Detection device

Abstract

The problem that this invention aims to solve is to provide a detection device that can achieve accurate correction in the transient response of the detection device. [Solution] The detection device of the embodiment comprises a container having a lid and a sensor substrate located inside the container and holding a sensor chip. The lid has two or more holes in a second region which is an area outside the first region which is an area of ​​the lid facing the sensor chip.

Description

Technical Field

[0001] This embodiment relates to a detection device.

Background Art

[0002] A detection device can measure the concentration of a gas in a container in which a sensor chip is disposed. At this time, when measuring the gas concentration, it is necessary to correct for fluctuations in temperature, humidity, and atmospheric pressure. When a transient response of the gas concentration occurs in the container, it is necessary to equalize the response speeds of each sensor in order to achieve accurate correction in the transient response. The response speed of each sensor depends on the flow rate of the gas flowing in the container in which the sensor is disposed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The problem to be solved by the present invention is to provide a detection device capable of achieving accurate correction in the transient response of the detection device. <00,00027>

Means for Solving the Problems

[0005] The detection device according to the embodiment includes a container having a lid, and a sensor substrate located inside the container and holding a sensor chip. The lid has two or more holes in a second region that is an outer region of the lid rather than a first region that is a region facing the sensor chip.

Brief Description of the Drawings

[0006] [Figure 1] It is a perspective view and a schematic cross - sectional view of the detection device 1 in the first embodiment. [Figure 2]This is a schematic cross-sectional view showing a part of the detection device 1 in the first embodiment. [Figure 3] This is a schematic diagram showing an example of the area around the sensor substrate. [Figure 4] This is a schematic diagram showing an example of the lid 18 in the first embodiment. [Figure 5] This is the simulation result of the gas flow near detection device 1. [Figure 6] This is the result of simulating the airflow velocity by changing the position of hole 20. [Figure 7] This is a schematic diagram showing an example of the lid 18 in the first embodiment. [Figure 8] This is the result of simulating airflow velocity by changing the pore size. [Figure 9] This is an example of a simulation result of the gas flow near detection device 1. [Figure 10] This graph shows the velocity distribution measured along the x-axis. [Figure 11] This is a schematic diagram showing an example of the lid 18 in the first embodiment. [Figure 12] This is a schematic diagram showing an example of the lid 18 in the first embodiment (first modified example). [Figure 13] This is a schematic cross-sectional view showing a part of the detection device 1 in the second embodiment. [Figure 14] This is the result of simulations with varying pore sizes. [Figure 15] This is the result of simulations with varying pore sizes. [Figure 16] This is the result of simulations performed by changing the distance h2 between the lid 18 and the sensors. [Figure 17] This is a schematic diagram showing the relationship between airflow and diffusion direction. [Figure 18] This graph shows the time evolution of the normalized diffusion amount N(z,t) / N0. [Modes for carrying out the invention]

[0007] The embodiments will be described below with reference to the attached drawings. In each embodiment, substantially identical components will be denoted by the same reference numerals, and their descriptions may be partially omitted. The drawings are schematic, and the relationship between the thickness of each part and its planar dimensions, the ratio of the thicknesses of each part, etc., may differ from those in reality.

[0008] (First embodiment) Figure 1 is (a) a perspective view and (b) a schematic cross-sectional view of the detection device 1 in this embodiment. The detection device 1 has a housing wall 10, a package 12 is arranged in the space enclosed by the housing wall 10, and a sensor substrate 15 equipped with a sensor chip 14 is arranged inside the package 12. A battery 30 for supplying power to the sensor substrate 15 is provided below the package 12. The space outside the housing wall 10 and the space inside the package 12 are separated by a membrane 16 and a lid 18. The shape of the detection device 1 shown is merely an example, and the shape of the housing wall 10, the position, size, and shape of the container 12 are not limited to the configuration shown in the figure. Figure 2 is a schematic cross-sectional view showing a part of the detection device 1. The detection device 1 according to this embodiment includes a housing wall 10, a package 12 (container), a sensor chip 14, a sensor substrate 15 that holds the sensor chip 14, a membrane 16, and a lid 18. The top surface of the package 12 is an opening, and this opening is closed by a flat lid 18. On the opposite side of the package 12 from the lid 18, a membrane 16 is positioned. In one example shown in the figure, the membrane 16 is attached so as to cover the lid 18, and the lid 18 and the membrane 16 are in contact. The vertical relationship between the membrane 16 and the lid 18 may be as shown in the figure, or the membrane 16 may be positioned between the lid 18 and the package 12. According to this embodiment, there is a space partitioned from the outside by the lid 18, the membrane 16 and the package 12. This space will be referred to as the "first space" from now on.

[0009] On one hand, the space surrounded by the housing wall 10 and the membrane 16 is defined as the "second space". The bottom surface of the second space is the membrane 16, and the side surface of the second space is the housing wall 10. Since the surface facing the bottom surface of the second space is the opening of the housing wall 10, the second space is an open system. In this embodiment, if the depth of the second space, that is, the dimension h1 in the direction perpendicular to the bottom membrane 16, is significantly smaller than the distance L1 between the housing walls 10, no vortex will occur in the second space. If the dimension h1 is significantly larger than the distance L1, a plurality of turbulent flows will occur in the second space and the flow velocity at the bottom of the second space will slow down. Therefore, it is preferable that h1 is not less than 1 / 2 times and not more than 3 times of L1.

[0010] Figure 3 is a schematic diagram showing an example around the sensor substrate. Figure 3(a) is a schematic diagram when the sensor substrate 15 is viewed from the lid 18 side (upper surface), Figure 3(b) is a schematic diagram when the sensor substrate 15 is viewed from the back side (lower surface) of the surface facing the lid 18, and Figure 3(c) is a schematic diagram corresponding to a cross-sectional view along A - A' in Figures 3(a) and 3(b). In Figure 3, the direction from the surface (lower surface) of the sensor substrate 15 with the microcontroller circuit 54 to the surface (upper surface) with the sensor chip 14 and the sensor circuit is defined as the Z-axis direction, the direction intersecting the Z-axis direction is defined as the X-axis direction, and the Y-axis direction is defined as shown in Figure 3.

[0011] Inside the package 12 is a sensor substrate 15, and multiple sensor chips 14 are arranged on the upper surface of the sensor substrate 15. At least one of the sensor chips 14 is a TC (Thermal Conductivity) sensor capable of detecting at least one selected from the group consisting of hydrogen, oxygen, and VOCs (Volatile Organic Compounds). In addition, as a sensor chip 14 other than the TC sensor, at least one of either a temperature sensor capable of measuring the temperature inside the package 12 or a humidity sensor capable of measuring the humidity inside the package 12 is arranged inside the package 12. The sensor chips 14 are attached to the sensor substrate 15 and arranged inside the package 12. It is preferable that the distance from the upper surface of the sensor chip 14 to the lid 18 is approximately constant. That is, it is preferable that the surface of the sensor chip 14 facing the lid 18 has a structure that is as flat as possible. This is to ensure that the shape and arrangement of the sensor chip 14 do not obstruct the airflow in the first space by the upper surface of the sensor chip 14. It is preferable that the sensor chips 14 and the sensor substrate 15 are arranged in the center of the package 12.

[0012] Although not shown in other drawings, as shown in Figure 3(a), the sensor circuit on the top surface of the sensor board 15 includes an AD conversion circuit 51, a boost circuit 52, and a buck circuit 53, in addition to the sensor chip 14. The AD conversion circuit 51 is a circuit that converts voltage and capacitance analog signals into voltage digital signals. The boost circuit 52 and buck circuit 53 are used to adjust the power supply provided to the sensor chip 14. Other circuits may also be provided.

[0013] Although not shown in other drawings, as shown in FIG. 3(b), a communication unit 40, a microcomputer circuit 54, a power supply circuit 55, and a power supply unit 56 are provided on the lower surface of the sensor substrate 15. The communication unit 40 can transmit information regarding the detection result of the sensor chip 14 to an external device. The detection result includes, for example, information (data) regarding the concentration of the target detection object. The transmission may be performed, for example, by at least either wired or wireless means. The microcomputer circuit 54 controls data communication, controls the sensor circuit, and controls the on / off of the sensor chip 14. The microcomputer circuit 54 is provided with means for executing control based on changes in the detector in the sensor chip 14 as a software configuration that functions by executing a built-in control program. The power supply circuit 55 supplies an appropriate voltage to the microcomputer circuit 54 and the sensor circuit. The power supply unit 56 is a location connected to the battery 30 that serves as a power source.

[0014] FIG. 3 shows an example in which the microcomputer circuit 54 is provided on one surface of the sensor substrate 15 and the sensor circuit is provided on the other opposite surface, but the substrate on which the microcomputer circuit 54 is provided and the substrate on which the sensor circuit is provided may be prepared separately. In such a case, for example, by connecting each substrate with something like a cable connector, a control signal from the microcomputer circuit 54 is sent to the sensor circuit, and data acquired from the sensor circuit is sent to the microcomputer circuit 54.

[0015] At least a part of the film 16 is, for example, a microporous film or non-woven fabric containing PTFE (polytetrafluoroethylene). Since the film 16 can permeate gases such as air, moisture, and gas, the first space and the second space are not in a strictly isolated state, but since the film 16 does not permeate liquid, liquid cannot enter or exit between the first space and the second space. The sensor chip 14 is disposed in the first space. In the present embodiment, the thickness and pore diameter of the film 16 are not particularly limited, but an appropriate film can be selected according to the properties of the gas to be detected and the measurement environment when actually using the detection device 1.

[0016] The lid 18 has multiple holes 20. Since gas enters and exits between the first space and the second space through the holes 20, the position, size, shape, and number of holes 20 affect the gas flow in the first space. A schematic diagram showing an example of the lid 18 in this embodiment is shown in Figure 4. The lid 18 of the detection device 1 has two or more holes 20 in the second region, which is the region outside the first region, which is the region of the lid 18 facing the sensor chip 14. In Figure 4, the second region is shown in shaded area.

[0017] Figure 5 shows the simulation results of the gas flow near the detection device 1. Figure 5 shows the flow velocity in a cross-sectional view along the dashed line X-X' in Figure 4. In the region opposite the first space across the second space (hereinafter referred to as the "upper region of the detection device 1" in this specification), there is gas flowing from left to right on the drawing. This airflow corresponds to the white arrow in Figure 4. As a result, a clockwise vortex of airflow is generated in the second space. As a result, an airflow directed to the left is generated near the sensor chip 14 in the first space. The simulation was performed assuming a gas flow velocity of approximately 1 m / sec in the upper region of the detection device 1, and the flow velocity along the line connecting the center of the sensor chip 14 and the center of the lid 18 (the point where the horizontal axis value is 0.003 in Figure 5) was calculated by simulation. Here, L2 is the distance between one inner wall surface of package 12 and the other inner wall surface facing it, and d is the shortest distance from the center of the hole 20 to the outer edge of the space enclosed by package 12 and lid 18 (first space) when projected perpendicularly onto lid 18. The simulation was performed with L2 = 4 mm. Figure 5 shows the results when d / L2 is the ratio of the distance (width) between the inner walls of package 12 to the distance from hole 20 to the inner wall surface, and d / L2 = 0.1, 0.2, 0.3, and 0.4 from left to right. Note that the larger d / L2 is, the closer hole 20 is positioned to the inside of lid 18. When d / L2 = 0.1 or d / L2 = 0.2, according to the settings of this simulation, hole 20 is located in the second region (the region of lid 18 that is outside the first region, which is the region facing the sensor chip 14). Since a uniform flow is formed between the two holes 20, when d / L2 = 0.1 or d / L2 = 0.2, the airflow over the top surface of the sensor chip 14 can be made uniform. On the other hand, when d / L2 = 0.3 or d / L2 = 0.4, in addition to the uniform flow from one hole 20 (right side in the figure) to the other (left side in the figure) within the first space, a flow is also generated outside the holes 20, resulting in an uneven flow over the top surface of the sensor chip 14. Figure 6 also shows the results of simulating the airflow velocity along the line connecting the center of the bottom surface of the first space and the center of the lid 18, by changing the position (value of d) of the hole 20, which has a hole diameter of 0.3 mm.Figure 6 shows the results when d = 0.4, 0.8, 1.2, and 1.5 mm, respectively. The values ​​on the horizontal axis of the graph in Figure 6 correspond to the vertical axis in Figure 5. The point where the Y position shown on the horizontal axis is Y position = 0.0012 [m] corresponds to the position of the upper surface of the sensor chip 14, where Y position = 0.0018. The location marked [m] corresponds to the surface of the lid 18 that is in contact with the first space. Regardless of the position of the hole 20 (value of d), the airflow velocity in the center of the first space reached its maximum value at the point where the distance from the top surface of the sensor chip 14 and the distance from the surface of the lid 18 that is in contact with the first space are equal (Y position = 0.0015 [m]). Changing the position of the hole 20 (value of d) resulted in a change in the maximum velocity. As d increased to 0.4, 0.8, and 1.2 mm, the maximum velocity increased, and when d=1.5 mm, the maximum value was slightly smaller than when d=1.2 mm. In other words, as far as the simulations show, with d=1.2 mm being the peak, the airflow velocity in the center of the first space decreases as d decreases, and the uniformity of the airflow velocity within the first space increases. In the detection device 1 shown in this embodiment, when the measurement result of the TC sensor is corrected by the measurement result of the temperature sensor or humidity sensor, a means to prevent the accuracy of the correction from decreasing due to differences in the response speed of each sensor is to suppress the generation of turbulence in the first space, reduce the velocity of the airflow, and make the velocity of the airflow in the first space uniform. Therefore, in this embodiment, it is preferable that the position of the hole 20 provided in the lid 18 of the detection device 1 is close to the package wall. Specifically, the shortest distance (here d) from the center of the hole 20 to the outer edge of the space enclosed by the package 12 and the lid 18 (the first space) when the first space is projected perpendicularly onto the lid 18 is 1 / 5 or less of the characteristic length (here L2) of the first space. Note that the lower limit of the ratio d / L2, which is the ratio of the shortest distance d from the center of the hole 20 to the outer edge of the first space to the characteristic length L2 of the first space, may change depending on the diameter of the hole 20, etc., so no specific lower limit is set, but the hole 20 may be provided so as to be in contact with the outer edge of the first space when the first space is projected perpendicularly onto the lid 18. The characteristic length L2 of the first space is defined as, for example, the length of the longer side of the first space if the shape of the first space is rectangular, the diameter of the first space if the shape of the first space is circular, the length of the major axis of the first space if the shape of the first space is elliptical, and the maximum length of the shadow when the first space is projected in a direction parallel to the lid 18 if the shape of the first space is any other shape.Furthermore, as shown in Figure 4, the lid 18 has holes 20 in a second region which is outside the first region which is the region facing the sensor chip 14. Moreover, as shown in Figure 7, it is more preferable to have two or more holes 20 in a fourth region which is outside the third region which is the region facing the sensor substrate 15. This is to make the airflow over the top surface of the sensor chip 14 uniform. In Figure 7, the fourth region is shown in shaded area.

[0018] Figure 8 shows the simulation results of the airflow velocity along the line connecting the center of the sensor chip 14 in the first space and the center of the lid 18, with varying hole diameters. The results are shown for hole diameters of 0.1, 0.2, 0.3, 0.4, and 0.5 mm, located at d=1.1 mm from the left and right package walls, respectively. The values ​​on the horizontal axis of the graph in Figure 8 correspond to the vertical axis in Figure 5. The Y position shown on the horizontal axis corresponds to the position of the top surface of the sensor chip 14 at Y position = 0.0012 [m], and the Y position corresponds to the surface of the lid 18 that is in contact with the first space at Y position = 0.0018 [m]. In addition, regardless of the hole diameter from the package wall, the airflow velocity in the center of the first space was maximized at the point where the distance from the top surface of the sensor chip 14 and the distance from the surface of the lid 18 that is in contact with the first space are equal (Y position = 0.0015 [m]). A significant change in the maximum velocity was observed by changing the hole diameter. In the range of pore diameters from 0.1 mm to 0.5 mm, the maximum velocity decreased as the pore diameter decreased. In other words, as far as the simulations show, the smaller the pore diameter, the lower the airflow velocity in the center of the first space, and the greater the uniformity of the airflow velocity within the first space. When correcting the measurement result of the TC sensor with the measurement result of a temperature sensor or humidity sensor, as in the detection device 1 shown in this embodiment, it is conceivable to reduce the airflow velocity within the first space and make the airflow velocity uniform as a means to prevent a decrease in the accuracy of the correction due to differences in the response speed of each sensor. Therefore, it is preferable that the pore diameter of the hole 20 provided in the lid 18 of the detection device 1 is sufficiently small compared to the dimensions of the lid 18. Specifically, the pore diameter is preferably 0.5 mm or less, and more preferably 0.3 mm or less. There is no particular lower limit for the pore diameter, but since it is necessary for the gas to be measured to flow into the first space to some extent, it is considered preferable to set it to, for example, 0.05 mm or more.

[0019] Next, we will explain the number of holes along the line X-X' connecting the first hole 21 and the second hole 22, when one of the two holes 20 provided in the first region is designated as the first hole 21 and the other as the second hole 22. In the lid 18 according to this embodiment, it is preferable that the number of holes along X-X' is two in principle. That is, it is preferable that there are no holes on X-X' between the first hole 21 and the second hole 22. However, this does not mean that the problem is not solved and the effects of the invention are not achieved as soon as another hole 20 is provided between the two holes 20 along X-X'. For example, another hole 20 may be provided between the two holes 20 along X-X', and the number of holes 20 along X-X' may be three. This is because when the number of holes 20 along X-X' is two or three, the velocity of the airflow in the first space is uniform. If there are four or more holes 20 along X-X', the velocity of the airflow in the first space becomes non-uniform, so it is preferable to limit the number of holes 20 along X-X' to two or three. Figure 9 shows an example of the simulation results of the gas flow near the detection device 1. Figure 9 shows the flow velocity in a cross-sectional view along X-X' as in Figure 4 or Figure 7. Similar to the simulation shown in Figure 5, there is gas flowing at 1 m / sec towards the right side of the drawing in the upper region of the detection device 1, and the distance L2 between one inner wall surface of the package 12 and the other inner wall surface facing it is 4 mm. The hole diameters in Figure 9 are all 0.2 mm. In Figure 9(a), there are two holes 20 along X-X', and the shortest distance between the center of the holes 20 and the outer edge of the lid 18 is 0.5 mm each. The hole 20 on the left in the figure is called the first hole 21, and the hole 20 on the right is called the second hole 22. In Figure 9(b), there are three holes 20 along X-X', and in addition to the case in (a), one more hole 20 is added between the first hole 21 and the second hole 22. In Figure 9(c), there are four holes 20 along X-X', and in addition to the case in (a), two holes 20 are added between the first hole 21 and the second hole 22, such that the shortest distance between the center of the hole 20 and the outer edge of the lid 18 is 1.3 mm. In Figure 9(d), there are five holes 20 along X-X', and in addition to the case in (c), a central hole 20 is added.Figure 10 is a graph showing the velocity distribution of the airflow measured along the horizontal axis of Figure 9 at the point where the distance from the top surface of the sensor chip 14 is equal to the distance from the surface of the lid 18 that contacts the first space (Y position = 0.0015 [m]). Results (a) are shown with a solid line, (b) with a dotted line, (c) with a dashed line, and (d) with a chained line. From Figure 10, the results can be broadly divided into two groups: when the number of holes 20 along X-X' is 2 or 3, and when the number of holes 20 along X-X' is 4 or 5. When the number of holes 20 along X-X' is 4 or 5, the flow velocity near the center of the first space was more than double the flow velocity when the number of holes 20 along X-X' was 2 or 3. From this result, it can be seen that in order to make the velocity distribution of the airflow in the first space uniform, it is preferable that the number of holes 20 along X-X' be 2 or 3. However, the number of holes 20 along X-X' is not necessarily limited to 2 or 3. The fast airflow in the graphs (c) and (d) of Figure 10 is thought to be due to the influence of the holes 20 near the center of the lid 18, so it is thought that if the diameter of these holes is sufficiently smaller than the diameter of the outer holes, it may be possible to suppress the fast airflow. Therefore, for example, small holes with a diameter of 1 / 3 or less of the diameter of the outer holes 20 (first hole 21, second hole 22) may be provided along X-X' in addition to the 2 or 3 holes 20 along X-X'.

[0020] If there are two holes 20 along X-X', and one hole 20 is designated as the first hole 21 and the other as the second hole 22, it is preferable that the first hole 21 and the second hole 22 are positioned approximately symmetrically with respect to the point obtained by projecting the center point of the sensor chip 14 perpendicularly onto the lid 18. Here, the center point of the sensor chip 14 is defined as the centroid of the projected shadow figure when all of the sensor chips 14 are projected perpendicularly onto the lid 18, in the case of one or more sensor chips 14. Furthermore, as shown in Figure 11(a), if one side of the outer circumference of the lid 18 is designated as the first side, the side parallel to the first side as the third side, the side intersecting the first side as the second side, and the side parallel to the second side as the fourth side, it is preferable to arrange the holes such that the distance between the first hole 21 and the first side is equal to the distance between the first hole 21 and the third side, and the distance between the second hole 22 and the first side is equal to the distance between the second hole 22 and the third side. In Figure 11, the white arrow indicates the direction of airflow in the upper region of the detection device 1. As shown in Figure 11(a), the straight line connecting the first hole 21 and the second hole 22 can be approximately parallel to the airflow indicated by the white arrow. In this specification, the distance between the hole 20 and the edge is described as the shortest distance between the center of the hole 20 and the outer edge of the lid 18.

[0021] However, the holes do not necessarily have to be positioned such that the distance between the first hole 21 and the first side is equal to the distance between the first hole 21 and the third side, and the distance between the second hole 22 and the first side is equal to the distance between the second hole 22 and the third side. In other words, the straight line connecting the first hole 21 and the second hole 22 does not necessarily have to be parallel to the airflow in the upper region of the detection device 1. As shown in Figure 11(b), the straight line connecting the two holes and the airflow may intersect. In the example shown in Figure 11(b), the hole 20 is located in the region near the corner of the lid 18. If we define one side of the outer circumference of the lid 18 as the first side, the side parallel to the first side as the third side, the side intersecting the first side as the second side, and the side parallel to the second side as the fourth side, then the distance between the first hole 21 and the first side is equal to the distance between the first hole 21 and the second side, and the distance between the second hole 22 and the third side is equal to the distance between the second hole 22 and the fourth side.

[0022] In this way, by providing holes 20 with a diameter of a predetermined size or less towards the outside of the lid 18, specifically in the second region, the flow velocity inside the container can be reduced, and the time constant associated with the gas inflow into the package 12 can be made larger than the time constant of the sensor chip 14, which has the largest time constant. This enables accurate correction of the transient response of the detection device.

[0023] The detection device 1 may further include a communication unit. The communication unit may be located inside the first space or outside the first space. The communication unit can transmit information regarding the detection results of the sensor chip 14 to an external device. The detection results include information (data) such as the concentration of the target substance to be detected. Transmission may be performed, for example, by wired or wireless connection.

[0024] (First variation) According to this modified example, the lid 18 of the detection device 1 may have a hole 20 in addition to the first hole 21 and the second hole 22. For example, according to the embodiment shown in Figure 12, the lid 18 of the detection device 1 further includes a third hole 23 and a fourth hole 24 in addition to the first hole 21 and the second hole 22, and the distance between the third hole 23 and the first hole 21 is equal to the distance between the third hole 23 and the second hole 22, and the distance between the fourth hole 24 and the first hole 21 is equal to the distance between the fourth hole 24 and the second hole 22. In Figure 12(a), if one side of the outer circumference of the lid 18 is designated as the first side, the side parallel to the first side as the third side, the side intersecting the first side as the second side, and the side parallel to the second side as the fourth side, then the holes 20 are arranged such that the distance between the first hole 21 and the first side is equal to the distance between the first hole 21 and the third side, the distance between the second hole 22 and the first side is equal to the distance between the second hole 22 and the third side, the distance between the third hole 23 and the second side is equal to the distance between the third hole 23 and the fourth side, and the distance between the fourth hole 24 and the second side is equal to the distance between the fourth hole 24 and the fourth side. In Figure 12(b), the holes 20 are positioned in the area near the corners of the lid 18, with the distance between the first hole 21 and the first side being equal to the distance between the first hole 21 and the second side, the distance between the second hole 22 and the third side being equal to the distance between the second hole 22 and the fourth side, the distance between the third hole 23 and the second side being equal to the distance between the third hole 23 and the third side, and the distance between the fourth hole 24 and the first side being equal to the distance between the fourth hole 24 and the fourth side.

[0025] (Second variation) According to this modified example, the shape of the hole 20 is not limited to a circle. It may be elliptical, square, rectangular, or other polygonal. In this case, when the hole diameter is the largest representative length, such as the major axis of an ellipse or the dimension of one of the longer sides of a square or rectangle, the hole diameter is preferably 0.5 mm or less, and more preferably 0.3 mm or less.

[0026] (Third variation) According to this modified example, the shape of the package 12 when viewed from the direction of the lid 18 is not limited to a square. It may be circular, elliptical, rectangular, or any other polygon.

[0027] If the shape of the package 12 as viewed from the direction of the lid 18 is circular, the distance between the hole 20 and the outer edge of the lid 18 is preferably 1 / 5 or less of the diameter of the package 12. If the shape of the package 12 as viewed from the direction of the lid 18 is elliptical, the distance between the hole 20 and the outer edge of the lid 18 is preferably 1 / 5 or less of the major axis. If the shape of the package 12 as viewed from the direction of the lid 18 is rectangular, the distance between the hole 20 and the outer edge of the lid 18 is preferably 1 / 5 or less of the long side. If the shape of the package 12 as viewed from the direction of the lid 18 is any other polygon, the characteristic length is the dimension parallel to the direction in which the distance between the hole 20 and the outer edge is measured, and the distance between the hole 20 and the outer edge is preferably 1 / 5 or less of the characteristic length. Furthermore, if the package 12 is rectangular when viewed from the direction of the lid 18, and the lid 18 is a rectangle consisting of a first long side, a second long side parallel to the first long side, a first short side shorter than the first long side, and a second short side parallel to the first short side, then it is preferable that the distance between the first hole and the first long side is equal to the distance between the first hole and the second long side, and the distance between the second hole and the first long side is equal to the distance between the second hole and the second long side. Also, in the same case, it is preferable that the distance between the first hole and the first short side is equal to the distance between the first hole and the second short side, and the distance between the second hole and the first short side is equal to the distance between the second hole and the second short side.

[0028] (Second embodiment) Figure 13 shows a schematic cross-sectional view of a part of the detection device 1 in this embodiment. In this embodiment, an airflow deceleration member 26, such as a filter, is provided in the opening between the second space surrounded by the housing wall 10 intersecting the lid 18 and the upper region of the detection device 1. The airflow deceleration member 26 is a physical means for decelerating the airflow in the second space. The airflow deceleration member 26 is, for example, a filter made of PTFE, which is a porous material with a pore size of 0.1 μm or more and 1.0 μm or less. In addition, the airflow deceleration member 26 may be a porous body containing zeolite, silica, organic material, wire mesh, nonwoven fabric, fiber, brush, etc., and the material of the airflow deceleration mechanism is not limited.

[0029] The placement of the airflow deceleration member 26 is not limited to the opening shown in the figure. The airflow deceleration member 26 can be placed in a position that can decelerate the airflow flowing through the first space and the second space. For example, it may be placed at the bottom of the second space, between the bottom of the second space and the opening, or outside the second space (near the white arrow in the figure). The airflow deceleration member 26 may also be placed inside the first space, for example, between the sensor chip 14 and the lid 18.

[0030] (Example 1) Figure 14 shows the simulation results when there are two holes 20 along X-X', and the diameter of each hole 20 is varied. As shown in Figure 14(a), assuming that the width of the second space is from X position = 1 mm to 5 mm on X-X', the simulation was performed when the two holes 20 are positioned at X position = 2.1 mm and 3.9 mm, i.e., d = 1.1 mm. When the X position values ​​of the holes 20 are arranged in ascending order (left, right), there are four possible patterns of each hole diameter (mm) that were simulated.

[0031] (i) (left, right) = (0.1, 0.3) (ii) (left, right) = (0.3, 0.1) (iii) (left, right) = (0.1, 0.1) (iv) (left, right) = (0.3, 0.3) The simulation was performed assuming a gas flow velocity of approximately 1 m / sec in the upper region of detection device 1, moving towards the right side of the diagram.

[0032] Figure 14(b) is a graph showing the velocity distribution in the Y direction at X position = 3 mm, with the direction of Y position in the figure being the Y direction. The simulation results for (i) are shown by a solid line, (ii) by a dashed line, (iii) by a dotted line, and (iv) by a dashed line. From Figure 14(b), it can be seen that of the four patterns above, the velocity is particularly high in the case of (iv) (left, right) = (0.3, 0.3). On the other hand, in the cases of (i) (left, right) = (0.1, 0.3) or (ii) (left, right) = (0.3, 0.1), the velocity is significantly lower than in the case of (iv), and it is clear that the velocity is limited by the smaller pore size. Note that the graphs showing (i) and (ii) overlap in Figure 14(b), which indicates that if the combination of pore sizes is the same, reversing the relationship between the pore sizes does not have any effect.

[0033] (Example 2) Figure 15 shows the simulation results when there are three holes 20 along X-X', and the diameter of each hole 20 is varied. As shown in Figure 15(a), assuming that the width of the second space is from X position = 1 mm to 5 mm on X-X', the simulation was performed when the three holes 20 were positioned at X position = 2.2 mm, 3.0 mm, and 3.8 mm, respectively. When the X position values ​​of the holes 20 are arranged in ascending order (left, middle, right), there are four possible patterns for the simulated hole diameters (mm).

[0034] (i) (Left, Center, Right) = (0.3, 0.3, 0.3) (ii) (Left, Center, Right) = (0.3, 0.1, 0.3) (iii)(left, middle, right)=(0.1, 0.3, 0.1) (iv) (Left, Center, Right) = (0.1, 0.3, 0.3) The simulation was performed assuming a gas flow velocity of approximately 1 m / sec in the upper region of detection device 1, moving towards the right side of the diagram.

[0035] Figure 15(b) is a graph showing the velocity distribution along the X direction. The simulation results for (i) are shown by a solid line, (ii) by a dashed line, (iii) by a dotted line, and (iv) by a dashed line. The graphs for (i), (iii), and (iv) show a difference between the right and left sides at X position = 3.0 mm, with the velocity on the right side (downstream) being greater than on the left side, whereas (ii) does not show as significant a difference between the left and right sides as the other cases. From these results, it can be seen that when three holes are provided in a straight line, the size of the middle hole becomes smaller than the holes at both ends, resulting in a more uniform airflow distribution. Therefore, for example, if another hole is provided between the first hole 21 and the second hole 22 on the line connecting them, and three holes are provided in a straight line, it is preferable that the size of the intermediate hole be less than or equal to the size of the smaller of the first hole 21 and the second hole 22.

[0036] (Example 3) Figure 16 shows the simulation results when there are two holes 20 along X-X', and the distance h2 between the lid 18 and the sensors contained in the sensor chip 14 is varied. As shown in Figure 16(a), assuming that the width of the second space is from X position = 1 mm to 5 mm along X-X', the simulation was performed for the case where the two holes 20 are located at X position = 2.1 mm and 3.9 mm, respectively. When the diameter of each of the two holes 20 is 0.3 mm, simulations were performed for seven patterns of distance h2 between the back surface of the lid 18 and the top surface of the sensor chip 14: (i) 0.2 mm, (ii) 0.4 mm, (iii) 0.6 mm, (iv) 0.8 mm, (v) 1.0 mm, (vi) 1.5 mm, and (vii) 1.8 mm. The simulation was performed assuming that the gas flow velocity in the upper region of the detection device 1, moving towards the right side of the diagram, was approximately 1 m / sec.

[0037] Figure 16(b) is a graph showing the velocity distribution in the Y direction at X position = 3 mm. The simulation results for (i) are shown as a solid line, (ii) as a fine dashed line, (iii) as a coarse dashed line, (iv) as a dotted line, (v) as a dashed-dotted line, (vi) as a solid white line, and (vii) as a dashed white line. According to Figure 16(b), in the above seven patterns, under the condition h2 = 0.6 mm or less, the maximum velocity increases as h2 increases, but beyond h2 = 0.6 mm, the maximum velocity decreases as h2 increases. However, even when the h2 condition is changed within this range, the velocity distribution remains approximately symmetrical on both sides along the X axis. Here, it is preferable that the flow in the first space is uniform and that the difference between the left and right sides is small. Regarding the type of flow generated in the first space, in all cases from (i) to (vii), turbulence did not occur, similar to the model shown in Figure 16(a). Therefore, in this embodiment, h2 can be set to any value from 0.2 mm to 1.8 mm.

[0038] However, depending on the arrangement, number, and shape of the holes 20, turbulence may occur in the first space even if h2 is set to 0.2 mm or more and 1.8 mm or less. In such cases, the detection accuracy of the detection device 1 can be improved by adjusting the value of h2 as appropriate to prevent turbulence from occurring in the first space.

[0039] (Example 4) In the above-described embodiments, the velocity distribution within the first space was examined along the velocity direction of the airflow. However, in this embodiment, the airflow within the first space in a direction approximately perpendicular to the velocity direction of the airflow is examined. Figure 17 is a schematic diagram showing the relationship between the airflow and the diffusion direction. The gas flowing in the upper region of the detection device 1 flows from left to right in the diagram. The direction of the airflow flowing within the first space along this airflow is indicated by the white arrow, and the diffusion of the airflow entering from the hole 20 in a direction approximately perpendicular to the white arrow is indicated by the black arrow. In this embodiment, it is assumed that the movement of gas in the direction of the black arrow is due to diffusion. The concentration along the white arrow is kept constant, and the surface concentration is kept constant, and the diffusion in the direction of the black arrow is considered. For the amount of diffusion, the normalized diffusion amount of hydrogen with respect to time was calculated from Fick's law.

[0040] The normalized diffusion amount N(z,t) / N0 at a distance z[mm] from the diffusion source, t seconds after the start of diffusion, can be calculated using the following formula (1).

[0041]

number

[0042] Figure 18 is a graph showing the time evolution of the normalized diffusion rate N(z,t) / N0 calculated using equation (1). (i) The simulation result for z=0.1mm is shown by a solid line, (ii) the simulation result for z=0.5mm is shown by a dotted line, (iii) the simulation result for z=1.0mm is shown by a dashed line, (iv) the simulation result for z=2.0mm is shown by a dashed line, and (v) the simulation result for z=3.0mm is shown by a double dashed line. From Figure 18, it can be seen that although diffusion takes longer as z increases, even in the case of z=2.0mm, about 85% has responded after 1.0 second. For example, since the inner dimensions of the package 12 used in the simulation in this specification are 4mm in length and width, it can be considered that more than 85% of the gas reaches the center of the package 12 after 1.0 second, and sufficient gas movement occurs in a short time by diffusion even in the direction of no flow. Therefore, according to this embodiment, diffusion perpendicular to the flow velocity occurs at a sufficient speed, and the airflow within the first space is considered to be uniform without any problems.

[0043] While embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These embodiments can be carried out in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents.

[0044] Furthermore, this disclosure includes the following examples:

[0045] [Note 1] A container with a lid, A sensor substrate located inside the aforementioned container and holding a sensor chip, Equipped with, The cover has two or more holes in a second region which is an area outside the first region which is an area of ​​the cover facing the sensor chip. Detection device.

[0046] [Note 2] The cover has the hole in a fourth region which is an area outside the third region which is an area of ​​the cover facing the sensor substrate. The detection device described in Appendix 1.

[0047] [Note 3] A container with a lid, A sensor substrate located inside the aforementioned container and holding a sensor chip, Equipped with, The lid has two or more holes, and the shortest distance from the center of the holes to the outer edge of the space enclosed by the container and the lid (the first space) when the space is projected perpendicularly onto the lid is 1 / 5 or less of the characteristic length of the space. Detection device.

[0048] [Note 4] The first hole and the second hole are positioned approximately symmetrically with respect to the point obtained by projecting the center point of the sensor chip perpendicularly onto the lid. A detection device as described in any one of the appendices 1 to 3.

[0049] [Note 5] The lid has a first side, a third side parallel to the first side, a second side intersecting the first side, and a fourth side parallel to the second side. The distance between the first hole and the first side is equal to the distance between the first hole and the third side. The distance between the second hole and the first side is equal to the distance between the second hole and the third side. A detection device as described in any one of the appendices 1 to 4.

[0050] [Note 6] The lid has a first side, a third side parallel to the first side, a second side intersecting the first side, and a fourth side parallel to the second side. The distance between the first hole and the first side is equal to the distance between the first hole and the second side. The distance between the second hole and the third side is equal to the distance between the second hole and the fourth side. A detection device as described in any one of the appendices 1 to 5.

[0051] [Note 7] The system further comprises a third hole, which is one of the aforementioned holes, and a fourth hole, which is one of the aforementioned holes. The distance between the third hole and the first hole is equal to the distance between the third hole and the second hole. The distance between the fourth hole and the first hole is equal to the distance between the fourth hole and the second hole. A detection device as described in any one of the appendices 1 to 6.

[0052] [Note 8] The distance between the third hole, which is one of the aforementioned holes, and the second side is equal to the distance between the third hole and the third side. The distance between the fourth hole, which is one of the aforementioned holes, and the first side is equal to the distance between the fourth hole and the fourth side. A detection device as described in any one of the appendices 1 to 7.

[0053] [Note 9] The lid is located on the line segment connecting the first hole and the second hole, and does not have a hole between the first hole and the second hole. A detection device as described in any one of the appendices 1 to 8.

[0054] [Note 10] The lid has one hole on the line connecting the first hole and the second hole, between the first hole and the second hole. The diameter of the hole located on the line connecting the first hole and the second hole, and between the first hole and the second hole, is less than or equal to the smaller of the first hole and the second hole. A detection device as described in any one of the appendices 1 to 8.

[0055] [Note 11] The airflow deceleration member comprises one of the following: a filter, a porous material, a wire mesh, a nonwoven fabric, a fibrous material, or a brush. The lid is provided between the airflow deceleration member and the sensor chip, or the airflow deceleration member is provided between the lid and the sensor chip. A detection device as described in any one of the appendices 1 to 10.

[0056] [Note 12] The diameter of the hole is 0.05 mm or more and 0.5 mm or less. A detection device as described in any one of the appendices 1 to 11. [Explanation of Symbols]

[0057] 1. Detection device 10 Cabinet Wall 12 packages 14 Sensor chips 15 Sensor board 16 membrane 18 Lid 20 holes 21~24 Holes 1~4 26 Airflow deceleration member 30 batteries 40 Communications Department 51 AD Conversion Circuit 52 Boost Circuit 53 Step-down circuit 54 Microcontroller Circuits 55 Power supply circuit 56 Power supply section

Claims

1. A container with a lid, A sensor substrate located inside the aforementioned container and holding a sensor chip, Equipped with, The cover has two or more holes in a second region which is an area outside the first region which is an area of ​​the cover facing the sensor chip. Detection device.

2. The cover has the hole in a fourth region which is an area outside the third region which is an area of ​​the cover facing the sensor substrate. The detection device according to claim 1.

3. A container with a lid, A sensor substrate located inside the aforementioned container and holding a sensor chip, Equipped with, The lid has two or more holes, and the shortest distance from the center of the holes to the outer edge of the space enclosed by the container and the lid, when the space is projected perpendicularly onto the lid, is 1 / 5 or less of the characteristic length of the space. Detection device.

4. The first hole and the second hole are positioned approximately symmetrically with respect to the point obtained by projecting the center point of the sensor chip perpendicularly onto the lid. The detection device according to claim 1 or 3.

5. The lid has a first side, a third side parallel to the first side, a second side intersecting the first side, and a fourth side parallel to the second side. The distance between the first hole and the first side is equal to the distance between the first hole and the third side. The distance between the second hole and the first side is equal to the distance between the second hole and the third side. The detection device according to claim 4.

6. The lid has a first side, a third side parallel to the first side, a second side intersecting the first side, and a fourth side parallel to the second side. The distance between the first hole and the first side is equal to the distance between the first hole and the second side. The distance between the second hole and the third side is equal to the distance between the second hole and the fourth side. The detection device according to claim 4.

7. The system further comprises a third hole, which is one of the aforementioned holes, and a fourth hole, which is one of the aforementioned holes. The distance between the third hole and the first hole is equal to the distance between the third hole and the second hole. The distance between the fourth hole and the first hole is equal to the distance between the fourth hole and the second hole. The detection device according to claim 4.

8. The distance between the third hole, which is one of the aforementioned holes, and the second side is equal to the distance between the third hole and the third side. The distance between the fourth hole, which is one of the aforementioned holes, and the first side is equal to the distance between the fourth hole and the fourth side. The detection device according to claim 6.

9. The lid is located on the line segment connecting the first hole and the second hole, and does not have a hole between the first hole and the second hole. The detection device according to claim 4.

10. The lid has one hole on the line connecting the first hole and the second hole, between the first hole and the second hole. The diameter of the hole located on the line connecting the first hole and the second hole, and between the first hole and the second hole, is less than or equal to the smaller of the two hole diameters. The detection device according to claim 4.

11. The airflow deceleration member comprises one of the following: a filter, a porous material, a wire mesh, a nonwoven fabric, a fibrous material, or a brush. The lid is provided between the airflow deceleration member and the sensor chip, or the airflow deceleration member is provided between the lid and the sensor chip. The detection device according to claim 1.

12. The diameter of the hole is 0.05 mm or more and 0.5 mm or less. A detection device according to any one of claims 1, 2, 3, or 11.

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