Vibrator controlling circuit
This invention includes a square wave signal generating circuit 20 for generating a square wave signal whose frequency changes; a MOS transistor 12 which is turned on/off on the basis of the square wave signal to supply a driving current to a vibrator 14 ; and a frequency shift detecting circuit 24 for detecting a frequency shift between the square wave signal from the square wave generating circuit and a resonance frequency of the vibrator. The shift in the frequency generated by the square wave generating circuit is trimmed by a signal detected by the frequency shift detecting circuit.
1. A vibrator controlling circuit comprising:
a square wave generating circuit for generating a square wave signal whose frequency changes according to the value of a voltage applied to a controlling terminal;
a switching element which is turned on/off on the basis of said square wave signal to supply a driving current to a vibrator; and
a frequency shift detecting circuit for detecting a frequency shift between the square wave signal from said square wave generating circuit and a resonance frequency of said vibrator, wherein
a shift in the frequency generated by said square wave generating circuit is trimmed by a signal detected by said frequency shift detecting circuit.
2. A vibrator controlling circuit according to claim 1 , wherein the square wave signal generated by said square wave generating circuit is divided by a half-divider and the divided signal is applied to said switching element.
3. A vibrator controlling circuit comprising:
a square wave generating circuit for generating a square wave signal whose frequency changes according to the value of a voltage applied to a controlling terminal:
a switching element which is turned on/off on the basis of said square wave signal to supply a driving current to a vibrator; and
a frequency shift detecting circuit for detecting a frequency shift between the square wave signal from said square wave generating circuit and a resonance frequency of said vibrator,
wherein a shift in the frequency generated by said square wave generating circuit is trimmed by a signal detected by said frequency shift detecting circuit, and
wherein said frequency shift detecting circuit includes a first switching element for switching a vibrating wave signal from said vibrator; an operational amplifier with the one input terminal supplied with a signal passed said first switching element and the other terminal supplied with the vibrating wave signal as it is; and a second switching element for passing an output signal from said operational amplifier to be supplied to a control (CTL) terminal of said square wave generating circuit.
4. A vibrator controlling circuit according to claim 3 , wherein said first switching element is ON during 0-40% of said square wave signal, said second switching element is ON during 40-100% of said square wave signal, and 0-40% and 40%-100% of said vibrating wave signal are compared with each other.
5. A vibrator controlling circuit according to claim 1 , wherein said square wave generating circuit, switching element and frequency shift detecting circuit are constructed of a single chip.
6. A vibrator controlling circuit according to claim 1 , wherein said square wave generating circuit further comprises a control (CONT) terminal, a CONT signal supplied to the CONT terminal turns on the square wave generating circuit when the CONT signal changes from a first level to a second level upon a detection of a ringing signal.
7. A vibrator controlling circuit comprising:
a square wave generating circuit for generating a square wave signal whose frequency changes according to the value of a voltage applied to a controlling terminal;
a switching element which is turned on/off on the basis of said square wave signal to supply a driving current to a vibrator; and
a frequency shift detecting circuit for detecting a frequency shift between the square wave signal from said square wave generating circuit and a resonance frequency of said vibrator, wherein:
a shift in the frequency generated by said square wave generating circuit is trimmed by a signal detected by said frequency shift detecting circuit,
the square wave signal generated by said square wave generating circuit is divided by a half-divider and the divided signal is applied to said switching element, and
said half-divider further comprises a control (CONT) terminal, a CONT signal supplied to the CONT terminal turns on the half-divider when the CONT signal changes from a first level to a second level upon a detection of a ringing signal.
8. A vibrator controlling circuit according to claim 3 , wherein said operational amplifier in said frequency shift detecting circuit further comprises a control (CONT) terminal, a CONT signal supplied to the CONT terminal turns on the operational amplifier when the CONT signal changes from a first level to a second level upon a detection of a ringing signal.