Crystal element and crystal device

1. A crystal element, comprising:

a crystal piece in a substantially rectangular shape in a plan view, which includes an oscillation section having a first protruded section and a second protruded section projected to mutually opposing directions and a peripheral section which is thinner than the oscillation section and provided along an outer edge of the oscillation section;

a pair of excitation electrodes provided on a top surface of the first protruded section and on a bottom surface of the second protruded section;

a pair of leading sections provided side by side along a prescribed side of the crystal piece; and

a wiring section whose one end is connected to the excitation electrode and other end is connected to the leading section, wherein:

the first protruded section includes a first planar side face extending directly from the top surface of the first protruded section to a top surface of the peripheral section and that is sloping with respect to the top surface of the first protruded section where the excitation electrode is provided, and a second planar side face extending directly from the top surface of the first protruded section to the top surface of the peripheral section and which is opposing to the first side face in a prescribed direction and opposing to the top surface of the first protruded section where the excitation electrode is provided;

the second protruded section includes a third planar side face extending directly from the bottom surface of the second protruded section to a bottom surface of the peripheral section and that is sloping with respect to the bottom surface of the second protruded section where the excitation electrode is provided, and a fourth planar side face extending directly from the bottom surface of the second protruded section to the bottom surface of the peripheral section and which is opposing to the third side face in a prescribed direction and opposing to the bottom surface of the second protruded section where the excitation electrode is provided;

the first side face is disposed to overlap with the third side face in a plan view of the crystal piece in a thickness direction; and

the second side face is disposed to overlap with the fourth side face in the plan view of the crystal piece in the thickness direction;

wherein an angle between the top surface of the first protruded section where the excitation electrode is provided and the first planar side face is larger than 135° and smaller than 155°;

an angle between the top surface of the first protruded section where the excitation electrode is provided and the second planar side face is larger than 150° and smaller than 170°;

an angle between the bottom surface of the second protruded section where the excitation electrode is provided and the third planar side face is larger than 150° and smaller than 170°; and

an angle between the bottom surface of the second protruded section where the excitation electrode is provided and the fourth planar side face is larger than 135° and smaller than 155°.

2. The crystal element as claimed in claim 1 , wherein, in a plan view:

the first side face is located on a positive direction side of an X-axis with respect to a virtual line which passes through a center of a main surface of the first protruded section and is perpendicular to the X-axis of crystalline axes of the crystal piece;

the second side face is located on a negative direction side of the X-axis with respect to the virtual line which passes through the center of the main surface of the first protruded section and is perpendicular to the X-axis;

the third side face is located on the positive direction side of the X-axis with respect to a virtual line which passes through a center of a main surface of the second protruded section and is perpendicular to the X-axis; and

the fourth side face is located on the negative direction side of the X-axis with respect to the virtual line which passes through the center of the main surface of the second protruded section and is perpendicular to the X-axis.

3. The crystal element as claimed in claim 2 , wherein, provided that a side which is perpendicular to the X-axis located on the positive direction side of the X-axis with respect to the virtual line is a prescribed other side of the crystal piece in a plan view of the crystal element:

a distance between the prescribed other side and a side of the third side face close to the prescribed other side is shorter than a distance between the prescribed other side and a side of the first side face distant from the prescribed other side; and

a distance between the prescribed other side and a side of the fourth side face close to the prescribed other side is shorter than a distance between the prescribed other side and a side of the second side face distant from the prescribed other side.

4. The crystal element as claimed in claim 3 , wherein:

a distance between the prescribed other side and the side of the first side face distant from the prescribed other side is equivalent to a distance between the prescribed other side and the side of the third side face distant from the prescribed other side; and

a distance between the prescribed other side and the side of the second side face close to the prescribed other side is equivalent to a distance between the prescribed other side and the side of the fourth side face close to the prescribed other side.

5. A crystal device, comprising:

the crystal element as claimed in claim 1 ;

an element loading member to which the crystal element is mounted; and

a lid which is bonded to the element loading member for air-tightly sealing the crystal element.