Contact-type object water content sensing device and method and computer program product

A contact-type object water content sensing device and method and a computer program product are presented. The device includes a power unit, a sensing unit, and an calculating unit. The sensing unit includes a substrate and a copper foil, and the copper foil is configured on the substrate. The sensing unit is used to contact a target object and a power unit is used to supply power to the copper foil. The copper foil when supplied with power forms an equivalent capacitor, and the equivalent capacitor has different capacitances in correspondence to a water content of the target object. The calculating unit is electrically connected to the sensing unit and is used to analyze the capacitance of the equivalent capacitor, so as to calculate the water content of the target object.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Taiwan Patent Application No. 099141009, filed on Nov. 26, 2010, which is hereby incorporated by reference for all purposes as if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention relates to an object water content sensing device and method, and more particularly to a sensing device and method for sensing a water content of an object by contacting the object and a computer program product.

2. Related Art

Contact-type water content sensors in the prior arts have the following types. (1) A sensing element is formed by etching a circuit on an insulating substrate and configuring a chemical substance, for example, a polymer material, on the substrate surface, so as to present a water content of the environment where the sensing element is located through the chemical changes of the chemical substance. (2) A sensing element is fabricated by a ceramic material together with a circuit design, that is, a porous water absorption characteristic of the ceramic in combination with an electric conductivity regulation technique, thereby deducing the water content of the environment where the sensing element is located through the electricity conductivity change of the substance caused by water absorption. (3) The sensing element is combined with an ionic conduction technique of an electrolyte solution, and the water absorption of the sensing element affects a variation of the ionic conductivity of the electrolyte solution, thereby deducing the water content of the environment where the sensing element is located through the variation. (4) The sensing element is combined with a heat transfer technology, and based on the characteristic that water absorbs heat, the variation of the thermal conductivity of the substance caused by the water absorption is utilized to deduce the water content of the environment where the sensing element is located.

However, the sensing element with the chemical substance configured on the surface is formed by combining two electrical pole pieces with the chemical substance, and combining the electrical pole pieces and the chemical substance with the circuit of the insulating substrate to form one piece, which has a rather complicated working process. Likewise, the sensing element adopting the electrolyte solution technique needs preparing the proper electrolyte solution to combine with the sensing element and meanwhile needs analyzing the ionic conductivity of the electrolyte solution, so the fabricating complexity of the sensing element is not low and the cost is high. Secondly, the contact-type water content sensor with chemical substances configured on the surface needs sensing the water content of the target object for example, a soil water content and a powder water content, in a contact manner. However, undesired chemical reactions of these chemical substances may occur due to the long-time contact with the target object, which induces the deterioration of the chemical substances (denaturalization, tendering, pulverization, and so on of the chemical substances). Also, the sensing element of the ceramic material contacts the target object for a long time for sensing the water content of the target object all day long, so ceramic parts of the element easily deteriorates, for example, becomes tender or pulverizes, which reduces the life cycle of the element, and the stability of the element is unsatisfied when sensing the water content. Thirdly, the contact-type sensor when applied in sensing the soil water content has the defects of low element life cycle and deterioration of the element, which causes that the contact-type sensor is difficult to be applied in sensing the soil water content for a long time. Moreover, once the element deteriorates, the measured water content data is abnormal and cannot be used, so the soil water content cannot be accurately measured. Fourthly, the target object like soil has complicated liquid components and the liquid components contain water, but the current water content sensors disregard the impure water components, so the measured water content is questionable.

Therefore, it is a subject needing consideration to provide a water content sensor which is not easy to deteriorate and can be used for monitoring the water content of a target object for a long time.

SUMMARY OF THE INVENTION

The present invention is directed to an object water content sensing device and method and a computer program product applicable to contact sensing a water content of a target object.

To solve the above problems of the device, the present invention provides a contact-type object water content sensing device, which comprises a power unit, a sensing unit, and an calculating unit. The sensing unit comprises a substrate and a copper foil, and the copper foil is configured on the substrate. The sensing unit is used to contact a target object, the copper foil when supplied with power form an equivalent capacitor, and the equivalent capacitor has different capacitances in correspondence to the water content of the target object. The power unit is electrically connected to and supplies power to the copper foil. The calculating unit is electrically connected to the sensing unit and is used to analyze the capacitance of the equivalent capacitor, so as to calculate the water content of the target object.

To solve the above problems of the method, the present invention provides a contact-type object water content sensing method, which comprises the following steps. A sensing unit contacts a target object, in which the sensing unit is equipped with a copper foil. A power unit supplies power to the copper foil, the copper foil when supplied with power forms an equivalent capacitor, and the equivalent capacitor has different capacitances in correspondence to different water contents of the target object. An calculating unit analyzes the capacitance of the equivalent capacitor, so as to calculate the water content of the target object.

The present invention further provides a computer program product, which is configured in an calculating unit. The calculating unit is connected to a sensing unit equipped with a copper foil, the sensing unit contacts a target object, and the calculating unit reads the computer program product to execute a contact-type object water content sensing method. The flow is illustrated as above and will not be repeated herein. The present invention may also be implemented as a computer program, and stored in a computer readable recording medium, so that a computer reads the recording medium and then executes the contact-type object water content sensing method. When the computer program is loaded by a computer, a machine, or an electronic device and executed, the computer, machine, or electronic device becomes the device for implementing the present invention.

The present invention is characterized in that, the copper foil is adopted as one of the components of the sensing unit, and the copper foil material may generate obvious physical quantity variation, for example, variation of impedance and capacitance mentioned in the present invention, due to different water contents of the object and the environment in contact and the physical quantity variation has a specific rule, so the copper foil material is beneficial to improving the accuracy in measuring the object water content. Then, due to the metal property of the copper foil, the copper foil will not have the deterioration like ceramic material and polymer material, which not only is beneficial to improving the accuracy in measuring the object water content, but also extends the life cycle of the sensing element and greatly improves the applicability of the sensing device. Thirdly, due to the capacitance variation characteristic of the copper foil, even if the sensing element is applied in sensing the target object having complicated components like the soil, the water content of the impure water liquid may also be measured, so the measured water content is quite accurate.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, the details of the embodiments of the present invention will be illustrated with reference to the drawings.

FIG. 1is a schematic architectural view of a contact-type object water content sensing device according to an embodiment of the present invention. Referring toFIG. 1, the device mainly includes a sensing unit10, an calculating unit21, and a power unit22.

The sensing unit10is equipped with a substrate11and a copper foil12, and the copper foil12is configured on the substrate11. In the following embodiments, the square copper foil12is taken as an example for illustration; however, the shape is not limited to square, and the copper foil12in the shape of circle, triangle, polygon, or other shapes is also applicable. The sensing unit10is used to contact a target object (not shown), and the target object is, for example, the soil, wall, electrical appliance, or an object that can be contacted. In some embodiments of the present invention, the sensing unit10may be further equipped with a protection layer13, and the protection layer13is configured on the surface of the copper foil12. The protection layer13is a layer of adhesive film or chemical film, and is used to prevent the oxidation of the copper foil to avoid the influence on the sensing accuracy caused by the oxidation of the copper foil.

The calculating unit21and the power unit22are respectively connected to the sensing unit10. The power unit22is used to supply power to the copper foil12, and the copper foil12when supplied with power and abutting the target object may form an equivalent capacitor to take a charging/discharging action. In correspondence to different water contents of the target object, the capacitance of the equivalent capacitor differs. The power supply of the power unit22may be controlled by the calculating unit21or operates independently, depending on the demands of the designer.

In some embodiments, the calculating unit21is used to analyze the capacitance of the equivalent capacitor, so as to calculate the water content of the target object. The calculating unit21analyzes the water content of the target object.FIG. 2is a schematic view of signal variations according to an embodiment of the present invention. Referring toFIG. 2, in this embodiment, the copper foil12receives the power supplied by the power unit22to generate a capacitance, and in correspondence to different water contents of the target object, the capacitance differs, that is to say, the value of the water content of the target object influences the capacitance, and different capacitances influence the charging/discharging time constant, so the corresponding charge/discharge signals are different. The charge/discharge signal is a time accumulated signal, the waveform is a sawtooth wave, and the frequency differs in correspondence to different capacitances, so the frequency may be utilized to calculate the water content.

In other embodiments, the sensing device may further include a memory unit23(as shown inFIG. 1), and the memory unit23stores a plurality of frequency data31and a plurality of water content data32corresponding to the frequency data31. The calculating unit21analyzes the capacitance of the equivalent capacitor through the sensing unit10.

In other embodiments, furthermore, the calculating unit21may analyze a charge/discharge signal40of the equivalent capacitor, convert the charge/discharge signal into a pulse signal, then convert the pulse signal into a frequency signal, and compare the frequency data by use of the frequency signal, so as to calculate the water content of the target object according to the water content data. The detailed structure of the calculating unit21is shown inFIG. 2. The calculating unit21includes three signal conversion modules, that is, a sawtooth-to-pulse wave conversion module211, a pulse-to-frequency conversion module212, and a frequency-to-water content conversion module213. When the charge/discharge signal40is converted into a timing diagram, a sawtooth wave41is presented. The sawtooth-to-pulse wave conversion module211regulates the charge/discharge signal40to convert the sawtooth wave41into a pulse signal42. Then, the pulse-to-frequency conversion module212calculates the frequency of the charge/discharge signal40according to the pulse signal42, so as to convert the above pulse into a corresponding frequency signal. However, according to different signal contents of the pulse signal42, the converted frequency signals, for example, a high-frequency signal43and a low-frequency signal44shown inFIG. 2, differ. Thereafter, the frequency-to-water content conversion module213compares the frequency data31by use of the frequency signal to find out water content data32corresponding to the frequency signal, so as to calculate the water content of the target object.

However, the operational data in converting the frequency into the corresponding water content may be stored in the calculating unit21or designed in the program executed by the calculating unit21in advance, and is not limited to the pre-stored water content data32and frequency data31.

In other embodiments, furthermore, the memory unit23further stores copper foil cross-sectional area information331and capacitance boundary information332corresponding to the copper foil cross-sectional area information331(seeFIG. 1). The calculating unit21firstly acquires the area of the copper foil12, in which the area is pre-stored in the memory unit23or input by the user through an interface of the calculating unit21for the calculating unit21to use. Then, the calculating unit21, when analyzing the above capacitance of the equivalent capacitor meets the capacitance boundary information332according to the capacitance boundary information332, starts calculating the water content of the target object.

In other embodiments, furthermore, the capacitance may be calculated according to the area of the area of the copper foil12.FIG. 3is a schematic view of an example of a comparison table of a copper foil area and a capacitance according to an embodiment of the present invention. Referring toFIG. 3together, the capacitance of the equivalent capacitor formed by the copper foil12may be obtained by the following Formula 1:

where C=capacitance, ∈0=dielectric constant of the liquid contained in the target object, A=surface area of the copper foil12(upper surface area or lower surface area, upper surface area=lower surface area, also the cross-sectional area of the equivalent capacitor), and d=height of the copper foil12(i.e., the pitch of the capacitor).

The dielectric constants and the area of the copper foil12are combined to be introduced into Formula 1, and then a comparison table60of the copper foil area and the capacitance ofFIG. 3is obtained. From Formula 1, when the surface area of the copper foil12increases (that is, the cross-sectional area of the equivalent capacitor is increased), the capacitance of the equivalent capacitor is increased. Therefore, difference between different acid and alkali liquids, solvents, and air in the soil may be further analyzed, thereby setting the corresponding copper foil cross-sectional area information331and capacitance boundary information332in advance. For example, when the surface area of the copper foil12is 5 cm2, the capacitance boundary information332may be set to be 20 uF, and the calculating unit21can analyze whether the target object contacted by the sensing unit10is a liquid or the sensing unit10contacts air. When the surface area of the copper foil12is 5 cm2, the capacitance boundary information332may be set to be 360 uF, and the calculating unit21can analyze whether the target object contacted by the sensing unit10is water or an acid/alkaline solution, thereby overcoming the problem that different acidity/alkalinity of the solvent contained in the target object may influence the accuracy of water content measurement.

Furthermore, the power unit22may be a battery or a solar energy-to-power conversion unit. Furthermore, the battery may be a rechargeable battery and is controlled together with a solar energy-to-power conversion unit by a charging control unit. The charging control unit uses the solar energy-to-power conversion unit to charge the rechargeable battery when the battery power is exhausted. Moreover, the charging control unit may transfer power to the entire device in the charging period. However, the power supply technique is well known to persons of ordinary skill in the art, so the details will not be repeated herein again.

Referring toFIG. 1, the sensing device further includes a prompt unit24, and the memory unit23stores a plurality of prompt conditions34. When the calculating unit21determines that the water content of the target object meets a target prompt condition34among all the prompt conditions34, the prompt unit24is used to output a prompt signal corresponding to the target prompt condition34. For example, when the sensing unit10is configured in the soil, as the calculating unit21determines that the soil water content is too high, the prompt unit24is used to send a prompt signal that the water content is too high. As the calculating unit21determines that the soil water content is too low, the prompt unit24is used to send a prompt signal that the soil water content is too low. As the calculating unit21determines that the soil water content is moderate, the prompt unit24is used to send a prompt signal that the soil water content is moderate or takes no action. The prompt unit24may be a light-emitting unit, e.g., a light-emitting diode, for differentiating different prompt signals by light of different colors or different brightness. Or, the prompt unit24may be a sound-emitting unit, e.g., a buzzer, for differentiating different prompt signals by different long and short tones or tones with different volumes. Or, the prompt unit24may be a display unit, for differentiating different prompt signals by text or graphs. Or even, the prompt unit24may be a combination of two or more of the above types. Moreover, the prompt unit24may be additionally configured other than inside the sensing device.

FIG. 4illustrates a contact-type object water content sensing device according to an embodiment the present invention. Referring toFIG. 4, the sensing unit10is configured in the soil of a flower pot51and the prompt unit24is electrically connected to the calculating unit21. The calculating unit21senses the soil water content in the flower pot51through the sensing unit10, and informs the user that the soil water content is high, low, or moderate through the prompt unit24. This configuration mode is also applicable to an electronic equipment using a liquid substance or solvent, e.g., a fridge or washing machine. The user may configure the sensing unit10in the electronic equipment, so the calculating unit21may sense the water content in the electronic equipment through the sensing unit10, thereby the prompt unit24provides a relevant prompt signal.

FIG. 5illustrates a contact-type object water content sensing device according to another embodiment of the present invention. Referring toFIG. 5, the above sensing device may be applied in a plant52, and the user may configure a plurality of sensing units10in the plant52on the important spots where the existence of water leakage, the equipment that leaks, the production line, pipelines, and so on are put on high alert. The calculating unit21, when sensing that the water content at any spot is abnormal through the sensing unit10, immediately informs the management personnel by the prompt unit24.

FIG. 6is a schematic flow chart of a contact-type object water content sensing method according to an embodiment of the present invention.FIG. 7andFIG. 8are detailed schematic flow charts of a contact-type object water content sensing method according to an embodiment of the present invention. Referring toFIG. 6,FIG. 7, andFIG. 8together withFIG. 1toFIG. 3for ease of understanding, the method is illustrated as follows.

A sensing unit10contacts a target object, in which the sensing unit10is equipped with a copper foil12(Step S110). As shown inFIG. 1, the sensing unit10includes a substrate11which is equipped with the copper foil12thereon, and a protection layer13may be configured on the surface of the copper foil12.

A power unit22supplies power to the copper foil12, and the copper foil12when supplied with power forms an equivalent capacitor (Step S120). The copper foil12when supplied with power and abutting the target object forms an equivalent capacitor to take a charging/discharging action.

An calculating unit21analyzes a capacitance of the equivalent capacitor, so as to calculate a water content of the target object (Step S130).

Furthermore, Step S130may be divided into the following steps, as shown inFIG. 7.

A charge/discharge signal40of the equivalent capacitor is converted into a pulse signal42(Step S131). The calculating unit21senses the charge/discharge signal40of the equivalent capacitor through the copper foil12, and when the charge/discharge signal40is converted into a timing diagram, a sawtooth wave is presented. The sawtooth-to-pulse wave conversion module211regulates the charge/discharge signal40to convert the sawtooth wave into the pulse signal42.

The pulse signal42is converted into a frequency signal (Step S132). The pulse-to-frequency conversion module212calculates the frequency of the charge/discharge signal40to convert the pulse into the corresponding frequency signal. Depending on different signal contents of the pulse signal42, the converted frequency signals differ.

The frequency-to-water content conversion module213compares the frequency signal with a plurality of frequency data31, in which each frequency data31corresponds to a water content data32(Step S133). Thereafter, the frequency-to-water content conversion module213finds out water content data32corresponding to the frequency signal from all water content data32according to a comparison result, so as to calculate the water content of the target object (Step S134). However, the frequency data31and the water content data32corresponding to the frequency data31may be stored in the calculating unit21or designed in the program executed by the calculating unit21in advance.

Capacitance boundary information332is recorded (Step S124). As described above, the memory unit23stores the copper foil cross-sectional area information331and the capacitance boundary information332.

Thereafter, the calculating unit21determines whether the capacitance meets the capacitance boundary information332(Step S126). When it is determined that the capacitance meets the capacitance boundary information332, the calculating unit21executes Step S130to calculate the water content of the target object. Otherwise, the calculating unit21takes no action and returns to Step S120to repeat Step S120to Step S126until the capacitance meets the capacitance boundary information332.