JPH0548002B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to a resonator oscillation circuit that includes a crystal resonator and various other types of resonators.

[Prior art]

For example, the natural frequency of a crystal resonator changes depending on changes in ambient temperature and the force applied to it, so various physical quantities can be measured from this natural frequency. Vibration sensors that utilize this technology are being put into practical use. in this case,
An oscillation circuit that includes a vibrator must have a circuit configuration that has circuit constants that are optimal for the oscillation frequency of each vibrator, and therefore it is necessary to share the oscillation circuit with each vibrator. I couldn't.

[Object of the present invention]

Here, the present invention attempts to realize a vibrator oscillation circuit that can oscillate various vibrators with different natural frequencies under optimal conditions using the same oscillation circuit.

〔overview〕

The device according to the present invention, in a vibrator oscillation circuit formed including a mechanical vibrator and a filter, converts the frequency signal from the vibration detection means of the mechanical vibrator into a frequency signal near the center frequency or corner frequency of the filter. a first frequency conversion circuit that converts the signal into the original frequency signal from the vibration detection means and applies it to the filter; and a second frequency conversion circuit that converts the signal after passing through the filter to the original frequency signal from the vibration detection means and applies it to the excitation means of the mechanical vibrator. A conversion circuit is provided, and the frequency of the signal passing through the filter is made to be substantially the same regardless of the type of the mechanical vibrator.

〔Example〕

FIG. 1 is a block diagram showing an example of a device according to the present invention.

In the figure, reference numeral 1 conceptually shows a mechanical resonator, and for example, a crystal resonator, a cylindrical resonator, or the like is used. This vibrator is coupled with excitation means 11 for vibrating the vibrator and vibration detection means 12 for detecting vibration. 2 is an amplifier for amplifying the frequency signal f _p from the vibration detection means 12, and 31 and 32 are both frequency conversion circuits, for example, a frequency divider circuit, a multiplier circuit, a frequency mixer, or the like. Reference numeral 4 denotes a filter through which the frequency signal converted by the first frequency conversion circuit 31 passes, and the signal passed through this filter is applied to the excitation means 11 through the second frequency conversion circuit 32. Each of these circuits forms a closed loop including the vibrator 1 and the filter 4, and constitutes an anti-coupling type oscillation circuit.

In the anti-coupling type oscillation circuit configured in this way, in order to sustain the vibration (oscillation) of the vibrator 1,
The transfer functions A and B of the vibrator part and other parts are selected so as to satisfy equation (1).

A・B≧1 (1) The first frequency conversion circuit 31 converts the frequency f _p from the amplifier 2 to a frequency near the center frequency (in the case of a band filter) f _s of the filter 4, for example k (k·f _p ≒f _s ), and the frequency signal of k·f _p is applied to the filter 4. This frequency signal is
After passing through the filter 4, the second frequency conversion circuit 3
2, the signal is multiplied by, for example, 1/k, converted to the original frequency f _p , and applied to the excitation means 11.

According to this circuit, the center frequency or corner frequency of the filter 4 can be fixed at approximately _fs regardless of the natural frequency of the vibrator 1, so the oscillation circuit part can be shared by each vibrator. I can do it.

FIG. 2 is a block diagram showing another embodiment of the apparatus according to the present invention. In this example,
The frequency signal from the vibration detection means 12 is applied to the first frequency conversion circuit 31 via the variable gain amplifier 21 and the phase control amplifier 22. Here, the variable gain amplifier 21 controls the gain using a signal from the gain control circuit 6 so that the amplitude of the frequency signal applied to the excitation means 11 becomes a constant value corresponding to the reference voltage E _S. . Further, the phase control amplifier 22 performs phase control based on the signal from the phase control circuit 6 so that the phase of the signal applied to the excitation means 11 and the signal obtained from the vibration detection means 12 are constant. is being carried out.

FIG. 3 is a block diagram showing an example of a vibrating transducer including a vibrator section and an oscillation circuit section.

Here, the frequency signal obtained from the oscillator circuit
The pulse width modulation circuit 7 modulates the pulse width of f _p using, for example, a temperature signal from the temperature signal detection means 8 and transmits the pulse width modulated signal f p. According to such a configuration, the frequency signal and the temperature signal from the oscillation circuit can be transmitted simultaneously.

[Effects of the present invention]

As explained above, according to the present invention, the frequency of the signal passing through the filter can be made approximately constant, so the oscillation circuit portion can be used for various vibrators having different natural frequencies. Therefore, the oscillation circuit portion can be shared or integrated into an IC.

[Brief explanation of the drawing]

1 and 2 are block diagrams showing an example of a device according to the present invention, and FIG. 3 is a block diagram showing an example of a vibrating transducer constructed using a circuit according to the present invention. 1... Mechanical vibrator, 11... Excitation means, 12...
...Vibration detection means, 2...Amplifier, 31, 32...
Frequency conversion circuit, 4...filter.

Claims (1)

[Claims] 1. In a vibrator oscillation circuit formed including a mechanical vibrator and a filter, the frequency signal from the vibration detection means of the mechanical vibrator is converted into a frequency signal near the center frequency or corner frequency of the filter. a first frequency conversion circuit that converts the signal into the original frequency signal from the vibration detection means and applies it to the filter; and a second frequency conversion circuit that converts the signal after passing through the filter to the original frequency signal from the vibration detection means and applies it to the excitation means of the mechanical vibrator. A resonator oscillation circuit comprising: a conversion circuit, the frequency of a signal passing through the filter being substantially the same regardless of the type of the mechanical resonator.