JPS6338580Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a comb-shaped filter constituted by an ultrasonic delay element, an impedance element, and a resistor, and more specifically relates to a comb-shaped filter having a built-in switching function.

As shown in Figure 1, the ultrasonic delay element is made of metal,
A delay medium 1 made of a solid material such as crystal, glass, or ceramics that propagates ultrasonic waves, and a piezoelectric material such as crystal or lead zirconate titanate mounted on an appropriately selected surface of this medium to transmit an electric signal. It consists of an input transducer 2 that converts into a mechanical signal and an output transducer 3 that converts the mechanical signal into an electrical signal. When an electrical signal is applied to the input transducer 2, this signal is converted into a mechanical signal, and the mechanical signal reaching the output transducer 3, which travels through the delay medium 1 as shown by the arrow 4, is an electrical signal. is converted to

Conventionally, a comb filter using an ultrasonic delay element, as shown in FIG. 2, includes a delay element consisting of an input transducer 2, an output transducer 3, and a delay medium 1, and an impedance element 5 connected in parallel with the delay element. It is composed of an input side resistor 6 and an output side resistor 7. When an input electrical signal is applied to the input terminal 8, the first signal is converted into a mechanical signal by the input transducer 2 and proceeds along the arrow 4, and is again converted into an electrical signal by the output converter 3 and output. It reaches terminal 9. The second signal passes through the impedance element 5, reaches the output terminal 9, and is summed with the first signal to exhibit comb filter characteristics.

In recent years, as the uses of delay elements have expanded, various functions have come to be required of comb filters.

For example, in a VTR, sometimes the signal is
I would like to process the signal through a comb filter, but sometimes it becomes necessary to simply delay the signal without passing it through the comb filter. If you try to perform this function with an external circuit that includes conventional delay lines and transistors,
Problems arise in terms of cost and space. Therefore, there has been a demand for a comb-shaped filter with a built-in switching function that can be switched very easily.

In view of these demands, the present inventor conducted various experiments and found that by dividing the impedance element into two in series and providing a grounding terminal between them,
We have discovered that it is possible to realize a comb-shaped filter having such a function, and we hereby submit it as the present invention.

FIG. 3 is a block diagram of the present invention. The comb-shaped filter of the present invention differs from conventional comb-shaped filters in that an impedance element connected in parallel is divided into two impedance elements 10 and 11 in series, and a grounding terminal is provided between the elements 10 and 11. 12
is provided.

In FIG. 3, when the grounding terminal 12 is not grounded, the input signal applied to the input terminal 8 reaches the output terminal 9 in exactly the same manner as in FIG. 2, forming a comb filter. However, when the grounding terminal 12 is grounded, the input signal flowing into the impedance element flows away from the grounded terminal 12 and does not reach the output terminal 9. Therefore, the signals that reach the output terminal 9 are only those that have passed through the delay element.

As described above, when the ground terminal 12 is not grounded, it functions as a comb filter, and when it is grounded, it functions simply to delay the input signal, and functions as a comb filter with a built-in switching function. I understand that.

[Brief explanation of drawings]

FIG. 1 is a plan view schematically showing an ultrasonic delay element, FIG. 2 is a circuit diagram illustrating a conventional comb filter, and FIG. 3 is a circuit diagram illustrating a comb filter according to the present invention. 1... Ultrasonic delay element, 2... Input side piezoelectric element, 3... Output side piezoelectric element, 6... Input side resistance,
7... Output side resistance, 10, 11... Impedance element, 12... Grounding terminal.

Claims (1)

[Scope of utility model registration request] In a comb filter consisting of an ultrasonic delay element 1, an impedance element connected in parallel with the ultrasonic delay element 1, an input side resistor 6, and an output side resistor 7, the impedance element is divided into two parts and an impedance element 10 and an impedance element 10 are connected in series. 11, and a grounding terminal 12 is provided therebetween.