JPS6042919A - Ultrasonic wave delay line - Google Patents

Abstract

PURPOSE:To obtain a delay line having excellent unnecessary reflecting characteristics without increasing the size by making the length of an electroacoustic transducer at the input side longer than that of the output side among the electroacoustic transducers fitted to the same side of a delay medium. CONSTITUTION:The input-side and output-side electroacoustic transducers 13, 14 are fitted to the same side face of one side of the delay medium made of glass formed in the form of modified pentagon. The size of the transducer 13 is prolonged longer than the transducer 14. In this case, the transducer 13 is formed longer than a transducer 2 in conventional examples, its directive angle is narrowed and then the component becoming unnecessary reflection is at a lower level than the conventional examples. Further, the length of the transducer 14 is shorter than that of the conventional examples, but the mismatching caused thereby is cancelled by the other method in this case. Moreover, an absorbing agent 16 for eliminating an unnecessary reflection signal is fitted to a part except a major propagation path 15 of the ultrasonic wave.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an ultrasonic delay line used for delaying electrical signals of video equipment such as VTRs, TVs, video discs, and video cameras.

Conventional Structures and Problems There has been a remarkable spread of VTRs in recent years, and video cameras have also been steadily increasing. Zaraniid: Improving the image quality of TVs, especially NTSC TVs, has become commonplace, and key components of such video equipment, including traditional PAL or SECAM TVs and future videodiscs, are becoming more common. The market for ultrasonic delay lines continues to expand.

FIG. 1 shows a conventional ultrasonic delay line. Glass delay medium 1
The input-side electroacoustic transducer 2 and the output-side electroacoustic transducer 3 are mounted on the same side, and an absorbent 6 for removing unnecessary reflected signals is installed in the part other than the main propagation path 4 of the ultrasonic wave. be. Figure 2 shows the unnecessary reflection characteristics of this ultrasonic delay line.

In contrast to the main signal 8, signals 9 to 11 are unnecessary signals, and it is desirable that these are smaller than the main signal.

In order to remove the unnecessary signals 9 to 11 from the toe lever, the directivity angle of the ultrasonic waves may be narrowed. In order to narrow the directivity angle, the length of the electroacoustic transducer may be increased. However, this has been difficult to implement due to the limited slopes on which the electroacoustic transducer can be accommodated - especially in the current trend towards miniaturized designs.

Purpose of the Invention In view of the above drawbacks, the present invention is equivalent to the conventional one! It is an object of the present invention to provide an ultrasonic delay line having a shape with a size of i or smaller and having better unwanted reflection characteristics.

Structure of the Invention In order to achieve the above-mentioned object, the present invention has been made in order to calculate the length of the input-side electro-acoustic transducer from among the electro-acoustic transducers for signal input and signal output attached to the same side of a delay medium. The length of the acoustic transducer is also longer.

DESCRIPTION OF EMBODIMENTS FIG. 3 shows an embodiment of the present invention. Reference numeral 12 denotes a modified pentagonal delay medium, which is a glass-like rectangle with one corner cut diagonally.On the same side of one side of this delay medium 12, there is an input-side electroacoustic transducer 13. An output side electroacoustic transducer 14 is attached. The electroacoustic transducer 13 on the input side 111 is longer than the electroacoustic transducer 14 on the output side, and both are mounted on the same slope as in the conventional example. In this case, the electroacoustic transducer 13 at the input end is configured to be longer than the electroacoustic transducer 2 of the conventional example, and its directivity angle is narrower, so that the unnecessary reflected components are at a lower level than the conventional example. Become. Also, at this time, the electroacoustic transducer 14 on the output side
is shorter than in the prior art, and therefore has a smaller capacitance - the mismatch caused by this can be eliminated by increasing the load resistance or by using a material with a high dielectric constant.

In the above configuration, an absorber 16 is attached to a portion other than the main propagation path 16 of the ultrasonic wave to remove unnecessary reflected signals.

Fig. 4 shows the unnecessary reflection characteristics of the present invention.O main signal 1γ, 18 to 20 are unnecessary signals;
is quite small. It can be seen that among the unnecessary reflection levels, especially the other unnecessary reflection levels that depend on the directivity are reduced.

Since the ultrasonic delay line of the present invention is configured as described above,
With a simple configuration, the unnecessary reflection level can be significantly reduced, and the characteristics are extremely excellent, making it a valuable product for industrial use.

[Brief explanation of drawings]

Fig. 1 is a front view of a conventional ultrasonic delay line, Fig. 2 is a diagram of unnecessary reflection characteristics of the conventional ultrasonic delay line, Fig. 3 is a front view of an ultrasonic delay line showing an embodiment of the present invention, and Fig. 4 is a front view of a conventional ultrasonic delay line. FIG. 3 is an unnecessary reflection characteristic diagram of the present invention. 12...Delay medium, 13...Input side electroacoustic transducer-14...Output side electroacoustic transducer-16...Main propagation path, 16...
absorbent. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 @ Lock

Claims (1)

[Claims] Of the electroacoustic transducers for signal input and signal output that are installed on the same side of the delay medium, the length of the electroacoustic transducer on the input side is longer than the length of the electroacoustic transducer on the output side. Sonic delay line.