JP2006220607A - Tilt sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tilt sensor having heightened detection sensitivity, and a heightened degree of freedom of a sensor output wherein the sensor output is changed greatly at some specific tilt angle, or a detection resolution in a specific tilt angle range is changed, or the like. <P>SOLUTION: A freely-movable electrode 5 is arranged in a body 2 whose internal bottom surface is formed in an arc shape, and the movable electrode 5 is moved on a guide means 6 formed along the arc shape of the arc-shaped internal surface 3. A pair of belt-shaped electrodes 7<SB>a</SB>, 7<SB>b</SB>is provided along the guide direction, centered at the guide means 6 from the lowermost point of the arc-shaped internal surface 3, and another pair of belt-shaped electrodes 7<SB>c</SB>, 7<SB>d</SB>is provided on the other side, centered at the lowermost point. A tilt angle is detected by a capacitance generated between the paired belt-shaped electrodes 7<SB>a</SB>-7<SB>d</SB>and the movable electrode 5. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a tilt sensor that detects a tilt angle by using, for example, a spherical electrode disposed in a case at the bottom of an arc, and the position of the spherical electrode relative to the arc changing as the case tilts.

Conventionally, many sensors for measuring inclination have been proposed. As a detection method of the tilt sensor, there are a method using a variable resistor and a method using a Hall element.
A method using a variable resistor shown in Patent Document 1 is shown in FIG. 15, and its configuration and operation will be described. As shown in FIG. 15A, a spherical moving conductor 134 is placed inside a cylindrical inclination sensor case 130 in which both side surfaces of the annular portion 133 are closed by circular side portions 131 and 132. FIG. 15B shows a cross-sectional view of the tilt sensor case 130 viewed from the side. A conductor film 138 is formed on the inner side of the circumferential portion of the side surface portion 131, and a resistance film 139 is formed on the inner circumferential portion of the side surface portion 132 at a position facing the conductor film 138. The conductor film 138 and the resistance film 139 are made conductive by the moving conductor 134 located at the lowest point of the cylindrical portion 133 by gravity. Now, as shown in FIG. 15A, when the tilt sensor case 130 is stood up, that is, when the side surface portion 131 or the side surface portion 132 is arranged so as to look circular when viewed from the front, the movable conductor 134 is located at the outermost portion of the annular portion 133. Stable at the bottom position. A terminal A135 that is electrically connected to the conductor film 138 is provided at a position opposite to the moving conductor 134 in the vertical direction. A resistance film 139 is cut out at a position facing the terminal A135 and the annular portion 133, and a terminal B136 and a terminal C137 are provided at both ends thereof.

Now, when the tilt sensor case 130 is tilted about the center of the circular side portions 131 and 132 as the rotation axis, the moving conductor 134 continues to be positioned at the lowermost portion of the annular portion 133 due to gravity. The position of 139 changes. As a result, the resistance value between the terminal A135, the terminal B136, and the terminal C137 changes. This is shown as an electric circuit symbol in FIG. As the moving conductor 134 moves along the resistance film 139, the length of the resistance film 139 between the terminal A135 and the terminal B136 changes. Similarly, the resistance value between the terminal A135 and the terminal C137 changes. As a result, the tilt angle can be detected as a change in resistance value.
JP-A-7-159165 (paragraphs 0013 to 0016, FIG. 1)

  In the conventional tilt sensor in which the moving conductor moves, the ease of movement of the moving conductor with respect to the tilt angle is a major factor that determines the detection sensitivity. In the case of the resistance detection type, the ease of movement of the moving conductor is determined by the rolling resistance and the electrical contact resistance of the moving conductor. In order to obtain a sufficiently small and stable contact resistance, it is necessary to hold the moving conductor with a certain contact pressure, which is a major factor that impairs the mobility of the moving conductor. The contact pressure applied to the moving conductor in order to obtain this small and stable contact resistance has deteriorated the detection sensitivity of the tilt sensor.

  In the present invention, at least the inner bottom surface of the main body case is formed in an arc shape, and a movable electrode is arranged on the inner surface of the arc shape so that the movable electrode can move freely along the arc shape of the inner surface of the arc shape by the guide means. Two pairs of strip electrodes are provided along the guide direction from the lowermost part of the arc-shaped inner surface by the guide means. The inclination angle is detected by the capacitance generated between the pair of strip-like electrodes and the movable electrode.

  As described above, since the inclination angle is detected by the change in the capacitance formed between the movable electrode movable on the arc-shaped inner surface and the strip-shaped electrode formed on the arc-shaped inner surface, the movable electrode is detected. The electrical contact resistance as a factor that hinders the movement of the sensor can be excluded, and the detection sensitivity can be increased as compared with the conventional resistance detection type inclination sensor.

Embodiments of the present invention will be described below with reference to the drawings. Corresponding portions in the drawings are denoted by the same reference numerals, and redundant description is omitted.
[First Embodiment]

  FIG. 1 shows an embodiment of a tilt sensor according to the present invention. FIG. 1A is a plan view, and FIG. 1B is a cross-sectional view taken along line I-I in FIG. The main body case 1 constituting the inclination sensor of this embodiment includes an outer back surface 2a of an elongated rectangular main body 2, side end surfaces 2b and 2c perpendicular to both ends, and side end surfaces 2b and 2c parallel to the outer back surface 2a. Side wall that closes both sides of the main body 2 in the longitudinal direction of the main body 2 by the short upper surfaces 2d and 2e having the other end and one end thereof continuous, and an arc-shaped inner surface 3 formed between the other ends of the upper surfaces 2d and 2e 4a and 4b, and the lid 4 attached over both upper surfaces of the short upper surfaces 2d and 2e. At least the main body 2 is made of an electrically insulating material. FIG. 1A shows only both end portions in the longitudinal direction of the lid 4 and omits the central portion.

A movable electrode 5 is movably disposed on the arc-shaped inner surface 3 in the main body case 1. The movable electrode 5 is positioned at the lowermost part of the arc-shaped inner surface 3 with the outer back surface 2 a of the main body 2 being horizontally disposed. Guide means 6 is provided for moving the movable electrode 5 along the arc of the arc-shaped inner surface 3 around the lowermost part of the arc-shaped inner surface 3. In the case of this embodiment, a groove 6a is formed on the entire inner surface 3 of the arc shape along the arc shape in the center portion of the width in the direction orthogonal to the arc shape. A pair of strip electrodes 7 _a and 7 _b are provided along the direction guided by the guide means 6. In this embodiment, strip electrodes 7 _a and 7 _b are formed so as to extend to one side from the lowermost portion with the narrowest spacing at the lowermost portion across the groove 6 a and the spacing gradually increasing as the distance from the lowermost portion increases. Another pair of strip electrodes 7 _c and 7 _d are also formed on the other side at positions symmetrical to the strip electrodes 7 _a and 7 _b with the center line orthogonal to the arc direction of the lowermost part of the arc-shaped inner surface as an axis. .

The strip electrodes 7 _a , 7 _c and 7 _b , 7 _d are integral electrodes connected to each other at the bottom of the arc-shaped inner surface 3, and the strip electrodes 7 _a , 7 _c are substantially central portions of the arc of the strip electrode 7 _a. To the bottom of one end in the longitudinal direction of the main body 2 by the internal wiring 10 as a terminal a8. The place where the strip electrodes 7 _a and 7 _c and the internal wiring 10 are connected may be anywhere as long as they are electrically connected. Similarly, the strip electrodes 7 _b and 7 _d are led out as a terminal _b < _b > 9 to the bottom of one end in the longitudinal direction of the main body 2 by the internal wiring 11.
In this embodiment, an example of an integral electrode in which the strip electrodes 7 _a , 7 _b and 7 _c , 7 _d are connected at the lowermost part of the arc-shaped inner surface is shown. It is good also as a form. Therefore, the reference numbers are changed and written. When the strip electrodes 7 _a and 7 _b and the strip electrodes 7 _c and 7 _d are separated from each other, four terminals described above may be provided corresponding to each strip electrode, although not shown.

FIG. 2 is an enlarged cross-sectional view taken along the line II-II shown in FIG. 1A, and shows a state in which the movable electrode 5 has moved onto the line II-II. The groove 6a has an inverted trapezoidal cross section perpendicular to its extending direction, that is, the guide means 6 is constituted by the groove bottom 20 and the slopes 21a and 21b on both sides thereof.
The movable electrode 5 makes point contact with the inclined surfaces 21a and 21b of the groove 6a and moves along the arc-shaped inner surface 3 according to an inclination angle with the center of the arc shape as the central axis.
Capacitance C _a between the movable electrode 5 and the strip electrode 7 _a is, the capacitance C _b is formed between the movable electrode 5 and the strip electrode 7 _b. These electrostatic capacities C _a and C _b are in a relationship of decreasing as the electrode interval increases.

The electrostatic capacitance C _a and the electrostatic capacitance C _b are schematically shown in FIG. _2B by electric circuit symbols. The electrostatic capacitance C _a and the electrostatic capacitance C _b are obtained in the form shown in the equation (1) as the electrostatic capacitance C between the terminal a20 and the terminal b21.

Ｃ_ａ＝Ｃ_ｂとするとＣ＝Ｃ_ａ/２で求められる。
〔傾斜角度の測定原理〕
傾斜角度を定量的に測定可能とするためには、可動電極５と帯状電極７_ａ〜７_ｄ間の静電容量Ｃが傾斜角度によって変化する必要がある。その為にこの実施例では、一対の帯状電極の位置を円弧形状内面３の最下点から離れるに従って間隔が広がるように構成している。図１（ａ）に示すように、円弧形状内面３の最下点で帯状電極７_ａ〜７_ｄが案内手段６を構成する溝部６ａに最も近く、最下点から円弧延長方向に向けて離れるに従い案内手段６からの距離が大きくなるように配置されている。すなわち、円弧形状内面３の最下点から案内手段６に対してある角度を持って帯状電極７_ａ〜７_ｄが形成されている。その結果、可動電極５が円弧形状内面３の最下点にある時に可動電極５と各帯状電極７_ａ〜７_ｄ間の間隔が最も近く、最下点から離れるしたがってその間隔は徐々に大きくなる。したがって、傾斜角度が変化することで可動電極５と各帯状電極７_ａ〜７_ｄとの間の静電容量が変化する。

When C _a = C _b , C = C _a / 2.
[Measurement principle of tilt angle]
In order to quantitatively measure the tilt angle, the capacitance C between the movable electrode 5 and the strip electrodes 7 _{a to} 7 _d needs to change depending on the tilt angle. For this purpose, in this embodiment, the position of the pair of band-shaped electrodes is configured such that the distance increases as the distance from the lowest point of the arc-shaped inner surface 3 increases. As shown in FIG. 1 (a), closest to the groove portion 6a which strip electrodes 7 _a to _7-d at the lowest point of the arc-shaped inner surface 3 constitute a guide means 6, away toward the arc extending direction from the lowest point Accordingly, the distance from the guiding means 6 is increased. That is, the strip electrodes 7 _{a to} 7 _d are formed with _a certain angle with respect to the guide means 6 from the lowest point of the arc-shaped inner surface 3. As a result, the movable electrode 5 and the movable electrode 5 spacing nearest between the strip electrodes 7 _a to _7-d, so that its distance away from the nadir gradually increases when in the lowest point of the arc-shaped inner surface 3 . Therefore, the capacitance between the movable electrode 5 and each of the strip electrodes 7 _{a to} 7 _d changes as the tilt angle changes.

This will be described using mathematical expressions. FIG. 3A shows a diagram for obtaining the horizontal movement distance X of the movable electrode 5 from the lowest point of the arc-shaped inner surface 3 when the movable electrode 5 moves along the guide means 6. If the radius of the arc-shaped inner surface 3 is ρ and the angle of the central portion forming the sector with the center of the arc shape as an axis is θ, the movement distance X can be obtained by Expression (2). Here, θ is an inclination angle θ of the main body case 1 with the center forming the arc-shaped inner surface 3 as an axis.
X = 2ρsinθcosθ = ρsin2θ (2)
In this embodiment, the distance L between the movable electrode 5 and the guide means 6 in the direction orthogonal to the moving direction of the movable electrode 5 gradually increases as the movable electrode 5 moves away from the lowest point of the arc-shaped inner surface 3. Become.
FIG. 3B shows _a part of the strip electrode 7 _a extending from the lowest point of the arc-shaped inner surface 3. When the angle of the extending direction of the strip electrode 7 _a from the lowest point for the groove 6a of the arc-shaped inner surface 3 phi, the distance L with respect to the movement distance X in the horizontal direction of the movable electrode 5 from the lowest point in the formula (3) Desired.

L = ρsin2θtanφ
When tanφ is A = tanφ, L = Aρsin2θ (3)
Next, the distance d between the movable electrode 5 and the strip electrode according to the distance L is shown in FIG. Here, the distance d is the length of the vertical line from a point on the circumference of the movable electrode 5 to the surface of the arc-shaped inner surface 3 where the band-like electrode is formed. When the coordinate of the central part of the movable electrode 5 in the direction orthogonal to the moving direction of the movable electrode 5 is the origin (0, 0) and the radius of the movable electrode 5 is r, the bottom of the movable electrode 5 is the arc-shaped inner surface 3. It touches at coordinates (0, -r) on the y-axis. Here, the guide means 7 is omitted. A distance d in the vertical direction between the movable electrode 5 and the movable electrode 5 at a distance L from the bottom of the movable electrode 5 can be expressed by Expression (4).

この結果、可動電極５と凹面６上に形成される帯状電極との鉛直方向の間隔ｄによって形成される静電容量Ｃは式（５）で表せる。

As a result, the capacitance C formed by the vertical distance d between the movable electrode 5 and the strip-shaped electrode formed on the concave surface 6 can be expressed by Expression (5).

ここでεは誘電率、Ｓは間隔ｄで対抗する帯状電極と可動電極で形成される電極面積。
以上、示したように静電容量Ｃは傾斜角度θの関数となる。間隔ｄと電極面積Ｓについては、正確には可動電極５が球体の例を示したので円弧形状を考慮した式にする必要があるが、煩雑になるためここでは省略した。
以上述べたようにこの実施例によれば、傾斜角度θの変化を静電容量として検出することが可能となる。このように静電容量で傾斜角度θを検出可能とすることで、可動電極５の移動性を損なう要因は、可動電極５と案内手段６との間に発生する転がり抵抗だけになり、可動電極に対する接触圧を必要とした従来の抵抗検出型の傾斜センサと比較して検出感度を向上させることが出来る。

Here, ε is a dielectric constant, and S is an electrode area formed by a strip electrode and a movable electrode that are opposed to each other by a distance d.
As described above, the capacitance C is a function of the tilt angle θ. The distance d and the electrode area S are precisely shown as an example in which the movable electrode 5 is a sphere, and therefore it is necessary to use an equation that takes into account the arc shape.
As described above, according to this embodiment, a change in the inclination angle θ can be detected as a capacitance. Since the inclination angle θ can be detected by the capacitance as described above, the only factor that impairs the mobility of the movable electrode 5 is the rolling resistance generated between the movable electrode 5 and the guide means 6. The detection sensitivity can be improved as compared with a conventional resistance detection type inclination sensor that requires a contact pressure with respect to.

FIG. 1A shows an example in which the distance between the pair of strip-like electrodes is increased as the distance from the lowest point of the arc-shaped inner surface 3 increases. However, the present invention is not limited to this embodiment.
Figure 4 shows another embodiment of a strip electrode ₇ a to _7-c. Figure 4 is a plan view showing another embodiment of a strip electrode 7 _a to _7-c, in a plan view of the tilt sensor shown in the side walls and the lid is a diagram omitted (later shown in FIG. 1 (a) Also omit side walls and lids). In the embodiment shown in FIG. _4A , the distance between the strip-like electrodes 7 _a , 7 _c and 7 _b , 7 _d formed at symmetrical positions with the guide means 6 interposed is set at the lowest point of the arc-shaped inner surface 3. The gap is gradually narrowed along the arc shape, and the strip electrodes 7 _{a to} 7 _c are arranged closest to the guide means 6 at the uppermost point of the arc.

When the strip electrodes 7 _{a to} 7 _c are formed in this way and the main body 2 is tilted clockwise or counterclockwise around the central portion in the longitudinal direction of the main body 2, the movable electrode 5 and the strip electrodes 7 _{a to} 7 _{c are formed.} And the distance d changes. Therefore, the capacitance C changes in the direction in which the capacitance C increases regardless of the inclination.
In the embodiment shown in FIG. _4B , the distance between the strip electrodes 7 _a , 7 _c and 7 _b , 7 _d formed at symmetrical positions across the guide means 6 is the narrowest at the uppermost point of one arc. gradually spread at a constant rate toward therefrom to the other arc highest point, so that the distance between the strip electrode 7 _a and 7 _b are substantially equal magnitude to the diameter of the movable electrode 5 at the other arcuate uppermost point Is arranged.

In this case, when the main body 2 is tilted counterclockwise as described above, the distance d between the movable electrode 5 and the strip electrodes 7 _{a to} 7 _c approaches, so that the capacitance C increases. When tilted clockwise, the capacitance C changes so as to decrease. When the strip electrodes 7 _{a to} 7 _c are formed in this way, the change in the capacitance C with respect to the inclination angle θ can be uniformly changed in one direction.
An example of converting this capacity change into a quantitative value is shown in FIG. The example shown in FIG. 5 converts the capacity change into a binary number. In the feedback circuit 41 that delays the phase of the output signal of the amplifier circuit 40 by 180 ° and feeds back to the input side of the amplifier circuit 40, the capacitance between the terminal a8 and the terminal b9 is formed by the inclination sensor of this embodiment. A capacitance C is incorporated as the capacitance 42. When the amplifier circuit 40 and the feedback circuit 41 are designed to satisfy the oscillation condition, an oscillation signal having a single frequency depending on the capacitance 42 is generated at the output terminal of the amplifier circuit 40. A logical product of the oscillation signal and a gate signal _TG having a fixed time width generated based on a stable signal reference source (not shown) is taken by the AND gate 44 and the output is counted by the counter 45. C, that is, the inclination angle θ can be converted into a numerical value. In this way, the inclination angle θ can be obtained quantitatively. If the transmission frequency is designed in the MHz band, for example, the time width of the gate signal _TG may be a time width on the order of ms, and the tilt angle θ can be digitized at high speed.

Incidentally, two slopes forming the guide means 6 shown in FIGS. 2 (a) as an example of a guiding means 6, in this embodiment, between the movable electrode 5 and the strip electrode 7 _a, 7 _b of the spherical An angle formed by a straight line connecting the surface of the arc-shaped inner surface 3 forming the strip-shaped electrodes 7 _a and 7 _b and the center of the movable electrode 5 and a perpendicular from the center of the movable electrode 5 because of the necessity of forming a capacitance. α (see FIG. 3C) is preferably provided within a range of 45 ° or less.
Moreover, the shape of the groove part shown as an example of the guide means 6 is not restricted to the shape shown to Fig.2 (a). A simple groove shape may be used. As shown in FIG. 2C, the movable electrode 5 is supported at two corners of the groove 6b by a shallow groove having a rectangular cross-sectional shape. Alternatively, in this example, since the movable electrode 5 is a sphere, as shown in FIG. 2D, a groove 6c having a shallow arc shape in cross section may be used.

When the groove 6a is used as the guide means 6, it is preferable that the movable electrode 5 immediately returns to the groove 6a even if the movable electrode 5 is detached from the groove 6a. An example of such a configuration is shown in FIG. 6A in a sectional view corresponding to FIG.
Each part of the cross-sectional shape of the arc-shaped inner surface 3, band-shaped electrodes ₇ a, _{7 b} vertical portion 50a from where it approaches the strip electrode ₇ a, _{7 b} at both outer sides of, and one step higher by 50b, the vertical portion 50a , 50b, the slopes 51 and 52 are gradually increased in height as they become farther to the outer sides of the groove 6a.

The tilt sensor of this embodiment does not assume a response to acceleration acting in the vertical direction. However, in handling the tilt sensor, it is inevitable that vertical acceleration acts, and it can be easily assumed that the movable electrode 5 is detached from the groove 6a depending on the acceleration. The vertical portions 50a and 50b and the inclined surfaces 51 and 52 function so as to easily return to the groove portion 6a when the movable electrode 5 is detached from the groove portion 6a.
The guide means 6 is not necessarily required by the groove 6a. FIG. 6B shows an embodiment in which the side wall that guides the moving direction of the movable electrode 5 that is a sphere is guided by the side wall. FIG. 6B also shows a cross-sectional view of the main body 2 in a direction orthogonal to the guiding direction by the guiding means. The thickness of the main body 2 is made thinner than that of the first embodiment, and the distance between the side walls 4 a and 4 b is slightly larger than the diameter of the movable electrode 5. That is, the side walls 4 a and 4 b are as close as possible to the movable electrode 5 within a range that does not affect the smooth movement of the movable electrode 5. When the bottom surface of the main body 2 is inclined with respect to the horizontal plane, the movable electrode 5 is guided and moved by the side walls 4a and 4b, and is positioned at the lowest point of the arc-shaped inner surface 3 in that state.

The center of the interval between the side walls 4a and 4b. That relative width direction of the center line of the arc-shaped inner surface 3, ₍₇ c, _{7 d} is not shown in FIG. 6 (b)) strip electrode ₇ symmetrically in this example _a and _{7 b} and _{7 c} and _{7 d} Are formed respectively.
Regarding the relationship between the diameter of the movable electrode 5 and the distance between the side walls 4a and 4b, if the difference is too small, the mobility of the movable electrode 5 with respect to the inclination is impaired. Therefore, in order to improve the sensitivity to the tilt angle θ, it is preferable to increase the difference. However, when the difference is increased, the backlash in the direction orthogonal to the moving direction of the movable electrode 5 increases, and the capacitance variation between the movable electrode 5 and the strip electrodes 7 _a and 7 _b increases.

Thus, the relationship between the distance between the side walls 4a and 4b and the diameter of the movable electrode 5 is determined based on the accuracy of the change in capacitance with respect to the inclination angle θ. Since there is no relationship for reducing the contact resistance between the movable electrode 5 and the side walls 4a and 4b, the relationship between the distance between the movable electrode 5 and the side walls 4a and 4b when compared with a conventional resistance detection type inclination sensor. Can be loose.
If the accuracy of the capacitance is required, the distance between the side walls 4a and 4b and the movable electrode 5 can be determined by using only the side walls 4a and 4b shown in FIG. The accuracy needs to be remarkably increased, and manufacturing becomes difficult. Therefore, when it is desired to increase the accuracy of the tilt sensor, it may be used in combination with the groove 6a. In that case, the distance between the side walls 4a and 4b and the movable electrode 5 may not be strictly managed. At this time, the side walls 4a and 4b not only act as guide means but also function to return the movable electrode 5 onto the groove 6a when the movable electrode 5 is detached from the groove 6a due to vertical acceleration.

Since the inclination sensor of the present invention is a capacitance detection type, various actions and effects can be obtained by changing the belt-like electrode structure. FIG. 7 shows another embodiment in which the electrode structure is changed. FIG. 7 is a cross-sectional view in a direction orthogonal to the guide direction of the guide means 6 as in FIG. The groove 6a forming the guiding means 6 is the same as the groove having the shape shown in FIG. 2A, and is common to the groove bottom surface 20 and the surfaces of the inclined surfaces 21a and 21b over the entire moving path of the movable electrode 5. An electrode 60 is formed, and the movable electrode 5 is configured to move in contact with the common electrode 60. By providing the common electrode 60, the capacitance C _b to be formed between the capacitance C _a and the strip electrode 7 _b and the movable electrode 5 which is formed between the strip electrode 7 _a and the movable electrode 5 Can be detected independently of each other.

This is represented by an electric circuit symbol in FIG. Capacitance C _a can be detected between a terminal a 8 connected to the strip electrode 7 _a and a terminal c 61 connected to a common electrode 60 (not shown in FIG. 7A). Also it is possible to detect the electrostatic capacitance C _b between the terminal b9 and the terminal c61 connected to the strip electrodes 5 _b. Thus, by electrically taking out the movable electrode 5 with the common electrode 60, it is possible to measure the capacitance C _a and the capacitance C _b independently.
In the example of FIG. 7A, the case where the groove 6a is present is shown, but the groove 6a may be omitted. In the case of the example in which the guide means shown in FIG. 7B is configured by a pair of side walls, the same configuration can be obtained by arranging a common electrode on the center line in the width direction of the arc-shaped inner surface 3. I can do it.
[Reason why contact resistance can be ignored]
By providing the common electrode 60 that is in direct contact with the movable electrode 5, a contact resistance is generated between the movable electrode 5 and the common electrode 60. If the capacitance obtained between the terminal a8 and the movable electrode 5 is C14, and the contact resistance generated between the terminal c61 and the movable electrode 5 is R15, the equivalent circuit can be expressed as shown in FIG. The impedance Z due to the capacitance C and the contact resistance R can be expressed by equation (6).

この式（６）から分かるようにこの等価回路に交流を印加することで変化するインピーダンス成分は１/ｊωＣの項だけであるので、図５で説明したような交流的な方法で容量変化を検出することで、接触抵抗は無視することが可能である。
これは従来の抵抗検出型の傾斜センサの等価回路を示す図８（ｂ）と比較すると容易に理解できる。すなわち検出部を形成する検出抵抗ＳＲ１６と接触抵抗Ｒ１５が直列に接続された関係なので、交流的な方法で検出しても検出抵抗ＳＲ１６と接触抵抗Ｒ１５のどちらが変化したのかを分離することは出来ない。

As can be seen from this equation (6), the impedance component that changes when AC is applied to this equivalent circuit is only the 1 / jωC term, so the capacitance change is detected by the AC method as described in FIG. By doing so, the contact resistance can be ignored.
This can be easily understood by comparing with FIG. 8 (b) showing an equivalent circuit of a conventional resistance detection type inclination sensor. That is, since the detection resistance SR16 and the contact resistance R15 forming the detection unit are connected in series, it is impossible to separate which of the detection resistance SR16 and the contact resistance R15 has changed even if detection is performed by an AC method. .

  In this way, by using the capacitance type detection, the contact resistance between the movable electrode and the common electrode can be ignored. Therefore, in principle, it is possible to make the sensitivity higher than that of the conventional resistance detection type inclination sensor.

FIG. 9 shows another embodiment in which the inclination direction can be easily distinguished by providing the common electrode. FIG. 9 is a plan view of a tilt sensor showing an example of the present invention. In the embodiment shown in FIG. 9, a pair of strip-like electrodes 7 _a and 7 _b and strip-like electrodes 7 _c and 7 _d formed across a groove 6 a that forms a movement path of the movable electrode 5 are respectively connected to the movement path (groove 6 a. 1) is different from FIG. 1A described above in that it is formed asymmetrically. Strip electrode 7 _b and 7 _c in this example is parallel to the groove portion 6a, the strip electrodes 7 _a and 7 _d are farther away toward the opposite directions from the lowest point of the arc-shaped inner surface 3, with gradual groove 6a The distance is getting bigger.

The movable electrode 5 is located at the lowermost part of the arc-shaped inner surface 3. Tilting the body 2 in a clockwise direction in the longitudinal direction around the central portion of the body 2, i.e. the movable electrode 5 when the strip electrode 7 _a, 7 _b-side lower moves to strip electrode 7 _a, 7 _b side.
On the contrary, when the main body 2 is tilted counterclockwise around the central portion in the longitudinal direction, the movable electrode 5 moves to the side of the strip electrodes 7 _c and 7 _d .
Therefore a strip electrode 7 _a was then extended have an angle to the extension direction from the lowest point of the arc-shaped inner surface 3 groove 6a as shown in FIG. 9, the strip electrode 7 _b into the groove 6a from the lowest point Extend in parallel to. Thus configured to be inclined in a clockwise direction as the main body 2 described above, the and the strip electrode 7 _a movable electrode 5 is movable electrode 5 be moved to the strip electrode 7 _a, 7 _b-side from the lowest point _the capacitance C _a are formed in will vary, the capacitance C _b to be formed in the movable electrode 5 and the strip-shaped electrodes 8 _b will not change.

Conversely, when the main body 2 is tilted counterclockwise as described above, the capacitance C _a does not change and the capacitance C _b changes.
Thus, by providing the common electrode 60 and allowing the capacitance C _a and the capacitance C _b to be measured independently, it is possible to provide a change in individual capacitance without providing complicated detection means. It is possible to simply detect the inclination direction and the inclination angle θ simply by determining the direction.

FIG. 10 shows an embodiment in which the detection of a specific inclination angle that is to delete a part of the strip electrode is facilitated. In the embodiment shown in FIG. 10, the strip electrodes 7 _{a to} 7 _d are formed in parallel to the groove 6 _a, and the strip electrodes 7 _a and 7 _c are partly removed in the extension direction. However, it is different from FIG.
Thus, it can utilize as an inclination switch by deleting a part of strip | belt-shaped electrode. Tilting around the central portion in the longitudinal direction of the main body 2 clockwise, the movable electrode 5 moves to the strip electrode 7 _a, 7 _b side. Now, increasing the inclination angle θ for strip electrode 7 _a, 7 _b is formed parallel to the grooves 6a, the capacitance C formed between the movable electrode 5 and the strip electrode 7 _{a a} represents a constant value. Similarly, the capacitance _Cb also shows a constant value. When the movable electrode 5 reaches the delete portions of the strip electrode 7 _a further increased inclination angle theta, _the capacitance C _a, which shows a constant value until it to the electrodes are removed rapidly decreases. By using this rapid change in capacitance as a switching signal, it is possible to realize a tilt switch with simple detection means.

In the embodiment shown in FIG. 10A, since the band-like electrode is formed again on the arc outer extension line via the band-shaped electrode deletion portion 80, the binary inclination angle θ can be detected. That is, once the capacitance C _a suddenly decreases, the inclination angle θ is further increased, and when the movable electrode 5 reaches the portion where the strip electrode 7 _a is formed, the capacitance C _a is detected again. The The inclination angle θ at this time can be set to the second value. This detection angle can be arbitrarily set according to the radius ρ of the arc-shaped inner surface 3, the radius r of the movable electrode 5, and the position where the deletion portion is provided.

Further, according to this method, it is possible in principle to detect a plurality of inclination angles θ by providing a plurality of deletion portions on the strip electrode. However, this is a case where the tilt angle θ continuously increases in one direction, and erroneously detects if the tilt angle θ changes in the decreasing direction during the process.
In order to prevent this, as shown by a broken line in FIG. 10A, the strip electrode is disposed at an angle with respect to the guide means, and the capacitance C varies with the inclination angle θ. In addition, it is preferable to provide a deletion portion of the strip electrode. As a result, the inclination angle θ can be discriminated from the capacitance value, so that it is possible to prevent erroneous detection when the inclination direction changes in the middle.

  With this configuration, since the inclination angle θ can be determined from the capacitance value, there is a question that it is not necessary to provide a deletion part on the strip electrode, but it is possible to incline from the capacitance value by providing the deletion part. Compared to the method of determining the angle θ, the detection means for the specific inclination angle θ, that is, the inclination angle θ corresponding to the deleted portion 80 can be configured more simply.

FIG. 10B shows an embodiment in which chattering is reduced when the tilt sensor of the present invention is applied as a tilt switch. FIG. 10B is a plan view of an inclination sensor showing an example of the present invention. The difference between the embodiment shown in FIG. 10 (b) and FIG. 10 (a) described above is that the groove 6a at the portion parallel to the deleted portion 80 of the strip electrode is bent.
Tilting around the central portion in the longitudinal direction of the main body 2 clockwise, the movable electrode 5 moves to the strip electrode 7 _a, 7 _b side. At the beginning after the start of the inclination, _a capacitance C is formed by the movable electrode 5 and the strip electrodes 7 _a and 7 _b . Then, the inclination angle θ As you increase when the movable electrode 5 reaches the bent portion 82, the capacitance C in order to strip electrode 8 _a is removed rapidly decreases. The movement up to this point is the same as that shown in FIG. When the movable electrode 5 reaches the bent portion 82, the bent portion 82 becomes rolling resistance, and the swing back based on the inclination of the movable electrode 5 can be reduced, and the capacitance C generated based on the swing back is increased or decreased. It is possible to reduce the chattering detected.

By providing the bent portion 82 in the belt-like electrode in this way, the occurrence of chattering when detecting the tilt angle θ can be reduced. Figure In the embodiment shown in 10 (b), the position of the deletion part 80 and the bent portion 82 and the symmetry of the strip electrodes 7 _a an axis perpendicular to the extending direction of the groove 6a of the lowest point as the center line of the arcuate inner surface 3 A deleted portion 81 and a bent portion 83 are formed. Therefore, even if the main body 2 is tilted counterclockwise around the central portion in the longitudinal direction, the tilt angle θ can be detected by reducing chattering.
The angle of the bent portions 82 and 83 with respect to the arc shape extending direction will be described. FIG. 10 (c) shows an enlarged view of the groove 6a around the bent portion 82. FIG. If the angle of the bent portion 82 with respect to the arc-shaped extension direction is δ, the moving distance x ^′ on the groove 6a with respect to the distance x in the arc-shaped extension direction is given by x ^′ = x / cos δ. The force increased by multiplying the force that the movable electrode 5 tries to roll by the distance x by 1 / cos δ works as a rolling resistance against the movable electrode 5. For example, when the angle δ is 90 °, the braking force is infinite, that is, the movable electrode 5 hits the groove 6a bent at a right angle, and chattering does not occur, but it does not move even if the inclination angle θ is increased. This state can also be used as a tilt sensor. That is, it can be used as a point where the sensor output does not change even when the inclination angle θ is increased.

  As described above, the angle δ can be set in the range of 0 to 90 °, and if it is less than 90 °, the sensitivity to the inclination angle θ is reduced. The occurrence of chattering can be suppressed as much as the sensitivity is lowered.

FIG. 11 shows another embodiment that more effectively suppresses chattering when detecting the tilt angle θ. Fig.11 (a) is sectional drawing of the XX line shown to Fig.10 (a). The embodiment shown in FIG. 11A is an example in which the height in the vertical direction of the arc-shaped inner surface 3 of the deleted portion 80 of the strip electrode is lowered by one step.
The arc-shaped inner surfaces 111 and 112 in which the height of the arc-shaped inner surface 3 of the deleted portions 80 and 81 from which the strip electrodes 7 _a and 7 _c are deleted are one step lower. After the height of the arc-shaped inner surface 3 is formed one step lower, the height on the arc extension line from the lowest point of the arc-shaped inner surface 3 again when the strip electrodes 7 _a and 7 _c are formed again on the arc outer extension line. An arc-shaped inner surface 3 having

When the inclination angle θ increases and the movable electrode 5 reaches the deleted portion of the strip electrodes 7 _a and 7 _c , the movable electrode 5 immediately falls to the lower arc-shaped inner surfaces 111 and 112, and chattering occurs due to the swinging back of the movable electrode 5. It becomes possible to suppress. In the embodiment shown in FIG. 11 (a), the step between the arc-shaped inner surface 3 and the arc-shaped inner surfaces 111 and 112 is increased for the sake of explanation, but this step may be small in practice.
Another embodiment is shown in FIG. FIG. 11B is an example in which the height of the arc-shaped inner surface 3 at the bending points 84 and 85 where the bending portions 82 and 83 described with reference to FIG. The height in the vertical direction of the arc-shaped inner surface 3 gradually increases from the lowest point of the arc-shaped inner surface 3 toward the guide direction of the movable electrode 5, that is, both upper sides of the arc. Is forming. The height in the vertical direction of the arc-shaped inner surface 3 on both outer sides of the bending points 84 and 85 is temporarily lowered with the bending points 84 and 85 as apexes. Thereafter, arc surfaces that become higher toward both outer sides of the arc are formed to extend to both outer sides.

In this way, by forming the vertical height in the vicinity of the bending points 84 and 85 with the bending points 84 and 85 as apexes, the inclination angle θ changes and the movable electrode 5 gets over the bending points 84 and 85. The movable electrode 5 quickly moves to the lower part of the bent portions 82 and 83 and is stabilized.
As a result, it is possible to more effectively suppress chattering due to the swinging back of the movable electrode 5 at the time of detection.
In the embodiment shown in FIG. 11, the vertical heights of the arc-shaped inner surface 3 before and after the bent points 84 and 85 on the lowest point side of the arc-shaped inner surface 3 are lowered, but the bent portions 82, The same configuration may be applied to the bending point of the portion where 83 ends on the upper side of the arc.

Another embodiment in which the shape of the strip electrode is changed is shown in FIG. The embodiment shown in FIG. 12 differs from that shown in FIG. 1 in that a wide portion 100 _a that is widened in the middle of the method of extending the strip electrodes 7 _a and 7 _b is provided. In this example a case where the wide portion 100 _b is formed at a position of the wide portion 100 _a symmetric to strip electrode 7 _b are placed symmetrically around the groove 6a. The wide portion does not have to be formed symmetrically across the groove. That is, you may form only in one side.
Wide portion 100 _b in the middle also a wide portion 100 _a symmetrical position of the strip electrode 7 _b are placed symmetrically about the groove 6a is formed.

FIG. 12B shows a tendency of the capacitance C to change when the main body 2 is tilted clockwise about the central portion in the longitudinal direction. The horizontal axis of FIG.12 (b) shows clockwise inclination | tilt angle (theta). The vertical axis shows the changing tendency of the capacitance C. Here, the expression of the absolute amount by which the capacitance C changes does not represent the actual change amount. When the inclination angle θ is 0, the vertical distance d between the movable electrode 5 and the strip-like electrodes 7 _a and 7 _b is the smallest, so that a relatively large capacitance C is exhibited. Thereafter, as the inclination angle θ is increased, the interval d gradually increases, so that the capacitance C decreases. When the tilt angle θ further increases and the movable electrode 5 reaches the wide portions 100 _a and 100 _b , the electrode area S for forming the capacitance C increases, and thus the capacitance that has been gradually decreased until now. C increases. After the increase, since the widths of the strip electrodes 7 _a and 7 _b are formed wide, the amount of change in the capacitance C per unit inclination angle θ increases. That is, while the movable electrode 5 is in the range of the wide portions 100 _a and 100 _b with respect to the inclination of the change in the capacitance C with respect to the inclination angle θ before the movable electrode 5 reaches the wide portions 100 _a and 100 _b . The inclination of the change in the capacitance C with respect to the inclination angle θ can be increased. When the inclination angle θ further increases, the electrode widths of the strip-like electrodes 7 _a and 7 _b again become the same width as the central portion of the arc-shaped inner surface 3, so the inclination of the change in the capacitance C with respect to the inclination angle θ becomes smaller again. . Thus, the sensor output with respect to the tilt angle θ is not uniform, and it is possible to increase the sensor output at a specific angle or increase the resolution with respect to the tilt angle θ. Conversely, it is easy to reduce the sensor output at a specific angle and reduce the resolution with respect to the angle.

  Thus, by changing the shape of the strip electrode, it is possible to give a characteristic to the output of the tilt sensor with respect to the tilt angle θ. This is not possible with the conventional tilt sensor shown in FIG.

FIG. 13 shows an embodiment in which the capacitance C can be increased. FIG. 13A is a plan view of this embodiment, FIG. 13B is a cross-sectional view taken along line XII-XII in FIG. 13A, and FIG. 13C is a cross-sectional view taken along line XIII-XIII. Each is shown. As the dielectric layer, such as for example, specific dielectric constant greater barium titanate and titanium oxide in this embodiment can be formed large electrostatic capacitance C by placing between the movable electrode 5 and the strip electrode 7 _a to _7-d It is a thing.
A dielectric layer 110 is embedded along the arc shape of the arc-shaped inner surface 3, and a groove portion 6 d having an arc shape in cross section is formed on the dielectric layer 110 as shown in FIG. Strip electrodes 7 _{a to} 7 _d are formed on the side opposite to 6 _d . In this example, the strip electrodes 7 _{a to} 7 _d are opposed to the dielectric layer 110 within a certain range from the lowermost part, and the upper side thereof is not opposed to the dielectric layer 110. . In this example, the width of the dielectric layer 110 is made equal to the diameter of the movable electrode 5.

The strip electrodes 7 _a , 7 _{b and} 7 _c , 7 _d are symmetrical with respect to the center line of the groove 6 _d . This is the same as the embodiment shown in FIG. 1 in that the strip electrode is symmetrical with respect to the center line.
By configuring in this way, within the range of the diameter of the movable electrode 5, the strip electrodes 7 _{a to} 7 _d and the movable electrode 5 are opposed to each other with the dielectric 110 having a large relative dielectric constant in between. The electrostatic capacitance C can be formed large. A portion where the dielectric layer 110 is not interposed between the belt-like electrodes 7 _{a to} 7 _d formed in a range larger than the diameter of the movable electrode 5 and the movable electrode 5 becomes large, but electrostatic coupling between them is possible. Exists. Therefore, the main body 2 is made of, for example, plastic having a small relative dielectric constant, and the dielectric 110 is made of, for example, barium titanate having a large relative dielectric constant as described above. Then, since there is a difference of 100 times or more in relative dielectric constant between the two, the capacitance C can be greatly changed in combination with the effect of widening the electrode interval. Accordingly, when the movable electrode 5 moves to a portion where the belt-like electrode does not face the dielectric layer 110, the capacitance is rapidly reduced. This sudden change can be used as a tilt switch. Alternatively, the movable electrode 5 side of the belt-like electrode may all be the dielectric layer 110.

By using a dielectric having a large relative dielectric constant in this way, the capacitance C can be increased, so that the capacitance change can be increased without changing the shape of the strip electrode. According to this configuration, it is possible to realize a tilt sensor in which the sensor output with respect to the tilt angle θ has high resolution, and it is possible to realize a suitable tilt sensor by using it as a tilt switch.
As described above, the detection sensitivity can be increased by detecting the inclination angle θ by the capacitance generated between the strip electrode and the movable electrode. In addition, by devising the shape of the strip electrode forming the electrostatic capacity, it was possible to realize a tilt sensor with a large degree of freedom in sensor output, which could not be realized with a conventional resistance detection type tilt sensor.

In addition, although the movable electrode in the Example used so far has shown the example of a sphere, this invention is not limited to this Example. For example, the movable electrode may have an abacus ball shape shown in FIG. 14A is a plan view of an abacus-shaped movable electrode, FIG. 14B is a front view thereof, and FIG. 14C is a side view thereof. By holding both ends 120a and 120b in the vertical direction of the abacus-shaped movable electrode 120 with less friction, the embodiments described so far can be configured.
In short, the tilt sensor of the present invention can be realized regardless of the shape of the movable electrode as long as the cross section of the movable electrode in the direction orthogonal to the moving direction becomes higher from the central portion toward the outer direction orthogonal to the moving direction. It is possible.

It is a figure which shows one Example of the inclination sensor by this invention. It is sectional drawing of the II-II line | wire shown to Fig.1 (a). It is a figure which shows the movement distance X which forms the electrostatic capacitance C, the distance L, and the space | interval d. It is a figure which shows the other Example of a strip electrode. It is a figure which shows an example which converts a capacity | capacitance change into a quantitative value. It is a figure which shows the specific Example of a guidance means. It is a figure which shows the Example which changed the electrode structure. It is a figure which shows the equivalent circuit of an inclination sensor. It is a figure which shows an example of the shape of a strip | belt-shaped electrode when a common electrode is provided. It is a figure which shows the Example which changed the shape of the strip electrode. It is sectional drawing of the XX line shown in FIG. It is a figure which shows the other Example which changed the shape of the strip | belt-shaped electrode. It is a figure which shows the other Example which can comprise the electrostatic capacitance C largely. It is a figure which shows the other Example of a movable electrode. It is a figure which shows the inclination sensor using the conventional variable resistance.

Claims (12)

A main body case having at least an inner bottom surface formed in an arc shape;
A movable electrode movably disposed on the arc-shaped inner surface;
Guiding means for moving the movable electrode along the arc shape of the arc-shaped inner surface;
Two pairs of strip electrodes provided along the guiding direction by the guiding means from the lowermost part of the arc-shaped inner surface;
An inclination sensor characterized by detecting a capacitance generated between a pair of strip electrodes and a movable electrode.   2. The inclination sensor according to claim 1, wherein the guide means is a groove located between the pair of electrodes and extended along the arc-shaped inner surface. In claim 1 or 2,
The inclination sensor characterized in that the guide means is a pair of side walls that allow the movable electrode to move and restrict the movable electrode along the arc shape of the arc-shaped inner surface. In any one of Claims 1 to 3,
Each of the pair of belt-like electrodes is separated from the lowermost part of the arc-shaped inner surface, and the interval changes accordingly. In any one of Claims 1 thru | or 4,
An inclination sensor comprising a common electrode that contacts the movable electrode on a moving path along which the movable electrode moves along the guide means. In claim 5,
Each of the pair of strip electrodes is formed asymmetrically with the moving passage as a center. In any one of Claims 1 thru | or 6,
An inclination sensor characterized in that at least one of each of the pair of strip-like electrodes formed along the arc shape from the lowermost part of the inner surface of the arc shape is deleted at least partway. In claim 7,
The tilt sensor according to claim 1, wherein the guide means is a groove portion, and the groove portion is bent at a position where at least the strip electrode is removed. In claim 7 or claim 8,
An inclination sensor, wherein the height of the arc-shaped inner surface is made deeper at least in a portion where the strip electrode is removed. In claim 8,
A tilt sensor characterized in that the height of the arc-shaped inner surface at the bent bending point is increased. In any one of Claims 1 thru | or 6,
An inclination sensor, characterized in that at least a part of a width of at least one of each of the pair of band-shaped electrodes formed along the arc shape is formed from a lowermost part of the inner surface of the arc shape. In claim 2 and any one of claims 4 to 11,
The groove is formed of a dielectric layer;
Each of the pair of strip electrodes is opposed to at least a part thereof with a dielectric layer forming a groove interposed therebetween.

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