JP2002188922A - Tuning fork type angular velocity sensor element and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an angular velocity sensor with increased detection accuracy and sensitivity by flattening tuning-fork grooves in two fork-shaped quartz pieces bonded together to prevent a tuning-fork vibration from being coupled to a vertical vibration, and to provide a manufacturing method thereof. SOLUTION: In the case of an angular velocity sensor element comprising the two fork-shaped quartz pieces bonded together with their ±X axes reversely directed to each other, the tuning fork type angular velocity sensor element according to this manufacturing method is made by bonding together two quartz wafers having crystal axes X, Y, and Z with their Y- and Z-axis directions agreeing with each other and their ±X axes reverse directed to each other, and by working the front and rear quartz wafers by etching into the fork-shaped quartz pieces each comprising a tuning fork base part 2 and a pair of tuning fork arm parts 3 with their width, length, and thickness being in the X-, Y-, and Z-directions, respectively. In the bonding, the +X axis of the front quartz wafer is directed leftward in a direction normal to the extending direction of the arm parts from the base part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tuning fork type angular velocity sensor element (hereinafter referred to as "angular velocity sensor") used for prevention of camera shake of an automobile guidance system and a camera, etc. The present invention relates to an angular velocity sensor by etching obtained by attaching a tuning fork-shaped quartz piece.

[0002]

2. Description of the Related Art An angular velocity sensor of this type is known to detect Coriolis force due to rotation by vertical vibrations in directions opposite to each other with respect to a tuning fork vibration, and has been rapidly spreading in recent years. One such example is a bonding type angular velocity sensor that improves the detection sensitivity.

FIG. 4 is a diagram of an angular velocity sensor for explaining a conventional example. The angular velocity sensor is formed by bonding two tuning fork-shaped quartz pieces 1 (ab). Each tuning fork-shaped crystal piece 1 (ab) extends a pair of tuning fork arms 3 from the tuning fork base 2. The length in the extending direction of each tuning fork arm 3 is defined as the Y-axis direction of the crystal axis (XYZ), the X-axis direction is defined as the width,
The thickness in the Z-axis direction is defined as the thickness. Then, the tuning fork-shaped quartz pieces on the front and rear sides are bonded with different ± directions of the X axis. The bonding is performed by so-called direct bonding in which the main surface is made hydrophilic and abuts, and heat treatment is performed. Also, there is no ± directionality in the Y and Z axes.

Normally, two crystal wafers 4 (ab) having the same crystal axes (XYZ) are bonded by direct bonding with the X-axis directions differing from each other (FIG. 5).
Then, a large number of tuning fork-shaped quartz pieces 1 are punched out by etching, and a large number of bonded angular velocity sensors are obtained. However, after that, a drive electrode and a sensor electrode (not shown) are formed and are held and sealed by the base.

[0005]

[Problems to be Solved by the Invention]
However, the angular velocity sensor having the above configuration has the following problem due to etching. That is, the etching rate of the crystal wafer differs depending on the axial direction of the crystal axis (XYZ), and the order of the rates is Z axis ≫ + X axis> −X axis> Y axis.

For this reason, for example, when a tuning fork-shaped quartz piece is obtained by etching from one quartz wafer, the tuning fork groove has a slope on the + X axis side larger than that on the −X axis side due to a difference in etching rate in each axial direction. It is shaped like a letter (FIG. 6). In this case, the tuning fork vibration and the vertical vibration combine to exhibit an oblique vibration,
It has adverse effects such as lowering detection accuracy and sensitivity.

(Object of the Invention) It is an object of the present invention to provide an angular velocity sensor having a flat tuning fork groove to prevent the coupling of tuning fork vibration and vertical vibration and to improve detection accuracy and sensitivity.

[0008]

Means for Solving the Problems (Points of Interest) In the present invention,
In the bonded type tuning fork-shaped quartz piece (angular velocity sensor), attention was paid to the fact that the tuning fork groove portion may be V-shaped or flat. That is, when the two tuning fork-shaped quartz pieces are bonded together, if the left side perpendicular to the extending direction of the tuning fork arm from the tuning fork base is set in the −X-axis direction of the front tuning fork-shaped quartz piece, the tuning fork groove becomes Attention was paid to an experimental result that the tuning fork groove becomes V-shaped and the tuning fork groove becomes substantially flat when it is set in the + X axis direction.

(Solution) According to the present invention, based on the above-mentioned point of interest (experimental results), the left side perpendicular to the direction in which the tuning fork arm extends from the tuning fork base is located on the + X axis of the tuning fork-shaped crystal piece on the front surface. The basic solution is to bond them in the same direction.

[0010]

According to the present invention, the left side perpendicular to the direction in which the tuning fork arm extends from the tuning fork base is located at + X of the tuning fork-shaped crystal piece on the front surface.
Since the alignment is performed in the axial direction, the bottom surface of the tuning fork groove becomes flat compared to the case where the alignment is performed in the −X axis direction. Hereinafter, an embodiment of the present invention including a manufacturing method will be described.

[0011]

FIG. 1 is a diagram of an angular velocity sensor for explaining an embodiment of the present invention. The same parts as those in the prior art are denoted by the same reference numerals, and description thereof will be simplified or omitted. The angular velocity sensor is formed by bonding two tuning fork-shaped crystal blanks 1 (ab) each including a tuning fork base 2 and a pair of tuning fork arms in the same manner as described above by direct joining in the Y and Z axis directions. Each tuning fork-shaped crystal piece 1 (ab) is formed by a pair of tuning fork arms 3 from a tuning fork base 2.
To extend. In this embodiment, the left side of the direction perpendicular to the extending direction of the tuning fork arm 3 extending from the tuning fork base 2 is set to the + X-axis direction of the front tuning fork crystal blank 1a (the rear of the tuning fork crystal blank 1b). −X-axis direction).

In this case, first, as shown in FIG.
The Y and Z axes of the two quartz wafers 4 (ab) are matched,
Laminate in different ± X-axis directions. However, the + X axis of the crystal wafer 4a as the front surface (the −X axis of the rear surface 4b)
The tuning fork arm 3 is attached so as to be aligned on the left side in a direction perpendicular to the direction in which the tuning fork arm 3 extends from the tuning fork base 2. Then, a large number of tuning fork-shaped quartz pieces (angular velocity sensors) are obtained by etching.

In such a case, as shown in FIG. 3, the bottom surface of the tuning fork groove of the angular velocity sensor after etching becomes flat in the X-axis direction, and the inclined surface disappears. However, in the thickness direction, it has a mountain shape with the bonding surface at the top. Therefore, the disappearance of the inclined surface from the bottom of the tuning fork groove prevents the coupling of the tuning fork vibration and the vertical vibration, thereby preventing the oblique vibration, and increasing the detection accuracy and sensitivity.

Conversely, when the left side in the direction orthogonal to the extending direction of the tuning fork arm 3 extending from the tuning fork base 2 is set to the -X axis direction of the tuning fork-shaped quartz piece 1a on the front surface. Produces a V-shaped inclined surface in the tuning fork groove in the same manner as when one tuning fork-shaped crystal blank 1 is used.

[0015]

According to the present invention, the tuning fork groove is flat because the left side perpendicular to the direction in which the tuning fork arm extends from the tuning fork base is aligned with the + X axis direction of the tuning fork-shaped quartz piece on the front surface. As a result, it is possible to provide an angular velocity sensor that prevents the coupling of the tuning fork vibration and the vertical vibration and increases the detection accuracy and sensitivity.

[Brief description of the drawings]

FIG. 1 is a diagram of an angular velocity sensor (adhering a tuning fork-shaped crystal piece) for explaining an embodiment of the present invention.

FIG. 2 is a bonding view of a crystal wafer for manufacturing the angular velocity sensor according to one embodiment of the present invention.

FIG. 3 is a partial view of an angular velocity sensor illustrating an operation and effect of one embodiment of the present invention.

FIG. 4 is a diagram of an angular velocity sensor for explaining a conventional example.

FIG. 5 is a bonding diagram of a quartz wafer for manufacturing a conventional angular velocity sensor.

FIG. 6 is a partial front view of an angular velocity sensor illustrating a problem of a conventional example.

[Explanation of symbols]

1 tuning fork crystal blank, 2 tuning fork base, 3 tuning fork arm, 4
Quartz piece.

Claims (2)

[Claims] 1. A tuning fork base having a width along the X axis of a crystal axis (XYZ), a length along the Y axis, and a thickness direction along the Z axis, and two tuning fork-shaped quartz pieces each having a pair of tuning fork arms are attached to each other. In the tuning fork type angular velocity sensor element comprising the front and rear tuning fork-shaped quartz pieces, the left side perpendicular to the direction in which the tuning fork arm extends from the tuning fork base is attached. An angular velocity sensor element which coincides with the + X-axis direction of the tuning fork-shaped quartz piece on the front surface. 2. The two crystal wafers having crystal axes (XYZ) are bonded together so that the Y-axis and Z-axis directions are matched and the ± X-axis directions are different, and the front and rear crystal wafers are etched to form an X-axis. In a method of manufacturing a tuning fork type angular velocity sensor element formed by processing a tuning fork-shaped crystal piece including a tuning fork base and a pair of tuning fork arms each having an axis as a width, a Y axis as a length, and a Z axis as a thickness direction, A method for manufacturing a tuning fork type angular velocity sensor element, wherein a quartz wafer is bonded so that a + X axis thereof is aligned with a left side in a direction orthogonal to a direction in which the tuning fork arm extends from the tuning fork base.