JPS5843341B2 - Glass for ultrasonic delay line - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a glass for ultrasonic delay lines suitable for miniaturization.

Generally, an ultrasonic delay line consists of a delay medium such as glass, an input transducer attached to a suitable surface of the medium that converts an electrical signal into a mechanical signal, and an output transducer that converts the mechanical signal into an electrical signal.

Ultrasonic delay lines having such a structure are used in delay circuits of recording devices such as PAL color TV receivers, VTRs, and VDs.

Since other parts used in this type of device have become smaller with the adoption of ICs, there is a strong desire to make the ultrasonic delay line as small as the other parts.

Conventionally, delay media have been made smaller by increasing the number of reflections of sound waves within the delay medium, but if the number of reflections is increased and the delay medium is made smaller, spurious signals due to the diffraction of sound waves will significantly increase. It had drawbacks.

In order to miniaturize the delay medium without increasing spurious signals, to minimize the number of reflections of sound waves inside the delay medium, and to facilitate manufacturing, the inventors of the present invention have:
As a result of various studies and examinations, we found that the speed of sound is extremely small, and within the range where changes in the speed of sound due to temperature do not affect the function of the element (T-C for VTR dropout compensation).
, D is ±6.7X10'/C, -10~60°C)
In addition, a stable glass with a significantly low melting temperature has been discovered and proposed as the present invention.

The composition of the glass used as the delay medium of the present invention is Si02 42-27%, Pb071-57% by weight.
, to 20+Na2O+ZnO+CdO+BaO+5r0
3-12%, and 20 + Na20 + ZnO
+CdO+BaO+SrO+ZrO2+TiO2+La
2 o3+ A I 20s + B2033~12
% (K2010~00I), Na 205~0%,
ZnO 3-0%.

cdo 5~0%, Ba09~0%, 5r05~0φ,
ZrO24~0φ, Ti024~0%, La2036
~0%, Al2034~0%, B2037~0φ), S
It consists of b203 + A, B203 1-0%.

The reason for limiting the composition to the above is that the glass has a low sound velocity (transverse wave), has excellent homogeneity, durability, and stability, and has a low melting temperature and is easy to manufacture.
<27%, PbO>71, the glass becomes inhomogeneous.
S i02 ) 42%, PbO<57 has a high sound velocity and a high melting temperature, making it not only impossible to miniaturize but also difficult to manufacture.

When K2O > 12% and Na2O > 6%, the durability of the glass is poor and it is impossible to produce a practically stable glass.
Small amounts of ZnO, CdO, Bad.

SrO, ZrO2, 'rio2. La2O3, Al2O
The introduction of 3 and B2O3 is effective in improving the durability and stability of the glass, but if too much is added, the speed of sound increases.

S b 2035 A S 203 is introduced because it has a bubble cutting effect during vitrification.

Next, examples will be shown.

As can be seen from the above examples, the ultrasonic delay line glass of the present invention has an extremely low sound velocity (transverse wave) (the smallest known glass is 2.50 km/sec).
, commonly used ones are 2,80~2.60k
m/3cc), it is not only possible to downsize without increasing the number of reflections, that is, without increasing spurious signals, but also because the melting temperature is 1000 to 1250.
It has the advantage of being extremely easy to manufacture due to its low temperature.

Claims (1)

[Claims] 1 Weight width: 5in2 42-27 Rice Pb0 71-57 20 10-O Rice Na2O5- 0 Zn0 5-0 Rice Cd0 5-0 Rice Ba0 9-0 Rice Sr0 5-0饅ZrO24〜0φ TiO24〜 0饥La2O36〜 0% AI□03 4〜0φ B2O37〜 0% sb, o31〜0φ A S 203 3〜12 It has the composition of Glass for ultrasonic delay line, characterized in that the transverse wave) is smaller than 2.4 Km Aec.