JPH0138986Y2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field The present invention relates to a frequency discrimination device used to separate a specific frequency signal from a plurality of frequency signals for remote control, etc. This invention relates to a frequency discrimination device using a vibrator.

Prior Art A conventional frequency discriminator using two piezoelectric tuning fork vibrators has an input amplifier 2 connected to an input terminal 1 and an output transmission line of this amplifier 2 connected in series, as shown in FIG. a two-element reed filter 7 consisting of an input coupling capacitor 3, a matching resistor 4 connected in series to the capacitor 3, and first and second piezoelectric tuning fork vibrators 5 and 6 having slightly different resonance frequencies; , an output coupling capacitor 8 connected in series to the output line of this filter 7,
It consists of an output amplifier 9 provided on the output side of this capacitor 8 and an output terminal 10. The piezoelectric tuning fork vibrator 5 has electrodes 12 and 13 provided on a piezoelectric substrate 11, one electrode 12 is connected to an input terminal 14, the other electrode 13 is connected to an output terminal 15, and a second electrode 12 is connected to an input terminal 14. The piezoelectric tuning fork vibrator 6 has a piezoelectric substrate 16
electrodes 17 and 18 are provided, one electrode 17 is connected to the input terminal 19, and the other electrode 18 is connected to the output terminal 2.
It is connected to 0. Furthermore, the two vibrators 5 and 6 are differentially connected so that their impact responses cancel each other out.

When a composite signal consisting of _frequency components ₁ , ₂ , . amplified to the level. The amplified composite signal is sent to a first input terminal 14 and a second input terminal 19 of a reed filter 7 via an input coupling capacitor 3 and a matching resistor 4. The reed filter 7 acts as a bandpass filter that passes only the frequency components resonating with the unique frequency of the tuning fork, and only _one component of the composite signal passes through the filter 5 and is sent to the first output terminal 15 and the second output terminal. It is output from the output terminal 20. This output signal passes through an output coupling capacitor 8, is amplified by an amplifier 9 to compensate for the insertion loss of the filter 7, and is sent out from an output terminal 10.

By the way, in the conventional frequency discriminator, as shown in FIG. 3, the input signals are frequencies ₁ , ₂ ,
When a composite signal consisting of ..., _o is input to input terminal 1 with an on period T _ON , an off period T _OFF , and a period T,
For example, the output of frequency ₁ obtained for the input signal occurs even during the off period T _OFF of the input signal, as shown in Figure 4, and the output does not naturally attenuate and disappear over time, but at frequency 2. It occurred with a transient vibration having a peak point of ~3. Therefore, when remote control is performed using the output signal of frequency ₁ shown in FIG. 4 as a control signal, there is a risk that malfunction may occur due to the output during the off period.

Purpose of the invention Therefore, the purpose of the present invention is to provide a frequency discriminator that suppresses transient vibrations.

Structure of the Invention The present invention to achieve the above object includes an input coupling capacitor connected in series to a frequency signal transmission line, first and second piezoelectric tuning fork vibrators having slightly different resonance frequencies, and the first and second piezoelectric tuning fork vibrators having slightly different resonance frequencies. a first resistor connected between the input terminal of the first piezoelectric tuning fork vibrator and the input coupling capacitor; and a first resistor connected between the input terminal of the second piezoelectric tuning fork vibrator and the input coupling capacitor. a second resistor, and an output coupling capacitor connected to the output terminal of the first piezoelectric tuning fork vibrator and the output terminal of the second piezoelectric tuning fork vibrator, respectively, and connected in series to the output line.
This invention relates to a frequency discrimination device using piezoelectric tuning fork vibrators.

Effects of the invention According to the above invention, it becomes possible to significantly suppress transient vibrations occurring in a frequency discriminator using two piezoelectric tuning fork vibrators. The effect of suppressing transient vibrations according to the present invention is that the first and second resistors inserted into the parallel circuit of the two piezoelectric tuning fork vibrators are accumulated in the two piezoelectric tuning fork vibrators and move relative to each other. It is presumed that this occurs due to the consumption of charge.

Embodiment Next, a frequency discrimination device according to an embodiment of the present invention will be described with reference to FIGS. 2 and 5. However, since the parts indicated by reference numerals 1 to 3 and 5 to 20 in FIG. 2 are substantially the same as those shown by the same reference numerals in FIG. 1, their explanation will be omitted.

In the device shown in FIG. 2, a first
A second resistor 22 is connected between the input terminal 19 of the second piezoelectric tuning fork vibrator 6 and the input coupling capacitor 3. That is, 2
There is a resistor 2 in the parallel circuit of the inputs of the two oscillators 5 and 6.
1 and 22 are connected to each other.

A third terminal is connected to the input terminal 1 of the device configured in this way.
When the input signal shown in the figure is input, the output terminal 10
From this, an output as shown in FIG. 5 is obtained. As is clear from a comparison between FIG. 4 and FIG. 5, the output corresponding to the ON period T _ON of the input signal in FIG. 3 is almost the same between the conventional and this embodiment, but the transient vibration is There are far fewer examples. That is, the peak value of the transient vibration becomes about 1/5, and the duration becomes about 1/2.

In this way, the effect of greatly suppressing transient vibrations during the off period T _OFF of the input signal is due to the fact that the charges accumulated in the piezoelectric substrates 11 and 16 during the on period T _ON of the input signal are transferred to the substrate 11, the electrode 12, and the input a closed circuit consisting of a terminal 14, a first resistor 21, a second resistor 22, an input terminal 19, an electrode 17, a substrate 16, and a ground;
Or a closure consisting of the substrate 11, the electrode 12, the input terminal 14, the first resistor 21, the second resistor 22, the input terminal 19, the electrode 17, the substrate 16, the electrode 18, the output terminal 20, the output terminal 15, and the electrode 13. This occurs because the charges accumulated on the substrates 11 and 16 are consumed or attenuated by the resistors 21 and 22 as they move through the circuit.

As described above, if transient vibrations are reduced, it becomes possible not only to perform control using the extracted frequency signal reliably, but also to shorten the off period T _OFF .

Modifications The present invention is not limited to the above embodiments,
For example, the following modifications are included.

(A) Between electrode 13 and output terminal 15, and between electrode 1
A resistor may also be connected between the output terminal 8 and the output terminal 20, respectively.

(B) In the embodiment, the resistors 21 and 22 also function as matching resistors, but a matching resistor may be further connected in series with the capacitor 3.

(C) If a low signal level is acceptable,
Amplifiers 2 and 9 may be omitted.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing a conventional frequency discriminator;
Fig. 2 is a circuit diagram showing a frequency discriminator according to an embodiment of the present invention, Fig. 3 is a waveform diagram showing the principle of a composite input signal, and Fig. 4 shows the output of the conventional frequency discriminator shown in Fig. 1. Waveform diagram showing the principle, Figure 5 is the second waveform diagram.
FIG. 2 is a waveform diagram theoretically showing the output of the frequency discriminator according to the embodiment of the present invention; FIG. 3... Input coupling capacitor, 5, 6... Piezoelectric tuning fork vibrator, 7... Two-element type reed filter, 8...
...Output coupling capacitor, 21...First resistor, 2
2...Second resistance.

Claims (1)

[Claims for Utility Model Registration] An input coupling capacitor connected in series to a frequency signal transmission line, first and second piezoelectric tuning fork vibrators having slightly different resonance frequencies, and the first piezoelectric tuning fork vibrator. a first resistor connected between the input terminal of the second piezoelectric tuning fork vibrator and the input coupling capacitor; a second resistor connected between the input terminal of the second piezoelectric tuning fork vibrator and the input coupling capacitor; two piezoelectric tuning fork vibrators comprising an output coupling capacitor connected to an output terminal of the first piezoelectric tuning fork vibrator and an output terminal of the second piezoelectric fork vibrator and connected in series to an output line; Frequency discriminator using.