CN1146558A - Installation configuration of acceleration detection element - Google Patents

Abstract

An acceleration detection element installation configuration structure, which uses as few elements as possible to detect acceleration in a wide range of directions and has substantially the same detection sensitivity for accelerations generated in any direction along orthogonal coordinate axes, two accelerations The detection element is arranged on the XY element mounting end surface in the orthogonal X, Y, Z coordinate system, so that its direction is the same as that of the X axis and Y axis on the element mounting end surface, and the maximum sensitivity direction of one of the two elements is from X One axis is inclined 40° and 50° toward the Z axis, and the other is inclined 40° to 50° from the X axis toward the Z axis.

Description

Installation configuration of acceleration detection element

The present invention relates to a mounting configuration structure of an acceleration detection element used in shock detection.

There is known an acceleration detection element composed of a bimorph type element with both ends fixed. For example, in Fig. 11, in the example of the conventional element shown in a simplified manner, the acceleration sensor 20a includes a bimorph type element 1 as an acceleration detection element and an insulating case 2 containing the element, and after positioning the case 2, the It is mounted in a fixed manner on the sensor mounting face 3 , for example a circuit board.

The bimorph element 1 is in the shape of a rectangular sheet, composed of two laminated piezoelectric ceramic sheets 6 , and a signal electrode 4 and an intermediate electrode 5 are formed on the top and bottom surfaces of each ceramic sheet. Each of the two piezoelectric ceramic sheets 6 oppositely bonded via the intermediate electrode 5 is polarized along the thickness direction, which is opposite to the polarization sensing direction of the other piezoelectric ceramic sheet 6 . The dotted arrow marks in FIG. 11 mark this polarization direction. The respective signal electrodes 4 in this example are formed along the longitudinal direction of the respective piezoelectric ceramic pieces 6 and extend to end portions different from each other.

At the same time, the insulating housing 2 is composed of a pair of fastening frame parts 7 and a pair of housing cover plates 8. The fastening frame parts 7 are in the shape of a channel on a plane, and only along the direction of the thickness of the double wafer-shaped element The longitudinal direction of 1 compresses the two end parts, and a pair of housing cover plates 8 closes the open end surface formed by the bimorph element 1 and the two fastening frame members 7 arranged transversely opposite to the element. The respective signal electrodes 4 of the bimorph type element 1 contained in the insulating case 2 are connected to mutually different external electrodes (not shown) formed on the outer end surface of the insulating case 2 .

The outer surface of the fastening frame member 7 or the housing cover plate 8 constituting the insulating housing 2 is positioned and mounted on the sensor mounting end face 3, whereby the acceleration sensor is mounted. The respective signal electrodes 4 of the bimorph type element 1 are connected to wiring pattern lines (not shown) on the sensor mounting end face 3 via external electrodes formed on the insulating case 2 . These wiring patterns are connected to signal processing circuits (not shown). The signal processing circuit detects the acceleration caused by the impact by processing the electric signal output by the acceleration sensor.

Fig. 12 shows another conventional example of such an acceleration detecting element, which is different from the above-mentioned conventional examples in the form of polarization. Figure 12 shows the electrodes and elements in more detail than the corresponding parts of the acceleration detection element in Figure 11.

The piezoelectric ceramic element main body 23 included in the acceleration sensor 20b is in the shape of a rectangular sheet, the signal output electrode 21 is formed on its main surface, and the internal electrode 22 parallel to the signal output electrode 21 is built therein. Each signal output electrode 21 is made up of three surface electrodes 24 and a connection electrode 25, and the three surface electrodes 24 are respectively distributed at the central position and two end positions along the longitudinal direction of the piezoelectric ceramic element main body 23, and the connection electrode 25 The respective surface electrodes 24 are covered together.

One acceleration element is composed of a signal output electrode 21 and a piezoelectric ceramic element main body 23 .

One side electrode (top side in FIG. 12 ) of the signal output electrodes 21 extends up to one outer end surface (left side in FIG. 12 ) of the piezoelectric ceramic element main body 23 . Meanwhile, the other side electrode (the bottom side in FIG. 12 ) of the signal output electrodes 21 extends up to the other outer end face (the right side in FIG. 12 ). In addition, the ceramic element regions 26 and 27 constituting the two piezoelectric ceramic element main bodies 23 and facing each other across the internal electrodes 22 are respectively divided into three parts in the longitudinal direction, that is, central parts 26a and 27a and both side end parts formed by the border. 26b and 27b, the direction of the stress at the boundary due to acceleration is changed. By using the internal electrodes 22 and the respective surface electrodes 24, both sides of the central portions 26a and 27a and the end portions 26b and 27b are polarized in sensing directions that are different from each other along the thickness.

Here, the polarization directions of the central portion 26a and the end portion 26b constituting the ceramic element region 26 are denoted by H and I, which are different from each other, and the central portion 27a and the end portion 27b constituting the ceramic element region 27 are denoted by J and K. different polarization directions. Furthermore, in this case, for example, the polarization direction indications H and J of the central portions 26a and 27a are directed inwardly, wherein these two direction indications are identical to each other; the polarization direction indications of the end portions 26b and 27b I and K are directed outwards, where the two directions are directed away from each other.

Both ends of the acceleration sensor 20b in the longitudinal direction are supported in a fixed manner by a pair of fastening frame members 28 having a channel shape in side view. The respective signal output electrodes 21 formed on the main surface of the piezoelectric ceramic element body 23 are connected to external output electrodes 29 and 30 formed on different outer end surfaces of the piezoelectric ceramic element body 23 and the fastening frame member 28 .

The acceleration sensor 20b having such a structure is used for the following reason. When acceleration is generated on the acceleration sensor 20b including the acceleration detection element composed of the signal output electrode 21 and the piezoelectric ceramic element main body 23, the central parts 26a and 27a in the ceramic element regions 26 and 27 constituting the acceleration ceramic element main body 23 and The end portions 26b and 27b are deformed due to inertial force. In this case, the respective portions 26a, 27a, 26b, and 27b are subjected to tensile stress and compressive stress caused by this deformation. In each of the portions 26a, 27a, 26b and 27b, the amount of generated charges is increased due to the superposition of the polarization effects of the respective indicated directions (from H to K), the stress borne by the acceleration sensor 20b and the total amount of generated charges are increased, This improves the detection sensitivity of the acceleration sensor.

Meanwhile, when an acceleration is generated in a direction perpendicular to the surface of the piezoelectric ceramic sheet 6 or 23, that is, in the thickness direction, a maximum electric signal is output in the acceleration sensor 20a or 20b. Furthermore, when acceleration is generated in the opposite direction, that is, in a direction 180° therefrom, the maximum electric signal having the same absolute value but having opposite positive/negative signs is output. That is, the direction in which the acceleration is generated is the direction in which the maximum sensitivity is formed, which is called the maximum sensitivity direction P of the main axis of the acceleration sensor. When acceleration is generated in a direction tangential to the surface of the piezoelectric ceramic sheet 6 or 23 in the acceleration sensor 20a or 20b, no electrical signal is output, and thus the detection sensitivity is zero. Meanwhile, when acceleration is generated in a direction between the vertical direction and the tangential direction, the detection sensitivity has a magnitude corresponding to the angle θ formed by the direction of maximum sensitivity P and the direction in which the acceleration is generated, that is, the sensitivity of the direction The magnitude is the product of the maximum sensitivity S and Cosθ.

When the acceleration sensor 20a having the above-mentioned conventional structure is installed on the sensor installation end surface 3 as shown in FIG. 11 , the maximum sensitivity direction P is either parallel or perpendicular to the sensor installation end surface 3 . As shown in Figure 11, place the two-dimensional orthogonal coordinate axes (plane coordinate axes) X and Y on the sensor installation end surface 3, and set the three-dimensional coordinate axes (spatial coordinate axes) X, Y and Z to install the sensor The end face 3 serves as an X-Y plane, so that in it, one of the case cover plates 8 of the insulating case 2 combined with the bimorph type piezoelectric element 1 is mounted on the sensor mounting end face 3, and is set so that acceleration therein The maximum sensitivity direction P of the longitudinal configuration of the sensor 20a is the direction of the Y axis on the sensor installation end surface 3, so the acceleration along the X axis or the Z axis, that is, the acceleration generated in any direction in the X-Z plane, cannot be detected.

In addition, although not illustrated, when one of the fastening frame members 7 of the insulating case 2 is installed on the sensor installation end surface 3, the orthogonal coordinate axes X and Y are set and the acceleration sensor 20a is maximized. The sensitivity direction P is the direction of the Z axis perpendicular to the sensor mounting end surface 3, and acceleration in any direction in the X-Y plane formed by the X axis and the Y axis cannot be detected. Therefore, to detect the accelerations along the respective directions of the mutually orthogonal coordinate axes X, Y and Z, it is necessary to install three acceleration sensors on the sensor installation end face 3, and their maximum sensitivity directions P are respectively X-axis, Y-axis, direction of the Z axis, which increases the number of acceleration sensor elements and installation space, increases the cost, and complicates the signal processing circuit for processing the electrical signals output by the three acceleration sensors.

Furthermore, when the acceleration sensor 20b shown in FIG. 12 is mounted on the sensor mounting end face 3 instead of the acceleration sensor 20a, the same problem naturally arises.

In order to avoid this inconvenience, an acceleration detection element has been proposed which can detect the acceleration in three directions along the orthogonal X, Y, and Z axes by inclining the maximum sensitivity direction of the acceleration detection element upward from the sensor mounting end face. acceleration. Although not stated, a second acceleration detection element is disclosed in Unexamined Japanese Patent Publication No. 133974/93, in which the direction of maximum sensitivity of the acceleration detection element in the shape of a rectangular sheet is inclined at 45° to the sensor mounting end face, And one side line in the acceleration detection element is further inclined at 45° from one side line of the element mounting base. When an acceleration detecting element having such a structure is used in an acceleration sensor, three directions along the X axis, Y axis, and Z axis (hereinafter, these three directions coincide with those shown in FIG. 11 ) are generated to some extent. The acceleration can be detected using a single element.

However, even though accelerations occurring in three directions along the three orthogonal coordinate axes X, Y, and Z can be detected, accelerations in all directions cannot be detected. It is not possible to detect accelerations occurring in a plane orthogonal to the direction of maximum sensitivity. Furthermore, although the direction of maximum sensitivity is naturally inclined at 45° from the Z-axis in the above structure, in this case, the directions of the X-axis and Y-axis are actually inclined at 60° from the direction of maximum sensitivity, therefore, along the X-axis , Y-axis and Z-axis detection sensitivities are actually different.

Consider overcoming this inconvenience and propose the present invention, the purpose of the present invention is to provide the installation device of acceleration detection element, utilize the detection element of as few as possible to detect the acceleration of wide range of directions, and the acceleration in each direction along the orthogonal coordinate axis The resulting acceleration has essentially the same sensitivity.

In order to achieve this object, the present invention provides a mounting device for an acceleration detection element comprising two acceleration detection elements, wherein the first maximum sensitivity direction of one acceleration detection element is inclined from 40° to 50° from the Y axis to the Z axis, and The second maximum sensitivity direction of the other acceleration detecting element is 40° to 50° inclined from the X axis to the Z axis. Also, the acceleration detection element in this case is a bimorph type element composed of both ends fixed piezoelectric ceramic elements.

Furthermore, in order to achieve the object, the present invention provides an acceleration detection element mounting device including two acceleration detection elements, further comprising a calculation means for calculating the sum of the absolute values of the electric signals output from the respective acceleration detection elements. Calculate, and the direction of the first maximum sensitivity of one of the acceleration detection elements is inclined from 20° to 30° from the Y axis to the Z axis, and the second maximum sensitivity direction of the other acceleration detection element is inclined from 20° to 30° from the X axis to the Z axis °. In addition, the acceleration detection element in this case is a bimorph type element composed of piezoelectric ceramic elements fixed at both ends.

In addition, the present invention provides a mounting device for an acceleration detection element, wherein internal electrodes are installed on the inner part of the main body of the piezoelectric ceramic element in the shape of a rectangular sheet, and they are distributed longitudinally in the center of the main body of the piezoelectric ceramic element in a divided manner. The position and both end positions, signal output electrodes are installed on the main surface of the piezoelectric ceramic element body, and the different transmissions along the thickness direction of each central portion and end portion of the piezoelectric ceramic element body facing each other in the longitudinal direction through the internal electrodes The sense direction produces polarization.

1 is a partially cutaway perspective view showing the structure of an acceleration detecting element according to a first embodiment;

FIG. 2 is an explanatory view showing a mounting structure of the acceleration detecting element of the first embodiment;

Fig. 3 is a functional block diagram representing the working state of the mounting structure of the first embodiment;

4 is a partially cutaway perspective view showing a mounting structure of an acceleration detecting element according to a second embodiment;

5 is an explanatory view showing a mounting structure of an acceleration detecting element of a second embodiment;

Fig. 6 is a functional block diagram representing the working state of the mounting structure of the second embodiment;

7 is a partially cutaway perspective view of an acceleration detection element according to a third embodiment;

8(a), 8(b) and 8(c) are explanatory sectional views showing the preceding steps of the manufacturing method in the third embodiment;

9(a) and 9(b) are explanatory cross-sectional views showing the subsequent steps of the manufacturing method in the third embodiment;

Fig. 10 (a), 10 (b) and 10 (c) represent the explanatory cross-sectional view of the transformation example of the former stage step of the manufacturing method in the 3rd embodiment;

11 is a partially cutaway perspective view showing the structure of an acceleration detecting element according to a conventional example;

12 is a partially cutaway perspective view showing the structure of a piezoelectric element according to another conventional embodiment;

Example 1

Embodiment 1 of the present invention is explained with reference to the drawings.

1 is a partially cutaway perspective view showing an acceleration sensor, which is a partial mounting structure of an acceleration detecting element according to a first embodiment, FIG. 2 is an explanatory view showing an overall mounting structure of the acceleration detecting element, and FIG. 3 is a functional block diagram showing the operation of the mounting structure of the first embodiment. In addition, the structure of the acceleration sensor including the acceleration detection element is basically the same as that in the conventional example. Therefore, parts or elements in FIGS. 1 and 2 that are the same as those shown in FIG. 11 are denoted by the same reference numerals, and their detailed explanations are omitted.

As shown in FIG. 1 , an acceleration sensor A or B in the first embodiment is composed of a both-fixed bimorph type element 1 serving as an acceleration detection element and an insulating case 2 containing the bimorph type element 1 . The acceleration sensors A and B are mounted on the sensor mounting end surface 3 which is, for example, a circuit board. The bimorph type element 1 in this example is housed and positioned in the insulating case 2 in such a state that the direction of maximum sensitivity P is in oblique relation to the sensor mounting end face 3 . The direction of maximum sensitivity P is set upward at an oblique angle to the sensor mounting end face 3, 40° or more and 50° or less, hereinafter for example 45°.

In the bimorph element 1 of the first embodiment, a pair of piezoelectric ceramic sheets 6 are in the shape of a rectangular sheet, and signal electrodes 4 and intermediate electrodes 5 are formed on the top and bottom surfaces of each ceramic sheet. The sheets were opposed and bonded together, and their end portions were cut off at corresponding inclined planes at an inclined angle of 45° to the thickness direction. The respective piezoelectric ceramic sheets 6 bonded via the intermediate electrodes 5 are polarized in the thickness direction with sensing directions different from each other, and each signal electrode 4 extends to each other along the longitudinal direction of the respective piezoelectric ceramic sheets 6 identical to the conventional example. Not the same end section. Furthermore, the insulating case 2 in this example is constituted by the fastening frame member 7 and the case cover plate 8 as in the conventional example, and the respective signal electrodes 4 of the bimorph type element 1 are connected to the insulative case 2 on the external electrodes (not shown) formed on the different outer end faces of each other.

Meanwhile, as shown in FIG. 2 , the installation structure of the acceleration detection element has two acceleration sensors A and B, which are installed on the sensor installation end surface 3 in the same direction as the directions along the orthogonal coordinate axes X and Y respectively. In addition, as shown in Fig. 3, the installation structure is connected to the first and second comparator circuits _X1 and _X2 , and these two comparator circuits realize the function of the comparator, and are respectively outputted by the electronic components A and B. The electrical signals V _A and V _B are compared, and a logic circuit _X3 implements OR logic operation processing on the comparator signals V _S1 and V _S2 respectively output by the first and second comparator circuits X ₁ and X ₂ . Comparator circuits _X1 and _X2 and logic circuit _X3 are integrated in a signal processing circuit (not shown).

The acceleration sensors A and B are mounted by positioning and fixing the outer surface of the housing cover 8 constituting the insulating housing 2 on the sensor mounting end face 3 . Each signal electrode 4 of the bimorph element 1 is connected to the connection pattern line (not shown) formed on the sensor mounting end surface 3 through the external electrode (not shown) on the insulating case 2 by means of welding or the like. The maximum sensitivity direction P of the bimorph type element 1 serving as an acceleration detection element and included in the acceleration sensor A is in a direction inclined upward, that is, at an angle of 45° from the Y axis to the Z axis. The maximum sensitivity direction P of the element 1 of the bimorph type, which is also used as an acceleration detection element and included in the acceleration sensor B, is in a direction inclined upward, that is, from the X axis to the Z axis.

Next, the operation of the mounting structure of the acceleration detecting element in this embodiment will be explained with reference to FIGS. 2 and 3. FIG. In the explanation below, the maximum sensitivity of the acceleration detection elements (acceleration sensors A and B) is S(mv/G), where G is the acceleration due to gravity, and a threshold value at or above a certain magnitude for detecting shock Designated as S ₁ and S ₂ .

First, assume a case where the installation structure of two acceleration sensors A and B arranged in the positioning relationship shown in FIG. 2 generates an acceleration of 1G along the positive direction of the orthogonal coordinate axis X. Then, the detection sensitivity of the acceleration sensor A arranged in the same direction as the Y-axis direction is 0, and the detection sensitivity of the acceleration sensor B arranged in the same direction as the X-axis direction is represented by the product of the maximum sensitivity S and Cos45°. Therefore, in this case, the electrical signal V _A output by the acceleration sensor A is 0 (mv), and the electrical signal V _B output by the acceleration sensor B is S Cos45°×1 (mv). In the second comparator circuit _X2 to which only the electric signal _VB is input, a comparator operation process is performed using a predetermined value _S2 as a threshold. That is, when V _B >S ₂ , the comparator signal V _S2 =1 and when V _B ≤ S ₂ , the comparator signal V _S2 =0. The comparator signal V _S2 output by the second comparator circuit _X2 is sent to the logic circuit _X3 .

In addition, when an acceleration of 1G is generated along the positive direction of the orthogonal Y coordinate axis, the detection sensitivity of the acceleration sensor A arranged in the same direction as the Y axis direction is represented by the product of the maximum sensitivity S and Cos45°, while along the X The detection sensitivity of the acceleration sensors B arranged in the same axial direction is zero. Correspondingly, in this case, the electrical signal V _A output by the acceleration sensor A is represented by S×Cos45°×1 (mv), and the electrical signal V B output by the acceleration sensor _B is 0 (mV). Therefore, in the first comparator circuit _X1 to which only the electric signal V _A from the acceleration sensor A is input, comparator operation processing is performed using the predetermined value _S1 as a threshold. That is, when V _A >S ₁ , the comparator signal V _S1 =1, and when V _A ≤ S ₁ , the comparator signal V _S1 =0. After that, the comparator signal V _S1 output by the first comparator circuit X ₁ is sent to the logic circuit X ₃ .

At the same time, when an acceleration of 1G is generated along the positive direction of the orthogonal coordinate axis Z, the two detection sensitivities of the acceleration sensors A and B are represented by the product of the maximum sensitivity S and Cos45°, and the signals V output by the acceleration sensors A and B _A and V _B are represented by S×Cos45°×1 (mv). In addition, in the first comparator circuit _X1 inputting only the electric signal V _A from the acceleration sensor A, comparator operation processing is performed using _S1 as the threshold value, while in the first comparator circuit X1 inputting only the electric signal V B from the acceleration sensor _B In the second comparator circuit _X2 , a comparator operation process is performed using _S2 as a threshold value. After that, the comparator signals V _S1 and V _S2 output by the first and second comparator circuits X ₁ and X ₂ are sent to the logic circuit X ₃ .

In addition, in two or one of _the logic circuits X3 that input the comparator signals V _S1 and V _S2 from the comparator circuits X ₁ and X ₂ , OR logic operation processing is performed according to the comparator signals V _S1 and V _S2 , That is, OR logic operation processing is performed to generate the logic circuit signal V _t =1 if V _S1 =1 or V _S2 =1. After that, the logic circuit signal V _L is output to the outside.

As explained above, when adopting the installation structure of the acceleration detection element in this embodiment, for any one of the directions of the orthogonal coordinate axes X, Y and Z, each detection sensitivity has substantially the same range, that is, the formed The detection sensitivity is the product of the maximum sensitivity S and Cos45°. Furthermore, in the mounting structure in this embodiment, the direction in which the detection sensitivity becomes 0 is only the direction orthogonal to the direction P of maximum sensitivity of the accelerations A and B, thus providing an advantage that acceleration can be detected in a wide range of directions.

Incidentally, although in the mounting structure of this embodiment, the maximum sensitivity direction P of the bimorph type elements 1 respectively included in the acceleration sensors A and B is inclined by the sensor mounting end face 3 at an inclination angle of 45°. However, it has been confirmed by the inventors of the present invention that the inclination angle is not limited to 45°, but may actually be within a range of 40° or more and 50° or less. In the case of an inclination angle of 40°, the ratio of Cos40° to Cos45°, that is, Cos40°/Cos45°=1.083 . . . In the case of an inclination angle θ of 50°, the ratio of Cos50° to Cos45°, that is, Cos50°/Cos45°=0.909 . . . Therefore, the ratio is substantially in the range of ±10% of the value at an inclination angle of 45°. Therefore, it is apparent that substantially the same detection sensitivity as in this embodiment can be produced along any one of the orthogonal axes X, Y, and Z.

Example 2

Fig. 4 is a partially cutaway perspective view showing an acceleration sensor, which is a partial mounting structure of the acceleration detecting element in the second embodiment, Fig. 5 is an explanatory view showing the overall mounting structure of the acceleration detecting element, Fig. 6 is a functional block diagram showing the operation of the mounting arrangement structure of the second embodiment. In addition, since the structure itself of the acceleration sensor including the acceleration detecting element is basically the same as that described in the conventional example and the first embodiment, in FIGS. 4 and 5 the same parts or elements as those in FIG. 11 and FIG. and their detailed explanations will be omitted.

As shown in FIG. 4, each acceleration sensor corresponding to the second embodiment is composed of a double-terminal fixed type bimorph type element 1 and an insulating case 2 containing the element, and these acceleration sensors are mounted on, for example, a circuit board. The sensor is mounted on end face 3. The bimorph type element 1 in this example is housed and positioned in the insulating case 2 in a state of being in an oblique relation to the sensor mounting end face 23, and the direction of maximum sensitivity P is set so that it is aligned with the sensor mounting end face 3 An upward inclination angle θ is formed, and its range is 20° and above 20° and 30° and below 30°, for example, 25°.

In the bimorph type element 1 used as the acceleration detecting element of the second embodiment, a pair of piezoelectric ceramic sheets 6 are each in the shape of a rectangular sheet, and signal electrodes 4 and intermediate electrodes are formed on the top and bottom surfaces of each ceramic sheet. 5. The two ceramic sheets are opposed and bonded, and their edge portions are cut off along the inclined plane corresponding to the thickness direction with an inclined angle θ of 25°. In addition, the piezoelectric ceramic sheets 6 bonded by the intermediate electrodes 5 are polarized in the thickness direction in opposite sensing directions, and the respective signal electrodes 4 are along the longitudinal direction of each piezoelectric ceramic sheet 6 that is the same as the conventional example. extend to end portions different from each other. In addition, the insulating case 2 in this example is composed of a fastening frame member 7 and a case cover plate 8 as in the conventional example, and each signal electrode 4 of the bimorph type element 1 is connected to the insulating case 2. On the external electrodes (not shown) formed on the different outer end faces of the

As shown in Figures 5 and 6, the installation configuration structure of the acceleration detection element in the second embodiment is connected to two acceleration sensors A' and B', which are along the coordinate axes X and Y orthogonal to The direction with the same direction is installed on the same sensor installation end face 3, and is also connected to the calculation device X4 and then to the comparison circuit _X5 . The calculation device _X4 is used to calculate the absolute value of the electrical signals output by the acceleration sensors A' and B' respectively. Sum of values (|V'A|+, |V'B|). The structure of the computing device _X4 that realizes the above calculations is well known, and their detailed explanation will be omitted.

The outer surface of the housing cover plate 8 constituting the insulating housing 2 is positioned and fixed, whereby the respective acceleration sensors A' and B' are mounted and fixed on the sensor mounting end surface 3 . Each signal electrode 4 of the bimorph element 1 is connected to the respective wiring pattern lines (not shown) formed on the sensor mounting end surface 3 through the external electrodes (not shown) formed on the insulating case 2 by welding or the like. . In this example, the direction P of maximum sensitivity of the bimorph type element 1 included in the acceleration sensor A' is inclined upward by 25° from the Y axis to the Z axis, while the bimorph type element included in the acceleration sensor B' The maximum sensitivity direction P of 1 is inclined upward, and is inclined 25° from the X-axis to the Z-axis.

The working conditions of the mounting arrangement structure of the acceleration detecting element in the second embodiment will be described in detail below with reference to FIGS. 5 and 6 . In the following description, the maximum sensitivity of the acceleration detection elements (acceleration sensors A' and B') is S'(mv/G), where G is the gravitational acceleration.

Next, assume a case in which the mounting structure composed of two acceleration sensors A' and B' distributed in the positional relationship shown in FIG. Then, the detection sensitivity of the acceleration sensor A' installed in the same direction as the Y axis is represented by the product of the maximum sensitivity S' and Cos90°, and the detection sensitivity of the acceleration sensor B' installed in the same direction as the X axis is represented by the maximum sensitivity S ' and the product of Cos25°. The electrical signal V A ' output by the acceleration sensor _A ' is expressed by S'×Cos90°×1 (mv), and the electrical signal V B ' output by the acceleration sensor _B ' is expressed by S'×Cos25°×1 (mv) . In the computing device _X4 , the sum (|A'|+|B'|) of the absolute values of the electrical signals A' and B' respectively output by the acceleration sensors A' and B' is calculated, that is, |S'×Cos90° |+|S'×Cos25°|=S'×0.91 (mv) as the composite signal V'AB. The resultant signal _VAB ', which has been calculated according to this procedure, is output to the comparator circuit _X5 . In the comparator circuit _X5 , a comparator operation process is performed using a predetermined value _S0 as a threshold. In the comparator circuit _X5 , when V _AB ′>S ₀ , the comparator signal V′S=1, and when V _AB ′<S ₀ , the comparator signal V _S ¹ ′=0. After that, the comparator signal V _S ' is output to the outside. In addition, although the above description is for a situation in which 1GR acceleration is generated along the positive direction of the orthogonal coordinate axis X, it is equally applicable to a situation in which acceleration is generated in the positive direction of the orthogonal coordinate axis Y For an acceleration of 1G, S'×0.91 (mv) is calculated as the composite signal V'AB.

In addition, when an acceleration of 1 GR is generated in the positive direction of the orthogonal coordinate axis Z using the mounting structure shown in FIG. 5 , the following arithmetic processing is performed. The detection sensitivity of the acceleration sensors A' and B' along the same direction as the Z-axis is represented by the product of the maximum sensitivity S' and Cos65°, that is, the product of S' and Cos (90°-25°), which is Since the inclination angle formed by the acceleration sensors A' and B' and the sensor mounting end surface 3 is 25°. Therefore, in this case, both of the electrical signals respectively output from the acceleration sensors A' and B' are represented by S'×Cos65°×1 (mv). In the calculation device _X4 , calculate the sum of the absolute values of the electric signals V _A ' and V _B ' output by the acceleration sensors A' and B' respectively, that is, |S'×Cos65°|+|S'×Cos65°| =S'×0.85 (mv) is taken as the composite signal VAB.

In the mounting structure of the acceleration detection element in the second embodiment, there is substantially the same detection sensitivity along any one of the orthogonal coordinate axes X, Y, and Z. In addition, in the mounting arrangement structure of the second embodiment, the direction in which the detection sensitivity is 0 is the direction orthogonal to the maximum sensitivity direction P of the acceleration sensors A' and B', respectively, thus providing the advantage that the detection sensitivity can be adjusted in a wide range of directions. Detect acceleration.

By the way, according to the second embodiment, the composite signal V _AB ' in the case of acceleration in the X-axis and Y-axis directions is S'×0.91 (mv), and the composite signal V in the case of acceleration in the Z-axis direction _AB ' is S' x 0.85 (mV). This difference arises because the inclination angle θ formed by the acceleration detecting element (dual wafer type element 1) and the sensor mounting end face 3 in the acceleration sensors A' and B' is set to 25° from the viewpoint of manufacturing convenience. By setting the inclination angle θ to 26.565 . . . °, exactly the same detection sensitivity along any direction of the X-axis, Y-axis, and Z-axis is obtained in the calculation.

It has been confirmed by investigations conducted by the inventors of the present invention that when the inclination angle formed by the direction of maximum sensitivity P of each bimorph type element 1 and the sensor mounting end 3 varies between 0° and 90°, and contains two The bimorph elements 1 of the acceleration sensors A' and B' are distributed on the sensor mounting end face 3 in the same direction as the orthogonal coordinate axes X and Y, and the electrical signals V output by the acceleration sensors A' and B' The change in the sum of the absolute values of 'A and V'B (|V _A '| + |V _B '| is shown in Table 1.

Table 1 Tilt angle θ(°C) Detection sensitivity along the X-axis direction Detection sensitivity along the Y axis direction Detection sensitivity along the Z axis A' B' |V _A ′|＋|V _B ′| A' B' |V _A ′|＋|V _B ′| A' B' |V _A ′|＋|V _B ′| 051015202530354045505560657075808590 0.000.000.000.000.000.000.000.000.000.000.000.000.000.000.000.000.000.000.00 1.001.000.980.970.940.910.870.820.770.710.640.580.500.430.350.260.180.090.01 1.001.000.980.970.940.910.870.820.770.710.640.580.500.430.350.260.180.090.01 1.001.000.980.970.940.910.870.820.770.710.640.580.500.430.350.260.180.090.01 0.000.000.000.000.000.000.000.000.000.000.000.000.000.000.000.000.000.000.00 1.001.000.980.970.940.910.870.820.770.710.640.580.500.430.350.260.180.090.01 0.000.090.170.260.340.420.500.570.640.710.760.820.860.900.940.960.981.001.00 0.000.090.170.260.340.420.500.570.640.710.760.820.860.900.940.960.981.001.00 0.000.170.350.520.680.841.001.141.281.411.531.631.731.811.881.931.971.992.00

In Table 1, by calculating the sum of the absolute values of the electric signals V _A ' and V B ' output by the acceleration sensors A' and _B ', it is clearly shown that only in such a case, that is, each of the acceleration sensors A' and When the inclination angle between the maximum sensitivity direction P of B' and the sensor installation end surface 3 is in the range from 20° to 30°, the detection sensitivity in the directions of three mutually orthogonal axes is basically the same.

Example 3

A third embodiment of the present invention is explained below. The third embodiment discloses the structure and manufacturing method of the acceleration detection element applicable to the first and second embodiments.

Fig. 7 is a partially cutaway perspective view showing an acceleration sensor in a state where the housing cover is removed, including an acceleration detection element according to a third embodiment, and Figs. 9 (a) and 9 (b) are explanatory sectional views showing the latter steps of the above-mentioned manufacturing method, and FIGS. 10 (a) to 10 (c) is an explanatory cross-sectional view of a modified example in the previous step of the above-mentioned manufacturing method.

The acceleration detection element C including one acceleration detection element is constituted by a double chip structure, which can realize the same function as in the conventional example. As shown in FIG. 7, the sensor includes a piezoelectric ceramic element main body 32 having a rectangular sheet shape and a predetermined thickness, for example, a piezoelectric ceramic element main body 32 produced by firing a semi-finished piezoelectric ceramic sheet. A signal output electrode 33 of a single-layer structure is formed on the main surface of each piezoelectric ceramic element main body 32 . The signal output electrode 33 on one side (top side in FIG. 7 ) extends to one side outer edge surface of the piezoelectric ceramic element main body 32 (left side in FIG. 7 ). Meanwhile, the signal output electrode 33 on the other side (bottom side in FIG. 7 ) extends to the other side outer edge surface of the piezoelectric ceramic element main body 32 (right side in FIG. 7 ).

At the inner portion of each piezoelectric ceramic element main body 32, three inner electrodes 34 distributed in the longitudinal direction at the central position and the end positions respectively are built so as to be parallel to the signal output electrodes. The ceramic element regions 35 and 36 which are opposed to each other with three internal electrodes 34 therebetween and constitute the piezoelectric ceramic element main body 32 are divided into three parts, namely the central part, in the longitudinal direction of the piezoelectric ceramic element main body 32 similarly to the internal electrodes 34 35a and 36a and end portions 35b and 36b. Further, the respective central portions 35a and 36a and end portions 35b and 36b in the ceramic element regions 35 and 36 are polarized in mutually different sensing directions in the thickness direction as in the conventional example.

The acceleration detection element is composed of a piezoelectric ceramic element main body 32 , a signal output electrode 33 and an internal electrode 34 .

Polarization of the ceramic element regions 35 and 36 is formed by using the signal output electrode 33 and the internal electrode 34 . Here, the central portion 35a and the end portions 35b constituting the ceramic element region 35 are polarized in the sensing directions H and I. As shown in FIG. The central portion 36a and the end portions 36b constituting the ceramic element region 36 generate polarizations in the sensing directions J and K. FIG. Further, both end edges in the longitudinal direction of the acceleration sensor C are supported in a fixed manner by a pair of fastening frame members 37 that are channel-shaped in side view. The signal output electrodes 33 formed on the main surface of the piezoelectric ceramic element main body 32 are connected to the respective external output electrodes 38 and 39 on.

Next, referring to explanatory cross-sectional views showing steps in FIGS. 8(a) to 8(c) and FIGS. The manufacturing process of the acceleration sensor C. Also, in these views, the range and shape corresponding to each acceleration sensing element and acceleration sensing element C are separated by dotted lines.

First, as shown in FIG. 8(a), a semi-finished sheet having a rectangular sheet shape and a size and shape corresponding to the size and shape of the plurality of piezoelectric ceramic element bodies 32 constituting the acceleration detection element is prepared, that is, the piezoelectric ceramic Manufactured and will eventually become two semi-finished sheets of ceramic element regions 35 and 36. In addition, a conductive paste of silver, silver-palladium or the like is applied on one surface of a semi-finished sheet 40 (the bottom one in FIG. At each central position and each end position on an end surface corresponding to each piezoelectric ceramic element main body 32 in the longitudinal direction, the conductive paste is dried at a temperature close to 1000° C., thereby forming internal electrode patterns distributed separately from each other Structure 41.

As shown in Figure 8 (b), on the other side of the semi-finished sheet, that is, the side of the semi-finished sheet 40 that has not formed the internal electrode pattern structure 41 is laminated to the end face of the semi-finished sheet 40 that has formed the respective internal electrode pattern structure 41, and the The assembly is baked at a temperature close to 100°C. Then, the two semi-finished sheets 40 in a laminated state are bonded together by baking, whereby an integral piezoelectric ceramic substrate 42 is prepared. Furthermore, the baking of the internal electrode pattern structure 41 sandwiched between the two semi-finished sheets 40 is performed simultaneously with the baking process to form the individual internal electrodes 34 distributed separately from each other.

Next, as shown in Fig. 8 (c), the conductive paste is respectively applied on the main surface of the piezoelectric ceramic substrate 42, and the signal output electrode pattern is formed by drying the applied base 42 at a temperature close to 100°C. structure 43, and bake the assembly at a temperature close to 800° C., thereby forming the respective signal output electrodes 33. After that, by applying a DC electric field between the signal output electrode 33 and the internal electrode 34, the central portions 35a and 36a and the end portions 35b and 35b of the ceramic element regions 35 and 36 constituting the piezoelectric ceramic element main body 32 are formed into electrodes. change. Furthermore, the polarization of the respective sections 35a, 36a, 35b and 36b produces a polarization sensing direction from H to K as shown in FIG. 7 .

After that, as shown in FIG. 9( a), each fastening frame member base 45 is prepared in which grooves 44 each having a predetermined width are formed at each predetermined position on the inner surface, and each The fastening frame base 45 is pasted onto the piezoelectric ceramic base 42 on which the signal output electrodes 33 have been formed to form a whole. In addition, the piezoelectric ceramic base 42 and the fastening frame member base 45 are cut off at respective dotted lines, each dotted line is determined by separating each range, and each range has a size and shape corresponding to each piezoelectric ceramic element main body 32. correspond. In this way, the acceleration sensor shown in FIG. 9( b ) is constituted, that is, a pair of fastening frame members 37 and an acceleration detection element including a piezoelectric ceramic element main body 32 , signal output electrodes 33 and internal electrodes 34 .

Then, the external output electrodes 38 and 39 are formed on the respective outer end faces of the acceleration detection element, that is, formed on the outer end faces of the piezoelectric ceramic element main body 32 and the fastening frame member 37, and the frame member 37 is finally formed as The acceleration sensor C of the bimorph structure is shown in FIG. 7 . Further, the respective signal output electrodes 33 are connected to the respective external output electrodes 38 and 39 formed in a T shape and conducted to each other.

Incidentally, the manufacturing method of the acceleration sensor C according to the third embodiment is not limited to the processes shown in FIGS. process shown. Fig. 10 (a) to 10 (c) has shown the improvement example in the former stage step in manufacturing acceleration detecting element, in Fig. 10 (a) to 10 (c), for and in Fig. 8 (a) to 8 ( The corresponding parts common to each element and each part in c) are given the same label.

As shown in Fig. 10(a), in this modification example, firstly, a piezoelectric ceramic sheet in the shape of a rectangular sheet that has been baked previously, that is, its size and shape is the same as that of the plurality of piezoelectric ceramics constituting the acceleration sensor, is first prepared. The two piezoelectric ceramic sheets 47 correspond to the element body 32 . On the surface of each piezoelectric ceramic sheet 47, that is, on each surface corresponding to a single piezoelectric ceramic element main body 32, a conductive paste is applied and dried to form The respective internal electrode pattern structures 41 are distributed separately from each other.

After this, as shown in Figure 10 (b), the conductive paste is applied to the other face of each piezoelectric ceramic sheet 47, thereby forming the signal output electrode pattern structure 43, and the internal electrode pattern structure 41 and the signal output electrode The pattern structure 43 is baked at the same time, and each signal output electrode 33 and each internal electrode 34 are formed by baking. By applying a DC electric field between each signal output electrode 33 and internal electrode 34 in each piezoelectric ceramic sheet 47, the central portion 47a and end portions 47b distributed along the longitudinal direction of each piezoelectric ceramic sheet 47 are polarized. The respective piezoelectric ceramic pieces 47 eventually become the ceramic element regions 35 and 36, and the central portions 35a and 36a and the end portions 35b and 36b in the ceramic element regions 35 and 36 are polarized in this operation.

In addition, as shown in FIG. 10(c), the surface of the piezoelectric ceramic sheet 47 on which each internal electrode 34 has been formed is bonded with a thermosetting adhesive (not shown), and the assembly is heated to make the Each piezoelectric ceramic sheet 47 is combined to form a piezoelectric ceramic matrix 42 . The piezoelectric ceramic base 42 which has been formed according to the above process has the same structure as shown in FIG. 8(c). After that, the subsequent steps of the manufacturing method as shown in FIGS. 9(a) and 9(b) are carried out to the integral piezoelectric ceramic substrate 42, thereby finally forming a bimorph structure as shown in FIG. Acceleration sensor C.

According to the acceleration detecting element and the manufacturing method in the third embodiment, after the internal electrodes are separated, polarization processing is performed. Therefore, it is not necessary to perform polarization treatment after separating the previously formed surface electrodes, and it is not necessary to constitute the signal output electrodes by forming connection electrodes after the polarization treatment.

In addition, since the acceleration sensor C in the third embodiment can be naturally formed, the acceleration detection element composed of the piezoelectric ceramic element main body 32, the signal output electrode 33, and the internal electrode 34 is made like that used in the first and second embodiments. Like the accelerometer of the accelerometer, it forms an inclination angle with the sensor mounting end face.

As explained above, according to the installation structure of the acceleration detection element of the present invention, by utilizing two acceleration detection elements, it is possible to detect accelerations generated in directions of three axes orthogonal to each other with substantially the same detection sensitivity, And can detect acceleration in a wide range of directions. Thus, the present invention produces the effect of not only simplifying the mounting arrangement structure but also reducing the cost.

Furthermore, according to the acceleration detecting element and manufacturing method of the present invention, internal electrodes distributed separately are arranged on the inner portion of the piezoelectric ceramic element body and each portion in the ceramic element region is polarized by the internal electrodes. Therefore, it is not necessary to perform polarization treatment after previously forming the divided surface electrodes on the main surface of the piezoelectric ceramic element main body, and after polarization, it is not necessary to constitute the signal output electrodes having a two-layer structure by forming connection electrodes. Therefore, the present invention produces an effect that various inconveniences are not caused in constituting the signal output electrodes having a two-layer structure, and the time and labor for manufacturing the acceleration detecting element can be saved.

Claims (8)

1. assembly configuration structure that is relevant to the acceleration test components of mutually orthogonal X, Y, Z axle, comprise two acceleration test components, wherein first acceleration test components has a peak response direction, this direction is to tilt 40 ° to 50 ° towards the Z axle from Y-axis, second acceleration test components has a peak response direction, this direction is to tilt 40 ° to 50 ° from X-axis towards the Z axle, therefore has substantially invariable acceleration detection sensitivity along described each all three directions.

2. assembly configuration structure that is relevant to the acceleration test components of mutually orthogonal X, Y, Z axle comprises:

Two acceleration test components;

-counting circuit, be used to calculate by the absolute value of the electric signal of each acceleration test components output and; And

Wherein first acceleration test components has a peak response direction, this direction is to tilt 20 ° to 30 ° towards the Z axle from Y-axis, and second acceleration test components have a peak response direction, this direction is to tilt 20 ° to 30 ° from X-axis towards the Z axle, therefore has substantially invariable acceleration detection sensitivity along described each all three directions.

3. the assembly configuration structure of acceleration test components according to claim 1 and 2, wherein each acceleration test components is included in the fixing piezoelectric ceramics twin lamella type element in its two ends.

4. the assembly configuration structure of acceleration test components according to claim 3, wherein said element comprises the ceramic component main body of a pair of rectangular sheet; Internal electrode is located at the inside between each piezo ceramic element main body and vertically is configured in middle body and end sections in the mode that is separated from each other along the piezo ceramic element main body, signal output electrode is located on the outer major surface of piezo ceramic element main body, and polarizes with opposite sensing direction generation on thickness direction through each middle body vertical opposite each other and the end sections of internal electrode along the piezo ceramic element main body.

5. method of making acceleration test components, the step that comprises is:

Prepare two rectangular sheets and by the semi-finished products of piezoelectric ceramics system;

Stick with paste along vertically will conducting electricity of the first surface of first semi-finished products and to apply, form internal electrode graphic structure separately whereby at middle position and end position;

First surface layer of second semi-finished products is stacked on first of first semi-finished products, on this first semi-finished products, has formed the internal electrode graphic structure;

Cure by curing to handle, so that form internal electrode and piezo ceramic element main body simultaneously;

On second first type surface of piezo ceramic element main body, apply with after the conduction paste, form signal output electrode by curing to handle; And

By utilizing each signal output electrode and each internal electrode, make the middle body of piezo ceramic element main body and end sections produce polarization.

6. method of making the acceleration sensing element, the step that comprises is:

Preparation and cure the piezoelectric ceramic piece of two rectangular sheets;

Stick with paste along first of each piezoelectric ceramic piece vertically will conduct electricity and to be applied to middle position and end position, form whereby separately internal electrode '

Stick with paste after second of applying at each piezoelectric ceramic piece form the signal output electrode graphic structure will conducting electricity, form internal electrode and signal output electrode by curing to handle;

By utilizing separately signal output electrode and the middle body that makes each piezoelectric ceramic piece of internal electrode separately and end sections to form and polarize; And

Each second of the bonding piezoelectric ceramic piece that has formed internal electrode on it forms the piezo ceramic element main body whereby.

7. acceleration transducer comprises:

Be relevant to two acceleration test components of mutually orthogonal X, Y, the installation of Z axle;

Wherein first acceleration test components has a peak response direction, this direction tilts 40 ° to 50 ° towards the Z axle from Y-axis, and second acceleration test components has a peak response direction, this direction tilts 40 ° to 50 ° from X-axis towards the Z axle, has substantially invariable acceleration detection sensitivity along described each all three directions whereby.

8. acceleration transducer comprises:

Be relevant to two acceleration test components of mutually orthogonal X, Y, the installation of Z axle;

One calculation element, be used to calculate by the absolute value of the electric signal of each acceleration test components output and; And

Wherein first acceleration test components has a peak response direction, this direction is to tilt 20 ° to 30 ° towards the Z axle from Y-axis, and second acceleration test components has a peak response direction, this direction is to tilt 20 ° to 30 ° from X-axis towards the Z axle, has substantially invariable acceleration detection sensitivity along described each all three directions whereby.

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