SC-Cut Crystal Resonator Structure for Stable C-Mode Oscillation
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Solution Overview
Problem
SC-cut crystal resonators tend to oscillate in B mode instead of C mode, leading to low reliability due to equivalent resistance differences, which can result in unstable frequency oscillations.
Innovation Solution
Incorporating an inclined surface on the SC-cut crystal resonator plate, specifically designed to reduce B-mode oscillations by forming a penetrating part with an inclined surface that protrudes in the thickness direction, ensuring C-mode oscillation as the main vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If no special measures are taken in SC-cut crystal resonator design, then the structure remains simple, but B-mode oscillation occurs which reduces reliability
Solution Approach 1:
The patent applies asymmetry by providing inclined surfaces at specific end parts of the vibrating part that protrude in the thickness direction. These inclined surfaces create an asymmetric structure that selectively suppresses B-mode oscillation while maintaining C-mode oscillation, thereby improving reliability without requiring complete structural redesign
Solution Approach 2:
The patent applies local quality by positioning inclined surfaces only at specific end parts of the vibrating part adjacent to penetrating parts, rather than modifying the entire structure. This localized modification targets the specific region where B-mode oscillation occurs, suppressing unwanted modes while preserving the overall simplicity of the resonator plate structure
2Reliability
If inclined surfaces are added to suppress B-mode oscillation, then C-mode oscillation reliability improves, but manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by forming the inclined surfaces during the frequency adjustment etching process that is already performed in the manufacturing sequence. By integrating the inclined surface formation into the existing etching step rather than adding a separate manufacturing operation, the patent suppresses B-mode oscillation while minimizing the impact on manufacturing ease
Data Source
AI summary
In a crystal resonator (100), a crystal resonator plate (10) includes: a vibrating part (11); an external frame part (12) provided at a side of an outer periphery of the vibrating part (11); and a penetrating part (10a) provided between the vibrating part (11) and the external frame part (12) so as to penetrate the crystal resonator plate (10) in a thickness direction of the crystal resonator plate (10). An inclined surface (11c) is provided at an end part of the vibrating part (11) at the side of the penetrating part (10a) so as to protrude in the thickness direction and to be inclined with respect to a vibrating surface (11b) of the vibrating part (11).