Sensor element and imaging element

Abstract

To provide a sensor element and an imaging element that can suppress a fringe electric field that is unnecessary in detection.SOLUTION: A sensor element 10 includes a capacitor 30 and a floating conductor 50. The capacitor 30 has a first electrode 31 and a second electrode 32 provided with a space therebetween on the same surface. The floating conductor 50 is located so as to be apart from the capacitor 30 in a thickness direction of the capacitor 30. The floating conductor 50 includes an opening 51 at a position corresponding to the capacitor 30. The capacitor 30 is electrically connected to an oscillator 61 that oscillates in accordance with the application of voltage. The oscillation frequency of the oscillator 61 changes depending on the change of at least any one of the dielectric constant and the conductivity of an object 9 to be detected.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a sensor element and an image sensor including the same.

Background Art

[0002] For example, as described in Patent Document 1, there is known a sensor that uses a capacitor connected in series with an oscillator such as a crystal oscillator and detects the conductivity of an object based on a change in the oscillation frequency of the oscillator. The sensor described in Patent Document 1 includes a first capacitor connected in series with the oscillator and a second capacitor connected in parallel with the first capacitor and having a liquid as an object disposed between its electrodes.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] As described in Patent Document 1, the configuration in which an object is disposed between the opposing electrodes of a capacitor is not suitable for applications that detect the object non-contact because the electric field is confined between the opposing electrodes. To detect an object non-contact, a method of expanding the fringe electric field generated in the capacitor out of the plane by using a capacitor composed of a pair of electrodes developed on the same plane (hereinafter referred to as a same-plane developed capacitor) can be considered. However, simply using a same-plane developed capacitor alone may cause the fringe electric field to spread too much and capture state changes other than the desired object.

[0005] The present invention has been made in view of the above circumstances, and an object thereof is to provide a sensor element and an image sensor capable of suppressing a fringe electric field unnecessary for detection.

Means for Solving the Problems

[0006] To achieve the above object, a sensor element according to a first aspect of the present invention includes: a capacitor having a first electrode and a second electrode provided at intervals on the same surface; a floating conductor positioned at a distance from the capacitor in the thickness direction of the capacitor; an opening is provided in the floating conductor at a position corresponding to the capacitor; the capacitor is electrically connected to an oscillator that oscillates in response to the application of a voltage; the oscillation frequency of the oscillator changes in response to at least a change in the dielectric constant and conductivity of the object to be detected.

[0007] The sensor element may further include a dielectric positioned between the capacitor and the floating conductor.

[0008] The capacitor is in a series connection relationship with the oscillator; the second electrode is provided around the first electrode; the first electrode may be connected to the oscillator.

[0009] The sensor element may further include a plurality of minute floating conductors positioned in the opening.

[0010] To achieve the above object, an imaging element according to a second aspect of the present invention includes: a plurality of the sensor elements arranged.

Advantages of the Invention

[0011] According to the present invention, it is possible to suppress a fringe electric field unnecessary for detection.

Brief Description of the Drawings

[0012]

Figure 1

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Figure 10

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Embodiments for Carrying Out the Invention

[0013] An embodiment of the present invention will be described with reference to the drawings.

[0014] (First Embodiment) As shown in FIG. 1, the non-contact detection device 100 according to the first embodiment includes a non-contact sensor 110 and a control unit 70. The non-contact detection device 100 detects, for example, the state of an object 9 such as soil or cement in a non-contact and non-destructive manner. Here, the state of the object 9 refers to various states that can be specified based on at least one of the dielectric constant and the conductivity of the object 9, and of course includes the dielectric constant and the conductivity themselves, as well as the moisture content, density, and degree of porosity specified according to the dielectric constant, and the ion release degree and corrosion degree specified according to the conductivity.

[0015] The non-contact sensor 110 includes a sensor element 10 and an oscillation circuit 60 including an oscillator 61. The non-contact sensor 110 is a so-called complex capacitance sensor, and outputs a change in the oscillation frequency of the oscillator 61 in response to a change in the complex capacitance of the object 9 located in the fringe electric field.

[0016] The sensor element 10 includes a substrate 20, a capacitor 30, a dielectric 40, and a floating conductor (non-grounded conductor) 50. The substrate 20 has insulating properties and is made of, for example, a glass substrate. The sensor element 10 is manufactured by, for example, a MEMS (Micro Electro Mechanical Systems) process. In the schematic cross-sectional view of the sensor element 10 shown in FIG. 1, the hatching indicating the cross-sections of the substrate 20 and the dielectric 40 is omitted for ease of viewing.

[0017] The capacitor 30 has a first electrode 31 and a second electrode 32 provided on the main surface 21 (the surface facing upward in FIG. 1) of the substrate 20. As shown in FIG. 2, the first electrode 31 and the second electrode 32 are provided at intervals from each other on the main surface 21 (that is, on the same plane). By configuring the capacitor 30 in this way, the electric field generated between the first electrode 31 and the second electrode 32 can be expanded in the out-of-plane direction, that is, the direction in which the object 9 is located. In FIG. 2, the position of the opening 51 described later is represented by a virtual line.

[0018] In this embodiment, the first electrode 31 and the second electrode 32 are formed concentrically so that local detection can be performed using a fringe electric field. Specifically, the first electrode 31 is formed in a circular shape. The first electrode 31 is connected to the vibrator 61 via the first wiring 31a. The second electrode 32 is provided around the first electrode 31 and is formed in a substantially ring shape with a portion where the first wiring 31a passes cut out. The second electrode 32 is connected to the ground side via the second wiring 32a. Note that the connection of the second electrode 32 to the ground side includes not only the mode in which the second wiring 32a is directly connected to the ground terminal, but also any mode in which the second electrode 32 and the second wiring 32a are electrically connected to a predetermined reference potential point. The first electrode 31, the first wiring 31a, the second electrode 32, and the second wiring 32a are formed, for example, by printing a conductor such as a copper foil on the main surface 21.

[0019] In the example of FIG. 2, the second electrode 32 is formed in a substantially ring shape with a part cut out. However, the second electrode 32 may be formed in a complete ring shape by configuring the first wiring 31a to pass through a through hole provided in the substrate 20 and reach the back surface of the main surface 21.

[0020] The dielectric 40 shown in FIG. 1 is made of a well-known dielectric such as plastic or ceramics and is formed in a plate shape. The dielectric 40 is located between the capacitor 30 and the floating conductor 50. The dielectric 40 guides the electric field generated in the capacitor 30 to the object 9.

[0021] The floating conductor 50 is positioned at a distance from the capacitor 30 in the thickness direction of the capacitor 30 (the vertical direction in FIG. 1). The thickness direction of the capacitor 30 is the thickness direction of the first electrode 31 and the second electrode 32 and corresponds to the normal direction of the main surface 21. The floating conductor 50 is formed, for example, on the main surface 41 of the dielectric 40 (the surface facing upward in FIG. 1). The floating conductor 50 is formed, for example, by printing a conductor such as a copper foil on the main surface 41.

[0022] The floating conductor 50 is provided with an opening (aperture) 51 at a position corresponding to the capacitor 30. The opening 51 in this embodiment is a through-hole formed in a circular shape centered on the center line 30a of the capacitor 30. The hole diameter of the opening 51 is slightly larger than the outer diameter of the second electrode 32 constituting the capacitor 30. For example, the hole diameter of the opening 51 is set according to the purpose within the range of 0.1 to 100 mm. The center line 30a is a line that passes through the center of the circular first electrode 31 and extends in the thickness direction of the capacitor 30.

[0023] The floating conductor 50 is provided to control the electric field generated from the capacitor 30. When the floating conductor 50 is not provided, the electric field spreads too much, but with the floating conductor 50, the electric field can be concentrated between the floating conductor 50 and the capacitor 30. Furthermore, by providing the opening 51 with an appropriate shape and size in the floating conductor 50, it is possible to block the leakage of the electric field outside the desired measurement range in the object 9. The demonstration of this effect will be described later.

[0024] The oscillation circuit 60 is a well-known configuration that oscillates the oscillator 61, which is a crystal oscillator for example. The oscillation circuit 60 applies a voltage to the oscillator 61 under the control of the control unit 70 to oscillate the oscillator 61. Also, the oscillation circuit 60 outputs the change in the oscillation frequency of the oscillator 61 to the control unit 70. The oscillation circuit 60 can be composed of, for example, a Colpitts-type transistor oscillation circuit, a Clapp-type transistor oscillation circuit, a Pierce-type transistor oscillation circuit, a Hartley-type transistor oscillation circuit, a Butler-type transistor oscillation circuit, a gate-type inverter oscillation circuit, etc.

[0025] The control unit 70 is configured to include, for example, a microcontroller, and executes a program stored in the built-in memory to control the operation of the oscillation circuit 60. Also, the control unit 70 measures the change in the oscillation frequency of the oscillator 61 based on the output from the non-contact sensor 110, and evaluates the state of the object 9 based on the change in the oscillation frequency.

[0026] Here, when at least either the dielectric constant or the conductivity of the object 9 changes, the complex capacitance of the object 9 on the capacitor 30 changes. When the complex capacitance changes, the oscillation frequency of the oscillator 61 changes. Using this characteristic, the non-contact detection device 100 detects the state of the object 9 by measuring the oscillation frequency of the oscillator 61. The detection principle will be described below.

[0027] The complex capacitance is a function of the complex dielectric constant ε * of the object 9 existing in the fringe electric field and is expressed by the following formula (1).

[0028]

Equation

[0029] Here, ε’ is the relative dielectric constant, σ is the conductivity, F is the frequency, and ε0 is the permittivity of vacuum. When the complex capacitance changes due to these changes, the resonance frequency of the circuit composed of the capacitor 30 and the oscillator 61 shown in FIG. 3 changes. The oscillator 61 can be treated as the equivalent circuit shown in the figure. In the figure, R is the equivalent series resistance, L is the equivalent series inductance, C1 is the equivalent series capacitance, C0 is the equivalent parallel capacitance, and C L is the complex capacitance of the capacitor 30. The resonance frequency F is expressed by the following formula (2).

[0030]

Equation

[0031] At this time, the components C1 and C0 in the equivalent circuit of the oscillator 61 are the eigenvalues of the oscillator 61 and are constant. Although L is a variable component, since the change is very small compared to C L , it can be regarded as an eigenvalue. As a result, the change amount ΔF of the resonance frequency is expressed by the following formula (3).

[0032]

Equation

[0033] Here, C L1 , C L2 are the complex capacitances before and after the measurement of the object 9, and ΔC L is ΔC L = C L2 - C L1 .

[0034] Of the above formula (1) representing the complex permittivity ε * of the object 9, the first term which is the real part is the relative permittivity of the object 9, that is, related to the dielectric property and dominant on the high frequency side. On the other hand, the second term which is the imaginary part is the dielectric loss of the object 9, that is, related to the conductivity and dominant on the low frequency side. Here, examples of the change over time of the frequency response (change in the resonance frequency) in the cement hardening process are shown in FIGS. 4(a) and (b). FIG. 4(a) shows the case where the oscillator 61 with a fundamental frequency (standard frequency) of 16 MHz is oscillated, and represents the state where the frequency response changes with the decrease in permittivity starting from after about 2 hours. That is, it can be seen that the change in the state of drying and porosity of the cement accompanying the hardening of the cement is represented as the frequency response. FIG. 4(b) shows the case where the oscillator 61 with a fundamental frequency of 2 MHz is oscillated, and represents the state where the frequency response changes with the increase in conductivity starting from after about 2 hours. That is, it can be seen that the change in the progress of the hydration of the cement accompanying the hardening of the cement is represented as the frequency response.

[0035] Also, an example of the change over time of the frequency showing the difference in the water penetration rate depending on the type of soil is shown in FIG. 5. In the figure, α is leaf mold, β is loess, and γ is black soil, and water was given to each soil by spraying at about 900 seconds. The locations where the frequency change amounts of α, β, and γ are steep (immediately after about 900 seconds for α and β, and around about 2700 seconds for γ) correspond to the state where water penetrates into the micro gaps (that is, the influence of gravitational water). The locations where the frequency change amounts of α, β, and γ are gentle (after about 900 seconds for α, after a slightly longer period than α for β, and after about 2700 seconds for γ) correspond to the state where water penetrates into the micro gaps (that is, the influence of capillary water).

[0036] As illustrated in FIGS. 4 and 5, it can be seen that the resonance frequency changes according to at least one of the dielectric constant and the conductivity of the object 9. Utilizing this characteristic, the control unit 70 detects the state of the object 9 based on the amount of change in the resonance frequency. Note that the oscillation frequency of the oscillator 61 also changes according to the change in the resonance frequency. Therefore, detecting the change in the resonance frequency is synonymous with detecting the change in the oscillation frequency of the oscillator 61. The control unit 70 calculates at least one of the dielectric constant and the conductivity from the change in the resonance frequency, for example, using the data indicating the above mathematical formula stored in the memory in advance. Further, the control unit 70 may detect the moisture content, density, degree of porosity, etc. of the object 9 specified according to the dielectric constant from the change in the resonance frequency, or may detect the ion release degree, corrosion degree, etc. of the object 9 specified according to the conductivity. For example, table data, mathematical formula data, etc. in which the states of these objects 9 and the amount of change in the resonance frequency are associated are stored in the memory in advance, and the control unit 70 detects the state of the object 9 based on the measured amount of change in the resonance frequency and the data. Further, a plurality of oscillators 61 having different fundamental frequencies are provided in the oscillation circuit 60, and the control unit 70 can select whether to measure either the dielectric constant or the conductivity of the object 9 by switching the oscillator 61 to be oscillated. Further, the control unit 70 may switch the oscillation of the oscillator 61 between oscillation at the fundamental frequency and oscillation at the overtone to select whether to measure either the dielectric constant or the conductivity of the object 9. This is the description of the non-contact detection device 100.

[0037] Subsequently, as Example 1, an experiment demonstrating the effect of providing the floating conductor 50 in the sensor element 10 will be described. For configurations having the same functions as those in the first embodiment, the same reference numerals as those in the first embodiment will be used for the description.

[0038] (Example 1) The inventors of the present application created a sensor model described with reference to FIGS. 6 and 7 and conducted experiments. As shown in FIG. 6(a), both the floating conductor 50 and the opening 51 in the sensor model are square. The length of the side of the floating conductor 50 (illustrated as m) is 50 mm, and the length of the side of the opening 51 (illustrated as n) is 16 mm. Also, the first electrode 31 and the second electrode 32 constituting the capacitor 30 of the sensor model were created as shown in FIG. 6(b). The first electrode 31 was made square with one side being 7 mm. That is, the size of the first electrode 31 is 7×7 mm 2 The second electrode 32 was formed in a frame shape with a square outer periphery. The length of the side constituting the outer periphery of the second electrode 32 (illustrated as f) is 14 mm. That is, the opening 51 is slightly larger than the outer shape of the second electrode 32. Also, the sensor model was created such that the center of the opening 51 coincides with the center of the capacitor 30 (that is, the center of the first electrode 31). The width of the second electrode 32 (illustrated as h) is 1.5 mm.

[0039] As shown in FIG. 7(a), in the sensor model, the thickness (illustrated as t1) of the dielectric 40 located between the substrate 20 on which the capacitor 30 is formed and the floating conductor 50 is 1 mm. Then, a structure (hereinafter, silicone part) having a plurality of cells 8 formed of silicone was disposed above the floating conductor 50. As shown in FIG. 7(b), the silicone part includes nine cells 8 arranged in a matrix. The area of each cell 8 is 14×14 mm 2 , the height is 1 mm, and the thickness of the bottom surface is 0.5 mm. Also, each cell 8 in the silicone part was numbered with rows x to y and columns 1 to 3 as shown in FIG. 7(b).

[0040] In this experiment, similar to the above-described embodiment, a vibrator 61, which is a crystal oscillator with a fundamental frequency of 16 MHz, was connected to the first electrode 31 by wiring, and the second electrode 32 was connected to the ground side by wiring. These wirings were provided so as to pass below the cell 8 at (x,2), which is the second column in the x row, as schematically shown in FIG. 7(b). Also, as Comparative Example 1, an experiment was conducted under the same conditions for a model in which the floating conductor 50 provided with the opening 51 was excluded from the sensor model according to Example 1. Using a frequency counter manufactured by Keysight Technologies, the frequency responses from each of the models of Example 1 and Comparative Example 1 were measured.

[0041] The experimental procedure is as follows. (1) Pure water (0.5 ml) is dropped onto any one of the cells 8. (2) The amount of frequency change before and after dropping the pure water is measured. (3) Steps (1) and (2) are repeated until the measurement is completed for all the cells 8.

[0042] As experimental results, FIG. 8(a) shows the amount of frequency change of the sensor model of Comparative Example 1, and FIG. 8(b) shows the amount of frequency change of the sensor model of Example 1. Each shows the amount of frequency change when pure water is dropped onto each cell 8. Also, FIG. 9(a) corresponds to FIG. 8(a), and FIG. 9(b) corresponds to FIG. 8(b), and each is a diagram showing the frequency response as a percentage based on the maximum value. Naturally, in both Example 1 and Comparative Example 1, the location at (y,2) corresponding to the position where the capacitor 30 is formed shows the maximum value.

[0043] As shown in FIG. 9(a) for Comparative Example 1, it can be seen that at the location at (x,2) corresponding to the location where the wiring is provided, a response of 9.76% occurs due to the influence of the wiring. Note that the maximum value of the amount of frequency change in Comparative Example 1 was 337 Hz.

[0044] On the other hand, as shown in Fig. 9(b), in Example 1, even at the position (x, 2) corresponding to the location where wiring is provided, the frequency response is 0.14%. Thus, according to Example 1, it can be seen that the influence of the wiring can be dramatically reduced to one tenth or less of that in Comparative Example 1. Further, according to Example 1, it can be seen that the frequency response at locations other than the position (y, 2), that is, at locations other than the opening 51, can be reduced to 1 / 1000 or less of the response at the position (y, 2) corresponding to the formation location of the opening 51. Thereby, it can be seen that the leakage of the fringing electric field at the location of the opening 51 can be substantially blocked. Although the maximum value of the frequency change amount in Example 1 is 331 Hz and there is a slight decrease compared to the maximum value in Comparative Example 1, this decrease is negligibly small.

[0045] From the above experimental results, it can be seen that the sensor element 10 according to the above embodiment can effectively suppress the fringing electric field unnecessary for detection. That is, if the opening 51 of the floating conductor 50 is directed toward the object 9, the state of the object 9 can be satisfactorily measured within the measurement range corresponding to the opening 51. According to the sensor element 10, by adjusting the sizes and shapes of the opening 51 and the capacitor 30, even if the measurement target is small, it can be measured, and visualization of both dielectric and conductive information, which are characteristics of the radio wave band, becomes possible. This sensor element 10 can be used in almost all industrial fields (such as cement-based materials, soil, materials handling liquids, etc.) that are targets of non-destructive inspection.

[0046] Also, in the sensor element 10, the unit composed of the floating conductor 50 and the dielectric 40 functions like an interchangeable lens in a camera, and the opening 51 functions like a diaphragm. Therefore, by replacing the unit composed of the floating conductor 50 and the dielectric 40 with another unit in which the shape and size of the opening 51 are adjusted, etc., a sensor element 10 with a measurement range suitable for the application can be prepared.

[0047] (Example 2) Subsequently, in order to examine the influence of the polarity of the capacitor 30, the inventors of the present application conducted an experiment using Example 2 in which the first electrode 31 was connected to the vibrator 61 and the second electrode 32 was connected to the ground side, and Comparative Example 2 in which the first electrode 31 was connected to the ground side and the second electrode 32 was connected to the vibrator 61. In this experiment, a sensor model without the floating conductor 50 was used in both Example 2 and Comparative Example 2, and the experiment was conducted under the same conditions as in Example 1 except for the difference in polarity, following the same procedure as in Example 1.

[0048] As a result of the experiment, FIG. 10(a) shows the amount of frequency change of the sensor model of Comparative Example 2, and FIG. 10(b) shows the amount of frequency change of the sensor model of Example 2. Also, FIG. 11(a) corresponds to FIG. 10(a), and FIG. 11(b) corresponds to FIG. 10(b). These are diagrams showing the frequency response as a percentage when the response measured when pure water was dropped into the central cell 8 (that is, the cell 8 at the position of (y, 2)) was taken as 100%. From these diagrams, it can be seen that in Comparative Example 2, significant responses occur in cells 8 other than the center, while in Example 2, responses occur only in the cell 8 almost at the center. That is, similar to Example 1, it can be seen that Example 2 (that is, the mode in which the vibrator 61 is connected to the first electrode 31), in which the floating conductor 50 provided with the opening 51 is arranged above the capacitor 30, is excellent in that it can generate a response at the location corresponding to the opening 51.

[0049] From the above experimental results, it can be seen that according to the sensor element 10 in which the first electrode 31 is conductively connected to the vibrator 61, a sufficient frequency response can be obtained at the location corresponding to the formation range of the opening 51, and the frequency response at other locations can be almost eliminated.

[0050] (Second Embodiment) As shown in Fig. 12, the non-contact monitoring device 200 according to the second embodiment includes an oscillation circuit 60, a control unit 70, an imaging element 80, and a display unit 90. Regarding the components having the same functions as those in the first embodiment, the same reference numerals as those in the first embodiment are used for explanation, and the differences from the first embodiment will be mainly described. The non-contact monitoring device 200 is a device that monitors the state of the object 9 in a non-contact and non-destructive manner.

[0051] The imaging element 80 is a sensor array including a plurality of arranged sensor elements 10. For example, the sensor elements 10 are arranged in a matrix. Note that "including a plurality of arranged sensor elements 10" indicates that at least a capacitor 30 and an opening 51 are provided corresponding to each sensor element 10, and it is not limited to the case where the substrate 20, the dielectric 40, and the floating conductor 50 are separate for each sensor element 10. It goes without saying that the substrate 20, the dielectric 40, and the floating conductor 50 may be a configuration shared by the sensor array.

[0052] The control unit 70 controls the oscillation circuit 60 to selectively switch the conduction destination of the vibrator 61 to each sensor element 10, for example, and acquire the frequency response corresponding to each sensor element 10 in a time-division manner. Then, the control unit 70 specifies the state of the object 9 (such as the moisture content, density, degree of porosity, etc. described above) for each sensor element 10 based on the frequency response corresponding to each sensor element 10. The specific method is the same as that in the first embodiment. Then, the control unit 70 outputs image data composed of pixels having shades corresponding to the value indicating the state of the object 9. Note that each sensor element 10 corresponds to a pixel. The image data is data for displaying a state image 9a indicating the state of the object 9. As described above, the state of the object 9 indicates various states that can be specified based on at least either the dielectric constant or the conductivity of the object 9. The display unit 90 is composed of a liquid crystal display, an organic EL display, etc., and displays the state image 9a under the control of the control unit 70.

[0053] According to the imaging device 80 described above, it is possible to use radio waves in the MHz band and provide a technique for visualizing dielectric and conductive composite information that is difficult to obtain in other frequency bands. In addition, since the imaging device 80 includes the sensor element 10 that can suppress the fringe electric field unnecessary for detection, it can be used for emphasizing an image according to a specific state of the object 9 and spatio-temporal analysis such as the progress inside a crack.

[0054] The present invention is not limited by the above embodiments and drawings. Modifications (including deletion of components) can be appropriately made without changing the gist of the present invention.

[0055] (Modification example) As a modification example, as shown in FIG. 13, the sensor element 10 may further include a plurality of micro floating conductors 52 located in the opening 51 of the floating conductor 50. The micro floating conductors 52 are arranged in plurality in the opening 51. The micro floating conductors 52 are floating conductors having a diameter on the order of μm (for example, several tens of μm to several hundreds of μm). The micro floating conductors 52 are formed, for example, by printing a conductor such as a copper foil on the main surface 41 of the dielectric 40. As an example, the micro floating conductors 52 are formed in a circular shape with a diameter of 150 μm, and adjacent ones are arranged at an interval of 150 μm. And the collection consisting of a plurality of micro floating conductors 52 forms a circular shape in plan view (seen from the thickness direction of the capacitor 30), and the diameter of the collection is set to about 7 mm. It has been clarified by the research of the inventors of the present application that suppressing the spread of the electric field out of the plane at the location where the micro floating conductors 52 are provided in this way enables local sensitization. Note that the size and shape of the micro floating conductors 52 can be arbitrarily changed according to the purpose.

[0056] The sizes (including thickness), shapes, and materials of the respective parts constituting the sensor element 10 described above can be arbitrarily changed as long as the state of the object 9 can be detected by the above-described principle. For example, in the floating conductor 50, the fact that the opening 51 is provided at a position corresponding to the capacitor 30 means that the opening 51 is provided so that at least the central portion of the capacitor 30 is located within the opening 51 when viewed from the thickness direction of the capacitor 30.

[0057] In the above, an example in which the first electrode 31 and the second electrode 32 are provided on the same plane has been shown. However, as long as the state of the object 9 can be detected by the above-described principle, the first electrode 31 and the second electrode 32 may be provided on the same curved surface. That is, the first electrode 31 and the second electrode 32 only need to be provided at intervals from each other on the same plane. Further, in the above, an example in which the capacitor 30 is in a series connection relationship with the vibrator 61 has been shown. However, the capacitor 30 may be provided in a parallel connection relationship with the vibrator 61. That is, the capacitor 30 of the sensor element 10 only needs to be electrically connected to the vibrator 61, and the connection mode between the capacitor 30 and the vibrator 61 can be arbitrarily changed as long as the state of the object 9 can be detected by the above-described principle.

[0058] In the above, an example in which the dielectric 40 is provided between the capacitor 30 and the floating conductor 50 has been shown. However, the dielectric 40 does not have to be provided. For example, in the sensor element 10, a configuration may be adopted in which the floating conductor 50 is supported at a position spaced apart from the capacitor 30, and an air layer is formed between the capacitor 30 and the floating conductor 50.

[0059] The type of the vibrator 61 is not limited. As the vibrator 61, an AT-cut crystal oscillator, an SC-cut crystal oscillator, a SAW (Surface Acoustic Wave) oscillator, etc. can be adopted according to the purpose.

[0060] The object 9 is not limited to soil, cement, etc., and can be any object as long as its state can be specified according to at least either the dielectric constant or the conductivity.

[0061] In the above description, for the sake of facilitating the understanding of the present invention, the description of known technical matters has been appropriately omitted.

[0062] This invention can be implemented in various embodiments and modifications without departing from the broad spirit and scope of the present invention. Also, the above-described embodiments are for explaining the present invention and do not limit the scope of the present invention. That is, the scope of the present invention is indicated not by the embodiments but by the claims. And various modifications made within the scope of the claims and within the scope of the meaning of the invention equivalent thereto are considered to be within the scope of the present invention.

Explanation of Reference Numerals

[0063] 100... Non-contact detection device, 110... Non-contact sensor 10... Sensor element 20... Substrate, 21... Main surface 30... Capacitor, 30a... Center line 31... First electrode, 31a... First wiring, 32... Second electrode, 32a... Second wiring 40... Dielectric, 41... Main surface 50... Floating conductor, 51... Opening, 52... Micro floating conductor 60... Oscillation circuit, 61... Vibrator 70... Control unit 200... Non-contact monitoring device, 80... Image pickup element, 90... Display unit 8... Cell, 9... Object, 9a... State image

Claims

1. A capacitor having a first electrode and a second electrode provided at intervals on the same plane, and a floating conductor positioned at an interval from the capacitor in the thickness direction of the capacitor, wherein an opening is provided in the floating conductor at a position corresponding to the capacitor, the capacitor is electrically connected to a vibrator that oscillates in response to the application of a voltage, and the oscillation frequency of the vibrator changes in response to at least a change in the dielectric constant and the conductivity of the object to be detected. A sensor element.

2. The sensor element according to claim 1, further comprising a dielectric positioned between the capacitor and the floating conductor. The sensor element according to claim 1.

3. The capacitor is in a series connection relationship with the vibrator, the second electrode is provided around the first electrode, and the first electrode is connected to the vibrator. The sensor element according to claim 1 or 2.

4. The sensor element according to any one of claims 1 to 3, further comprising a plurality of minute floating conductors positioned in the opening. The sensor element according to any one of claims 1 to 3.

5. An imaging element comprising a plurality of sensor elements according to any one of claims 1 to 4 arranged. An imaging element.

Images