JPH0470002A - Piezo-oscillator - Google Patents

Abstract

PURPOSE:To attain the control of frequency at the outside of a sealed container by providing a switching circuit which selects the outputs of a counter circuit and a memory circuit and outputs a digital coded signal and a D/A converter and connecting the output of this converter to a variable capacity diode. CONSTITUTION:A magnetic detector 1 outputs an analog signal to a converter 2, and the converter 2 converts the change of the analog signal into a pulse signal to output it to a counter circuit 3. The circuit 3 counts these pulse signals and outputs the digital coded signals to a memory circuit 4 and a switching circuit 5. The circuit 4 stores the received coded signal in an address with a control signal and then outputs it. The circuit 5 selects the outputs of both circuits 3 and 4 with a switching signal and outputs the digital coded signal. Then a D/A converter 6 converts the digital coded signal into an analog signal and applies this signal to a variable capacity diode 8. Thus the control of frequency is attained in a sealed structure.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a piezoelectric oscillator, and in particular, a piezoelectric oscillator and an oscillation circuit are built in a sealed container, and the frequency can be adjusted from outside the sealed container. Regarding piezoelectric oscillators.

Conventional technology Conventionally, in piezoelectric oscillators, and especially in crystal oscillators that are widely used, a variable capacitor is inserted into an oscillation circuit constructed in a container, or a variable capacitor diode is used to adjust the frequency by voltage. You can make fine adjustments to the frequency before sealing by inserting a variable resistor to adjust the volume, or you can make a hole in a part of the container and use an adjustment rod such as a screwdriver to adjust the variable capacitance or variable resistor. , we have made fine adjustments to the frequency.

FIG. 3 is a cross-sectional view showing an example of a conventional piezoelectric oscillator with holes drilled in its container. In FIG. 3, a container 13 is provided that covers the substrate 12 and the components attached to the substrate 12. A hole 13a is made in a part of the container 13, and an adjustment rod 15 is inserted through the hole 13a to connect a variable capacitor or variable resistor 14. and fine-tuned the frequency.

Problems to be Solved by the Invention However, in the conventional piezoelectric oscillator described above, when the frequency is finely adjusted and then sealed, the frequency changes before and after sealing, so it is difficult to improve frequency accuracy. This had become an obstacle.

In addition, if you make a hole in the container and use an adjustment rod to make fine adjustments to the frequency, the frequency accuracy can be improved, but since the seal is no longer sealed, the printed circuit board can be removed while the oscillator is attached to the printed circuit board. There was a problem in that it was difficult to clean with solvents and the like.

The present invention has been made in view of the above-mentioned conventional situation,
Accordingly, an object of the present invention is to provide a novel piezoelectric oscillator which solves the above-mentioned problems inherent in the conventional technology and enables frequency adjustment of the piezoelectric oscillator in a compact sealed structure.

Means for Solving the Problems In order to achieve the above object, the piezoelectric oscillator according to the present invention has the following features:
Magnetic detection includes a pressure oscillation circuit that includes a circuit configuration in which a piezoelectric vibrator and a variable capacitance diode whose capacitance can be varied by DC voltage are connected in series, and a magnetic resistance element that outputs an analog signal according to the strength of the surrounding magnetic field. a converter that converts the change in the analog signal into a pulse signal and outputs it; a counter circuit that counts the number of the pulse signals and outputs a digital code signal corresponding to the number of counts; a memory circuit that stores a digitally coded signal or outputs the stored digitally coded signal;
a switching circuit that selects the output of the counter circuit and the output of the memory circuit using a switching signal to output a digital coded signal; and a switching circuit that outputs an analog control signal obtained by converting the digital coded signal output from the switching circuit. D
-A converter, the output of the D-A converter is connected to one end of the variable capacitance diode, and each of these elements is housed inside a sealed container. The memory circuit is electrically written and erased by ultraviolet rays, or electrically written and erased, and the written contents are made of elements that cannot be erased even if the power is turned off.

Embodiment Next, a preferred embodiment of the present invention will be specifically explained with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention.

Referring to FIG. 1, a piezoelectric vibrator 7 and a variable capacitance diode 8 are connected in series, and the other end of each element 7.8 is connected to a piezoelectric oscillation circuit 9. The magnetic detector 1 outputs an analog signal to the converter 2 according to the strength of the surrounding magnetic field. converter 2
converts the variation of the analog signal into a pulse signal and outputs it to the counter circuit 3. The counter circuit 3 counts the pulse signals and outputs a digital coded signal corresponding to the count number to the memory circuit 4 and the switching circuit 5. The memory circuit 4 stores the digital coded signal at a predetermined address according to the control signal, and outputs the stored digital code f-hi signal. The switching circuit selects the output of the counter circuit 3 and the output of the memory circuit 4 using a switching signal and outputs a digitally coated signal. D-A
Converter 6 converts the digital coded signal into an analog signal and applies it to variable capacitance diode 8 .

Next, the operation of the present invention will be explained. When a magnetic field is applied to this oscillator, the magnetic detector 1 outputs an analog signal corresponding to the magnetic field strength to the converter 2. When the magnetic field strength is changed, the analog signal also changes, and the converter 2 outputs a pulse signal to the counter circuit 3 when the amount of change exceeds a certain level. Therefore, if the magnetic field strength is repeatedly changed by a certain amount or more, a pulse signal is repeatedly output from the converter 2. The counter circuit 3 counts the number of pulse signals and supplies a digital coded signal to the memory circuit 4 and the switching circuit 5 according to the counted number. At this time, the memory circuit 4 is in the read state by the control signal, so it does not store anything.

On the other hand, the switching circuit 5 outputs the digital coded signal of the counter circuit 3 to the AD converter 6 in response to the switching signal.

The DA converter 6 converts the digitized signal into an analog signal and applies it to the variable capacitance diode 8 . Since the variable capacitance diode 8 has a capacitance value that corresponds to the value of the applied analog signal, the oscillation frequency also has a frequency that corresponds to the value of the analog signal. Therefore, the oscillation frequency can be changed by changing the number of times the magnetic field strength changes by a certain amount or more.

In this way, the oscillation frequency is changed, and when the target oscillation frequency is reached, the change in the magnetic field strength is stopped, and the control signal sets the memory circuit 4 in the write state, and the digital coded signal supplied to the memory circuit 4 is changed. is memorized in the preset atsushi. After storing the digital coded signal in the memory circuit 4, the control signal causes the memory circuit 4 to be placed in a read state again, and outputs the stored digital coded signal to the switching circuit 5.
The switching circuit 5 selects the output of the memory circuit 4 based on the switching signal and supplies it to the DA converter 6.

As a result, the present oscillator can always obtain the oscillation frequency determined by the digitally coded signal stored in the memory circuit 4 using the control signal and the switching signal. Of course, even if the power is turned off, the digital coded signal stored in the memory circuit 4 will not be erased, so if the power is turned on again, the oscillation frequency determined by the digital coded signal stored in the memory circuit 4 can be obtained again. .

FIG. 2 is a sectional view showing an embodiment of the sealed container according to the present invention.

Referring to FIG. 2, the configuration of the embodiment shown in FIG. 1 is placed on a substrate 12 in a sealed container 11, and when the permanent magnet 10 is moved closer to or closer to the sealed container 11, the structure shown in FIG. The magnetic detector 1 detects the magnetic change, and as described above, the converter 2, counter circuit 3, memory circuit 4, switching circuit 5, D-
The A converter 6 moves to change the capacitance value of the variable capacitance diode 8 to adjust the oscillation frequency.

As described in detail, according to the present invention, the frequency can be adjusted from outside the sealed container.

Even if the frequency changes before and after sealing, which was the case in the past, it is only necessary to finely adjust the frequency after sealing, and as a result, it is possible to improve the accuracy of the oscillation frequency.

Furthermore, according to the present invention, there is no need to make holes in the container for conventional variable capacitors and variable resistors, so a completely sealed structure can be achieved. The effect is that the printed circuit board can be cleaned with an organic solvent or the like while it is attached to the board.

Furthermore, according to the present invention, since variable capacitors and variable resistors are not required, the circuit can be easily integrated into an IC, and a piezoelectric oscillator that is small and has high oscillation frequency accuracy can be easily realized. .

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG.
The figure is a cross-sectional view of a container housing each element of the embodiment shown in FIG. 1, and FIG. 3 is a cross-sectional view of a conventional piezoelectric oscillator. 1...Magnetic detector, 2...Converter, 3...Counter circuit, 4...Memory circuit, 5...Switching circuit, 6...0
-A converter, 7. Piezoelectric vibrator, 8.. Variable capacitance diode, 9.. Piezoelectric oscillation circuit, 11.1+. Permanent magnet, 11.
sealed container, 12... substrate, 13... container, 14...
・Variable capacitance or volume patent applicant Mimoto Electric Co., Ltd. Representative Patent attorney Yutabe Kumagai 1: Gas detector 2: Moxibustion device 3 ・Counter circuit 4: Memory circuit 5: Kirishinguchi 6 ・DI At Switch g, at** circuit diagram

Claims (2)

[Claims] (1) In a piezoelectric oscillator that has a piezoelectric vibrator and an oscillation circuit built into a container, the piezoelectric oscillation circuit includes a circuit configuration in which the piezoelectric vibrator and a variable capacitance diode whose capacitance can be varied by DC voltage are connected in series; a magnetic detector that includes a magnetoresistive element and outputs an analog signal according to the strength of a surrounding magnetic field; a converter that converts a change in the analog signal into a pulse signal and outputs the pulse signal; and a count number that counts the number of the pulse signals. a counter circuit that outputs a digitally coded signal according to the digital coded signal; a memory circuit that stores the digitally coded signal according to a control signal or outputs the stored digitally coded signal; an output of the counter circuit and an output of the memory circuit; and a D-A converter that outputs an analog control signal obtained by converting the digital coded signal outputted from the switching circuit. - A piezoelectric oscillator characterized in that the output of the A converter is connected to one end of the variable capacitance diode. (2) The piezoelectric oscillator according to claim (1), further characterized in that the container has a sealed structure, and the oscillation frequency of the piezoelectric oscillation circuit is adjusted by moving a permanent magnet near or near the sealed container.