JPS6347078Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an ultrasonic delay line that can be used in television receivers, video tape recorders, etc., and aims to reduce unnecessary reflected output of this ultrasonic delay line.

As shown in FIG. 1, a conventional ultrasonic delay line consists of a delay medium 2 made of a solid such as glass or crystal, and an input/output piezoelectric element 1 bonded to the input/output piezoelectric element 1 to allow the generated ultrasonic wave to propagate along a path 3. I'm getting a delay time. Here, ultrasonic waves passing through a path other than the normal path become unnecessary reflected output and are detected at a time other than the desired delay time. Therefore, in the past, a resin 4 was applied to the delay medium 2 in order to absorb the ultrasonic waves passing through other than the normal path.
The number is decreasing. However, its effectiveness was limited to around -30dB relative to the main signal.

The present invention eliminates the above-mentioned conventional drawbacks. An example of this will be described below with reference to FIGS. 2 and 3.

Considering the combination 5 of surfaces like the tip of a needle with a paraboloid as shown in Figure 2, when an unnecessary ultrasonic wave hits this approximately flower-shaped hole (recess) while trying to pass through, in what direction will it travel as shown in path 6? Even if the ultrasonic wave enters from the inside, it will be reflected toward the center of the flower shape 7 on the reflecting surface, so that it will not go out to the outside, and the unnecessary ultrasonic wave can be reliably absorbed. By constructing this flower shape by making a hole in the portion 7' of the delay medium 2' other than the normal reflection path of the ultrasonic wave as shown in Figure 3, it was possible to reduce the unnecessary reflected output to less than -40 dB. . Therefore, it greatly contributes to improving the image quality of television receivers and video tape recorders.

As is clear from the above embodiments, according to the present invention, by forming a substantially flower-shaped hole formed by a combination of paraboloids in a portion of the delay medium other than the regular ultrasonic propagation path, unnecessary reflected output can be suppressed as much as possible. It is possible to improve the performance.

[Brief explanation of the drawing]

Figure 1 shows a conventional ultrasonic delay line, Figure 2 shows the structure of the unnecessary reflection absorption hole of the present invention, and Figure 3 shows a conventional ultrasonic delay line.
The figure is a diagram showing an ultrasonic delay line in an embodiment of the present invention. 1, 1'... piezoelectric element, 2, 2'... delay medium,
3... Ultrasonic propagation path, 4... Resin, 5... Part of unnecessary reflection absorption hole, 6... Unnecessary ultrasound path, 7,
7'...Unnecessary reflection absorption hole.

Claims (1)

[Scope of utility model registration request] In an ultrasonic delay line in which a solid such as glass or crystal is provided as an ultrasonic propagation medium, a piezoelectric element serving as an input/output terminal of the ultrasonic wave is fixed to this propagation medium, and the ultrasonic wave is reflected within the propagation medium, An ultrasonic delay line formed by forming a generally flower-shaped hole formed by a combination of paraboloids in a portion other than the normal propagation path of the propagation medium.