of the present invention is a pair of thin film metal resistance thermometers formed on an insulating base material and a thin film metal heater formed in parallel between the pair of resistors, A pair of conductive materials for taking out electrical signals of the pair of thin film metal resistance thermometers, a stem liquid flow measurement sensor comprising a conductive material for supplying current to the thin film metal heater, and the thin film metal heater. Application means for applying a pulse current, measurement means for measuring the resistance value of the pair of thin film metal resistance thermometers, and the temperature of the pair of thin film metal resistance thermometers from the resistance values measured by the measurement means, respectively After the pulse current is applied to the thin film metal heater by the temperature calculation means to be calculated and the application means, the time until the temperatures of the pair of thin film metal resistance thermometers calculated by the temperature calculation means become equal measurement That the measuring means, said flow rate calculation means from the measurement time measured by the measuring means for calculating the flow rate of the stem solution, and output means for outputting a signal corresponding to the flow velocity of the stem solution consists.

  In recent years, for example, in a greenhouse for tomato cultivation, computer control has been introduced to reduce the burden on farmers. This system measures the cultivation environment such as temperature, humidity, and illuminance, and grasps the state in the greenhouse. However, since the state of the plant was visually observed by humans, the amount of water and fertilizer was ultimately determined and supplied by humans. According to the present invention, since the flow rate of tomato stem liquid can be automatically detected, it is only necessary to add water or fertilizer in an amount corresponding thereto, and cultivation can be automated.

  Further, the stem fluid flow measuring device of the present invention is a pair of the thin film metal thermometers, wherein the distance between the centers of the thin film metal thermometer and the thin film metal heater disposed above the plant stem is Xa, Xb (Xa> Xb) is the distance between the thin film metal resistance thermometer and the thin film metal heater arranged below the plant stem, and the pulse current is applied to the thin film metal heater by the applying means. When the time until each temperature of the pair of thin film metal resistance thermometers calculated by the temperature calculation means becomes equal to t0 and the calibration constant determined in advance as b, the flow rate F of the plant stem fluid is Since the calculation means for calculating F = b (Xa + Xb) / (2 × t0) is provided, the flow rate of the stem fluid can be obtained with a simple calculation formula, and the measurement time can be shortened.

  The stem fluid flow measuring device of the present invention comprises a heater measuring means for measuring the resistance value of the thin film metal heater, and a heater temperature calculating means for calculating the temperature of the thin film metal heater from the resistance value, Since the applying means determines the pulse current to be applied to the thin film metal heater based on the temperature of the thin film metal heater, the temperature setting and heating time of the thin film metal heater are set according to the temperature of the thin film metal heater. Since it can be controlled, more accurate measurement can be performed.

  Further, in the stem fluid flow measuring apparatus of the present invention, the applying means applies a pulse current to the thin film metal heater at a predetermined cycle, and the output means responds to the flow rate of the stem fluid calculated by the speed calculating means. Since a signal for adjusting the amount of water and / or fertilizer is output, the amount of water and / or fertilizer can be adjusted according to the flow rate of the stem liquid, and cultivation can be automated.

  Further, the stem fluid flow measuring method of the present invention includes a pair of thin film metal resistance thermometers formed on an insulating substrate and a thin film metal heater formed in parallel between the pair of resistors, Constructed using a pair of conductive materials for taking out electrical signals of the pair of thin-film metal resistance thermometers, and a stem fluid flow measuring sensor and a computer comprising a conductive material for supplying current to the thin-film metal heater In the stem fluid flow measurement system, the step of applying the pulse current to the thin film metal heater by the application means provided in the computer and the step of measuring the resistance value of the pair of thin film metal resistance thermometers by the measurement means provided in the computer And a step of calculating a temperature of the pair of thin-film metal resistance thermometers from the resistance value measured by the measuring unit by a temperature calculating unit included in the computer, After the pulse current is applied to the thin film metal heater by the applying means, the measuring means provided in the computer takes time until the temperatures of the pair of thin film metal resistance thermometers calculated by the temperature calculating means become equal. The flow rate calculating means provided in the computer calculates the flow rate of the stem fluid from the measurement time measured by the measuring means, and the output means provided in the computer outputs a signal corresponding to the flow rate of the stem fluid A configuration for executing the steps is adopted.

  Further, the stem fluid flow measuring method of the present invention is a pair of the thin film metal thermometers, wherein the distance between the centers of the thin film metal thermometer and the thin film metal heater arranged above the plant stem is Xa, Xb (Xa> Xb) is the distance between the thin film metal resistance thermometer and the thin film metal heater arranged below the plant stem, and the pulse current is applied to the thin film metal heater by the applying means. When the time until each temperature of the pair of thin film metal resistance thermometers calculated by the temperature calculation means becomes equal to t0 and the calibration constant determined in advance as b, the flow rate F of the plant stem fluid is And F = b (Xa + Xb) / (2 × t0).

  In the stem fluid flow measuring method of the present invention, the heater measuring means measures the resistance value of the thin film metal heater, the heater temperature calculating means calculates the temperature of the thin film metal heater from the resistance value, and the applying means is Since the pulse current applied to the thin film metal heater is determined based on the temperature of the thin film metal heater, the temperature setting and heating time of the thin film metal heater can be controlled according to the temperature of the thin film metal heater. More accurate measurement can be performed.

  In the stem fluid flow measuring method of the present invention, the applying means applies a pulse current to the thin film metal heater at a predetermined cycle, and the output means responds to the flow rate of the stem fluid calculated by the speed calculating means. Since a signal for adjusting the amount of water and / or fertilizer is output, the amount of water and / or fertilizer can be adjusted according to the flow rate of the stem liquid, and cultivation can be automated.

  A sensor for measuring stem fluid flow according to the present invention includes a pair of thin film metal resistance thermometers formed on an insulating base material, and a thin film metal heater formed in parallel between the pair of resistors, Since it has a pair of conductive materials for taking out electrical signals of the pair of thin film metal resistance thermometers, and a conductive material for supplying current to the thin film metal heater, the sensitivity is low, the stem diameter is high. Small plant stem fluid flow can be measured.

  A pair of thin-film metal resistance thermometers formed on an insulating substrate, a thin-film metal heater formed in parallel between the pair of resistors, and an electric signal of the pair of thin-film metal resistance thermometers And a pair of conductive materials that respectively take out and a conductive material that supplies current to the thin film metal heater.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a perspective view showing a first embodiment of a sensor for measuring stem fluid flow according to the present invention.

  As shown in FIG. 1, a sensor 1 for measuring stem fluid flow includes a base material 2 made of an insulating synthetic resin film or sheet, or a sheet or thin plate of an inorganic material such as an insulating ceramic wafer, and its surface. Of the pair of thin film metal resistance thermometers 3 and 5, the thin film metal heater 4 formed in parallel between the pair of resistor bodies 3 and 5, and the thin film metal resistance thermometer resistors 3 and 5 It consists of a pair of conductive materials 6 for extracting electrical signals, and a conductive material 7 for supplying current to the thin film metal heater 4. The surface of the substrate 2 is coated with an insulating material 8 after the thin film metal resistance thermometers 3 and 5 and the thin film metal heater 4 are arranged.

  The substrate 2 is, for example, an insulating synthetic resin film (particularly an insulating plastic film) having a thickness of 1 μm to 300 μm, particularly preferably a thickness of 10 μm to 250 μm, and more preferably a thickness of 50 μm to 200 μm, or It can be composed of an insulating film or sheet such as an insulating synthetic resin sheet (particularly an insulating plastic sheet) having a thickness of 200 μm to 1000 μm, particularly preferably a thickness of 250 μm to 800 μm. An insulating inorganic material sheet or a thin plate having a thickness of 200 μm to 1000 μm, particularly preferably a thickness of 250 μm to 800 μm (particularly, an insulating inorganic material sheet or thin plate such as a ceramic wafer) can be preferably exemplified. If the substrate 2 is composed of a ceramic wafer, the stem liquid flow measurement sensor 1 can be made robust, and therefore effective when inserted into a stem. Further, if the substrate 2 is made of a thin plastic film, the stem fluid flow measuring sensor 1 can be curved, which is effective when the stem fluid flow measuring sensor 1 is wound around the stem.

  As an insulating base material, for example, a plastic film or sheet such as polyester, polyamide, polyetherimide, Teflon (registered trademark) or other fluororesin, or aromatic polyester, aromatic polyamide, aromatic polyetherimide, An insulating synthetic resin film or sheet having heat resistance such as polyimide and fluororesin can be preferably exemplified.

  The pair of conductive materials 6 for taking out the electrical signals of the thin film metal resistance thermometers 3 and 5 and the conductive material 7 for supplying a current to the thin film metal heater 4 can be of the same material and shape. However, the conductive material 6 and the conductive material 7 may be different. The material is preferably copper wire, but the present invention is not limited to this, and various materials can be used.

  The thin-film metal resistance thermometers 3 and 5 and the thin-film metal heater 4 can be the same metal resistors. The relationship between the resistance value R and the temperature T of the metal resistor is defined as R = A (1 + αT) where A is the resistance value at a temperature of 0 ° C. and α is the temperature coefficient. Therefore, the temperature can be calculated by measuring the resistance value R of the resistor. In the present invention, the thin-film metal resistance thermometers 3 and 5 and the thin-film metal heater 4 can also have the same shape. Thereby, it is suitable for mass production and can be made inexpensive.

  In the present invention, the thin-film metal resistance thermometers 3 and 5 and the thin-film metal heater 4 can be composed of platinum thin-film resistors having the same shape. The thin-film metal resistance thermometers 3 and 5 and the thin-film metal heater 4 are formed with a pattern whose thickness and area are defined so that the resistance becomes 100Ω when the temperature is 0 ° C. As the thin-film metal resistance temperature detectors 3 and 5 and the thin-film metal heater 4, those of Pt100 phase or the like can be used. The resistance value R can be set to R = 100 (1 + 0.3851T) when the temperature is T degrees. In addition, although the platinum resistor was mentioned as an example as a material of the thin film metal resistance temperature detectors 3 and 5 and the thin film metal heater 4, this invention is not limited to this, Various materials, such as copper and nickel Can be used.

  In this example, the center-to-center distance Xa between one thin-film metal resistance thermometer 3 and the thin-film metal heater 4 is 10 mm, and the center-to-center distance Xb between the other thin-film metal thermometer 5 and the thin-film metal heater 4 is 5 mm. The center-to-center distance is, for example, the distance between the center points of the pattern areas of the thin film metal resistance thermometers 3 and 5 and the thin film metal heater 4. Since Xa and Xb are not equally spaced in this manner, the flow rate of plant stem fluid can be calculated by the heat pulse method, as will be described in detail later. In addition, when attaching to a stem, the thin film metal resistance thermometer 3 with a large center distance is arranged above the stem, and the thin film metal resistance thermometer 5 with a small center distance is arranged below the stem.

  The thin-film metal resistance thermometers 3 and 5 and the thin-film metal heater 4 can be formed on the surface of the substrate 2 by sputtering or vapor deposition, or a commercially available platinum thin-film resistor previously formed in a predetermined pattern. It can also be placed on a substrate.

  In the sputtering method, first, platinum (target) as a film raw material is disposed near the surface of the substrate 2. When the substrate 2 and the entire target are brought into a vacuum state and a voltage is applied between the substrate 2 and the target, electrons and ions move at high speed in the vacuum, and the electrons and ions collide with the target. The ions that collide with the target repel the target particles, and the repelled target particles collide and adhere to the substrate 2 to form a film.

  In the vapor deposition method, first, platinum, which is a raw material of the film, is arranged at a predetermined interval from the surface of the substrate 2. Then, by vacuuming the whole and melting the raw material with heat, the raw material evaporates and becomes gas molecules which collide with and adhere to the base material 2 to form a film. Depending on the heating and melting method, there are a resistance heating type, an electron beam type, a high frequency induction type, and a laser type.

Next, a method for attaching the stem fluid flow measuring sensor according to the present invention to the plant stem will be described.
2A and 2B are diagrams showing a first method of attaching the stem fluid flow measuring sensor to the plant stem, wherein FIG. 2A is a front view thereof and FIG. 2B is a cross-sectional view thereof. FIG. 3 is a diagram showing a second method of attaching the stem fluid flow measurement sensor to the plant stem, wherein (a) is a front view thereof and (b) is a sectional view thereof.

  As shown in FIGS. 2 (a) and 2 (b), a small cut is made along the stem fiber on the side of the stalk 11 such as tomato, and the stalk fluid flow measurement sensor 1 is inserted into the cut. Insert about two thirds. According to this method, since only a small cut is made along the fiber of the stem 11, there is little adverse effect on the plant. Moreover, since the front-end | tip of the sensor 1 for stem fluid flow measurement can be directly arrange | positioned in the conduit | pipe inside the stem 11, accurate measurement is attained.

  Further, as shown in FIGS. 3 (a) and 3 (b), the stem fluid flow measuring sensor 1 is curvedly arranged along the surface of the stem 11 such as a tomato and the heat insulating material 12 is wound around the sensor. You can also. According to this method, since no cut is made in the stem 11, adverse effects on the plant can be minimized. Moreover, since the heat insulating material 12 is wound, an accurate measurement can be performed without being influenced by the external environment.

Next, the stem liquid flow measuring device according to the present invention will be described.
FIG. 4 is a block diagram showing a stem fluid flow measuring device according to the present invention. FIG. 5 is a block diagram of a computer constituting the stem fluid flow measurement device according to the present invention.

  The stem fluid flow measuring device 20 shown in FIG. 4 controls the thin-film metal resistance thermometers 3 and 5 and the thin-film metal heater 4, a power source for supplying current to them, and the current flowing through the thin-film metal resistance thermometer 3. A constant current diode 21, a constant current diode 22 for controlling a current flowing through the thin film metal heater 4, a constant current diode 23 for controlling a current flowing through the thin film metal resistance temperature detector 5, and a pulsed current in the thin film metal heater 4 A switching circuit 24 for supplying electric current, a data logger 25 for outputting electric signals to the switching circuit 24 and inputting voltage values of the thin-film metal resistance thermometers 3 and 5 and the thin-film metal heater 4, and a data logger 25 The computer 26 is connected via a LAN (Local Area Network) or the like.

  A current of 1 mA is supplied to the thin film metal temperature measuring resistors 3 and 5 by the constant current diodes 21 and 23. On the other hand, a current of 20 mA is supplied to the thin film metal heater 4 by the constant current diode 22, and a rectangular pulse current is applied by the switching circuit 24. And after flowing a pulse-shaped electric current, each resistance value of the thin-film metal resistance thermometers 3 and 5 and the thin-film metal heater 4 is measured, and those each temperature is calculated. Regarding the measurement of the resistance value, since the actual measurement data includes noise, it is preferable to remove the noise with a low-pass filter. In this example, the data logger 25 and the computer 26 are used. However, for simple use, a 1-chip microprocessor having an AD conversion function can be used instead.

  As shown in FIG. 5, the computer 26 includes a CPU 27 with a built-in timer 28, a storage unit such as a RAM 29, a ROM 30, a hard disk 31 (HD), an input interface 32 (input I / F), and an output interface 33 (output). I / F) and the like, which are connected via a bus line 34. In addition, a LAN communication line is connected to the input I / F 32, and a keyboard 35 and a mouse 36 are connected as input devices, and a speaker 37 is connected to the output I / F 33. In the case of a desktop, the personal computer main body 38 is used. The output I / F 33 is connected to a display 39 and a valve (see FIG. 6) for adjusting the amount of water and fertilizer in the greenhouse.

  If such a stem fluid flow measuring device 20 is used, the flow rate of plant stem fluid can be measured and an electric signal can be output to a valve for adjusting water and fertilizer, so that the supply of water and fertilizer can be automated. it can. In addition, since the state of the plant can be grasped by measuring the flow rate of the stem fluid, a means for notifying the state using a message display device that displays voice, LED (Light Emitting Diode), characters, etc. is provided separately. By this, it can be used as a communication toy with plants or a healing toy.

Next, a stem fluid flow measurement system using the sensor for measuring stem fluid flow according to the present invention will be described.
FIG. 6 is a configuration diagram showing a stem fluid flow measurement system using the stem fluid flow measurement sensor according to the present invention.

  As shown in FIG. 6, the stem fluid flow measurement system 50 using the stem fluid flow measurement sensor 1 includes a greenhouse 51, a skylight 52 provided on the roof of the greenhouse 51, and the ground in the greenhouse 51. The arranged pot 53, a tomato seedling 54 planted in the soil of the pot 53, a pipe 55 for supplying water and fertilizer to the seedling 54, and a valve 56 connected to the pipe 55 for adjusting the amount of water and fertilizer A wind sensor 57 that measures the air volume outside the greenhouse 51, an illuminance sensor 58 that measures the illuminance outside the greenhouse 51, a temperature sensor 59 that measures the temperature inside the greenhouse 51, and the inside of the greenhouse 51 A carbon sensor 60 for measuring the amount of carbon dioxide, a humidity sensor 61 for measuring the humidity in the greenhouse 51, a valve 56 and various sensors 1, 57 to 61. It is, based on various measured values of the various sensors 1, 57 to 61, and a control panel 62 for outputting a signal to the valve 56. The above-described sensors 57 to 61 are not limited to these in the present invention, and can be appropriately selected and arranged from these, and other sensors can be added.

  As shown in FIGS. 2 and 3, the stem fluid flow measuring sensor 1 is used by being inserted into the stem 11 or wound around the stem 11. As shown in FIG. 4, the control panel 62 includes the data logger 25, the computer 26, and the like. By using these devices, it is possible to automatically supply water and fertilizer by outputting a signal to the valve 56 based on the various measured values of the various sensors 1 and 57 to 61. The measurement with the stem fluid flow measuring sensor 1 is performed by applying a pulse current to the thin film metal heater 4 every 30 minutes, measuring the resistance values of the thin film metal resistance thermometers 3 and 5, and measuring the temperature. By calculating, the flow rate of the stem liquid every 30 minutes is obtained. Then, for example, the supply amount of water and fertilizer on the day is determined from the change in the flow rate of the stem liquid from the previous day and the measured values of various sensors from the previous day. The measurement every 30 minutes is an example of the time until the temperature of the stem that has been warmed by applying the pulse current is sufficiently lowered, and this time can be set as appropriate.

Next, the stem fluid flow measuring method according to the present invention will be described.
FIG. 7 is a flowchart showing a method for measuring stem fluid flow according to the present invention.
In the present invention, the stem fluid flow is measured by the heat pulse method.

  In the method for measuring stem fluid flow according to the present invention, first, a pulse current is applied to the thin film metal heater 4 by the application means provided in the computer 26 (S101). Here, the reason why the current is a rectangular pulse current is that when a rectangular pulse current is applied to the thin film metal heater 4, a temperature difference is once generated in the thin film metal resistance thermometers 3 and 5, and the stem fluid flows. This is because the temperature coincides again so that the heat pulse method is used in which the flow rate of the stem liquid is determined by measuring the required time t0. The temperature of the thin film metal heater 4 raised by the pulse current is about 5 to 10 ° C. higher than the stem temperature.

  As the temperature of the thin film metal heater 4 rises, the heat is transmitted through the stem 11 and reaches the pair of thin film metal resistance thermometers 3 and 5. Then, since the resistance value of the thin-film metal resistance thermometers 3 and 5 changes, the resistance value is measured (S102). Since the resistance value R and the temperature T are in a relation represented by the relational expression R = 100 (1 + 0.3851T), the temperatures of the pair of thin-film metal resistance thermometers 3 and 5 are calculated from the measured resistance values, respectively. (S103).

  Next, after applying the pulse current, the measurement is repeated until the temperatures of the thin-film metal resistance thermometers 3 and 5 become equal (S104), and the time t0 until both temperatures become equal is measured (S105). .

  Here, the distance between the centers of the thin film metal resistance thermometer 3 and the thin film metal heater 4 is Xa, and the center distance between the thin film metal resistance thermometer 5 and the thin film metal heater 4 is Xb (Xa> Xb). Assuming that the temperature resistor 3 is disposed above the stem 11 and the thin-film metal resistance thermometer 5 is disposed below the stem 11, when a pulse current is applied to the thin-film metal heater 4, first, heat is transmitted through the stem 11. The temperature of the thin film metal resistance temperature detector 5 arranged below the stem 11 with a small distance from the center to the thin film metal heater 4 rises. Then, the stem liquid flows through the stem 11, and the heat of the thin film metal heater 4 is carried above the stem 11. If it does so, the temperature of the thin-film metal resistance thermometer 3 arrange | positioned above the stem 11 will rise gradually. On the other hand, the temperature of the thin-film metal resistance thermometer 5 arranged below the stem 11 is gradually lowered by the heat from the stem liquid. In this way, after applying a pulse current to the thin film metal heater 4, a temperature difference once occurs in the thin film metal resistance thermometers 3 and 5, and the temperatures again coincide with each other. Therefore, the required time t0 is measured.

  Subsequently, the flow rate of the stem fluid is calculated from the measurement time measured by the measuring means (S106). Here, the heat pulse velocity v is calculated by v = (Xa + Xb) / (2 × t0). Further, the flow rate F of the stem fluid is calculated as F = bv, where b is a previously obtained calibration constant. When the flow rate of the stem fluid is calculated in this way, a signal corresponding to that is output (S107). For example, if the flow rate of the stem fluid is slow, a signal can be output to the valve 56 while taking into account the measurement values of various sensors, and a large amount of water and fertilizer can be supplied.

  In the present invention, the resistance value of the thin film metal heater 4 is measured using a measuring means having the same configuration as the resistance value measuring means of the thin film metal resistance thermometers 3 and 5, and the temperature calculating means is a thin film. The temperature of the heater 4 and the heating time can be feedback-controlled by calculating the temperature of the metal heater 4 and intermittently applying the current applied to the thin film metal heater 4 based on the temperature of the application means. If the thin film metal heater 4 is made of a platinum resistor, the resistance value R is calculated as R = 100 (1 + 0.3851T) if the temperature is T degrees.

  Further, the applying means applies a pulse current to the thin film metal heater 4 at a predetermined cycle, and the output means outputs a signal for adjusting the amount of water and / or fertilizer according to the flow rate of the stem liquid calculated by the flow rate calculating means. You can also. Thereby, the flow rate of stem liquid can be measured automatically, and the quantity of water and / or fertilizer according to it can be supplied.

Next, experimental results of stem fluid flow measurement according to the present invention will be described.
FIG. 8 is a graph showing experimental results of stem fluid flow measurement according to the present invention.

  FIG. 8 shows a pulse current 71 applied to the thin film metal heater 4, a temperature 72 of the thin film metal resistance temperature detector 3, and a temperature 73 of the thin film metal resistance temperature detector 5. In this example, the center-to-center distance Xa between the thin-film metal resistance thermometer 3 and the thin-film metal heater 4 is 10 mm, and the center-to-center distance Xb between the thin-film metal resistance thermometer 5 and the thin-film metal heater 4 is 5 mm. The body 3 was placed above the stem 11, and the thin-film metal resistance thermometer 5 was placed below the stem 11. The pulse current 71 was energized at 20 mA for 40 seconds. Note that the pulse current may be a rectangular pulse current that continues to flow for a while after being applied to a constant current, and then eventually stops.The temperature gradually increases, reaches a predetermined value, and then gradually increases the temperature. A triangular pulse current that is lowered may be used. In this embodiment, the pulse current is applied for 40 seconds. However, in order to measure more accurately, it is preferable to apply for a short time, for example, within 10 seconds, more preferably within 5 seconds.

  When the pulse current 71 is applied to the thin film metal heater 4, first, the temperature 73 of the thin film metal resistance thermometer 5 rises. Then, the stem liquid flows through the stem 11, and the heat of the thin film metal heater 4 is carried above the stem 11. As a result, the temperature 72 of the thin film metal resistance thermometer 3 disposed above the stem 11 gradually increases. On the other hand, the temperature 73 of the thin-film metal resistance thermometer 5 arranged below the stem 11 is gradually deprived of heat by the stem liquid. Thus, after applying the pulse current to the thin film metal heater 4, the temperature difference once occurs in the thin film metal resistance thermometers 3 and 5, and the time when the temperatures again coincide with each other, the time t0 is measured. .

  In this example, the time t0 was 20 seconds. Therefore, the heat pulse velocity v calculated by v = (Xa + Xb) / (2 × t0) was 0.375 mm / sec. In this figure, noise is included in the measured value, but it is desirable to remove the noise with a low-pass filter or the like, so that the point at which the temperatures are equal can be measured more accurately.

FIG. 9 is a view showing a second embodiment of the sensor for measuring stem fluid flow according to the present invention, wherein (a) is a front view thereof and (b) is a side view thereof.
Note that the same components and parts as those in the above-described embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 9, the stem liquid flow measurement sensor 101 includes thin film metal resistance thermometers 3 and 5 and a thin film metal heater 4 that are made of an insulating film (for example, an insulating synthetic resin film having a thickness of 10 μm to 200 μm, In particular, a plastic film having heat resistance and insulating properties) 102) is formed. Specifically, an insulating film 102 having a surface area approximately twice as large as the surface area of the stem fluid flow measurement sensor 101 is prepared, and a thin-film metal temperature measuring device is provided in a range approximately half of the insulating film 102. The resistors 3 and 5 and the thin film metal heater 4 are arranged, and the other half of the insulating film is folded back so as to cover the surfaces of the thin film metal resistance thermometers 3 and 5 and the thin film metal heater 4. Both sides of the resistance temperature detectors 3 and 5 and the thin film metal heater 4 are sandwiched. By adopting such a configuration, the stem fluid flow measurement sensor 101 can be formed using the commercially available thin film metal resistance thermometers 3 and 5 and the thin film metal heater 4 and the commercially available insulating film 102. Therefore, the apparatus can be made inexpensive. Further, the stem fluid flow measuring sensor 101 can be bent, and therefore can be used by being wound around the stem.

  The embodiment of the present invention has been described above, but the present invention is not limited to such an embodiment, and is merely an example, and various modifications can be made without departing from the scope of the present invention. Of course, the scope of the present invention is indicated by the description of the scope of claims, and further, the equivalent meanings described in the scope of claims and all modifications within the scope of the scope of the present invention are included. Including.

  A sensor for measuring stem fluid flow, a device for measuring stem fluid flow, and a method for measuring stem fluid flow according to the present invention include a sensor for measuring stem fluid flow, a stem fluid flow measuring device, and a stem fluid flow measuring device for measuring a flow rate of plant stem fluid by a heat pulse method. Applicable to stem fluid flow measurement method.

It is a perspective view which shows 1st Embodiment of the sensor for stem fluid flow measurement which concerns on this invention. It is a figure which shows the 1st attachment method to the stem of a plant of the sensor for stem fluid flow measurement, (a) is the front view, (b) is the sectional drawing. It is a figure which shows the 2nd attachment method to the stem of a plant of the sensor for stem fluid flow measurement, (a) is the front view, (b) is the sectional drawing. It is a block diagram which shows the stem liquid flow measuring apparatus which concerns on this invention. It is a block diagram of the computer which comprises the stem fluid flow measuring apparatus which concerns on this invention. It is a block diagram which shows the stem liquid flow measurement system using the sensor for stem liquid flow measurement which concerns on this invention. It is a flowchart which shows the method for stem fluid flow measurement which concerns on this invention. It is a graph which shows the experimental result of stem liquid flow measurement concerning the present invention. It is a figure which shows 2nd Embodiment of the sensor for stem fluid flow measurement which concerns on this invention, (a) is the front view, (b) is the side view.

Explanation of symbols

1, 101 .... Sensor for measuring stem fluid flow 2 ... Base material 3, 5, ... Thin film metal resistance thermometer 4・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Thin metal heaters 6, 7 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Conductive material 8 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Insulating material 11 ・ ・ ・ ・ ・ ・... Stem 12 ... Thermal insulation 20 ... Stem liquid flow measuring device 21, 22, 23 ... Constant current diode 24 ...・ ・ ・ ・ Switching circuit 25 ・ ・ ・ ・ ・ ・ Data logger 26 ・ ・ ・ ・ ・ ・ Computer 27 ・ ・ ・ ・ ・ ・ CPU
28 ... Timer 29 ... RAM
30 ... ROM
31 ... Hard disk 32 ... Input interface 33 ... Output interface 34 ... Bus Line 35 ... Keyboard 36 ... Mouse 37 ... Speaker 38 ... PC 39 ... Display 50 ... Stem fluid flow measurement system 51 ... Vinyl greenhouse 52 ... .. Skylight 53 ... Pot 54 ... Seedling 55 ... Pipe 56 ... Valve 57 ... Wind sensor 58 ... Illuminance sensor 59 ... Temperature sensor 60 ... Carbon sensor 61 Humidity sensor 62 Control panel 71 Pulse current 72, 73 .... Temperature 102 of thin-film metal resistance thermometer ..... Insulating film

Claims (8)

  A pair of thin-film metal resistance thermometers formed on an insulating substrate, a thin-film metal heater formed in parallel between the pair of resistors, and an electric signal of the pair of thin-film metal resistance thermometers A sensor for measuring stem fluid flow, comprising: a pair of conductive materials for taking out each of the first and second conductive materials for supplying a current to the thin film metal heater.   The sensor for measuring stem fluid flow according to claim 1, wherein the thin film metal temperature measuring resistor and the thin film metal heater are resistors of the same shape and the same metal.   The stem fluid flow measuring sensor according to claim 1 or 2, wherein the substrate is a plastic film. A pair of thin-film metal resistance thermometers formed on an insulating substrate, a thin-film metal heater formed in parallel between the pair of resistors, and an electric signal of the pair of thin-film metal resistance thermometers A pair of conductive materials for taking out each of them, and a stem liquid flow measurement sensor comprising a conductive material for supplying current to the thin film metal heater,
Applying means for applying a pulse current to the thin film metal heater;
Measuring means for measuring the resistance value of the pair of thin film metal resistance thermometers,
Temperature calculating means for calculating the temperatures of the pair of thin-film metal resistance thermometers from the resistance values measured by the measuring means;
A measuring means for measuring a time until each temperature of the pair of thin film metal resistance thermometers calculated by the temperature calculating means becomes equal after a pulse current is applied to the thin film metal heater by the applying means;
A flow rate calculating means for calculating a flow rate of the stem fluid from the measurement time measured by the measuring means, and an output means for outputting a signal corresponding to the flow rate of the stem fluid;
Stem fluid flow measuring device.   In the pair of thin-film metal resistance thermometers, the distance between the centers of the thin-film metal resistance thermometer and the thin-film metal heater disposed above the plant stem is Xa, and the thin-film metal disposed below the plant stem The distance between centers of the resistance temperature detector and the thin film metal heater is Xb (Xa> Xb), and a pulse current is applied to the thin film metal heater by the applying means, and then the pair of thin films calculated by the temperature calculating means Assuming that the time until each temperature of the metal resistance thermometer is equal is t0 and the calibration constant determined in advance is b, the flow rate F of the plant stem fluid is F = b (Xa + Xb) / (2 × t0) The stem fluid flow measuring device according to claim 4, further comprising a calculating means for calculating in step (5).   A heater measuring means for measuring a resistance value of the thin film metal heater; and a heater temperature calculating means for calculating a temperature of the thin film metal heater from the resistance value, wherein the applying means is a temperature of the thin film metal heater. The stem fluid flow measuring device according to claim 4 or 5, wherein a pulse current applied to the thin film metal heater is determined based on the above. A pair of thin-film metal resistance thermometers formed on an insulating substrate, a thin-film metal heater formed in parallel between the pair of resistors, and an electric signal of the pair of thin-film metal resistance thermometers In a stem fluid flow measurement system constructed using a pair of conductive materials for taking out each, and a stem fluid flow measurement sensor and a computer comprising a conductive material for supplying current to the thin film metal heater,
An application means provided in a computer applies a pulse current to the thin film metal heater;
Measuring means provided in the computer measures the resistance value of the pair of thin-film metal resistance thermometers;
A step of calculating a temperature of the pair of thin-film metal resistance thermometers from the resistance value measured by the measuring unit by a temperature calculating unit included in the computer;
After the pulse current is applied to the thin film metal heater by the applying means, the measuring means provided in the computer takes time until the temperatures of the pair of thin film metal resistance thermometers calculated by the temperature calculating means become equal. Measuring steps,
A step of calculating a flow rate of the stem fluid from a measurement time measured by the measurement unit by a flow rate calculation unit included in the computer;
A stem fluid flow measuring method in which an output means included in a computer executes a step of outputting a signal corresponding to the flow rate of the stem fluid.   In the pair of thin-film metal resistance thermometers, the distance between the centers of the thin-film metal resistance thermometer and the thin-film metal heater disposed above the plant stem is Xa, and the thin-film metal disposed below the plant stem The distance between centers of the resistance temperature detector and the thin film metal heater is Xb (Xa> Xb), and a pulse current is applied to the thin film metal heater by the applying means, and then the pair of thin films calculated by the temperature calculating means Assuming that the time until each temperature of the metal resistance thermometer is equal is t0 and the calibration constant determined in advance is b, the flow rate F of the plant stem fluid is F = b (Xa + Xb) / (2 × t0) The stem fluid flow measuring method according to claim 7, further comprising the step of calculating:

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