Oscillator using H-shaped single crystal silicon vibrator

• US 4,926,143 A
• Filed: 09/16/1988
• Issued: 05/15/1990
• Est. Priority Date: 05/27/1988
• Status: Expired due to Term

• Current Assignee: Yokogawa Electric Corporation
• Original Assignee: Yokogawa Electric Corporation
• Inventors: Kobayashi, Takashi, Yoshida, Takashi, Watanabe, Tetsuya, Ikeda, Kyoichi, Nishikawa, Tadashi, Kuwayama, Hideki, Harada, Kinji
• Primary Examiner(s): Grimm, Siegfried H.
• Application Number:
  US07/245,681
• Time in Patent Office: 606 Days
• Field of Search: 331/6 J, 331/116 R, 331/116 M, 331/116 FE, 331/154, 331/156, 331/158, 310/25, 318/128
• US Class Current: 331/156
• CPC Class Codes: G01H 13/00 Measuring resonant frequency
• CPC Class Codes: G01L 9/0019 of a semiconductive element
• CPC Class Codes: Y10T 29/49103 Strain gauge making

Abstract

A vibrating type transducer wherein an H-shaped vibrator, formed integrally with a silicon substrate and having a hollow chamber provided therearound, is kept self oscillating at its natural resonance frequency together with an amplifier. A physical quantity, such as force, pressure, differential pressure, or the like, which is applied to the silicon substrate is detected by a change in the natural frequency arising at the vibrator corresponding to the physical quantity. The invention also includes a method for manufacturing such transducer using a semiconductor technique, including steps for keeping a vacuum internally in the hollow chamber, imparting an initial tension to the vibrator, and then operating the amplifier to have stable self oscillation.

Claims

1. In a vibrating type transducer comprising

a vibrator body comprising a silicon single crystal provided on a silicon single crystal substrate,

an excitation means for exciting said vibrator body,

a vibration detection means for detecting an excited vibration of said vibrator body,

the improvement comprising

an H-shaped vibrator body having two first vibrators with opposite ends thereof fixed on said substrate, each being disposed in parallel with each other and a second vibrator mechanically coupled to central portions of said first vibrators,

a magnetic field impression means for impressing a DC magnetic field orthogonally to said vibrator body,

an excitation means for vibrating said first vibrators together with said DC magnetic field by carrying an alternate current to either the opposite ends of one of said first vibrators or, in the alternative, to the same one ends of said two first vibrators,

a vibration detection means for detecting an electromotive force generated either on the opposite ends of the other of said first vibrators or, in the alternative, on the same other ends of said two first vibrators, and

an amplification means connected between said excitation means and said vibration detection means.

2. The transducer of claim 1, comprising an H-shaped vibrator body having said two first vibrators each formed in the shape of a beam in the direction <

001>

to a crystal plane (100) of said substrate, and said second vibrator being formed perpendicularly to said first vibrators.

3. The transducer of claim 2, wherein a predetermined initial tension is give to each said vibrators by implanting another atom with a bond radius smaller than that of an atom constructing the vibrators.

4. The transducer of claim 1, further comprising first amplification means for amplifying a signal generated by said vibrator body and for producing an output, gain control means for controlling gain by amplifying a signal related to said output of the first amplification means, comparision means for outputting a difference signal by comparing a signal relating to the amplitude of said output of said first amplification means with a predetermined reference value, wherein said gain control means is controlled by use of the difference signal, to thereby keep constant said amplitude of self oscillation.