JPS58204616A - Ultrasonic wave delay line - Google Patents

Abstract

PURPOSE:To attain miniaturization, by constituting the length of a path on which ultrasonic waves are propagated as the sum of the length of the paths where a bulk wave is propagated in a delay medium and a surface acoustic wave is propagated on the side of the delay medium. CONSTITUTION:In applying a high frequency electric signal to a piezoelectric element 5, the piezoelectric element 5 is vibrated mechanically to generate an ultrasonic wave signal in the delay medum. This ultrasonic wave is propagated in the medium 7, reaches a piezoelectric element 6, which is excited mechanically by the ultrasonic wave. An electric signal generated with the vibration of the element 6 is applied to a comb type electrode 10. This electric signal generates a surface wave on a piezoelectric thin film 8 at the side surface of the medium 7 and the surface wave is propagated on the film 8. The surface wave propagating on the film 8 reaches a comb type filter 11 while being reflected at a reflecting grating 12. The surface wave reaching the electrode 11 is converted again into an electric signal and extracted. Through the constitution like this, the delay time is doubled. That is, the size of the delay medium required to obtain a prescribed delay time is halved and the miniaturization of the ultrasonic wave delay line is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasonic delay line used for reproducing two-color signals to improve image quality in video equipment.

FIG. 1 shows a conventionally used ultrasonic delay line.

Here, 1 and 2 are piezoelectric elements, and 3 is glass. A high-frequency electric signal is applied to the piezoelectric element 1, the generated ultrasonic signal is propagated through the delay medium 3, and the output side piezoelectric element 2 receives the electric signal again. It is extracted as follows. In a delay line with such a configuration, in order to obtain a delay time of 1H (63,566 μ), the ultrasonic propagation length must be approximately 16 crn (
Considering the speed of sound (2.5 ICIn/5eC) and the spurious margin, the size of the delay medium cannot be made very small; it is approximately 30 x 20 mm, which is quite large compared to other electronic components. Put it away.

The object of the present invention is to miniaturize this ultrasonic delay line. An embodiment of the ultrasonic delay line according to the present invention is shown in FIG. In FIG. 2, 6 and 6 are piezoelectric elements, which are provided on the end face in the thickness direction of the delay medium 7 such as glass.
A piezoelectric thin film 8 is provided on at least one side surface of. 9 is an ultrasonic propagation path, 10.11 is a comb-shaped electrode for surface wave excitation and reception provided on the piezoelectric thin film 8, and 12 is a plurality of surface wave reflection paths 9 provided on the piezoelectric thin film 8.
A piezoelectric thin film (for example, Zn) is deposited on the parallel sides of the
O) 8 is formed, and a comb-shaped electrode 10 is formed on this piezoelectric thin film 8.
．． 11 and a reflective grating 12, and a comb-shaped electrode 1
o and the piezoelectric element 6 are electrically connected.

The operation of this ultrasonic delay line will be explained. When a high-frequency electric signal is applied to the piezoelectric element 6 without being switched, the piezoelectric element 6 mechanically vibrates and generates an ultrasonic signal in the delay medium 7. The generated ultrasonic wave propagates through the delay medium 7, reaches the piezoelectric element 6, and mechanically excites it. An electric signal generated by the vibration of the piezoelectric element 6 is applied to the comb-shaped electrode 1o. This electric signal generates a surface wave on the piezoelectric thin film 8 and propagates on the piezoelectric thin film 8. The surface wave propagating on the piezoelectric thin film 8 reaches the comb-shaped electrode 11 while being reflected by the reflection grating 12. The surface waves that have reached this comb-shaped electrode 11 are again converted into electrical signals and extracted.

According to the present invention, when a delay medium of the same size as the conventional one is used, the path length followed by the ultrasonic wave is equal to the path length of the bulk wave in the delay medium and the path length of the surface wave on the side surface of the delay medium. Therefore, the delay time will be doubled. In other words, the size of the delay medium required to obtain a constant delay time is h times that of the conventional one, making it possible to downsize the ultrasonic delay line.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a conventional ultrasonic delay line, and FIG. 2 is a schematic block diagram showing an embodiment of the ultrasonic delay line according to the present invention. 6.6...1st. Second piezoelectric element, 7...
...Delay medium, 8...Piezoelectric thin film, 9...
...Ultrasonic travel path, 10.1.1...1st.
Second comb-shaped electrode, 12... grating for surface wave reflection.

Claims (1)

[Claims] A piezoelectric thin film is provided on at least one side surface of a delay medium such as glass, and a first piezoelectric thin film is provided on an end surface in the thickness direction of the delay medium. A second piezoelectric element is provided, and a first piezoelectric element is provided on the piezoelectric thin film.
A second comb-shaped electrode for surface wave excitation and reception is provided, and the ultrasonic signal generated from the first piezoelectric element is converted into a high-frequency electric signal by the second piezoelectric element, which is then converted into a high-frequency electric signal by the first piezoelectric element. An ultrasonic delay line characterized in that a generated surface wave signal is applied to a comb-shaped electrode and then converted back into a high-frequency electric signal by a second comb-shaped electrode, and then extracted.