Miniaturized at-cut piezoelectric crystal resonator

• US 4,167,686 A
• Filed: 02/03/1978
• Issued: 09/11/1979
• Est. Priority Date: 12/21/1973
• Status: Expired due to Term

• Current Assignee: Hitohiro Fukuyo
• Original Assignee: Hitohiro Fukuyo
• Inventors: Fukuyo, Hitohiro
• Primary Examiner(s): Budd, Mark O.
• Application Number:
  US05/875,040
• Time in Patent Office: 585 Days
• Field of Search: 310/361, 310/320, 310/368, 310/369, 310/367
• US Class Current: 310/361
• CPC Class Codes: G04F 5/063 Constructional details
• CPC Class Codes: H03H 9/02023 consisting of quartz
• CPC Class Codes: H03H 9/0207 the vibration mode being harmonic
• CPC Class Codes: H03H 9/02157 Dimensional parameters, e.g. ratio between two dimension parameters, length, width or thickness

Abstract

An AT-cut piezoelectric crystal resonator having a plurality of contoured surfaces, two of these contoured surfaces being generated by translating contour lines parallel to the z-axis and perpendicular to the electric axis. At least one of these two surfaces is convex, and another two contoured surfaces are perpendicular to the z-axis and spaced apart by a length dimension z'"'"'₀ which is 0.1 to 1.3 of the maximum thickness dimension representing the distance between the first mentioned two surfaces and measured along a line perpendicular to the x-axis. The resonator is adapted for performing a mode of vibration along the thickness forming either a fundamental standing wave or an overtone thereof of a thickness-shear vibration. The free ends of the vibration are positioned at the first mentioned two surfaces, and the amplitude of vibratory displacements appearing along the x-axis is maximum at the center of each surface of the first mentioned two surfaces. The last mentioned center is the midpoint of a length taken along the x-axis dimension which is 3 to 15 of the maximum thickness dimension, and constituting the span of arc of the convex surface. The amplitude becomes null at a point on each of the first mentioned two surfaces where that point approaches each end of the convex line generating the convex surface, and the distribution of the amplitude is uniform on any point taken along the length of the above mentioned z-axis dimension on each of the first mentioned two surfaces.

Claims

1. An AT-cut piezoelectric crystal resonator comprising a plurality of contoured surfaces, two of said contoured surfaces being generated by translating contour lines parallel to the z-axis and perpendicular to the electric axis or x-axis, at least one of the said two surfaces being convex, and another two contoured surfaces being perpendicular to said z-axis and spaced apart by a length dimension z'"'"'₀ which is 0.1 to 1.3, preferably 0.3 to 1.0, of the maximum thickness dimension y₀ representing the distance between the first said two surfaces and measured along a line perpendicular to the said x-axis, said resonator being adapted for performing a mode of vibration along the said thickness forming either a fundamental standing wave or an overtone thereof of a thickness-shear vibration, the free ends of said vibration being positioned at the first said two surfaces, the amplitude of vibratory displacements appearing along said x-axis being maximum at the center of each surface of the first said two surfaces, the said center being the midpoint of a length taken along the said x-axis or the dimension x₀ which is 3 to 15 of the maximum thickness dimension y₀, and constituting the span of arc of the said convex surface, said amplitude becoming null at a point on each of the first said two surfaces where the said point approaches each end of the convex line generating said convex surface, and the distribution of the said amplitude being uniform on any point taken along the said length of the said z'"'"'₀ dimension on each of the first said two surfaces.

5. An AT-cut peizoelectric crystal resonator of claim 1, having means to drive the said resonator electrically along the y-axis perpendicular to said electric or x-axis and said z-axis.

9. An AT-cut piezoelectric crystal resonator of claim 1, having means to drive the said resonator electrically along said z-axis.

2. An AT-cut piezoelectric crystal resonator, comprising a plurality of contoured surfaces, six of said contoured surfaces being generated by translating contour lines parallel to the z-axis perpendicular to the electric axis or x-axis, two surfaces among the said six surfaces being parallel to each other and parallel to said x-axis, another four surfaces of the said six surfaces being tapered off from each end of the said two surfaces along the said x-axis by forming an opposed pair of wedge-shaped surfaces, another two of said contoured surfaces being perpendicular to said z-axis and spaced apart with a length dimension z'"'"'₀ which is 0.1 to 1.3, preferably 0.3 to 1.0, of the maximum thickness dimension y₀, representing the distance between the first said two surfaces and measured along a line perpendicular to said x-axis, said resonator adapted for performing a mode of vibration along said thickness forming either a fundamental standing wave or an overtone thereof of a thickness-shear vibration, the free ends of said vibration positioned at the first said two surfaces, the amplitude of vibratory displacements appearing along said x-axis being maximum at the center of the physical dimension of said resonator taken along said x-axis, the distribution of said amplitude being entirely uniform on any point taken along the length of said dimension z'"'"'₀ on each of the first said two surfaces, and said amplitude becoming null at the apexes of said wedge-shaped surfaces.

6. An AT-cut piezoelectric crystal resonator of claim 2, having means to drive the said resonator electrically along the y-axis perpendicular to said electric or x-axis and said z-axis.

10. An AT-cut piezoelectric crystal resonator of claim 2, having means to drive the said resonator electrically along said z-axis.

3. An AT-cut piezoelectric crystal resonator comprising a plurality of contoured surfaces, four of said contoured surfaces being generated by translating contour lines parallel to the z-axis perpendicular to the electric axis or x-axis, two of said four surfaces being parallel to each other and parallel to said x-axis, another two surfaces among the said four surfaces being tapered off from both ends of one of the first said two surfaces so as to represent sloping sections defined by the said four surfaces, said sloping sections being defined in the x-y plane in combination by a longer line of a planar base surface, a shorter line of a planar top surface and two sloping lines, another two of said contoured surfaces being perpendicular to the said z-axis and spaced apart with a length dimension z'"'"'₀ which is 0.1 to 1.3, preferably 0.3 to 1.0, of the maximum thickness dimension y₀ representing the distance between the first said two surfaces and measured along a line perpendicular to said x-axis, said resonator being adapted for performing a mode of vibration along the said thickness forming either a fundamental standing wave or an overtone thereof of a thickness-shear vibration, the free ends of said vibration being positioned at the first said two surfaces, the amplitude of vibratory displacements appearing along said x-axis being maximum at the center of the physical dimension of said resonator taken along said x-axis, the distribution of said amplitude being entirely uniform on any point taken on and along said dimension z'"'"'₀, on each of the first said two surfaces, and said amplitude becoming null at both ends of the said longer line of the planar base surface.

7. An AT-cut piezoelectric crystal resonator of claim 3, having means to drive the said resonator electrically along said y-axis.

11. An AT-cut piezoelectric crystal resonator of claim 3, having means to drive the said resonator electrically along said z-axis.

4. An AT-cut piezoelectric crystal resonator comprising a plurality of contoured surfaces, two of said contoured surfaces being generated by translating contour lines parallel to the z-axis perpendicular to the electric axis or x-axis, another two of said contoured surfaces being perpendicular to said z-axis and spaced apart with a length dimension z'"'"'₀ which is 0.1 to 1.3 of the maximum thickness dimension y₀, representing the distance between the first said two surfaces and measured on and along a line perpendicular to said x-axis, said resonator being adapted for performing a mode of vibration along said thickness in the form of either a fundamental standing wave or an overtone thereof of a thickness-shear vibration, the free ends thereof lying on the first said two surfaces, the distribution of the amplitudes of displacements being uniform at any point taken on and along the length of the dimension z'"'"'₀ taken on each of the first said two surfaces, and the ratio of the dimensions z'"'"'₀ to y₀ being so determined that the electric field intensity along the said length dimension z'"'"'₀ is sufficiently strong enough to drive the said resonator effectively.

8. An AT-cut piezoelectric crystal resonator of claim 4, having means to drive the said resonator electrically along said y-axis.

12. An AT-cut piezoelectric crystal resonator of claim 4, having means to drive the said resonator electrically along said z-axis.