Electronic apparatus

An electronic apparatus comprising a display portion and a quartz crystal oscillator at least, said electronic apparatus comprising at least one quartz crystal oscillator, said at least one quartz crystal oscillator comprising:

• a quartz crystal oscillating circuit comprising;
• an amplification circuit comprising an amplifier at least and a feedback circuit comprising a quartz crystal resonator and capacitors at least,
• said quartz crystal resonator being a length-extensional mode quartz crystal resonator capable of vibrating in a length-extensional mode, and said length-extensional mode quartz crystal resonator comprising:
• a vibrational portion having a length greater than a width and a thickness smaller than the width;
• connecting portions located at ends of said vibrational portion;
• supporting portions connected to said vibrational portion through said connecting portions;
• and
• electrodes disposed on upper and lower faces of said vibrational portion, wherein a piezoelectric constant e12 of said resonator is within a range of 0.095 C/m2 to 0.18 C/m2 in the absolute value,
• and wherein an output signal of said quartz crystal oscillating circuit comprising said length-extensional mode quartz crystal resonator is outputted through a buffer circuit, and said output signal is a clock signal which is used except time display of said electronic apparatus.

A method for manufacturing an electronic apparatus comprising a display portion and a quartz crystal oscillator at least, said electronic apparatus comprising at least one quartz crystal oscillator, said at least one quartz crystal oscillator comprising:

• a quartz crystal oscillating circuit comprising;
• an amplification circuit comprising an amplifier at least and a feedback circuit comprising a quartz crystal resonator and capacitors at least,
• said quartz crystal resonator being a quartz crystal tuning fork resonator capable of vibrating in a flexural mode, said quartz crystal tuning fork resonator comprising the steps of:
• forming integrally tuning fork tines each of which has a length, a width and a thickness and the length greater than the width and the thickness and a tuning fork base;
• disposing electrodes facing each other on sides of said tuning fork tines so that the electrodes that is disposed facing each other are of opposite electrical polarity and said tuning fork tines are capable of vibrating in inverse phase;
• and
• adjusting resonance frequency of said quartz crystal tuning fork resonator after mounting it at a mounting portion by conductive adhesives or solder so that a frequency deviation is within a range of −100 PPM to +100 PPM, and said at least one quartz crystal oscillator comprising the step of:
• constructing said quartz crystal oscillating circuit so that a ratio of an absolute value of negative resistance, |−RL1| of a fundamental mode vibration of said amplification circuit and series resistance R1 of the fundamental mode vibration is larger than that of an absolute value of negative resistance, |−RL2| of a second overtone mode vibration of said amplification circuit and series resistance R2 of the second overtone mode vibration, wherein said quartz crystal oscillating circuit comprises said quartz crystal tuning fork resonator whose figure of merit M1 of the fundamental mode vibration is larger than figure of merit M2 of the second overtone mode vibration to suppress the second overtone mode vibration and to get a high frequency stability for the fundamental mode vibration, and a ratio of an amplification rate α1 for the fundamental mode vibration and an amplification rate α2 for the second overtone mode vibration of said amplification circuit is larger than that of a feedback rate β2 of the second overtone mode vibration and a feedback rate β1 of the fundamental mode vibration of said feedback circuit and a product of the amplification rate α1 and the feedback rate β1 of the fundamental mode vibration is larger than 1,
• and wherein an output signal of said quartz crystal oscillating circuit comprising said quartz crystal tuning fork resonator capable of vibrating in the flexural mode has a frequency of the fundamental mode vibration of said resonator and is outputted through a buffer circuit, and said output signal is a clock signal which is used to display time at said display portion of said electronic apparatus.