Gas sensor detection module of wheatstone bridge circuit and gas sensor having same

Abstract

The present invention relates to a gas sensor bridge detection module and a method for manufacturing same. A sensing element, a pair resistor thereof, a compensation element, and a pair resistor thereof may constitute a gas sensor, and same may be regarded as four resistors such that the detection module performs detection in a bridge circuit. The pair resistor (R1) of the sensing element may be bound to and integrated with the sensing body (R3) of the sensing element, and the pair resistor (R4) of the compensation element may be bound to and integrated with the compensation body (R2) of the compensation element.

Description

Gas sensor detection module of Wheatstone bridge circuit and gas sensor having the same

[0001] The present invention relates to a gas sensor detection module of a Wheatstone bridge circuit and a gas sensor having 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 according to one embodiment of the present invention comprises 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 is a gas sensor detection module of a Wheatstone bridge circuit that constitutes a Wheatstone bridge circuit, and may include a detection element (210) that constitutes the gas sensor and reacts with gas; a compensation element (260) that constitutes the gas sensor and does not react with gas; and first and second power terminals (Vs1, Vs2) that provide power to the Wheatstone bridge circuit.

[0007] The above sensing element (210) comprises a sensing element bead (230); and a sensing element electrode line (530) (hereinafter, “third resistance electrode line”) that connects the second voltage terminal (Vo2) and the second power terminal (Vs2) and whose resistance value changes when reacting with a specific gas; and the sensing element electrode line (530) may comprise a third resistor (R3) corresponding to the resistance value of both ends thereof.

[0008] The above compensation element (260) may include a compensation element bead (280); and a second resistor (R2) having a resistance value corresponding to the third resistor (R3), and may include a compensation element electrode line (520) (hereinafter, “second resistance electrode line”) connecting the first power terminal (Vs1) and the second voltage terminal (Vo2).

[0009] It may further include a first resistor electrode line (510) having a first resistor (R1) corresponding to the third resistor (R3) and connecting the first power terminal (Vs1) and the first voltage terminal (Vo1); and a fourth resistor electrode line (540) having a fourth resistor (R4) corresponding to the second resistor (R2) and connecting the first voltage terminal (Vo1) and the second power terminal (Vs2).

[0010] The resistance of the first resistor (R1) can be varied in response to a change in the resistance of the third resistor (R3), and the resistance of the fourth resistor (R4) can be varied in response to a change in the resistance of the second resistor (R2).

[0011] The first and third resistance electrode lines (510, 530) may be adjacent to each other and attached to the bead (230) for the sensing element, and the second and fourth resistance electrode lines (520, 540) may be adjacent to each other and attached to the bead (280) for the compensation element.

[0012] It is preferable that the first and third resistance electrode lines (510, 530) are spaced apart from each other and are electrically insulated from each other.

[0013] It is preferable that the second and fourth resistance electrode lines (520, 540) are spaced apart from each other and are electrically insulated from each other.

[0014] The above gas sensor is a contact combustion type gas sensor, and the first and third resistors (R1, R3) are provided with first and third heating coils, respectively, and the first and third heating coils may be arranged and bonded to the inside of the sensing element bead (230), or at least a portion of the first and third heating coils may be attached to the outside of the sensing element bead (230), and at least another portion of the first and third heating coils may be exposed and bonded to the sensing element bead (230).

[0015] The second and fourth resistors (R2, R4) are provided with second and fourth heating coils, respectively, and the first to fourth heating coils can generate heat when power is applied.

[0016] The first resistance electrode wire (510) is attached to the outside of the bead (230) for the sensing element, and the first resistance electrode wire (510) has a winding wire (222) having a portion directly exposed to the outside air, and the winding wire (222) can directly react catalytically with a gas that comes into contact with the exposed portion in the outside air.

[0017] The bead (230) for the sensing element is disposed inside the winding wire (222), and is a heat block (240) that partially combines with the winding wire (222) to support the winding wire (222), the winding wire (222) is a platinum-based material, and the ratio of the exposed portion of the winding wire (222) can be 40% to 90% of the surface area of ​​the winding wire (222).

[0018] The above heat block (240) may have an exposed sensing element, which may include a cover block covering a portion of the winding wire (222), the cover block including at least one of a block ring (245) which is a portion of the circumference of the winding wire (222); and a block bar (246) in the shape of a bar attached to the heat block (240) in the longitudinal direction of the heat block (240).

[0019] The above winding wire (222) may be any one of platinum-based metals such as platinum (Pt), palladium (Pd), rhodium (Rh), iridium (Ir), and ruthenium (Ru), or an alloy of two or more of the platinum-based metals.

[0020] The wire diameter of the direct catalytic combustion reaction coil (220) is preferably 5 to 40 μm. The resistance of the direct catalytic combustion reaction coil (220) is preferably 2 to 20 Ω at room temperature. The coil diameter of the direct catalytic combustion reaction coil (220) is preferably 0.1 to 0.5 mm. The number of turns (number of turns) of the direct catalytic combustion reaction coil (220) is preferably 7 to 15 turns.

[0021] It further includes a direct catalytic combustion reaction coil (220) having the above-described winding wire (222), and the direct catalytic combustion reaction coil (220) receives power and emits power heat to maintain a preset reaction operating temperature, and generates combustion heat according to the direct catalytic combustion reaction of the contact gas to become higher than the reference operating temperature of the compensation element (260), and the heat block (240) stores the power heat and the combustion heat to reduce heat loss, and has pores therein, and can generate additional heat by catalytic combustion reaction with the contact gas.

[0022] The above heat block (240) may have any one of a cylindrical, ellipsoidal, and polygonal columnar shape.

[0023] The above heat block body (240) is divided into a plurality of blocks, and the plurality of blocks may have a base block (242) that serves as an internal foundation, and an adhesive block (244) that connects the base block (242) and the direct catalytic combustion reaction coil (220).

[0024] The above-mentioned base block (242) is any one of a metal oxide rod comprising at least one of oxidized Co, Ni, Mn, Cr, Ti, Cu, Sn, Fe, V, Ag, In, La, W and Zn, a ceramic rod comprising at least one of alumina and silicon dioxide, and a composite ceramic rod comprising the metal oxide and the ceramic oxide, and the above-mentioned adhesive block (244) may comprise at least the transition metal oxide among transition metal oxides and precious metal powders.

[0025] At least one of the first to fourth resistors (R1 to R4) may be platinum (Pt) or a platinum wire and a platinum-like metal having a temperature-resistance coefficient within a preset range.

[0026] The above platinum-like metal may be any one of Pd, Ir, Ru, Ni, Cr, Mn, W, Co, Ta, and Ti, or an alloy of two or more selected from these metals.

[0027] The center of the above platinum wire can be formed in a coil shape, wire roll shape, zigzag shape, plate shape, etc.

[0028] The above gas sensor is a semiconductor gas sensor and may include a heater electrode line (550) having a heating resistor (R_h) that emits heat when power is applied.

[0029] The above heater electrode line (550) may include a first heater electrode line penetrating between the first and third resistance electrode lines (510, 530); and a second heater electrode line penetrating between the second and fourth resistance electrode lines (520, 540).

[0030] The first to fourth resistors (R1 to R4) may be formed of a single or composite metal oxide semiconductor material of SnO2, TiO2, ZnO, In2O3, WO3, CuO, NiO, V2O5, Fe2O3, MnO2, Co2O3, Ag2O, ZrO2, and La2O3.

[0031] The first to fourth resistors (R1 to R4) are formed of the same material, and the first and third resistors (R1, R3) can use at least one of a noble metal and a transition metal as a catalyst.

[0032] A gas sensor according to one embodiment of the present invention may include any one of the gas sensor detection modules of the above-described Wheatstone bridge circuit.

[0033] The gas sensor detection module of the Wheatstone bridge circuit according to the present invention can improve the overall output sensitivity by two times, and the reference resistance of the compensation element bead module can be reduced or remain unchanged by interference such as external temperature, humidity, air pressure, and electromagnetic waves, thereby enabling ultra-precision measurement.

[0034] FIG. 1 is a perspective view of a contact combustion type gas sensor to which a gas sensor detection module of a Wheatstone bridge circuit according to the present invention is applied.

[0035] Figure 2 illustrates a Wheatstone bridge detection circuit.

[0036] FIG. 3 shows a plan view of a contact combustion gas sensor having a body disposed inside a bead for a sensing element, compared to FIG. 1.

[0037] Figure 4 illustrates the bead of Figure 3.

[0038] Figure 5 illustrates a plan view of a contact combustion gas sensor having a metal body disposed on the outside of a bead for a sensing element.

[0039] FIG. 6 is a perspective view of an exposed sensing element according to one embodiment.

[0040] Fig. 7 is a cross-sectional view of the heat block body or the heat block body wound with the winding wire of Fig. 6.

[0041] FIG. 8 illustrates a pair of detectors attached to the outer surface of a bead of an exposed sensing element according to another embodiment.

[0042] Figure 9 shows a plan view of a semiconductor gas sensor.

[0043] Figure 10 illustrates a stand.

[0044] Figure 11 illustrates a semiconductor sensing element formed on a substrate.

[0045] 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.

[0046] Although terms such as first, second, etc. may be used to describe various components, 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 multiple related items described above or any of multiple related items described above. The term "or" may be interpreted as a logical exclusion in the context, but in the absence of a direct description such as "otherwise, otherwise, logical exclusion," it is interpreted as having the same meaning as "and / or," i.e., a logical conjunction. In addition, singular expressions include plural expressions unless the context clearly indicates otherwise.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] FIG. 1 is a perspective view of a catalytic combustion gas sensor to which a gas sensor detection module of a Wheatstone bridge circuit according to the present invention is applied. FIG. 2 illustrates a Wheatstone bridge detection circuit. FIG. 3 is a plan view of a catalytic combustion gas sensor having a vapor deposition body arranged inside a bead for a sensing element, compared to the shape of FIG. 1. FIG. 4 illustrates the bead of FIG. 3. FIG. 5 is a plan view of a catalytic combustion gas sensor having a vapor deposition body arranged outside a bead for a sensing element. FIG. 6 is a perspective view of an exposed sensing element according to one embodiment. FIG. 7 is a cross-sectional view of a heat block body or a heat block body wound with a winding wire of FIG. 6. FIG. 8 illustrates a pair of sensing elements attached to the outer surface of a bead of an exposed sensing element according to another embodiment. FIG. 9 is a plan view of a semiconductor gas sensor. FIG. 10 illustrates a holder. FIG. 11 illustrates a semiconductor sensing element formed on a substrate.

[0053] Referring to FIG. 2, the gas sensor detection module of the present Wheatstone bridge circuit has a detection circuit of a gas sensor that senses gas using a voltage difference between the first and second voltage terminals (Vo1, Vo2), and the detection circuit can form a Wheatstone bridge circuit.

[0054] The gas sensor detection module of the Wheatstone bridge circuit according to the present invention can be used as a detection module for various gas sensors. This is not limited to the contact combustion gas sensor of FIG. 1, but can be used for all gas sensors utilizing a Wheatstone bridge circuit, such as a contact combustion gas sensor or a semiconductor gas sensor having a structure different from that of FIG. 1.

[0055] Representative gas sensors include contact combustion gas sensors and semiconductor gas sensors.

[0056] When a combustible gas reacts with oxygen, heat of reaction is generated. The contact combustion gas sensor (10) detects gas by converting this heat of reaction into an electrical signal. The contact combustion gas sensor (10) can be used for detecting city gas or propane gas, and for detecting combustible toxic gases in hydrogen vehicles, factories, etc.

[0057] A semiconductor gas sensor (20) can detect gas by utilizing changes in the density of surface electrons or electrical resistance caused by chemical interactions between gas components and the semiconductor surface. The semiconductor gas sensor (20) can detect gas by utilizing a mechanism in which oxygen ions chemically adsorbed on the semiconductor surface undergo ion exchange and electron donation through adsorption and desorption of external gases, thereby reducing the electrical resistance of the oxide semiconductor. The semiconductor surface may be a metal oxide, but is not limited thereto, and may be formed of CNT (Carbon nanotube), carbon powder, or the like.

[0058] The semiconductor gas sensor (20) may be any one of the Figaro type, hot wire type, thin film / thick film type, and bulk bead type depending on the sensor structure.

[0059] 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.

[0060] Bridge circuits were developed to measure the precision resistance of electronic components and are used in various fields. Referring to Fig. 2 and Mathematical 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.

[0061]

[0062] This method has been extended and applied to various sensor detection circuits, such as temperature sensors, load sensors, and gas sensors, by generating outputs corresponding to the unbalanced resistance in the form of mathematical equation 2. This method is more accurate than the voltage distribution method, as it has a smaller detection error.

[0063]

[0064] 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.

[0065] 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 it insensitive to small variations and has poor linearity, resulting in inaccurate output values ​​at high concentrations.

[0066] These limitations make it difficult for gas sensors to detect 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 where gas presence is crucial.

[0067] Referring to FIG. 1, a gas sensor detection module of a Wheatstone bridge circuit may include a detection element (210) that constitutes a gas sensor and reacts with gas, and a compensation element (260) that constitutes the gas sensor and does not react with gas. The gas sensor detection module of a Wheatstone bridge circuit may further include first and second power terminals (Vs1, Vs2) that provide power to the Wheatstone bridge circuit.

[0068] The present sensing element (210) may include a sensing element bead (230) and a sensing element electrode line (530).

[0069] The electrode wire (530) for the sensing element (hereinafter, shared with the 'third resistance electrode wire (R3)') connects the second voltage terminal (Vo2) and the second power terminal (Vs2), and its resistance value may change when reacting with a specific gas. The electrode wire (530) for the sensing element may be provided with a third resistor (R3) corresponding to the resistance values ​​of both ends thereof.

[0070] The compensation element (260) may be equipped with a compensation element bead (280) and a compensation element electrode line (520) (hereinafter, shared with the 'second resistance electrode line (R2)'). The compensation element electrode line (520) may be equipped with a second resistor (R2) having a resistance value corresponding to the third resistor (R3).

[0071] The electrode line (520) for the compensation element can connect the first power terminal (Vs1) and the second voltage terminal (Vo2).

[0072] The gas sensor detection module of the Wheatstone bridge circuit may further include a first resistance electrode line (510) and a fourth resistance electrode line (540).

[0073] The first resistance electrode line (510) has a first resistor (R1) corresponding to a third resistor (R3) and can connect a first power terminal (Vs1) and a first voltage terminal (Vo1). The resistance of the first resistor (R1) can be varied in response to a change in the resistance of the third resistor (R3).

[0074] The fourth resistor electrode line (540) has a fourth resistor (R4) corresponding to the second resistor (R2) and can connect the first voltage terminal (Vo1) and the second power terminal (Vs2). The resistance of the fourth resistor (R4) can be varied in response to a change in the resistance of the second resistor (R2).

[0075] Typically, the third resistor (R3) and the second resistor (R2) are positioned inside the sensing element (210) and the compensation element (260), 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).

[0076] 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 a completely exposed environment as general resistance elements. In this case, a significant imbalance may occur due to differences in the temperature coefficient of resistance (TCR), differences in resistor materials, and differences in operating temperature bands. In addition, there may be a significant lack of consistency in the output between the initial low-concentration detection and the increase in the leaked gas concentration.

[0077] To minimize this, the resistance specifications of each resistor are actually calculated as the same resistance (Ro), and it is recommended to do so in the circuit as well, if possible.

[0078] Referring to FIGS. 1 and 3, the first and third resistance electrode lines (510, 530) may be adjacent to each other and attached to the sensing element bead (230). The second and fourth resistance electrode lines (520, 540) may be adjacent to each other and attached to the compensation element bead (280). The first and third resistance electrode lines (510, 530) are arranged to be spaced apart from each other, and the second and fourth resistance electrode lines (510, 530) are arranged to be spaced apart from each other, so that they should be electrically open to each other.

[0079] For example, if the first to fourth resistors (R1 to R4) are made of platinum wire (coil) which is the same resistor and have substantially the same shape, and the positions of each bead are also made corresponding, each resistor (R1 to R4) can maintain the same temperature at all times. Under this configuration, each resistor (R1 to R4) reacts identically when the general external environment changes. When the sensing element reacts due to leaked gas, the resistance of the third resistor (R3) and the first resistor (R1) among the plurality of resistors (R1 to R4) change identically. This can mean that the size of the output signal doubles compared to a case where only the resistance of the existing third resistor (R3) changes.

[0080] In this case, the present Wheatstone bridge circuit can correspond to a half bridge circuit where R1=Ro+△R, R3=Ro+△R, and the output size can be expressed as in mathematical expression 3.

[0081]

[0082] If the third resistor (R3) and the first resistor (R1) are made of a material such as platinum, the TCR will move in the same direction even in high-concentration gases (in the case of a contact combustion gas sensor, high-temperature combustion heat is generated), which can reduce signal distortion or error and contribute to improved linearity. It is preferable that all resistors (R1 to R4) be made of the same material, and in particular, platinum is preferable.

[0083] The present invention can be applied to all types of gas sensors. The present invention basically has a half-bridge detection circuit, and in an actual sensor element, a first resistor (R1), a third resistor (R3), a second resistor (R2), and a fourth resistor (R4) are electrically insulated but integrated together. Therefore, the initial operating temperatures of the first to fourth resistors (R1 to R4) of the sensor are the same for all four.

[0084] The first and third resistors (R1, R3) may have both detection (sensing) functions, but are not limited thereto, and the first resistor (R1) may also be attached without a detection function and use only temperature.

[0085] The second and fourth resistors (R2, R4) have no detection function and can only function as compensation elements. It is desirable to configure the second and fourth resistors (R2, R4) with the same temperature, same material, and same shape to improve accuracy, etc.

[0086] In the case of a contact combustion gas sensor, the first resistor (R1), which is a platinum wire resistor, is connected in some way to the third resistor (R3), which is a sensing element bead, and is placed in an identical temperature environment as an integrated unit, and when it has almost the same constant resistance, it is completed. Similarly, the relationship between the fourth resistor (R4) and the second resistor (R2), which is a compensator, can also be implemented in the form of an integrated bead, like the first and third resistors (R1, R3).

[0087] When forming an integral bead, the pair of electrodes and the heating coil must not come into contact with each other (electrically insulated). In addition, the configuration positions of the first and third resistors (R1, R3) or the second and fourth resistors (R2, R4) must be symmetrical to prevent their temperatures or resistances from becoming uneven or different.

[0088] The central portions of the first to fourth resistors (R1 to R4) formed of platinum wires (the portions disposed inside or in the central portions of the sensing element bead (230) and the compensation element bead (280), respectively) may be simple wire-shaped, coil-shaped, or have various shapes. The first to fourth resistors (R1 to R4) may be disposed at any position of the sensing element bead (230) and the compensation element bead (280), for example, at any position among the top, bottom, left, and right of each bead, but it is preferable that paired resistors be disposed at corresponding positions. At least one of the sensing element bead (230) and the compensation element bead (280) may have various shapes, such as a straight line, an oval, or a curved shape overall.

[0089] The first to fourth resistors (R1 to R4) are preferably made of a material other than platinum, such as Pd, Ir, Ru, Ni, Cr, Mn, W, Co, Ta, and Ti, or an alloy of two or more of these (including platinum), and have a temperature-resistance coefficient similar to that of the platinum wire. It is preferable that all of the first to fourth resistors (R1 to R4) are made of the same material and have the same shape, and at least each pair of resistors (the first and third resistors (R1, R3), or the second and fourth resistors (R2, R4)) are preferably made of the same material and have the same shape.

[0090] It is preferable that the wires constituting the first to fourth resistors (R1 to R4), in particular, the platinum wires, are formed in any one of a coil shape, a wire roll shape, a zigzag shape, and a plate shape, so that heat generation occurs easily.

[0091] In the present invention, when manufacturing a contact combustion type gas sensor module, the integrated bonding of the sensing element (the sensing element bead (230), the first and third resistors (R1, R3)) or the compensator (the compensation element bead (280), the second and fourth resistors (R2, R4)) may be achieved by the wires constituting each resistor being bonded to the inside of the bead as shown in FIGS. 3 and 4, or by being attached to the surface of the bead as shown in FIG. 5. FIG. 5 illustrates only the sensing element being attached to the surface of the bead, but this is because the sensing element is preferably implemented like the externally exposed sensing element of FIGS. 5 to 8, and the compensator is preferably arranged inside the bead.

[0092] The detection body bead (230; 'detection body bead', 'bead for detection element') and the compensator bead (280; 'bead for compensation element') can be manufactured through a manufacturing process of simultaneously drying at room temperature, performing a low-temperature heat treatment at 200 to 300 degrees Celsius (℃), and performing a secondary high-temperature heat treatment at 700 to 1100 degrees Celsius (℃).

[0093] Each bead (230, 280) is a bead formed in the shape of a composite ceramic sphere composed of one or more materials such as metal oxide powder or non-metal oxide powder, and can be formed to surround an internal wire, for example, a platinum filament.

[0094] Fig. 4(a) illustrates a bead (230) for a sensing element, and Fig. 4(b) illustrates a bead (280) for a compensation element, and the shapes of each are not limited to those illustrated in this drawing. The shapes of the bead (230) for a sensing element and the bead (280) for a compensation element may be interchanged with each other in Fig. 4. The shapes of the bead (230) for a sensing element and the bead (280) for a compensation element may be formed into various shapes such as a sphere, an oval, a capsule, a cylinder, a plate, etc., and may be the same shape or different shapes.

[0095] Referring to FIGS. 3 and 4, the sensing element (210) may be formed such that the internal electrical resistance changes when the surface of the bead undergoes a catalytic combustion reaction with the contact gas. The sensing element (210) may include a platinum filament (531) for the sensing element, a bead (230) for the sensing element, and a nano-dispersed catalyst layer (231) for the sensing element.

[0096] The nano-dispersed catalyst layer (231) for a sensing element may be disposed on the surface of the bead (230) for a sensing element. The nano-dispersed catalyst layer for a sensing element may be a layer in which a catalyst such as platinum or palladium is dispersed and attached to the surface of the bead (230) for a sensing element in the form of nanometer-sized particles. When the catalyst of the nano-dispersed catalyst layer (231) for a sensing element comes into contact with a combustible gas (methane, propane, hydrogen, isobutane, etc.), a combustion reaction easily occurs, and the temperature of the bead (230) for a sensing element increases. As the temperature of the bead (230) for a sensing element increases, the temperature of the platinum filament (531) for a sensing element inside increases further, and accordingly, the electrical resistance value of the platinum filament for a sensing element increases.

[0097] The platinum filament (531) for the sensing element may correspond to the third resistor (R3). The first platinum filament (511) may be arranged inside the bead (230) for the sensing element and function like the platinum filament (531) for the sensing element. That is, when a combustion reaction occurs on the surface of the bead (230) for the sensing element, the temperature of the platinum filament (531) for the sensing element corresponding to the third resistor (R3) and the first platinum filament (511) corresponding to the first resistor (R1) increase, so that the respective electric resistance values ​​increase.

[0098] A platinum filament (521) for compensation elements corresponding to the second resistor (R2) and a fourth platinum filament (541) for compensation elements corresponding to the fourth resistor (R4) may be arranged inside the bead (280) for compensation elements. When current flows through the platinum filament (521) for compensation elements and the fourth platinum filament (541), each filament can emit heat.

[0099] When power is applied to each platinum filament (511, 521, 531, 541) in a state that does not react with gas, i.e., in a non-reacting state, each emits heat, but it is preferable that the temperature of the bead (230) for the sensing element and the temperature of the bead (280) for the compensation element be the same.

[0100] Each platinum filament (511, 521, 531, 541) is preferably in a coil shape. Each platinum filament (511, 521, 531, 541) may be referred to as a heating coil.

[0101] The compensation body part of Fig. 5 may be the same as Figs. 3 and 4.

[0102] Referring to FIGS. 6 and 7 according to one embodiment of FIG. 5 and FIG. 5, the sensing element (210) may include a direct catalytic combustion reaction coil (220) and a heat block (240).

[0103] Referring to Fig. 6(a), at least a portion of the direct catalytic combustion reaction coil (220) may be in contact with external air. The direct catalytic combustion reaction coil (220) may directly catalytically react with the contact gas. The heat block (240) may support the direct catalytic combustion reaction coil (220). The heat block (240) may be disposed inside the direct catalytic combustion reaction coil (220). Specifically, the heat block (240) may be disposed inside the winding wire (222).

[0104] It is preferable that the ratio of the outer line of the longitudinal cross-section of the winding wire (222) that winds the heat block (240) of the direct catalytic combustion reaction coil (220) of the contact combustion gas sensor equipped with the coil exposure type detection element of the present invention be exposed to the outside is 40% to 90%. The direct catalytic combustion reaction coil (220) may be equipped with the winding wire (222) and a connecting wire (224) that connects the winding wire (222) to a power source.

[0105] The winding wire (222) may be coil-shaped. The exposed portion of the coil-shaped winding wire (222) that directly contacts the outside air may directly undergo a catalytic combustion reaction with the contact gas. The heat block (240) may be disposed within the direct catalytic combustion reaction coil (220), particularly within the winding wire (222), and may be partially coupled with the winding wire (222) to support the winding wire (222).

[0106] The ratio of the exposed portion of the winding wire (222) may be 40% to 90% of the surface area of ​​the winding wire (222). If the exposure ratio of the winding wire (222) is less than 40%, the catalytic combustion reaction of the winding wire (222) with the contact gas may be too small, resulting in insignificant resistance change. If the exposure ratio of the winding wire (222) is greater than 90%, when the operating temperature of the winding wire (222) is maintained, too much heat is released into the air, resulting in increased power consumption, and the bonding strength between the winding wire (222) and the heat block (240) may be reduced, resulting in easy separation of the winding wire (222) and the heat block (240). Therefore, the exposure ratio of the winding wire (222) is preferably 40% to 90%.

[0107] The direct catalytic combustion reaction coil (220) is preferably made of one of platinum-based metals such as platinum (Pt), palladium (Pd), rhodium (Rh), iridium (Ir), and ruthenium (Ru), or an alloy of two or more of the platinum-based metals. The platinum-based metal alone or an alloy thereof can provide a catalytic function that allows a combustible gas (contact gas) to be combusted with oxygen at a high temperature. That is, since the platinum-based metal itself causes the combustible gas to be combusted, it is not necessary to form a nano-dispersed catalyst layer for a sensing element of a conventional sensing element. Throughout the specification, the term "direct catalytic combustion reaction" may refer to a combustion reaction of a combustible gas according to the catalytic function of the direct catalytic combustion reaction coil (220). The terms "direct catalytic combustion reaction" and "direct combustion reaction" may be used interchangeably. The term "direct catalytic combustion reaction" may refer to the catalytic combustion reaction of the direct catalytic combustion reaction coil (220). A 'direct catalytic combustion reaction' can be simply referred to as a 'direct combustion reaction'. A 'catalytic combustion reaction' can be referred to as a 'combustion reaction'.

[0108] The wire diameter of the direct catalytic combustion reaction coil (220) is preferably 5 to 40 μm. The resistance of the direct catalytic combustion reaction coil (220) is preferably 2 to 20 ohm at room temperature. The coil diameter of the direct catalytic combustion reaction coil (220) is preferably 0.1 to 0.5 mm. The number of turns (number of turns) of the direct catalytic combustion reaction coil (220) is preferably 7 to 15 turns. These specifications can be made compatible with existing catalytic combustion type gas sensors.

[0109] The direct catalytic combustion reaction coil (220) must perform operations such as catalytic combustion reaction while being maintained at a specific temperature. This specific operating temperature will be referred to as the "reaction operating temperature." Since the compensation element (260) must serve as a reference for the sensing element (210), it must be maintained at a specific reference temperature (hereinafter referred to as the "reference operating temperature"). It is preferable that the reference operating temperature be the same as the reaction operating temperature.

[0110] The direct catalytic combustion reaction coil (220) can receive power (not shown) and emit power heat (resistance heat) so that the direct catalytic combustion reaction coil (220) and / or the detection element (210) (in particular, meaning the heat block (240)) can maintain the reaction operating temperature. Since the direct catalytic combustion reaction coil (220) directly catalytically reacts with the contact gas, it is preferable that at least the direct catalytic combustion reaction coil (220) maintain the reaction operating temperature. However, since the catalytic combustion reaction also occurs in the heat block (240) that is in contact with the outside like the direct catalytic combustion reaction coil (220), it is even more preferable that the heat block (240) also maintain the reaction operating temperature.

[0111] The reaction operating temperature may be any specific temperature between 300 and 350°C. The reaction operating temperature may be determined depending on the type of gas to be detected.

[0112] Due to the combustion heat of the contact gas resulting from the direct catalytic combustion reaction of the direct catalytic combustion reaction coil (220), the temperature of the direct catalytic combustion reaction coil (220) may become higher than the reaction operation temperature.

[0113] Referring to FIG. 6, the heat block (240) may be placed inside the direct catalytic combustion reaction coil (220) to support the direct catalytic combustion reaction coil (220). The heat block (240) may be coupled to a portion of the direct catalytic combustion reaction coil (220). The heat block (240) may have a cylindrical shape, but is not limited thereto, and may have any one of an ellipsoidal shape and a polygonal columnar shape.

[0114] The heat block (240) according to the present embodiment can store power heat and combustion heat to reduce heat loss. In addition, it can play a significant role in the propagation and diffusion of the direct catalytic combustion reaction of the direct catalytic combustion reaction coil (220).

[0115] Referring to Fig. 7(a), it is preferable that the heat block body (240) has a plurality of pores (248) and / or internal passages (249) inside. The ventilation according to the plurality of pores (248) and internal passages (249) can provide the effect of expanding the surface area so that the combustion reaction of the combustible gas can occur inside the heat block body (240). In particular, the combustible gas can diffuse into the inside of the heat block body (240) through the internal passages (249).

[0116] The heat block (240) is preferably made of a large-particle ceramic material that is lightweight while maintaining structural strength. The heat block (240) is preferably made of a material capable of a co-catalyst function. The co-catalyst function can assist the catalytic combustion reaction of the direct catalytic combustion reaction coil (220) and can help maintain the diffusion reaction and heat of the catalytic combustion.

[0117] The heat block (240) can be formed as a sintered body. The material of the heat block (240) can be a composite ceramic composed of one or a combination of most metal oxides (oxides of Co, Ni, Mn, Cr, Ti, Cu, Sn, Fe, V, Ag, In, La, W, Zn, etc.), alumina, and silicon dioxide. These materials have excellent catalytic properties, far-infrared radiation properties, and long-term thermal stability. The metal oxide can undergo a catalytic combustion reaction with a contact gas to release reaction heat. This reaction heat can further increase the resistance of the winding wire (222), thereby further increasing the sensitivity of gas detection.

[0118] The particle size of the sintered body material of the heat block (240) is suitably 0.1 ㎛ to 0.4 mm. If it is smaller than 0.1 ㎛, the ventilation is poor, and if it is larger than 0.4 mm, molding may be difficult.

[0119] To ensure the ventilation of the heat block (240), it may be advantageous if the material itself has many pores and a large specific surface area. To ensure ventilation, an organic binder or carbon material may be mixed into the sintered body material. This can create a ventilation path as carbon dioxide and water vapor escape during the heat treatment process.

[0120] Referring to FIG. 7, the heat block body (240) can be divided into a plurality of blocks. The heat block body (240) can have at least a base block (242) and an adhesive block (244).

[0121] The base block (242) can be the base inside the heat block body (240). The adhesive block (244) can directly bond the base block (242) and the catalytic combustion reaction coil (220).

[0122] The base block (242) may be in the shape of a cylindrical rod. The base block (242) may be any one of a metal oxide rod, a ceramic rod, and a composite ceramic rod depending on the material. The metal oxide rod may be formed of a material including at least one of oxidized Co, Ni, Mn, Cr, Ti, Cu, Sn, Fe, V, Ag, In, La, W, and Zn. The ceramic rod may be formed of a material including at least one of alumina and silicon dioxide. The composite ceramic rod may be formed of a material including a metal oxide and a ceramic oxide.

[0123] The adhesive block (244) may be formed from a material comprising a transition metal oxide. The adhesive block (244) may be formed from a material comprising a transition metal oxide and / or a precious metal powder. Precious metal powders have good reactivity with contact gases, but their high cost may make it difficult to occupy a large portion.

[0124] Non-oxide metal powders may be further provided in the adhesive block (244), and the non-oxide metal powders may all be converted into oxides during the high-temperature heat treatment process and may have electrical insulating and catalytic properties.

[0125] Fig. 7(b) and Fig. 7(c) illustrate winding wire (222) around an adhesive block (244). As shown in Fig. 7(b) and Fig. 7(c), both ends of the heat block (240) may not be vertical and may have a round shape. Fig. 7(b) illustrates an adhesive block (244) created when the viscosity of the paste, which is the material of the adhesive block (244), is high, and Fig. 7(c) illustrates an adhesive block (244) created when the viscosity of the paste, which is the material of the adhesive block (244), is low. The exposure ratio of the winding wire (222) can be controlled by the viscosity of the paste.

[0126] The above drawings 6(a) and 7 are descriptions of a winding wire (222) that can be an example of a third resistor (R3) and a first resistor (R1).

[0127] The electrode wire (530) and the first resistance electrode wire (510) for the sensing element of FIG. 6(b) and FIG. 6(c) may each correspond to the direct catalytic combustion reaction coil (220) of FIG. 6(a). In addition, the third and first winding wires (531, 511) of FIG. 6(b) and FIG. 6(c) may each correspond to the winding wire (222) of FIG. 6(a). In addition, the heat block (240) and / or the base block (242) and the adhesive block (244) of FIG. 6(a) may correspond to the bead (230) for the sensing element.

[0128] FIG. 6(b) shows that two heat block bodies (240) are provided, such as first and second heat block bodies (240-1, 240-2). The first heat block body (240-1) may be placed inside the electrode line (530) for the sensing element, and the second heat block body (240-2) may be placed inside the first resistance electrode line (510). It is preferable that the first and second heat block bodies (240-1, 240-2) be placed adjacent to each other. The first and second heat block bodies (240-1, 240-2) may be fixed to each other by a connecting bridge (249). The connecting bridge (249) may be made of the same material as the heat block body (240). The connecting bridge (249) may be formed integrally with the heat block body (240). The number, arrangement and shape of the connecting bridge (249) can be free, and they can be in contact with or wrapped around a part of the third and first winding wires (531, 511).

[0129] Figure 6(c) illustrates that one heat block (240) is arranged so that the electrode line (530) for the sensing element and the first resistance electrode line (510) are shared with each other.

[0130] The electrode wire (530) for the sensing element and the first resistance electrode wire (510) that can be formed by the direct catalytic combustion reaction coil (220) are not limited to those in FIGS. 6(b) and 6(c), and may be arranged in a double helix shape that is twisted with each other while sharing a single heat block (240) as in FIG. 6(c). Of course, the electrode wire (530) for the sensing element and the first resistance electrode wire (510) must be electrically insulated.

[0131] The attachment of the first and third resistors (R1, R3) that can constitute the detection body to the surface of the bead (230) for the detection element can be implemented in various ways, and FIG. 8 illustrates one of them.

[0132] The bead (230) for the sensing element may be a rectangular parallelepiped, as shown in Fig. 8, but is not limited thereto. The bead (230) for the sensing element may correspond to the heat block body (240) described above. The first and third resistors (R1, R3) may be attached to positions corresponding to the outer surface of the bead (230) for the sensing element.

[0133] Semiconductor gas sensors can be classified into hot-wire semiconductor gas sensors with their own heaters and non-hot-wire semiconductor gas sensors without their own heaters in the form of thin films, thick films, or bulk sintered bodies.

[0134] The structure of the hot-wire semiconductor gas sensor is comparable to that of the previously described contact combustion gas sensor. The internal platinum coil functions as a heating element, ensuring that the bead remains at operating temperature.

[0135] A non-thermal semiconductor gas sensor may be equipped with a separate heater. Referring to Fig. 10, two sensing elements (first and third resistors (R1, R3)) may be formed on a single substrate, and a heater (R_h1, R_h2) may be formed in the center. The heater may be placed on the back of the substrate.

[0136] The sensor operating temperature can be transmitted equally to the sensing element and the compensation element so that they become the same temperature. It is preferable that the second and fourth resistors (R2, R4) use the same semiconductor material as the sensing element (the first and third resistors (R1, R3)) and have the same specifications. A catalyst should not be added when manufacturing the second and fourth resistors (R2, R4). They can be made as an integrated unit, such as in the contact combustion type.

[0137] The beads of a non-thermal semiconductor gas sensor can be circular or oval, similar to a contact electrode, or can be of various shapes and forms, such as square. Since a non-thermal semiconductor gas sensor does not have its own heater, a heater can be inserted into the center of the detection or compensating bead.

[0138] It is preferable that a pair of electrode wires inserted into the bead be arranged symmetrically with respect to the heater. Through the inserted electrode wires (510 to 540) and the sensor bead and compensator bead, a sensor (first and third resistors (R1, R3)) or a compensator (second and fourth resistors (R2, R4)) can be formed. The sensor must have a catalytic combustion function.

[0139] Specifically, the first and third resistance electrode lines (510, 530) of the semiconductor sensing element can be integrated by being bonded to the sensing element bead (230). In the present embodiment, the sensing element bead (230) is preferably made of a semiconductor material, unlike the contact combustion type gas sensor, and the same applies to the compensation element bead (280).

[0140] The second and fourth resistance electrode lines (520, 540) are also integrally connected to the compensation element bead (280), and a coil-shaped or zigzag-shaped heater (R_h2) can be placed in the central portion of the bead to have the same operating temperature.

[0141] The first to fourth resistance electrode lines (510 to 540) can be manufactured so that the middle is open and connected in series with a bead of semiconductor material.

[0142] The detector and compensator have a heater electrode line in the center and resistors (R1-R3, R2-R4) forming paired resistors on the left and right thereof. The electrode lines can be made of a material with excellent heat resistance, corrosion resistance, and electrical conductivity, such as gold (Au), platinum (Pt), and can be arranged at equal intervals.

[0143] In the case of semiconductor type, it is preferable to use materials for the paired resistor (R4) and compensator (R2) beads of the compensation element that are identical to the sensing element configuration, but without the addition of precious metal materials such as Pt, Pd, Rh, and Au that have a catalytic function required for adsorption / desorption or combustion.

[0144] At least one of the first to fourth resistors (R1 to R4) may be a single or composite metal oxide semiconductor material such as SnO2, TiO2, ZnO, In2O3, WO3, CuO, NiO, V2O5, Fe2O3, MnO2, Co2O3, Ag2O, ZrO2, La2O3, etc. having the same resistance value and the same temperature coefficient of resistance.

[0145] In the case of a self-heating hot wire semiconductor as a semiconductor gas sensor, it can be manufactured in a shape like that of Fig. 3 described above. In this case, it is preferable that each bead has a flat shape rather than a three-dimensional shape like that of Fig. 4.

[0146] A method of manufacturing a sensor or compensator bead using a substrate. The substrate may be an insulator such as alumina or a combustible material. The insulator substrate becomes part of the device, and the substrate of a combustible material such as paper, rubber, or plastic polymer is removed by combustion during high-temperature heat treatment.

[0147] The shape of the sensor or compensator bead may be circular, semicircular, square, or other shapes. The manufacturing method of each bead is described below.

[0148]

[0149] Example 1: Catalytic combustion gas sensor module for propane gas with integrated pair resistance of dispersed catalyst beads

[0150] The electrode resistance wire, which is made of a single metal such as Pt, Pd, Rh, Ir, Os, or Ru or an alloy thereof with other metals, has a diameter of 10 to 40 μm, a resistance of 3 to 20 ohms at room temperature, a coil diameter of 0.1 to 0.5 mm, a length of 0.3 to 1.2 mm, a number of coils of 4 to 12 turns, and lead wires at both ends of 0.4 to 0.8 mm. The coil for the sensing element (R3) and its counterpart resistor coil R1, the coil for the compensation element (R2) and its counterpart resistor coil R4 can be prepared with the same specifications.

[0151] Referring to Fig. 10(a), in order to manufacture a sensing element bead module, a pair of W-shaped stands (700) are provided at intervals of 1.5 mm, and these are suspended in the air, and the above R1 and R3 coils are each positioned in the W-shaped grooves of the stands (700). At this time, the two coils are brought as close as possible so that they do not come into contact with each other.

[0152] Referring to Fig. 10(b), a carrier of the sensing paste is applied so that two coils are sufficiently contained inside, as in Fig. 4. After drying in the air for more than one hour, the sensing paste with the secondary catalyst dispersion can be further coated and dried.

[0153] Meanwhile, the compensation element bead module is manufactured similarly to the sensing element bead module described above. Compensation paste can be first applied and air-dried. Then, a second layer of nanopaste can be applied and dried.

[0154] After that, the above two final heat treatments can be performed by placing the above sensing element and compensation element bead modules simultaneously in a 900°C electric furnace. The heating time is 1 hour and the holding time is 30 minutes, and each module is completed through natural cooling, and a platinum coil exposed-pair resistance integrated contact combustion gas sensor module consisting of a sensing element module and a compensation element module can be completed by wedding each pin electrode.

[0155]

[0156] Example 2: Manufacturing of a contact combustion gas sensor module for methane gas with an exposed platinum coil and a paired resistor integrated therein.

[0157] In this embodiment, almost all processes are the same as in Embodiment 1, but only the sensing element bead module is different.

[0158] As shown in Fig. 5, the outer surfaces of the two coils (R1 and R3) are exposed, and the sensing paste is applied only once so that the common inner surface is connected. It can be dried in the air for more than one hour. The final heat treatment and pin electrode connection can be performed as in Example 1.

[0159]

[0160] Example 3: Manufacturing of a semiconductor carbon monoxide gas sensor module with a paired resistor integrated therein.

[0161] The heater wire, which is made of Pt, Pd, Rh, Ir, Os, Ru alone or in the form of an alloy with other metals, has a diameter of 10 to 40 μm and a resistance of 3 to 20 ohms at room temperature. The coil diameter of the heating part is 0.1 to 0.5 mm, the length is 0.3 to 1.2 mm, the number of coils is 4 to 12 turns, and the lead wires at both ends are 0.4 to 0.8 mm. All electrode wires can use materials of the same specifications as the above heater wire, but additionally, gold (Au) wire can also be used. In this implementation, gold wire is used.

[0162] As shown in Fig. 11, the sensing element bead module may have a heater coil in the center, and sensing element (R3) electrode lines and their matching resistor R1 electrode lines may be formed on both sides. The spacing between the sensing element (R3) electrode lines may be 0.01 to 0.1 mm, and may be positioned close to the heater coil without contacting it. The matching resistor R1 electrode line may also be positioned on the opposite side from the sensing element (R3) electrode line.

[0163] When performing this task, a hemispherical or thin-walled elliptical column detector can be formed on a substrate (600) as shown in Fig. 11. The substrate can be a heat-resistant, general ceramic plate or a combustible paper or polymer material that is combusted and disappears through high-temperature heat treatment. In this example, general paper was used.

[0164] A bead module for an integrated semiconductor carbon monoxide gas sensor including a paired resistor can be formed by applying a SnO2 metal oxide semiconductor paste to which a 5% weight ratio of Pd catalyst is added.

[0165] The manufacture of a bead module for a compensation element, which is composed of a compensation element (R2) electrode wire and its matching resistor (R4), can also be formed using the same heater coil and electrode wire. However, the paste used here can be the same SnO2 paste without a catalyst added.

[0166] After drying each bead module in the air for 1 to 3 hours, heat treatment can be performed by placing each sensing element and compensation element bead module simultaneously in a 900°C electric furnace. The heating time is 1 hour and the holding time is 30 minutes, and each module is completed through natural cooling. By welding each pin electrode, a paired resistor integrated semiconductor carbon monoxide gas sensor module consisting of a sensing element module and a compensation element module can be completed.

[0167] Referring to FIG. 1, a gas sensor having a gas sensor detection module of a Wheatstone bridge circuit may further include a sensor body (30) and a plurality of electrode poles (110) in addition to the detection module described above.

[0168] 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.

[0169] 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.

[0170] The lower side of the plurality of electrode poles (110) can be connected to a sensing circuit as shown in Fig. 2. The sensing circuit is a circuit that can measure at least one of current, voltage, and resistance, or measure the on / off of current, and may include a Wheatstone bridge circuit.

[0171] Referring to FIGS. 1 and 2, the semiconductor and contact combustion composite gas sensor may further include a blocking plate (40). When the detection module (120) contacts and combusts with gas, the temperature may further increase. The blocking plate (40) may block the radiant heat of the detection module (120), thereby preventing the high temperature of the detection module (120) from affecting the compensation module (140).

[0172] In a Wheatstone bridge detection circuit type gas sensor, the compensation element corresponding to the reference resistance is made to have the same operating temperature, material, and shape as the detection element, thereby eliminating external influences such as temperature, humidity, air pressure, and other miscellaneous gases compared to using a general resistance element, thereby improving the accuracy and stability of the output value and greatly increasing long-term reliability.

[0173] In addition, by connecting the paired resistor of the sensing element to the sensing element detection body bead, the paired resistor can also obtain a resistance change due to the same reaction as the sensing element, thereby increasing the detection sensitivity by up to two times, which is advantageous for low-concentration gas detection, and can reduce noise signals resulting from output signal amplification.

[0174] 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.

[0175] 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.

[0176] <Explanation of symbols>

[0177] 30: Sensor body 40: Blocking plate

[0178] 210: Sensing element 230: Bead for sensing element

[0179] 260: Compensation element 280: Bead for compensation element

Claims

1. A gas sensor detection module of a Wheatstone bridge circuit, comprising a detection circuit of a gas sensor that senses gas using a voltage difference between first and second voltage terminals, wherein the detection circuit constitutes a Wheatstone bridge circuit. A sensing element that constitutes the above gas sensor and reacts with gas; Compensation element that constitutes the above gas sensor and does not react with gas; and comprising first and second power terminals for providing power to the Wheatstone bridge circuit; The above sensing element comprises: a sensing element bead; and an electrode line for the sensing element that connects the second voltage terminal and the second power terminal and whose resistance value changes when reacting with a specific gas; The electrode wire for the above sensing element has a third resistor corresponding to the resistance value at both ends thereof, The above compensation element comprises a bead for the compensation element; and a second resistor having a resistance value corresponding to the third resistor; and an electrode line for the compensation element connecting the first power terminal and the second voltage terminal; A first resistor electrode line having a first resistor corresponding to the third resistor and connecting the first power terminal and the first voltage terminal; and It further includes a fourth resistor corresponding to the second resistor, and a fourth resistor electrode line connecting the first voltage terminal and the second power terminal, A gas sensor detection module of a Wheatstone bridge circuit, wherein the resistance of the first resistor varies in response to a change in the resistance of the third resistor, and the resistance of the fourth resistor varies in response to a change in the resistance of the second resistor.

2. In paragraph 1, A gas sensor detection module of a Wheatstone bridge circuit, wherein the first and third resistance electrode lines are adjacent to each other and connected to the bead for the sensing element, and the second and fourth resistance electrode lines are adjacent to each other and connected to the bead for the compensation element.

3. In paragraph 2, The above gas sensor is a contact combustion type gas sensor, The first and third resistors each have first and third heating coils, The first and third heating coils are, Placed and bonded inside the bead for the above sensing element, and A gas sensor detection module of a Wheatstone bridge circuit, wherein at least a portion of the first and third heating coils are attached to the outside of the bead for the sensing element, and at least another portion of the first and third heating coils is exposed and attached to the bead for the sensing element.

4. In paragraph 3, The second and fourth resistors are provided with second and fourth heating coils, respectively, A gas sensor detection module of a Wheatstone bridge circuit, wherein the first to fourth heating coils generate heat when power is applied.

5. In paragraph 3, The above first resistance electrode line is attached to the outside of the bead for the sensing element, The above first resistance electrode wire has a winding wire having a portion directly exposed to the outside air, The above winding wire is a gas sensor detection module of a Wheatstone bridge circuit that directly reacts catalytically with gas that comes into contact with the exposed portion in the outside air.

6. In paragraph 3, A gas sensor detection module of a Wheatstone bridge circuit, wherein at least one of the first to fourth resistors is any one of platinum and platinum wire and a platinum-like metal having a temperature-resistance coefficient within a preset range.

7. In paragraph 2, The above gas sensor is a semiconductor gas sensor, It further comprises a heater electrode wire having a heating resistor that emits heat when power is applied, A gas sensor detection module of a Wheatstone bridge circuit, wherein the heater electrode wire comprises: a first heater electrode wire passing between the first and third resistance electrode wires; and a second heater electrode wire passing between the second and fourth resistance electrode wires.

8. In paragraph 7, A gas sensor detection module of a Wheatstone bridge circuit, wherein the first to fourth resistors are formed of a single or composite metal oxide semiconductor material of SnO2, TiO2, ZnO, In2O3, WO3, CuO, NiO, V2O5, Fe2O3, MnO2, Co2O3, Ag2O, ZrO2, and La2O3.

9. In paragraph 8, The first to fourth resistors are formed of the same material, A gas sensor detection module of a Wheatstone bridge circuit, wherein the first and third resistors use at least one of a noble metal and a transition metal as a catalyst.

10. A gas sensor having a gas sensor detection module of a Wheatstone bridge circuit according to any one of claims 1 to 9.

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