JPH04253406A - Piezoelectric oscillator - Google Patents

Abstract

PURPOSE:To facilitate washing with sealed structure by changing magnetic field intensity from the outside and adjusting an oscillation frequency corresponding to the output of a magnetic detector in a sealed enclosure. CONSTITUTION:When a magnetic field is applied from the outside of a sealed vessel 10 by a permanent magnet 9, an analog signal corresponding to the magnetic field intensity is outputted from a magnetic detector 1 to an A/D converter 2. The analog signal is converted to a digital signal 2a by the A/D converter 2 and supplied to a memory circuit 3 and a switching circuit 4. Since a switching signal to select the output of the A/D converter 2 is inputted to one switching circuit 4, the digital signal 2a supplied from the A/D converter 2 is outputted to a D/A converter 5. Then, the signal is converted to the analog signal and impressed to a variable capacity diode 7. As the result, the oscillation frequency is turned to a frequency corresponding to the analog signal impressed to the variable capacity diode 7.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric oscillator, and more particularly to a piezoelectric oscillator that includes a piezoelectric vibrator and an oscillation circuit inside a container.

0002

[Prior Art] In a conventional piezoelectric oscillator, a commonly used crystal oscillator is placed in a container, and the frequency is adjusted by inserting a variable capacitance into the oscillation circuit or by using a voltage using a variable capacitance diode. The frequency can be finely adjusted by inserting a volume to adjust the frequency before sealing, or by punching a hole in a part of the container and adjusting the variable volume or volume using a screwdriver or the like.

FIG. 2 is a sectional view showing an example of a conventional piezoelectric oscillator.
2, a hole is made in a part of the container 12, and a variable capacity or volume 13 is adjusted using a screwdriver to finely adjust the frequency.

0004

[Problems to be Solved by the Invention] In the conventional piezoelectric oscillator described above, when the frequency is finely adjusted and then sealed,
Since the frequency changes before and after sealing, it is necessary to make a hole in the container and use a screwdriver to fine-tune the frequency, making it difficult to clean the printed circuit board with an organic solvent while the oscillator is attached to the printed circuit board. There was a problem with becoming.

[0005]

[Means for Solving the Problems] The present invention provides a piezoelectric oscillator that includes:
A magnetic detector that includes a magnetoresistive element and outputs an analog signal according to the strength of a surrounding magnetic field, an A-D converter that outputs a digital signal obtained by converting the analog signal, and a control signal that stores the digital signal. a memory circuit that outputs the stored digital signal; a switching circuit that selects and outputs the output of the A-D converter and the output of the memory circuit using a switching signal; and the output from the switching conversion circuit is converted. The device includes a DA converter that outputs an analog control signal, a variable capacitance diode whose capacitance value changes according to the voltage of the analog control signal, and a piezoelectric oscillator whose oscillation frequency changes according to the capacitance value.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained with reference to the drawings. FIG. 1 is a block diagram (a) and a sectional view (b) of an embodiment of the present invention.

One end of each of the variable capacitance diodes 7 of the piezoelectric vibrator 6 is connected in series, and the other end of each is connected to a piezoelectric oscillation circuit 8. The magnetic detector 1 outputs an analog signal according to the strength of the surrounding magnetic field to the A-D converter 2. A-
The D converter 2 converts the analog signal into a digital signal 2.
a is output to the memory circuit 3 and the switching circuit 4. The memory circuit 3 stores the digital signal 2a at a predetermined address according to the control signal, and stores the stored digital signal 3a.
Output. The switching circuit 4 selects the digital signal 2a and the digital signal 3a using the switching signal and outputs the selected signal to the DA converter 5. The D-A converter 5 receives the digital signal 2a or 3
The analog signal obtained by converting a is applied to the variable capacitance diode 7.

Next, the operation of this embodiment will be explained.
As shown in FIG. 1(b), when a magnetic field is applied from outside the sealed container 10 by a permanent magnet 9, an analog signal corresponding to the magnetic field strength is output from the magnetic detector 1 to the AD converter 2. The analog signal is converted into a digital signal 2a which is digitally coded by the A-D converter 2, and is supplied to the memory circuit 3 and the switching circuit 4. At this time, since no control signal is input to the memory circuit 3, the input section and the storage section are separated, and no signal is stored. Since a switching signal for selecting the output of the A-D converter 2 is input to one of the switching circuits 4, the digital signal 2a supplied from the A-D converter 2 is output to the DA converter 5. . The DA converter 5 converts the digital signal into an analog signal and applies it to the variable capacitance diode 7. the result,
The oscillation frequency corresponds to the value of the analog signal applied to the capacitive diode 7. In this way, the oscillation frequency is adjusted by changing the magnetic field strength, and when the target oscillation frequency is reached, the change in the magnetic field strength is stopped and the digital signal 2a is transferred to the preset address of the memory circuit 3 by the control signal. Make me remember. Memory circuit 3
After storing the digital signal in , the input part of the memory circuit and the storage part are separated by the control signal, and the switching circuit 4 supplies the digital signal supplied from the memory circuit 3 to the DA converter by the switching signal. As a result, the piezoelectric oscillation circuit can always obtain the oscillation frequency determined by the digital signal stored in the memory circuit 3 using the control signal and the switching signal.

The memory circuit of this embodiment is electrically writable and erasable by ultraviolet rays, or is electrically writable and electrically erasable, and the written contents are made of elements that do not disappear even when the electricity is turned off.

0010

[Effects of the Invention] As explained above, the present invention changes the magnetic field strength from the outside and adjusts the oscillation frequency according to the output of the magnetic detector inside the sealed container. Since there is no need to open the oscillator into a container, the structure can be sealed, which has the effect that the printed circuit board can be cleaned with an organic solvent while the oscillator is attached to the printed circuit board.

[Brief explanation of the drawing]

FIG. 1 is a block diagram (a) and a cross-sectional view (b) of an embodiment of the present invention.

FIG. 2 is a cross-sectional view of an example of a conventional piezoelectric oscillator.

[Explanation of symbols]

1 Magnetic detector 2 A-D converter 3. Memory circuit 4 Switching circuit 5 DA converter 6 Piezoelectric vibrator 7 Variable capacitance diode 8 Piezoelectric oscillation circuit 9 Permanent magnet 10 Sealed container 11　　　　Substrate 12 Container 13 Variable capacity or volume

Claims (2)

[Claims] 1. A magnetic detector that includes a magnetoresistive element and outputs an analog signal according to the strength of a surrounding magnetic field; an A-D converter that outputs a digital signal obtained by converting the analog signal; a memory circuit that stores a digital signal and outputs the stored digital signal;
a switching circuit that selects and outputs the output of the converter and the output of the memory circuit using a switching signal; a D-A converter that outputs an analog control signal obtained by converting the output from the switching conversion circuit; A piezoelectric oscillator comprising: a variable capacitance diode whose capacitance value changes according to the voltage of a control signal; and a piezoelectric oscillator whose oscillation frequency changes according to the capacitance value. 2. The piezoelectric oscillator according to claim 1, wherein the memory circuit includes a memory element that retains stored information even when power is turned off.