JP2010096725A - Inclination sensor - Google Patents

Abstract

An inclination sensor is provided which has a simple manufacturing process and can be reduced in size and cost.
A tilt sensor 10 according to the present invention includes a substrate 11, a first drive electrode 21 and a second drive electrode provided on the substrate 11, and a lead portion for the first drive electrode 21 and the second drive electrode. Except for the vicinity, the common electrode 20 provided on the substrate 11 so as to surround the first drive electrode and the second drive electrode, and the surface of the substrate 11 on which the respective electrodes are formed. It has a cap 13 provided, and a detection liquid 14 sealed in a space provided between the substrate 11 and the cap 13.
[Selection] Figure 1

Description

  In the present invention, an electrode pattern is formed on a substrate, a space is formed between the cap provided on the surface on which the electrode pattern is formed and the substrate, and this space is filled with a non-aqueous electrolyte solution and a gas. The present invention relates to an inclination sensor having a structure.

The tilt sensor is an important device in surveying, posture control, and the like, and there is a great demand in the field of moving object control devices and mobile devices. Such a tilt sensor uses a resistance change in its tilt detection principle--for example, the principle of detecting tilt by enclosing an electrolyte and bubbles in a glass tube and detecting the resistance change of the upper and lower electrodes. Things are known. As an example using such a principle, for example, in Patent Document 1 (Japanese Patent Laid-Open No. 9-61162), the sealed container A includes a top plate 3, a cylindrical member 2, and a bottom plate 1 having a spherical concave surface 3a on the bottom surface. The electrolyte solution L that forms the bubble B is sealed in the sealed container A, and the spherical concave surface 3a in the sealed space A and the upper surface 1a of the bottom plate 1 are sealed in the sealed container A, respectively. An inclination sensor formed by forming electrodes 4, 5, and 6 that detect the position as a change in electrical resistance between the two is disclosed. Alternatively, Patent Document 2 (Japanese Patent Laid-Open No. 5-264274) discloses a resistance type inclination detecting device that detects an inclination angle based on a change in electric resistance.
Japanese Patent Laid-Open No. 9-61162 Japanese Patent Laid-Open No. 5-264274

  However, in the tilt sensor as described in Patent Document 1, the upper and lower electrodes need to be formed by machining, which complicates the manufacturing process and has become a barrier to downsizing the tilt sensor. . Patent Document 2 uses an AC voltage, and it is difficult to reduce the size and power consumption because it is necessary to provide an AC / DC conversion circuit and a switching circuit.

  In order to solve the above-described problem, an invention according to claim 1 of the present application includes a substrate, a first drive electrode and a second drive electrode which are provided on the substrate and both have a substantially semicircular shape, A common electrode having a substantially circular shape provided on the substrate so as to surround the first drive electrode and the second drive electrode, except in the vicinity of a lead portion of the first drive electrode and the second drive electrode; A cap provided on the surface of the substrate on which the electrodes are formed, and a non-aqueous electrolyte solution sealed in a space provided between the substrate and the cap, An inclination sensor characterized in that an inclination angle is obtained by measuring a resistance value generated through a non-aqueous electrolyte between the first drive electrode, the second drive electrode, and the common electrode.

  According to the tilt sensor of the present invention, since the electrode is present only on one side, electrode formation (patterning of the printed circuit board, lithography technology) using an exposure technique or the like is possible, and the manufacturing process of the tilt sensor is simplified. It is possible to reduce the size and cost of the tilt sensor.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a view showing a cross section of a tilt sensor according to an embodiment of the present invention, and FIG. 2 is a perspective view showing the appearance of the tilt sensor according to the embodiment of the present invention and an electrode pattern on a substrate. 1 and 2, 10 is a tilt sensor, 11 is a substrate, 13 is a cap, 14 is a detection liquid, 20 is a common electrode, 21 is a first drive electrode, 22 is a second drive electrode, 25 is a wiring section, C ₀ , C ₊ , and C− are terminals, and g is a gap.

FIG. 2A shows an external perspective view of the tilt sensor 10 and shows a general use posture of the tilt sensor 10. That is, the inclination sensor 10 is set so that the wiring portion 25 is directly above the vertical direction, and the inclination sensor 10 detects the degree of inclination in the DD ′ direction with respect to the set state. FIG. 2B is a view of the internal configuration of the tilt sensor 10 when the cap 13 is viewed as a transparent body. In FIG. 2B, terminals C ₀ , C ₊ , C− and the like are schematically shown. 1 is a cross-sectional view of the tilt sensor 10 shown in FIG. 1 when the electrode pattern on the substrate 11 in FIG. 2B is cut along a line AA ′ and arranged as shown in FIG. 1 with respect to the vertical direction. Shows the state.

On the substrate 11 of the tilt sensor 10, a common electrode 20, a first drive electrode 21, and a second drive electrode 22 are formed in an electrode pattern as shown. The first drive electrode 21 and the second drive electrode 22 are substantially semicircular patterns having substantially the same area, and are configured to be connected to lead terminals C ₊ and C−, respectively. As described above, the tilt sensor 10 of the present invention has a structure in which the electrodes are provided only on the substrate 11 and is not a structure in which two substrates provided with the electrodes are opposed to each other. It is possible to manufacture without requiring labor for accuracy and alignment accuracy such as a gap distance between substrates, and it is possible to realize a reduction in manufacturing cost. Further, as described above, since the tilt sensor 10 of the present invention has a structure in which electrodes are provided only on the substrate 11, it is possible to form electrodes using an exposure technique (patterning of a printed circuit board, lithography technique), and the tilt sensor 10. Simplification of the manufacturing process and downsizing and cost reduction of the sensor. An insulator is used for the substrate. Specifically, glass, plastic, ceramic or the like is used. In addition to copper, gold, aluminum, etc., molybdenum or the like can be used as the electrode material.

The common electrode 20 is formed so as to surround the pattern of the first drive electrode 21 and the second drive electrode 22 and is connected to the lead terminal C ₀ . A gap g is formed between the terminal end C0 of the common electrode 20 and the lead terminal C- of the second drive electrode 22 so as to ensure sufficient insulation. That is, the common electrode 20 is disposed so as to surround the first drive electrode 21 and the second drive electrode 22 except in the vicinity of the lead portions of the first drive electrode 21 and the second drive electrode 22. Moreover, even if the first drive electrode 21 and the second drive electrode 22 are interchanged in FIG. 2 according to circumstances, there is no problem. That is, the gap g may be between the common terminal 20 and the lead terminal C ₊ of the first drive electrode 21.

  On the main surface side of the substrate 11 where the common electrode 20, the first drive electrode 21, and the second drive electrode 22 are formed, a non-conductive cap 13 is provided so as to seal the periphery of the substrate 11. In the internal space formed between the substrate 11 and the cap 13, a detection liquid 14 occupying approximately half of the internal space is sealed. As a material of the non-conductive cap 13, for example, glass or plastic resin can be used.

  As the detection liquid 14, a liquid having a large resistance value is used. More specifically, as the detection liquid 14, a liquid such as propylene carbonate, γ-butyl lactone, or acetonitrile is particularly used as a non-aqueous electrolyte. When the tilt sensor 10 is in a standing state as shown in FIG. 2, the detection liquid 14 is placed on substantially half of the common electrode 20, the first drive electrode 21, and the second drive electrode 22. Enclosed in such an amount as to exist. In addition to the electrical properties as described above, the detection liquid 14 is also required to have a physical property that moves following the tilt angle θ of the tilt sensor 10 in the internal space. The detection liquid 14 is required to have a property that does not corrode the electrode.

  The tilt sensor 10 configured as described above is used, for example, as a uniaxial tilt sensor that detects the tilt of the tilt sensor 10 from a reference state as shown in FIG.

  Next, an outline of the principle of detecting the tilt angle θ using the tilt sensor 10 having the above configuration will be described. FIG. 3 is a diagram showing a usage state of the tilt sensor according to the embodiment of the present invention, and FIG. 4 is a diagram showing an outline of a circuit configuration used in the tilt sensor according to the embodiment of the present invention. 3A and 3B show states when the inclination angle of the inclination sensor 10 shown in FIGS. 2A and 2B is θ, respectively. In FIG. 4, the circuit within the dotted line is an equivalent circuit of the tilt sensor 10, Vdd indicates a DC voltage source, and V indicates a voltmeter.

The terminal C ₊ DC voltage source (Vdd) as shown in FIG. 4, also to the terminal C- ground (GND), The terminal C ₀ is connected to a voltmeter (V). With this circuit configuration, in the present embodiment, θ is detected by the output change of the voltmeter V corresponding to the inclination θ of the inclination sensor 10 that is a uniaxial inclination sensor.

  In the present embodiment, the inclination angle θ is obtained by measuring a DC voltage obtained by applying a DC voltage source (Vdd) to the terminal of the inclination sensor 10, but the AC voltage is changed to a DC voltage source. The inclination angle θ may be obtained using a voltage source. However, as described above, when an AC voltage is applied, an additional circuit is required, which makes it difficult to reduce the size and increases power consumption. Also, the calculation formula for deriving the inclination angle θ can be simplified only by using a DC voltage. As shown in the embodiment, by applying a DC voltage to the tilt sensor 10, the tilt angle θ can be accurately measured and low power consumption can be realized. However, it does not preclude the use of an alternating voltage as far as conditions permit.

Here, the state when the inclination angle of the inclination sensor 10 is set to θ as shown in FIG. 3 will be examined. When the tilt sensor 10 is tilted by θ, as shown in FIG. 3B, the liquid level of the detection liquid 14 remains horizontal with respect to the vertical direction, and the first drive electrode 21 and the detection liquid 14 There is a difference between the area S _{1 in} contact with and the area S _{2 in} contact with the second drive electrode 22 and the detection liquid 14. The area of contact between the common electrode 20 and the detection liquid 14 is constant as long as the inclination angle θ is within a predetermined range.

  Since the detection liquid 14 which is a non-aqueous electrolyte in contact with each electrode has slight conductivity, it apparently behaves as a resistor. Thus, the tilt sensor 10 according to the present invention uses a property as a resistor of the detection liquid 14 sealed in the internal space, and thus can be said to be a resistance value detection type tilt sensor.

In such a tilt sensor 10 of this embodiment, the output voltage with respect to the tilt angle θ until the detection liquid 14 reaches the vicinity P of the lead portions of the terminals C ₀ , C ₊ , C− is detected due to its structure. As a result, the inclination angle θ can be detected in a wide range.

The resistance R ⁺ between the first drive electrode 21 and the common electrode 20 and the second drive electrode 22 based on the behavior of the detection liquid 14 as a resistor when the tilt angle of the tilt sensor 10 is θ. And the common electrode 20 can be expressed by the following equations (1) and (2), respectively.

なお、ρは導電率であり、ｄは各駆動電極と共通電極２０との仮想的な距離で定数であり、Ｋは定数である。仮想的な距離ｄは、面積と導電率を用いて抵抗を算出するために導入した距離である。図２（Ｂ）に示すように、本実施形態に係る傾斜センサ１０では、仮想的な距離ｄを一定とするため、第１駆動電極２１および第２駆動電極２２を図示するように略半円状とし、共通電極２０は第１駆動電極２１および第２駆動電極２２を包囲するように略円形状に配置される。

Here, ρ is the conductivity, d is a virtual distance between each drive electrode and the common electrode 20, and K is a constant. The virtual distance d is a distance introduced to calculate the resistance using the area and the conductivity. As shown in FIG. 2B, in the tilt sensor 10 according to the present embodiment, the first drive electrode 21 and the second drive electrode 22 are substantially semicircular as shown in order to make the virtual distance d constant. The common electrode 20 is arranged in a substantially circular shape so as to surround the first drive electrode 21 and the second drive electrode 22.

  With the tilt sensor 10 in a standing state as shown in FIG. 2B, the detection liquid 14 is on approximately half of the drive electrode, and as the structure is tilted, detection on the drive electrode is performed. The area ratio between the working liquid 14 and the gas changes. Equations (1) and (2) show the resistance change associated with such inclination. The resistance of the gas part is assumed to be almost infinite. As for the approximation to the rightmost side of each of the expressions (1) and (2) (approximation for bringing θ to the numerator), when x << 1, 1 / (1 + x) ≈1-x and 1 / This is based on (1−x) ≈1 + x. It goes without saying that it is preferable not to perform such an approximation when performing a detailed analysis, but in the present embodiment, for the sake of simplicity, the equation is simplified using the above approximation.

  In the tilt sensor 10, contact resistance due to contact between the electrode and the detection liquid 14 exists. Based on such contact resistance, the resistance between the first drive electrode 21 and the common electrode 20 and the detection liquid 14 is Rs and between the second drive electrode 22 and the common electrode 20 and the detection liquid 14. The resistance is also Rs. From the above, it can be seen that the equivalent circuit of the tilt sensor 10 is surrounded by a dotted line in FIG.

At this time, as shown in FIG. 4, the terminal C ₊ DC voltage source (Vdd), also, connecting terminals C- to ground (GND), the output voltage V _out to be outputted to the terminal C _0, under It can be represented by equation (3).

ここで、接触抵抗Ｒｓを無視することによって式（３）を簡略化すると、電圧はＲ⁺の面積Ｓ₁に反比例して角度に比例するため、出力電圧Ｖ_outは下式（４）となり傾斜角θにほぼ比例することがわかる。（ただしθは±９０［ｄｅｇ］以内とする）これにより、出力電圧Ｖ_outを測定することによって、傾斜センサ１０の傾斜角θを検出することが可能となる。

Here, to simplify the equation (3) by ignoring the contact resistance Rs, the voltage is proportional to the angle in inverse proportion to the area S ₁ of R ^+, the output voltage V _out is the following formula (4) and inclined It can be seen that it is substantially proportional to the angle θ. (However, θ is within ± 90 [deg].) Thus, the inclination angle θ of the inclination sensor 10 can be detected by measuring the output voltage _Vout .

なお、本実施形態に係る傾斜センサ１０の出力電圧Ｖ_outは抵抗比で与えられるため、抵抗の温度特性をキャンセルする性質があり精度の高い傾斜角情報を得ることができる。以上のような構成の傾斜センサ１０によれば、電極が片側のみに存在する構造になるため、露光技術などを用いた電極形成（プリント基板のパタニング、リソグラフィ技術）が可能となり傾斜センサの製造工程の簡易化と傾斜センサの小型化・低コスト化を可能とする。
（実施例）
図５は実施例に係る傾斜センサ１０の電極パターン寸法を示す図である。図５に示すように、共通電極２０の外周の直径は４ｍｍとした。また、それぞれの電極の間に形成されたスリット状の絶縁領域については、およそ１００μｍに設定した。基板１１にはプラスチック、また共通電極２０、第１駆動電極２１及び第２駆動電極２２の材料としては、銅を用いた。

In addition, since the output voltage _Vout of the inclination sensor 10 according to the present embodiment is given as a resistance ratio, it has a property of canceling the temperature characteristic of the resistance, and highly accurate inclination angle information can be obtained. According to the tilt sensor 10 having the above-described configuration, since the electrode is present only on one side, it is possible to form an electrode using an exposure technique or the like (patterning of the printed circuit board, lithography technique), and the manufacturing process of the tilt sensor. Can be simplified and the tilt sensor can be reduced in size and cost.
(Example)
FIG. 5 is a diagram illustrating electrode pattern dimensions of the inclination sensor 10 according to the embodiment. As shown in FIG. 5, the diameter of the outer periphery of the common electrode 20 was 4 mm. Further, the slit-like insulating region formed between the respective electrodes was set to about 100 μm. The substrate 11 was made of plastic, and copper was used as a material for the common electrode 20, the first drive electrode 21 and the second drive electrode 22.

  FIG. 6 is a diagram for explaining the meniscus force in the tilt sensor. FIG. 6 is a view of the internal configuration of the tilt sensor when the cap 13 is viewed as a transparent body. The detection liquid 14 filled in the internal space between the substrate 11 and the cap 13 is in a state of being attracted to the inner wall surface of the cap 13 by a meniscus force as shown in S of FIG. If the diameter of the outer periphery of the common electrode 20 is less than 4 mm, the influence of the detection liquid 14 attracted by the meniscus force cannot be ignored, which is not preferable. Also, considering the downsizing of the tilt sensor 10, it is reasonable that the maximum diameter of the outer periphery of the common electrode 20 is about several centimeters. However, it is not always necessary to provide an upper limit for the maximum diameter of the outer periphery of the common electrode 20.

The inclination sensor 10 as described above was actually made on a trial basis, the terminal C− was grounded, and the DC power supply voltage Vdd (3V, 5V) was applied to the terminal C ₊ . The current consumption at that time was 0.2 μA when Vdd = 3 V and 0.5 μA when Vdd = 5 V, and it was confirmed that the power consumption of the tilt sensor 10 according to the present invention was reduced.

Further, the positive terminal of the voltmeter V and the terminal _C0 were connected, and the negative terminal was grounded. A state in which the areas of the first drive electrode 21 and the second drive electrode 22 immersed in the detection liquid 14 are the same is defined as an inclination angle θ = 0 deg, and the leftward inclination is positive. The tilt sensor was fixed to the rotary stage, and the output voltage V _out of the terminal C ₀ was measured while rotating counterclockwise from −90 deg to 90 deg using a stepping motor. The rotation speed of the stepping motor is 20 deg / s.

As described above, the output voltage when the tilt sensor 10 is rotated by ± 90 [deg] is as shown in FIG. FIG. 7 is a graph showing the relationship between the tilt angle and the output voltage of the tilt sensor according to the embodiment of the present invention. Propylene carbonate is used as the detection liquid 14 and Vdd = 3.0V. As shown in FIG. 7, according to the prototyped tilt sensor 10 according to the present invention, an output voltage _Vout substantially proportional to the tilt angle θ could be obtained in a wide range of ± 90 [deg]. As can be seen from FIG. 7, the output voltage of the tilt sensor 10 according to the present invention has a merit that there is a region with very good linearity, and the signal output from the tilt sensor 10 is easy to handle.

  In addition, an experiment was conducted on the temperature characteristics of the tilt sensor 10 according to the present invention. As a result, when the temperature was changed, the sensitivity tended to decrease as the temperature decreased. In addition, the temperature characteristic of the resistance greatly depends on the temperature. However, since the resistance change accompanying this temperature characteristic is canceled by the resistance ratio as described above, a relatively good temperature characteristic of the output voltage is obtained. Yes. As described above, the tilt sensor 10 of the present invention has a good temperature characteristic, but does not prevent the provision of a compensation circuit that compensates for an output change accompanying a temperature change.

  As described above, according to the configuration of the present invention, since the electrode is present only on one side, it is possible to form an electrode using an exposure technique or the like (patterning of the printed circuit board, lithography technique), and simplify the manufacturing process of the tilt sensor. And downsizing and cost reduction of the tilt sensor.

  Further, according to the configuration of the present invention, it is possible to provide a resistance value detection type inclination sensor with low power consumption. In addition, according to the configuration of the present invention, it is possible to provide a tilt sensor having a stable output even when there is a temperature change.

Next, in the previous embodiment, the expression of the output voltage V _out accompanying the change in the inclination angle θ of the inclination sensor 10 is approximately derived. Here, the derivation of the logical expression will be described. Here also, description will be made with reference to FIG.

When the tilt angle of the tilt sensor 10 is θ, the total resistance R ⁺ _tot between the first drive electrode 21 and the common electrode 20 is a resistance value based on the behavior of the detection liquid 14 as a resistor, contact The total resistance R- _tot between the second drive electrode 22 and the common electrode 20 is based on the resistance value based on the behavior of the detection liquid 14 as a resistor and the contact resistance. It is the sum of the resistance Rs. Therefore, R ⁺ _tot and R− _tot can be expressed by the following equations (5) and (6), respectively.

ここで、ρは導電率であり、ｄは駆動電極と共通電極２０と間の仮想的な距離で定数であり、Ｋは定数である。図４に示すように、端子Ｃ₊を直流電圧源（Ｖｄｄ）に、また、端子Ｃ―をグランド（ＧＮＤ）に接続すると、端子Ｃ₀に出力される出力電圧Ｖ_outは、下式（７）によって表すことができる。

Here, ρ is the conductivity, d is a virtual distance between the drive electrode and the common electrode 20, and is a constant, and K is a constant. As shown in FIG. 4, the terminal C ₊ DC voltage source (Vdd), also, connecting terminals C- to ground (GND), the output voltage V _out to be outputted to the terminal C _0, the following equation (7 ).

出力電圧Ｖ_outはＲ⁺ _totの面積Ｓ₁に反比例して角度に比例するため、出力電圧Ｖ_outは下記（８）式のようになる。

The output voltage V _out is proportional to the angle in inverse proportion to the area S ₁ of the R ⁺ _tot, the output voltage V _out is as follows (8).

この式（８）によれば、傾斜センサ１０の傾斜角θと出力電圧Ｖ_outとの関係を現すことができる。ここで、接触抵抗Ｒｓがρｄ／Ｓ₁やρｄ／Ｓ₂などの成分に比べ小さければ、出力電圧Ｖ_outは下式（９）のように整理することができ、傾斜角θにほぼ比例することがわかる。

According to this equation (8), the relationship between the inclination angle θ of the inclination sensor 10 and the output voltage V _out can be expressed. Here, if the contact resistance Rs is smaller than components such as ρd / S ₁ and ρd / S ₂ , the output voltage V _out can be arranged as shown in the following equation (9) and is substantially proportional to the inclination angle θ. I understand that.

実際には、接触抵抗Ｒｓの影響で感度はこれより低くなる。また、傾斜センサ１０の傾斜角θが９０［ｄｅｇ］に近づくと検出用液体１４が電極におけるギャップｇなどにかかってくるので出力は飽和する。

Actually, the sensitivity is lower than this due to the influence of the contact resistance Rs. Further, when the inclination angle θ of the inclination sensor 10 approaches 90 [deg], the output is saturated because the detection liquid 14 is applied to the gap g in the electrode.

It is a figure which shows the cross section of the inclination sensor which concerns on embodiment of this invention. It is a figure which shows the external appearance perspective view of the inclination sensor which concerns on embodiment of this invention, and the electrode pattern on a board | substrate. It is a figure which shows the use condition of the inclination sensor which concerns on embodiment of this invention. It is a figure which shows the outline | summary of the circuit structure used with the inclination sensor which concerns on embodiment of this invention. It is a figure which shows the electrode pattern dimension of the inclination sensor which concerns on an Example. It is a figure explaining the meniscus force in the inclination sensor. It is a graph which shows the relationship between the inclination angle of the inclination sensor which concerns on embodiment of this invention, and output voltage.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Tilt sensor, 11 ... Board | substrate, 13 ... Cap, 14 ... Liquid for detection, 20 ... Common electrode, 21 ... 1st drive electrode, 22 ... 2nd drive Electrode, 25... Wiring part, C ₀ , C ₊ , C−... Terminal, g.

Claims (1)

A substrate,
A first drive electrode and a second drive electrode provided on the substrate and having a substantially semicircular shape,
A common electrode that is provided on the substrate so as to surround the first drive electrode and the second drive electrode except for the vicinity of the lead portion of the first drive electrode and the second drive electrode, and has a substantially circular shape. When,
A cap provided on the surface of the substrate on which the electrodes are formed;
A non-aqueous electrolyte solution sealed in a space provided between the substrate and the cap,
An inclination sensor that obtains an inclination angle by measuring a resistance value generated through a non-aqueous electrolyte between the first drive electrode, the second drive electrode, and the common electrode.

Images