JPS5847320A - Surface acoustic wave device - Google Patents

Abstract

PURPOSE:To realize the miniaturization and high efficiency of a surface acoustic wave device, by using a surface acoustic wave element to form a filter which separates a chrominance signal from a luminance signal. CONSTITUTION:An input end reed-screen type electrode 22 which converts an electric signal into a surface acoustic wave and output end reed-screen electrodes 23, 24, 25 and 26 which convert the surface acoustic wave radiated from the electrode 22 into the electric signal are provided on a piezoelectric substrate. The electrodes 23 and 24 plus electrodes 25 and 26 divide the transmission path of the surface acoustic wave into two parts and at the same time are formed so as to be electrically parallel to each other. The delay time tauD between the electrodes 23/24 and 25/26 is set equal to a horizontal scan time of the TV signal. AT the same time, the polarities are set opposite to each other between the electrodes 25 and 26. When the TV signal is fed to a terminal 21, a luminance signal 30 is formed at a terminal 27 and then delivered. Then a chrominance signal 31 is separated at a terminal 28.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a surface acoustic wave device, and more specifically, the electrode structure of a surface acoustic wave element is devised to have a function of separating a luminance signal from a color signal. This relates to a device that is significantly smaller and more efficient than a device that separates signals.

FIG. 1 shows a separation comb filter conventionally used to separate a luminance signal and a monochromatic signal. When a television signal is input to the input terminal 1, this signal is processed by the slow grinding line 2, the addition element 3, and the subtraction element 4, and the color signal and luminance are output from the color signal output terminal 5 and the luminance signal output terminal 6, respectively. Output as a signal. The amplitude components of the color signal and luminance signal are as follows.

Color signal output component・・・・・・・・・l −1+
arp(-iwτD)l luminance signal output component...
11+gxpc-)"wrB)l Fig. 2 is a frequency spectrum showing this amplitude characteristic, where 7 indicates the color signal output and 8 indicates the luminance signal output. Chrominance signal output cuff and luminance signal output 8 On the other hand, since the luminance signal and chrominance signal of the NTSC signal have their frequencies interpolated, they appear at each time as shown in FIGS. 3(a) and 3(A). Therefore, in FIG. , the delay time of slow g-line 2 τ
By selecting n = '/f□ and adding and subtracting the signal from t, only the color signal is obtained at the color signal output terminal 5, and only the luminance signal is obtained at the luminance signal output terminal 6.
Signal separation becomes possible.

However, conventional separation comb filters use discrete transistors or transformers to calculate the sum and difference between the input signal and the signal delayed by time τD, which has the disadvantage of increasing the number of parts and making the circuit bulky. It had

FIG. 4 shows a conventional example of a separation comb filter using a transformer, in which the television signal input from the input terminal 11 first compensates for the insertion loss of the 1H1M wire extension 13. It is input to amplifier 12. Then, a signal having a predetermined delay time becomes the output of the transformer 14 through a 1H delay line 13 made of a glass delay line. These outputs are signals with equal amplitudes and inverted phases at both ends of the secondary side of the transformer 14. Then, the television signal is applied to the middle point of the secondary side of the transformer 14 via the amplitude adjuster 20, and the above-mentioned addition and subtraction are performed. In FIG. 4, transistors 15 and 16 are inserted for impedance conversion. Further, the terminal 26 is a power supply terminal, and a DC voltage is directly applied thereto. In this manner, a luminance signal is output from the luminance signal output terminal 27, and a color signal is output from the one-color signal output terminal 28.

As explained above, the conventional separation comb filter for separating color signals and luminance signals has the disadvantage that it is very large and requires a large number of parts, making it uneconomical.

The present invention was made in view of the drawbacks of the prior art,
It is an object of the present invention to provide a surface acoustic wave device in which the separation comb filter for separating color signals and luminance signals is constructed using surface acoustic wave elements, and the above-mentioned drawbacks are eliminated.

The surface acoustic wave device of the present invention includes: a piezoelectric substrate on which surface acoustic waves are excited and propagated; an input end interdigital electrode for converting an electrical signal into a surface acoustic wave; first and twentieth output-end interdigital electrodes are provided for converting the emitted surface acoustic waves into electrical signals, and the first output-end interdigital electrode and the second output-end interdigital electrode are internally connected to each other. They are electrically connected in parallel and are formed so as to output output signals with the same time delay from each other, and one of these two output signals has a phase opposite to that of the human input signal.

The present invention will be explained in more detail below with reference to embodiments shown in the accompanying drawings.

FIG. 5 is a diagram showing an embodiment in which a comb filter for separating color signals and luminance signals used in a color television receiver is constructed using the present invention. As shown in the figure, the output end interdigital electrode 2 is opposite to the input terminal 21 and the input end interdigital electrode 22.
5.24.25.26 are deployed. The output end interdigital electrodes 25.24° and 25.26 are configured to divide the propagation path of the surface acoustic wave into two and to be electrically parallel to each other. Then, the delay time τD between the output end interdigital electrode 25.24 and the output end interdigital electrode 25.26 is defined as one horizontal scanning time of the television signal (65,556 μ5).
was taken equal to. In addition, the electrode width of both electrodes is 8.6 μm.
, a regular wave interdigital double electrode structure with 5 pairs of electrodes, 5
An aluminum vapor-deposited film of No. 000.4 was formed on a lithium niobate single crystal by photolithography technology.

Since the output end interdigital electrodes 25 and 26 have opposite polarities as shown in FIG.
A luminance signal as shown by rc5o in FIG. 6 (α) is formed and output. That is, the envelope 2 is determined by the transfer characteristics of the input end interdigital electrode 22 and the output end interdigital electrode 25.
9, a comb-shaped characteristic for each frequency corresponding to the reciprocal of the delay time τD determined by the output end interdigital electrode 23 and the output end interdigital electrode 24 is superimposed with the center frequency of the filter as a peak.

Further, a color signal as shown at 51 in FIG. 6<b> is formed and outputted to the color signal output terminal 28. That is, at the color signal output terminal 28, a comb-shaped characteristic with a valley at the center frequency is obtained. Therefore, the luminance signal and the chrominance signal are deviated by 2τD as shown in FIG. 6, and the luminance signal and the chrominance signal are separated.

FIG. 7 shows a second embodiment of the present invention, in which a luminance signal forming portion 52 and a color signal forming portion 53 are formed on the left and right sides of the input electrode 22, and their functions are shown in FIG. This is similar to the first embodiment.

As is clear from the above description, according to the present invention, it is possible to provide a comb-shaped characteristic in the delay line by using a surface acoustic wave delay element9, and furthermore, by changing the polarity of the interdigital electrode, it is possible to create a luminance signal. It became possible to separate color signals. Therefore, according to the present invention, the number of parts can be significantly reduced, and the device can be made smaller and lower in price. Furthermore, since the delay line in the video frequency band is composed of 11 frequency bands, the overall size of the device can be reduced by about 10 minutes compared to the conventional one.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing the configuration of a conventional comb filter for separating color and brightness signals, Figure 2 is a diagram showing the frequency spectra of color and brightness signals, and Figure 3 (α) shows the color signal output. 3(A) is a diagram showing the luminance signal output, FIG. 9 is a circuit diagram showing a specific example of the conventional comb filter for separating color signals and luminance signals shown in FIG. 1, and FIG. 6(a) is a diagram showing the luminance signal formed by the first embodiment shown in FIG. 5, and FIG. 6(b) is a diagram showing the first embodiment of the present invention. FIG. 7 is a diagram showing a color signal formed by the first embodiment shown in the figure, and FIG. 7 is a diagram showing a second embodiment of the present invention. 1.11.21...Input terminal 2.15...
・・・・Delay line 5・・・・・・・・・・・・・−・・・・
Addition element 4... Subtraction element 5.19.28... Color signal output terminal 6.18.27... Luminance signal output terminal 7.51.・・・
......Color signal output 8.30...Brightness signal output 22......Input end interdigital electrode 25.24.25. 26...Output end interdigital electrode 32...Brightness signal forming part 35...Color signal forming part Oka 4I Figure 3 Frequency Figure 6 Figure 7 Procedural amendment (method) % formula % Name of the invention Person who makes an acoustic wave surface device hl'I city +11' 51θ thin paper meeting? 1 Hitachi F
'Address I' table? X, =:, m
Katsu Shigeyo Osamu Personnel Assistant Z1: Contents of the T94 specification page 9, line 5 says ``Su 9 times''. Correct it to ``Figure 4.''that's all

Claims (1)

[Claims] (1) On a piezoelectric substrate where surface acoustic waves are excited and propagate, there is an input end interdigital electrode that converts electrical signals into surface acoustic waves, and an input end interdigital electrode that converts the surface acoustic waves emitted from the input end interdigital electrode into electrical signals. First and second output transducer transducers are provided, the first output transducer and the second output transducer being electrically connected in parallel and identical to each other. What is claimed is: 1. A surface acoustic wave device that outputs an output signal with a two-hour delay, and one of the two output signals is in opposite phase to the input signal. (21) The first output end interdigital electrode includes a first interdigital electrode and a second interdigital electrode, and the second output end interdigital electrode includes a third interdigital electrode and a fourth interdigital electrode. One of the first, second, third, and fourth interdigital electrodes is arranged with opposite polarity. Between the first interdigital electrode and the second interdigital electrode. and the surface acoustic wave propagation time between the fifth interdigital electrode and the fourth interdigital electrode, and the surface acoustic wave propagation time corresponds to one horizontal direction of the television signal. The surface acoustic wave device according to claim 1, wherein the surface acoustic wave device is formed so as to be equal to the scanning time.