Gas sensor detection module having wheatstone bridge circuit and gas sensor device including same

Abstract

In this gas sensor detection module having a Wheatstone bridge circuit, at least one of first and third resistors (R1, R3), which are diagonal to each other, among the first to fourth resistors of the Wheatstone bridge circuit may be a positive-response sensing element that responds to a specific gas component and has an increased resistance value, and at least one of the remaining second and fourth resistors (R2, R4) may be a negative-response sensing element that responds to the specific gas component and has a reduced resistance value.

Description

Gas sensor detection module having a Wheatstone bridge circuit and gas sensor device including the same

[0001] The present invention relates to a gas sensor detection module having a Wheatstone bridge circuit and a gas sensor device including the same.

[0002] Circuits that detect signals using gas sensors can be categorized into voltage divider and Wheatstone bridge circuits. The former, while simple, has low precision and is particularly susceptible to external influences. Temperature compensation elements are typically used. The latter, while relatively precise, has the disadvantage of low output and is susceptible to external influences.

[0003] Resistors, mainly used behind circuit boards, are directly affected by the external environment, so their resistance values ​​can fluctuate frequently or even change over time. Depending on the material of the resistor, for example, whether it is a metal resistor or a ceramic type, the error can be greater due to the difference in temperature coefficient of resistance (TCR). In particular, the operating temperature of the contact combustion type is maintained at 300 to 350 degrees Celsius (℃), and the semiconductor type is 50 to 450 degrees Celsius (℃), and when the gas reaction occurs, the resistance change becomes greater due to the combustion or adsorption effect, and it operates. However, the temperature coefficient of the resistor operating at room temperature in the Wheatstone bridge circuit is different, so the output is inconsistent and lacks much as the initial low concentration detection and the leaked gas concentration increases, and the linearity can be distorted.

[0004] Furthermore, the output signal was too weak, making low-concentration detection difficult. Furthermore, accuracy was limited due to external environmental influences, and significant noise damage occurred due to high circuit amplification. In particular, long-term performance, reliability, and reproducibility were problematic.

[0005] The gas sensor bridge detection module and its manufacturing method according to the present invention aim to improve the output sensitivity of a gas sensor and increase the stability of low concentration detection and sensitivity.

[0006] A gas sensor detection module having a Wheatstone bridge circuit having first and second legs (L1, L2) according to one embodiment of the present invention, wherein first and second power sources (Vs1, Vs2) are applied to first and second contact points (T1, T2) of the first and second legs (L1, L2), the first leg (L1) having a first resistor (R1) disposed between the first contact point (T1) and a first voltage terminal (Vo1); and a fourth resistor (R4) disposed between the first voltage terminal (Vo1) and the second contact point (T2), and the second leg (L2) having a second resistor (R2) disposed between the first contact point (T1) and a second voltage terminal (Vo2); And a third resistor (R3) disposed at the second voltage terminal (Vo2) and the second contact point (T2), and further including a detection unit for measuring a change in an electric quantity of at least one of voltage and current between the first and second voltage terminals (Vo1, Vo2), wherein in a normal state, a product of the resistance values ​​of the first and third resistors (R1, R3) and a product of the resistance values ​​of the second and fourth resistors (R2, R4) are equal, and at least one of the first and third resistors (R1, R3) may be a positive reaction sensing element whose resistance value increases by reacting with a specific gas component, and at least one of the second and fourth resistors (R2, R4) may be a negative reaction sensing element whose resistance value decreases by reacting with the specific gas component.

[0007] Additionally, one of the positive and negative reaction sensing elements may include an n-type semiconductor material, and the other may include a p-type semiconductor material.

[0008] In addition, the n-type semiconductor material may be any one selected from the group consisting of SnO2, ZnO, In2O3, TiO2, WO3, V2O5, CeO2, ThO2, ZrO2, NbO2, Ta2O3, MoO3, MnO2, Fe2O3, SiO2, Al2O3, PbO2, MgO, CaO, SrO, BaO, and combinations thereof.

[0009] Additionally, the p-type semiconductor material may be at least one selected from the group consisting of a single precursor, a combination of single precursors, and a combination of precursors of NiO, MnO, FeO, CoO, PdO, PbO, Cu2O, Ag2O, Mn2O3, Cr2O3, and Co3O4.

[0010] Additionally, at least one of the positive and negative reaction detection elements may further include a catalyst material and a binder material.

[0011] Additionally, the catalyst material may be at least one selected from the group consisting of a single precursor, a combination of single precursors, and a combination of single precursors of Pt, Pd, Au, Rh, Ru, and Ir.

[0012] Additionally, the binder material may be at least one selected from the group consisting of a single precursor, a combination of single precursors, and a combination of precursors of SiO2, Al2O3, K2O, TiO2, CuO, MgO, and CaO.

[0013] In addition, the first and third resistors (R1, R3) react positively with the specific gas component, and the resistance changes of each of the first and third resistors (R1, R3) can correspond to each other. In addition, the resistance changes of each of the first and third resistors (R1, R3) can be substantially the same.

[0014] In addition, the second and fourth resistors (R2, R4) react negatively with the specific gas component, and the resistance changes of each of the second and fourth resistors (R2, R4) can correspond to each other. In addition, the resistance changes of each of the second and fourth resistors (R2, R4) can be substantially the same.

[0015] In addition, when reacting with the specific gas component, the absolute value of the resistance change amount of the third resistor (R3) and the resistance change amount of the second resistor (R2) may correspond to each other and may be substantially the same.

[0016] In addition, it may further include a first resistance electrode line (510) having the first resistor (R1) and connecting the first contact point (T1) and the first voltage terminal (Vo1); a second resistance electrode line (520) having the second resistor (R2) and connecting the first contact point (T1) and the second voltage terminal (Vo2); a third resistance electrode line (530) having the third resistor (R3) and connecting the second voltage terminal (Vo2) and the second contact point (T2); and a fourth resistance electrode line (540) having the fourth resistor (R4) and connecting the first voltage terminal (Vo1) and the second contact point (T2).

[0017] Additionally, at least one of the first and third resistors (R1, R3) and the second and fourth resistors (R2, R4) may be formed integrally.

[0018] In addition, the first and third resistors (R1, R3) form a bead for the first sensing element, and the first and third resistor electrode lines can be respectively attached to the bead for the first sensing element.

[0019] In addition, the second and fourth resistors (R2, R4) form a bead for the second sensing element, and the second and fourth resistor electrode lines can be respectively attached to the bead for the second sensing element.

[0020] A gas sensor device according to the present invention may include a gas sensor detection module having the above-described Wheatstone bridge circuit.

[0021] The gas sensor detection module of the Wheatstone bridge circuit according to the present invention can improve the overall output sensitivity.

[0022] Figures 1 and 2 illustrate corresponding Wheatstone bridge detection circuits.

[0023] Figure 3 shows a cross-sectional view of a hot wire semiconductor gas sensor.

[0024] Figure 4 shows a cross-sectional view of a non-thermal semiconductor gas sensor.

[0025] Fig. 5 is a perspective view of a sensor device to which a gas sensor detection module of a Wheatstone bridge circuit according to the present invention is applied.

[0026] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. When describing with reference to the drawings, identical or corresponding components are given the same reference numerals and redundant descriptions thereof will be omitted.

[0027] The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only to distinguish one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component. The term "and / or" includes a combination of a plurality of related described items or any item among a plurality of related described items. The term "or" may be interpreted as a logical exclusive in the context, but in the absence of direct descriptions such as "otherwise, otherwise, logical exclusive," it is interpreted as having the same meaning as "and / or," i.e., a logical exclusive.

[0028] Also, singular expressions include plural expressions unless the context clearly indicates otherwise.

[0029] When a component is referred to as being "connected" or "connected" to another component, it should be understood that it may be directly connected or connected to that other component, but that there may also be other components intervening. Conversely, when a component is referred to as being "directly connected" or "directly connected" to another component, it should be understood that there are no other components intervening. This also applies to vertical, horizontal, and right-hand placement relationships. For example, when a component is said to be above another component, this includes not only cases where the component is directly above the other part, but also cases where there are other components intervening between them.

[0030] Additionally, the fact that the first component and the second component on the network are connected or connected means that data can be exchanged between the first component and the second component either wired or wirelessly.

[0031] The suffixes "module" and "part" used in the following description are given solely for the convenience of writing this specification and do not impart any particularly significant meaning or role to the components themselves. Therefore, the terms "module" and "part" may be used interchangeably.

[0032] When implemented in actual applications, these components may be combined into a single component, or a single component may be subdivided into two or more components, as needed. Throughout the drawings, identical or similar components are assigned the same drawing reference numerals, and detailed descriptions of components with the same drawing reference numerals may be omitted and replaced with descriptions of the aforementioned components.

[0033] Furthermore, the present invention encompasses all possible combinations of the embodiments described herein. The various embodiments of the present invention, while different, are not mutually exclusive. One embodiment of a specific shape, structure, function, or characteristic described herein may be implemented in another embodiment. For example, components described in the first and second embodiments may perform all of the functions of the first and second embodiments.

[0034] In some embodiments, where implementations are otherwise feasible, specific process sequences may be performed in a different order than described. For example, two processes described in succession may be performed substantially simultaneously, or in a reverse order from the described order.

[0035] Figures 1 and 2 illustrate corresponding Wheatstone bridge detection circuits. Figure 3 illustrates a cross-sectional view of a hot-wire semiconductor gas sensor. Figure 4 illustrates a cross-sectional view of a non-hot-wire semiconductor gas sensor. Figure 5 is a perspective view of a sensor device to which a gas sensor detection module of a Wheatstone bridge circuit according to the present invention is applied.

[0036] Referring to FIGS. 1 and 2, a gas sensor detection module having the present Wheatstone bridge circuit has a detection circuit of a gas sensor that senses gas using a voltage difference between first and second voltage terminals (Vo1, Vo2), and the detection circuit can form a Wheatstone bridge circuit.

[0037] The gas sensor detection module comprising a Wheatstone bridge circuit according to the present invention can be used as a detection module for various gas sensors. For example, it can be used for all gas sensors utilizing a Wheatstone bridge circuit, such as semiconductor gas sensors and contact combustion gas sensors.

[0038] Representative gas sensors include contact combustion gas sensors and semiconductor gas sensors.

[0039] When combustible gases react with oxygen, heat of reaction is generated. Contact combustion gas sensors convert this heat into an electrical signal to detect the gas. Contact combustion gas sensors can be used to detect city gas, propane gas, and combustible and toxic gases in hydrogen vehicles and factories.

[0040] Semiconductor gas sensors can detect gases by utilizing changes in the density of surface electrons or electrical resistance resulting from chemical interactions between gas components and the semiconductor surface. Semiconductor gas sensors can detect gases by utilizing a mechanism in which oxygen ions chemically adsorbed on the semiconductor surface undergo ion exchange and electron transfer through the adsorption and desorption of external gases, thereby reducing the electrical resistance of the oxide semiconductor. The semiconductor surface may be, but is not limited to, a metal oxide, and may be formed of carbon nanotubes (CNTs), carbon powder, or the like.

[0041] Semiconductor gas sensors can be of any one of the Figaro type, hot wire type, thin film / thick film type, and bulk bead type depending on the sensor structure.

[0042] Semiconductor gas sensors detect gases using voltage distribution, but both contact combustion gas sensors and semiconductor gas sensors can detect gases using a Wheatstone bridge circuit.

[0043] The Wheatstone bridge circuit is widely known as a circuit in which resistors are placed between four nodes forming the vertices of a square. Referring to FIGS. 1 and 2, in the present embodiment, the four nodes may be referred to as a first voltage terminal (Vo1), a first contact point (T1), a second voltage terminal (Vo2), and a second contact point (T2).

[0044] Bridge circuits were developed to measure the precision resistance of electronic components and are used in various fields. Referring to FIGS. 1 and 2 and Equation 1, if the bridge voltage difference (Vout), which is the difference between the first and second voltages (Vo1 - Vo2), is 0 and three resistance values ​​are known, one unknown resistance value can be determined.

[0045]

[0046] This method can be extended and applied to various sensor detection circuits, such as temperature sensors, load sensors, and gas sensors, by generating output according to the unbalanced resistance in the form of mathematical equation 2. This method is characterized by being more accurate than the voltage distribution method, as it has a smaller error in the detection amount.

[0047]

[0048] Here, the input voltage (Vs) means the difference (Vs1 - Vs2) between the first and second power terminals (Vs1, Vs2). If the second power terminal (Vs2) is grounded or at 0 V, Vs becomes the voltage of the first power terminal (Vs1). Hereinafter, the explanation will be given assuming that the second power terminal (Vs2) is grounded.

[0049] In detection methods using Wheatstone bridge circuits, the initial output, the bridge voltage difference (Vout), is often extremely small. Consequently, the bridge voltage difference (Vout) must be significantly amplified, and this amplification process also increases noise. This makes the circuit insensitive to small variations and, due to poor linearity, results in inaccurate output values ​​at high concentrations.

[0050] These limitations make gas sensors difficult to detect at concentrations below several hundred ppm, and linearity issues arise at high concentrations in the percent range, making them difficult to use as measuring instruments. However, they are quite useful in industrial applications for determining the presence of gas.

[0051] The present invention aims to increase the output (voltage difference) to increase the accuracy of gas detection and its concentration.

[0052] The initial state of the Wheatstone bridge circuit (Mathematical Formula 1) is in a voltage equilibrium state where V0 = 0. Here, the output voltage is denoted as Vout or Vo, and the initial output voltage is denoted as V0.

[0053] When the circuit starts to detect gas, the resistance value of each resistor (R1, R2, R3, R4) will change by △R1, △R2, △R3, △R4, and the output voltage of the bridge at this time becomes △Vo = Vout - V0 = Vo (since V0 is 0). If this is reflected in mathematical expression 2, it can be organized as mathematical expressions 3 and 4 below. When organizing the expressions, the products between the minute changes are very small values, so these values ​​were removed from the expressions.

[0054]

[0055]

[0056] The voltage change in mathematical expression 4 can be expressed as an expression for concentration (D) as in mathematical expression 5 (α is a constant).

[0057]

[0058] Assuming that the initial resistance values ​​of the first to fourth resistors (R1 to R4) are the same, that at least one of the resistors reacts with the outside, and that the amount of resistance change due to the reaction is the same, the concentration according to the number of reacting resistors can be expressed as follows. This is only for the purpose of simplifying the expression, and the present invention is not limited thereto, and the absolute values ​​of the amount of resistance change may be different from each other. However, if the absolute values ​​of the amount of resistance change are the same, there may be an advantage of increasing linearity when detecting the concentration.

[0059] (R0=R1=R2=R3=R4, ΔR=ΔR1=ΔR2=ΔR3=ΔR4 (when all change), k=α(ΔR / R0))

[0060] When one resistor reacts, for example, when the resistance change of the third resistor (R3) is positive (+), the concentration (D1) can be expressed as follows (quater bridge) (ΔR=ΔR3, ΔR1=ΔR2=ΔR4=0).

[0061] D1 = k

[0062] When two resistors react, for example, when the resistance change of the first and third resistors (R1, R3) is positive (+), the concentration (D2) can be expressed as follows (half bridge) (ΔR=ΔR3=ΔR1, ΔR2=ΔR4=0).

[0063] D2 = 2k

[0064] As another example of a two-resistor reaction, when the resistance change of the third resistor (R3) is positive (+) and the resistance change of the second resistor (R2) is negative (-), the concentration (D2) can be expressed as follows (half bridge) (ΔR=ΔR3=-ΔR2, ΔR1=ΔR4=0).

[0065] D2 = 2k

[0066] When three resistors react, for example, when the resistance changes of the first and third resistors (R1, R3) are positive (+) and the resistance change of the fourth resistor (R4) is negative (-) complementary to the first resistor, the concentration (D3) can be expressed as follows (3 Q(Quater) bridge) (ΔR=ΔR3=ΔR1=-ΔR4, ΔR2=0).

[0067] D3 = 3k

[0068] When all four resistors react, for example, when the resistance changes of the first and third resistors (R1, R3) are positive (+) and the resistance changes of the second and fourth resistors (R2, R4) are negative (-) complementary to the first resistor, the concentration (D4) can be expressed as follows (Full bridge) (ΔR=ΔR3=ΔR1=-ΔR4=-ΔR2).

[0069] D4 = 4k

[0070] If a bridge circuit can be configured as above, the concentration size can be adjusted from 1 to 4 times, and when it is 4 times, the sensitivity can be made more precise.

[0071] Referring to FIGS. 1 and 2, a gas sensor detection module having a Wheatstone bridge circuit may include first and second legs (L1, L2) and a detection unit (G).

[0072] The first and second legs (L1, L2) can share the first and second contact points (T1, T2), respectively. That is, both ends of each of the first and second legs (L1, L2) can be connected through the first and second contact points (T1, T2).

[0073] First and second power sources (Vs1, Vs2) can be applied to first and second contacts (T1, T2). The voltage difference between the first and second power sources (Vs1, Vs2) can be an input voltage (Vs).

[0074] The first leg (L1) may include first and fourth resistors (R1, R4) connected in series. The first resistor (R1) may be arranged between the first contact point (T1) and the first voltage terminal (Vo1). The fourth resistor (R4) may be arranged between the first voltage terminal (Vo1) and the second contact point (T2).

[0075] The second leg (L2) may include second and third resistors (R2, R3) connected in series. The second resistor (R2) may be positioned between the first contact point (T1) and the second voltage terminal (Vo2). The third resistor (R3) may be positioned between the second voltage terminal (Vo2) and the second contact point (T2).

[0076] The detection unit (G) can measure a change in at least one of the electrical quantities of voltage and current between the first and second voltage terminals (Vo1, Vo2). In this embodiment, it is assumed and explained that the detection unit (G) measures the voltage between the first and second voltage terminals (Vo1, Vo2).

[0077] In a reaction state, at least one of the first to fourth resistors (R1 to R4) can react with a gas component and change its resistance value. The reacting gas component can be a component of a single gas or a composite of multiple gases. The reacting gas can be any one of a component of a specific gas, a composite of multiple specific gases, and each component of multiple specific gases. The user can determine the type of the reacting gas and its component range by adjusting the component or configuration of the resistor, the monitoring environment (operating temperature), etc. The type of the reacting gas and its component range will be referred to as a “specific gas component” throughout the specification. That is, the specific gas component can be a component of a single gas, each component of multiple gases, or a composite of multiple gases. However, when the resistance values ​​of the first to fourth resistors (R1 to R4) all change in a reaction state, it is preferable that the first to fourth resistors (R1 to R4) react to the same specific gas component.

[0078] In a normal state, it is preferable that the product of the resistance values ​​of the first and third resistors (R1, R3) and the product of the resistance values ​​of the second and fourth resistors (R2, R4) be equal. The normal state may mean a state in which the resistance values ​​of the first to fourth resistors (R1 to R4) are constant because they do not come into contact with a specific gas component.

[0079] It is preferable that at least one of the first and third resistors (R1, R3) adopts a positive reaction sensing element whose resistance value increases when reacting with a specific gas component, and at least one of the second and fourth resistors (R2, R4) adopts a negative reaction sensing element whose resistance value decreases when reacting with a specific gas component.

[0080] By combining positive and negative reaction detection in this way, as seen above based on mathematical expression 5, the minimum half bridge can be configured, or a 3Q bridge or a full bridge can be configured, thereby improving the concentration detection sensitivity, enabling detection of ultra-low concentrations, and increasing the stability of the sensitivity.

[0081] One of the positive and negative reaction sensing elements may include an n-type semiconductor material, and the other may include a p-type semiconductor material. The positive and negative reaction sensing elements adopted by the first to fourth resistors (R1 to R4) correspond to the characteristics of the reacting gas as described below, and are therefore not limited to the terms positive reaction or negative reaction. That is, at least one of the first and third resistors (R1, R3) may react with a specific gas component to change its resistance value, and at least one of the second and fourth resistors (R2, R4) may react with a specific gas component to change its resistance value in a direction complementary to and opposite to the resistance change amount of the first resistor (R1).

[0082] In general, non-thermal semiconductor gas sensors, thermal semiconductor gas sensors, and contact combustion gas sensors use metal oxide powder to create a detector (bead) that reacts with gas and a compensator (bead) that serves as a reference.

[0083] Metal oxide powders can be classified as n-type, p-type, and amphoteric (amorphous) semiconductors based on their electronic properties. Metal oxide semiconductor materials exhibit opposite outputs to the same gas depending on their p-type or n-type properties. For example, p-type metal oxide semiconductor materials exhibit increased resistance to carbon monoxide, while n-type materials exhibit decreased resistance. Similarly, p-type NiO exhibits increased resistance to ethanol, while n-type SnO2 exhibits decreased resistance. This is because they act as acceptors and donors, respectively, in solid-gas surface adsorption and desorption reactions. The surface of metal oxide semiconductor fine powders harbors numerous oxygen adsorbents with multiple oxidation states, and necks exist between the surface and surface particles, forming a potential barrier. When exposed to an external gas, this potential barrier changes. For n-type semiconductors, the potential barrier decreases, resulting in a decrease in resistance. For p-type semiconductors, the opposite is true. Of course, the phenomenon varies depending on whether the gas is reducing or oxidizing. The above cases are for reducing gases (hydrogen, methane, propane, carbon monoxide, hydrogen sulfide, alcohol, ammonia, etc.). For oxidizing gases (ozone, plasma, peroxide, sulfur oxide, etc.) such as nitrogen oxide (NOx), n-type semiconductors react and their resistance increases, and p-type semiconductors react and their resistance decreases.

[0084] The n-type semiconductor material may be any one selected from the group consisting of SnO2, ZnO, In2O3, TiO2, WO3, V2O5, CeO2, ThO2, ZrO2, NbO2, Ta2O3, MoO3, MnO2, Fe2O3, SiO2, Al2O3, PbO2, MgO, CaO, SrO, BaO, and combinations thereof.

[0085] The p-type semiconductor material may be at least one selected from the group consisting of NiO, MnO, FeO, CoO, PdO, PbO, Cu2O, Ag2O, Mn2O3, Cr2O3, and Co3O4, alone, in combination, as a single precursor, and as a combination precursor.

[0086] At least one of the positive and negative reaction detection elements may further comprise a catalyst material and a binder material. This is because the gas sensor detection module comprising the present Wheatstone bridge circuit can be formed as a bead, like the semiconductor gas sensor and the contact combustion gas sensor mentioned above. However, the present invention is not limited thereto, and the gas sensor may be formed in a thin film or thick film form, and the catalyst material and the binder material may be added to the thin film or thick film form.

[0087] The catalytic material may be at least one selected from the group consisting of single, combinations, single precursors, and combination precursors of Pt, Pd, Au, Rh, Ru, and Ir.

[0088] The binder material may be at least one selected from the group consisting of single, combinations, single precursors, and combination precursors of SiO2, Al2O3, K2O, TiO2, CuO, MgO, and CaO.

[0089] In terms of linearity, it is desirable that the absolute magnitudes of the resistance changes of the first to fourth resistors (R1 to R4) correspond to each other. In practice, it is more desirable that the absolute magnitudes of the resistance changes are equal to each other.

[0090] For example, it is preferable that the first and third resistors (R1, R3) react positively with a specific gas component, and the resistance changes of each of the first and third resistors (R1, R3) correspond to each other. In addition, it is preferable that the second and fourth resistors (R2, R4) react negatively with a specific gas component, and the resistance changes of each of the second and fourth resistors (R2, R4) correspond to each other. In addition, it is preferable that the absolute values ​​of the resistance changes of the third resistor (R3) and the resistance changes of the fourth resistor (R4) correspond to each other.

[0091] Referring to FIGS. 1 and 2, a gas sensor detection module having a Wheatstone bridge circuit may further include first to fourth resistance electrode lines (510 to 540).

[0092] The first resistance electrode line (510) has a first resistor (R1) and can connect a first contact point (T1) and a first voltage terminal (Vo1). The second resistance electrode line (520) has a second resistor (R2) and can connect a first contact point (T1) and a second voltage terminal (Vo2). The third resistance electrode line (530) has a third resistor (R3) and can connect a second voltage terminal (Vo2) and a second contact point (T2). The fourth resistance electrode line (540) has a fourth resistor (R4) and can connect the first voltage terminal (Vo1) and the second contact point (T2). In the present embodiment, the electrode line having a resistor may mean that the resistor is arranged inside the electrode line (Fig. 4), that the electrode line is connected in parallel with the resistor, or that the electrode line is influenced by the resistor (Fig. 3).

[0093] Referring to FIG. 3 or FIG. 4, at least one of the first and third resistors (R1, R3) and the second and fourth resistors (R2, R4) can be formed integrally.

[0094] The first and third resistors (R1, R3) can form a bead (230) for the first sensing element. The second and fourth resistors (R2, R4) can form a bead (280) for the second sensing element.

[0095] The first and third resistance electrode lines (510, 530) can be respectively attached to the bead (230) for the first sensing element.

[0096] The second and fourth resistance electrode lines (520, 540) can be respectively attached to the second sensing element bead (280).

[0097]

[0098] Typically, the third resistor (R3) and the second resistor (R2) are positioned inside the sensing element and the compensation element, and the first resistor (R1) and the fourth resistor (R4) are inserted into the back of the circuit board and used as general resistor elements. In the Wheatstone bridge detection circuit, if the second resistor (R2) is placed in an environment similar to that of the third resistor (R3) and used as a reference resistor, the influence of external temperature, humidity, air pressure, electromagnetic waves, etc. can be minimized or eliminated when detecting a signal. However, the equilibrium condition of the bridge circuit is the product of the remaining two paired resistors (R1, R4), as in mathematical equation (1).

[0099] In the actual sensor circuit configuration, although the contact combustion type maintains an operating temperature of 300 to 350 degrees Celsius, and the semiconductor type maintains an operating temperature of 50 to 450 degrees Celsius, the first resistor (R1) and the fourth resistor (R4) operate in an environment completely exposed as general resistor elements, so the difference in the temperature coefficient of resistance (TCR) may cause a significant imbalance due to the difference in the resistor material and the difference in the operating temperature band. In addition, the output may lack consistency in the initial low concentration detection and the output as the leaked gas concentration increases. However, as in the present invention, if the first and third resistor electrode lines (510, 530) and the first sensing element bead (230) are configured as one piece, and the second and fourth resistor electrode lines (520, 540) and the second sensing element bead (280) are configured as one piece, the sensitivity and linearity can be improved by reacting in the same manner.

[0100] Although Fig. 3 illustrates a hot-wire semiconductor gas sensor and Fig. 4 illustrates a non-hot-wire semiconductor gas sensor, the present invention is not limited thereto. For example, Fig. 3 may be a contact combustion gas sensor.

[0101] FIG. 5 may be a perspective view of FIG. 3 as an example, and in this case, FIG. 3 may be a configuration that shows a plan view in comparison with FIG. 5. If the heater of FIG. 4 described below is added to FIG. 5, it may become an embodiment of FIG. 3.

[0102] Referring to FIG. 5, a gas sensor device having a gas sensor detection module having a Wheatstone bridge circuit according to the present invention may include first and second detection elements (210, 260) that constitute a gas sensor and react with gas. The gas sensor detection module of the Wheatstone bridge circuit may further include first and second power terminals (Vs1, Vs2) that provide power to the Wheatstone bridge circuit.

[0103] The first sensing element (210) may include a bead (230) for the first sensing element, and first and third resistance electrode lines (510, 530).

[0104] The first resistance electrode line (510) can connect the first power terminal (Vs1) and the first voltage terminal (Vo1). The second resistance electrode line (520) can connect the first power terminal (Vs1) and the second voltage terminal (Vo2). The third resistance electrode line (530) can connect the second voltage terminal (Vo2) and the second power terminal (Vs2). The fourth resistance electrode line (540) can connect the first voltage terminal (Vo1) and the second power terminal (Vs2).

[0105] When a specific gas component comes into contact with the bead (230) for the first sensing element, the resistance of the first and third resistive electrode lines (510, 530) can be varied. When a specific gas component comes into contact with the bead (280) for the second sensing element, the resistance of the second and fourth resistive electrode lines (520, 540) can be varied. A detailed description thereof will be provided later.

[0106] The gas sensor device according to the present embodiment may further include a sensor body (30) and a plurality of electrode poles (110).

[0107] The sensor body (30) may be wrapped with a metal shield (not shown). A mesh cover (not shown) that allows gas to pass through may be attached to the upper portion of the sensor body (30). To attach the mesh cover, the side of the sensor body (30) may be stepped.

[0108] A plurality of electrode poles (110: 111 to 114, etc.) can be arranged to penetrate the sensor body (30). It is preferable that the plurality of electrode poles (110) be made of a metallic conductive material.

[0109] The lower side of the plurality of electrode poles (110) can be connected to a sensing circuit such as that shown in FIGS. 1 and 2. The sensing circuit is a circuit capable of measuring at least one of current, voltage, and resistance, or measuring the on / off of current, and may include a Wheatstone bridge circuit.

[0110] It is preferable that the gas sensor device according to the present embodiment further includes a blocking plate (40).

[0111] One of the beads (230, 280) for the first and second sensing elements may react with a specific gas component to increase in temperature, while the other may decrease in temperature. The blocking plate (40) may prevent temperature changes of the beads (230, 280) for the first and second sensing elements from affecting each other. The blocking plate (40) is preferably made of a thermally non-conductive material.

[0112] Semiconductor gas sensors can be classified into thermal semiconductor gas sensors with their own heaters and non-thermal semiconductor gas sensors without their own heaters, such as thin-film, thick-film, or bulk sintered types. Hereinafter, each detection module will be described with reference to FIG. 3 for the thermal semiconductor gas sensor and FIG. 4 for the non-thermal semiconductor gas sensor.

[0113] It is assumed and explained that when reacting with a specific gas component, the resistance of the bead (230) for the first sensing element decreases and the resistance of the bead (280) for the second sensing element increases.

[0114] Referring to FIG. 3, the first and third resistance electrode lines (510, 530) can be connected by penetrating the first sensing element bead (230), and the second and fourth resistance electrode lines (520, 540) can be connected by penetrating the second sensing element bead (280).

[0115] The first to fourth resistance electrode lines (510 to 540) may each be provided with first to fourth heating coils (R_h1 to 4) disposed within the first and second sensing element beads (230, 280). It is preferable that the first to fourth heating coils (R_h1 to 4) are platinum filaments. When current flows through the first to fourth heating coils (R_h1 to 4), each filament emits heat, thereby allowing the first and second sensing element beads (230, 280) to be at their operating temperatures.

[0116] When the resistance of the first sensing element bead (230) decreases and the electrical conductivity of the first sensing element bead (230) increases, the thermal conductivity also increases, so that heat can be dissipated well. As a result, the electrical conductivity of the first and third resistance electrode lines (510, 530), and particularly the first and third heating coils (R_h1, R_h3), increases, so that the resistance values ​​thereof can decrease.

[0117] The first resistance electrode line (510) can be seen as being connected in parallel with the first sensing element bead (230). Therefore, a decrease in the resistance value of the first sensing element bead (230) affects a decrease in the resistance value at both ends of the first resistance electrode line (510), so that the extent of the decrease in the resistance value of the first resistance electrode line (510) can become larger.

[0118] In the bead (280) for the second sensing element, the opposite situation to that in the bead (230) for the first sensing element occurs, so that the resistance values ​​of the second and fourth resistance electrode lines (520, 540) can increase.

[0119] The gas sensor module according to Fig. 3 may be either a contact combustion gas sensor module or a hot-wire semiconductor gas sensor module, but a hot-wire semiconductor gas sensor module may be more preferable. This is because, in the case of a contact combustion gas sensor module, the reaction heat from the combustion reaction has a significant effect on the internal resistance electrode wire, which may lower the resistance increase / decrease rate.

[0120] In the case of FIG. 3, the first to fourth resistors (R1 to R4) can be viewed as influencing the first to fourth resistor electrode lines (510 to 540) or being connected in parallel to the first to fourth heating coils (R_h1 to 4), which are internal resistances of the first to fourth resistor electrode lines (510 to 540).

[0121] Referring to FIG. 4, the first and third resistance electrode lines (510, 530) are short-circuited and connected in series with the first sensing element bead (230) and connected, and the second and fourth resistance electrode lines (520, 540) are short-circuited and connected in series with the second sensing element bead (280) and connected.

[0122] The resistance values ​​of the first to fourth resistance electrode lines (510 to 540) can be regarded as the resistance values ​​of the beads (230, 280) for the first and second sensing elements.

[0123] A non-thermal semiconductor gas module such as FIG. 4 may have separate first and second heating wires (R_h01, R_h02) so that the beads (230, 280) for the first and second sensing elements operate at an operating temperature. The first and second heating wires (R_h01, R_h02) may pass through the beads (230, 280) for the first and second sensing elements, respectively. When current flows through the first and second heating wires (R_h01, R_h02), heat may be released. The first and second heating wires (R_h01, R_h02) may be coiled or zigzag platinum wires.

[0124] In a reaction state, when the resistance of the bead (230) for the first sensing element decreases, the resistance of the first and third series-connected resistive electrode lines (510, 530) decreases, respectively. Conversely, when the resistance of the bead (280) for the second sensing element increases, the resistance of the first and third series-connected resistive electrode lines (510, 530) increase, respectively.

[0125] Example 1 - Contact combustion type manufacturing

[0126] SnO2, an n-type semiconductor material, Pd, a catalyst material, and Al(OH)x and CaO powder, a binder material, are mixed in a weight ratio of 80:5:10:5 to make a basis weight of 25 grams, and then 15 ml of a mixture of water and ethylene glycol is mixed and dispersed in a mill while adjusting the viscosity to make a paste.

[0127] This is done by forming an integrated bead by dropping two platinum coils side by side (Fig. 3), drying at room temperature and drying at 150 degrees in sequence, and then firing in an electric furnace in air at 800 degrees for 2 hours to complete the integrated first detector element (230).

[0128] The integrated second detector element (280) is manufactured using the same process as described above, except that NiO is used as the p-type semiconductor material. When manufacturing each paste, metal oxide semiconductors, catalysts, and binders can be appropriately selected and used. Depending on the corresponding gas, multiple semiconductor materials can be mixed, and the powder particle size can be adjusted to vary the content.

[0129] Example 2 - Semiconductor non-thermal linear fabrication

[0130] The n-type semiconductor materials In2O3 and ZnO, the catalyst material Au, the binder material calcium silicate (CaSiO3) and MgO powders are each mixed in a weight ratio of 50:30:5:10:5 to make a basis weight of 25 grams. Afterwards, 17 ml of a mixture of water and ethylene glycol is mixed and dispersed in a mill while adjusting the viscosity to make a paste.

[0131] This is done by forming an integrated bead by drop-processing with one platinum coil and an electrode wire arranged in parallel (Fig. 4), drying at room temperature and drying at 150 degrees in sequence, and then firing in an electric furnace in air at 800 degrees for 2 hours to complete an integrated first detector element (230).

[0132] The integrated second detector element (280) is manufactured using the same process as described above, except that NiO and Cu2O are used as p-type semiconductor materials. When manufacturing each paste, metal oxide semiconductors, catalysts, and binders can be appropriately selected and used. Depending on the corresponding gas, multiple semiconductor materials can be mixed, and the particle size of the powder can be adjusted to vary the content.

[0133] The present invention can be implemented in hardware or software. The present invention can also be implemented as computer-readable code on a computer-readable recording medium. That is, the present invention can be implemented in the form of a recording medium containing computer-executable instructions. Computer-readable media include all types of media that store data that can be read by a computer system. Computer-readable media can include computer storage media and communication storage media. Computer storage media includes all storage media implemented as any method or technology for storing information, such as computer-readable instructions, data structures, program modules, and other data, and is not limited to volatile / nonvolatile / hybrid memory, removable / non-removable memory, etc. Communication storage media include modulated data signals or transmission mechanisms such as carrier waves, any information transmission media, etc. In addition, functional programs, codes, and code segments for implementing the present invention can be easily inferred by programmers in the technical field to which the present invention pertains.

[0134] In addition, although the preferred embodiments of the present invention have been illustrated and described above, the present invention is not limited to the specific embodiments described above, and various modifications can be made by a person having ordinary skill in the art to which the present invention pertains without departing from the gist of the present invention as claimed in the claims, and such modifications should not be understood individually from the technical idea or prospect of the present invention.

[0135] <Explanation of symbols>

[0136] 30: Sensor body 40: Blocking plate

[0137] 110: Multiple electrode poles 210: First sensing element

[0138] 230: Bead for first sensing element 260: Second sensing element

[0139] 280: Bead for the second sensing element

Claims

1. A gas sensor detection module having a Wheatstone bridge circuit having first and second legs (L1, L2), First and second power sources (Vs1, Vs2) are applied to the first and second contacts (T1, T2) of the first and second legs (L1, L2), The first leg (L1) comprises a first resistor (R1) disposed between the first contact (T1) and the first voltage terminal (Vo1); and a fourth resistor (R4) disposed between the first voltage terminal (Vo1) and the second contact (T2). The second leg (L2) comprises a second resistor (R2) disposed between the first contact point (T1) and the second voltage terminal (Vo2); and a third resistor (R3) disposed between the second voltage terminal (Vo2) and the second contact point (T2). It further includes a detection unit that measures a change in at least one of the electrical quantity of voltage and current between the first and second voltage terminals (Vo1, Vo2), In a normal state, the product of the resistance values ​​of the first and third resistors (R1, R3) and the product of the resistance values ​​of the second and fourth resistors (R2, R4) are equal, At least one of the first and third resistors (R1, R3) is a positive reaction sensing element whose resistance value increases by reacting with a specific gas component, At least one of the second and fourth resistors (R2, R4) is a negative reaction sensing element whose resistance value decreases by reacting with the specific gas component. A gas sensor detection module having a Wheatstone bridge circuit.

2. In paragraph 1, One of the positive and negative reaction sensing elements comprises an n-type semiconductor material, and the other comprises a p-type semiconductor material. A gas sensor detection module having a Wheatstone bridge circuit.

3. In paragraph 2, The above n-type semiconductor material is any one selected from the group consisting of SnO2, ZnO, In2O3, TiO2, WO3, V2O5, CeO2, ThO2, ZrO2, NbO2, Ta2O3, MoO3, MnO2, Fe2O3, SiO2, Al2O3, PbO2, MgO, CaO, SrO, BaO, and combinations thereof, The above p-type semiconductor material is at least one selected from the group consisting of NiO, MnO, FeO, CoO, PdO, PbO, Cu2O, Ag2O, Mn2O3, Cr2O3, and Co3O4, alone, in combination, alone precursor, and combination precursor. A gas sensor detection module having a Wheatstone bridge circuit.

4. In paragraph 2, At least one of the positive and negative reaction detection elements further comprises a catalyst material and a binder material, The above catalyst material is at least one selected from the group consisting of a single precursor, a combination of single precursors, and a combination of single precursors of Pt, Pd, Au, Rh, Ru, and Ir, The above binder material is at least one selected from the group consisting of a single precursor, a combination of single precursors, and a combination of precursors of SiO2, Al2O3, K2O, TiO2, CuO, MgO, and CaO. A gas sensor detection module having a Wheatstone bridge circuit.

5. In paragraph 1, The first and third resistors (R1, R3) react positively with the specific gas component, and the resistance change amount of each of the first and third resistors (R1, R3) is the same. The second and fourth resistors (R2, R4) react negatively with the specific gas component, and the resistance change amount of each of the second and fourth resistors (R2, R4) is the same. A gas sensor detection module having a Wheatstone bridge circuit.

6. In paragraph 1, A first resistance electrode line having the first resistor (R1) and connecting the first contact point (T1) and the first voltage terminal (Vo1); A second resistor electrode line having the second resistor (R2) and connecting the first contact point (T1) and the second voltage terminal (Vo2); A third resistor electrode line having the third resistor (R3) and connecting the second voltage terminal (Vo2) and the second contact point (T2); and It further includes a fourth resistor electrode line having the fourth resistor (R4) and connecting the first voltage terminal (Vo1) and the second contact point (T2); At least one of the first and third resistors (R1, R3) and the second and fourth resistors (R2, R4) is formed integrally. A gas sensor detection module having a Wheatstone bridge circuit.

7. In paragraph 6, The first and third resistors (R1, R3) form a bead for the first sensing element, The second and fourth resistors (R2, R4) form a bead for the second sensing element, The first and third resistance electrode lines are each attached to a bead for the first sensing element, The second and fourth resistance electrode lines are each connected to the bead for the second sensing element. A gas sensor detection module having a Wheatstone bridge circuit.

8. A gas sensor device comprising a gas sensor detection module having a Wheatstone bridge circuit according to any one of claims 1 to 7.

Images