JPH02220511A - Ultrasonic wave delay line - Google Patents

Abstract

PURPOSE:To improve the band pass characteristic by providing a piezoelectric element to an input and an output side or a glass delay medium, and varying the shape, thickness or the shape of electrode to vary the impedance. CONSTITUTION:Piezoelectric elements 2a, 2b are provided to the input and output side of a glass delay medium 1, and an electric signal is supplied to the input element 2a. Then the converted ultrasonic wave is sent to the glass delay medium 1 and after the ultrasonic wave is propagated through a propagation path 5 for a prescribed time, the wave is extracted again as an electric signal from the output side piezoelectric element 2b. The impedance of the piezoelectric elements 2a, 2 is varied by varying the shape, the thickness of the piezoelectric elements or the shape of the electrodes. Thus, the impedance of the piezoelectric elements 2a, 2b is varied to improve the band pass characteristic being a general characteristic of the ultrasonic wave delay line.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is mainly applicable to color signal demodulation of PAL television systems, image quality improvement of NTSC television systems,
This invention relates to ultrasonic delay lines used to eliminate cross color during VTR playback, improve the S/N ratio, and improve the image quality of video equipment.

Conventional technology Conventionally, this type of ultrasonic delay line mainly consists of two piezoelectric elements and a glass delay medium, and an electric signal is applied to the piezoelectric element on the input side, thereby transmitting the converted ultrasonic waves to the glass delay medium. The operating principle is that the signal is sent into the medium, propagated within the glass delay medium for a certain period of time, and then converted into an electrical signal by the piezoelectric element on the output side and taken out.The piezoelectric elements on the input and output sides have the same design specifications. Impedance was the same.

Problems to be Solved by the Invention However, in the conventional configuration as described above, the piezoelectric elements on the input side and the output side were fixed to the same design specifications, so that the passthrough (;), which is a general characteristic of ultrasonic delay lines, was fixed. There was a limit to the improvement in carrying capacity.

The purpose of the present invention is to solve and pass the above problems;
The present invention aims to provide an ultrasonic delay line with excellent characteristics in the II region.

Means for Solving the Problems In order to achieve the above object, the present invention mainly consists of two piezoelectric elements and a glass delay medium, applies an electric signal to the piezoelectric element on the input side, and detects the converted ultrasonic signal. A sound wave is sent into a glass delay medium, and after propagating within the glass delay medium for a certain period of time, it is converted back into an electrical signal by a piezoelectric element on the output side. The ultrasonic delay line was changed by changing the shape, thickness, or electrode shape of the piezoelectric element.

Effect: The above configuration changes the impedance of the piezoelectric element, making it possible to provide an ultrasonic delay line with excellent passband characteristics, which is a general characteristic of ultrasonic delay lines.

Example The drawings shown as one embodiment will be explained below.

In Fig. 1, l is a glass retardation medium, 2a and 2b are piezoelectric elements, 3 is an electrode, 4 is a lead wire, and the glass retardation medium l
A piezoelectric element 2a having an electrode 3 and having an input impedance a for converting an electric signal into an acoustic signal, and an electrode 3
A piezoelectric element 2b having impedance b for output which converts an acoustic signal into an electric signal and having an opposite effect is attached, and lead wires 4 are attached to each electrode 3. These input and output piezoelectric elements 2a, 2
By changing the shape of the piezoelectric element 2 and the shape of the electrodes, the impedances a and b of b are not of the same specification (not shown). is indicated by a dotted line, and 6 is an ultrasonic absorbing material, which is installed on the side of the glass delay medium l to absorb and attenuate unnecessary reflections as delayed signals that are reflected from surfaces other than the regular reflecting surface and reach the output side. .

Piezoelectric element 2 for input of the ultrasonic delay line having such a configuration
An electric signal is applied to a, and the converted ultrasonic wave is sent to the glass delay medium 1, and after propagating for a certain period of time along the propagation path 5 shown by the dotted line, it is converted into an electric signal again by the piezoelectric element 2b on the output side and taken out. It is something.

Figure 2 is a diagram showing the passband characteristics, which are general characteristics of ultrasonic delay lines according to the technology (A) of the present invention and the conventional technology (+3), and the characteristics in the case of the present invention change compared to the conventional example. Indicates that the

Effects of the Invention Since the present invention has the above-described configuration, the impedance of the piezoelectric elements on the input side and the output side can be changed by changing the shape, thickness, or electrode shape of the piezoelectric elements to adjust the passband, which is a general characteristic of an ultrasonic delay line. It has the effect of improving characteristics.

[Brief explanation of the drawing]

Fig. 1 is a side view of an ultrasonic delay line shown as an embodiment of the present invention, and Fig. 2 is a comparison diagram of passband characteristics, which are general characteristics of ultrasonic delay lines according to the present invention and conventional techniques. be. 1...Glass delay medium 2a, 2b...Piezoelectric element 3...Electrode Figure 2 Frequency (M) (z)

Claims (1)

[Claims] (1) Two piezoelectric elements and a glass delay medium are the main components, and an electric signal is applied to the piezoelectric element on the input side, and the converted ultrasonic wave is sent into the glass delay medium for a certain period of time. After propagating, the piezoelectric element on the output side converts the signal into an electrical signal again and takes it out.In the ultrasonic delay line, the impedance of the piezoelectric elements on the input and output sides is changed by changing the shape, thickness, or electrode shape of the piezoelectric element. Ultrasonic delay line characterized by: