JPS5855689B2 - chiencairo - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is intended to eliminate the influence of reflected waves generated within delay elements used to delay electrical signals.

Recent television equipment sometimes uses a circuit that uses an ultrasonic delay element to delay a television signal or the like by a delay time equal to the horizontal scanning line period or an integral multiple or fraction thereof.

Specific examples include a TED video disc system, an RCA video disc system, a PAL color television receiver, and a SECAM color television receiver.

The ultrasonic delay elements currently available commercially use glass for one piece, and use transducers at the input and output terminals to convert electrical signals and ultrasonic signals. is configured to propagate as .

The delay time is determined by the propagation time within the glass.

The ultrasonic signal that has reached the output end is converted into an electrical signal by the transducer, but complete conversion is not possible and some of it returns to the input end as reflected waves.

When this reflected wave returns to the input end, a portion of it is reflected again and heads toward the output end.

This second reflected wave is mixed into the desired signal as an unnecessary signal.

Let us now explain the case of a TED type video disc system using a three-line sequential type as an example.

In the TED video disc system, the signals recorded on the disc are red, green, and blue (hereinafter R, G, B).
It is abbreviated as.

), which are converted into simultaneous signals using two or more delay elements having a delay time of one horizontal scanning line period on the player side.

A method of removing interference from reflected waves in a circuit using two or more delay elements has already been proposed by ``arranging two delay elements in a dependent manner and returning part of their output signal to the input of the first delay element.'' is being done.

However, there is no mention of a method for reducing the interference of reflected waves occurring at the last delay element when two or more delay elements are arranged in series, for example.

The present invention is an effective method that can be applied to such cases as well.

Assume that the three-wire sequential signal is repeated in the order R, G, B, R, G, B.

Now, if we consider the moment when a signal that shares the R signal is about to be added to a delay element with a delay time equal to the horizontal scanning line period (hereinafter abbreviated as IH), at this moment the B signal is propagating inside the delay element, and the output is just coming. It's time to start coming off the edge.

Further, the signal reflected and propagated from the output end to the input end is the G signal before IH of the B signal.

Furthermore, the reflected wave that is reflected once more at the input end, propagates toward the output end, and is about to start coming out from the output end is the R signal before IH of the above G signal, and is about to be added to the above delay element. This is a signal 3H before the R signal.

However, considering that these two signals both share the same color R and the linear correlation in the vertical direction, it can be said that these two signals are extremely similar signals.

Therefore, if a part of the input signal R is used to cancel the reflected wave R signal in consideration of its phase and amplitude, a signal in which the influence of the reflected wave is reduced can be extracted as the output signal B signal.

That is, the present invention is characterized by extracting a portion of the input signal and adjusting its phase and/or amplitude to reduce disturbances caused by unnecessary reflections within the delay element. In addition, the purpose is to reduce the influence of reflected waves.

Let's further explain using drawings.

FIG. 1 shows a line sequential signal waveform of a standard color bar signal.

FIG. 2 is an operational explanatory diagram for explaining the present invention in detail.

In FIG. 2, 1 is a delay element, which has an IH delay time.

2 and 3 are transducers.

4 is an input side terminal, 5 is an output side terminal, and 6 is a circuit diagram related to the features of the present invention, which may be a passive circuit network or an active circuit network depending on setting conditions.

In the present invention, there is no need to discuss the details of this circuitry, as long as the phase and amplitude of the output signal are at desired values.

In a simple case, it may be a single resistor, or in other cases, it may be a complex circuit including active elements such as transistors.

At the moment when the R2 signal is about to be applied to the input terminal 4,
That is, let us consider the input/output of the delay element and the state of the signal propagating within the element at time 10.

There are many propagation paths in the delay element 1, but considering the main propagation path 7°8.9 that is the subject of the present invention, 7 is the delay of the signal to be transmitted, which is the purpose of the delay element. This is the necessary propagation path to obtain time.

8 is a propagation path for unnecessary signals reflected from the output end and returned to the input end.

Reference numeral 9 denotes a propagation path for unnecessary signals, in which a portion of the signal that has returned through 8 is reflected again at the input end and heads toward the output end.

Note that the delay time of each propagation path is equal. Considering the above-mentioned instant 10, the signal B1 in FIG. 1 is propagating through the propagation path 7.

8, a part of the signal 01 in FIG. 1 is reflected by the transducer at the output end and returned to the input end.

Further, at 9, the signal of R1 in Fig. 1 is transmitted to the transducer 3.
A part of the wave is reflected by the transducer 2 and returns to the input end, and a part of it is further reflected by the transducer 2 and propagates toward the output end as an unnecessary reflected wave.

Although the propagation signals 7, 8, and 9 are shown shifted in the figure for convenience of explanation, they are considered to pass through the same propagation path.

Therefore, the signals propagating through the propagation paths 7 and 9 after 10 are mixed and output to the output terminal 5.

At this time, the signal propagated through 9 and output is an internal unnecessary signal generated inside the transducer, and it interferes with the signal of 7. In the above example, the signal of B1 of 7 is combined with the signal of R1 of 9. The signal will be mixed in.

In the case of a 3-wire sequential signal, R2 is applied to input terminal 4 at the moment of tO.
signal is about to be added.

The unnecessary signals R1 and R2 of No. 9 share the same color signal and have extremely similar waveforms when it is considered that there is a linear correlation in the vertical direction.

Therefore, if the R2 signal is added to the R1 signal of 9 through the circuit network of 6 with equal amplitude and in opposite phase to the signal output to 5, then 7
The interference to the output of the B1 signal can be extremely reduced.

The above is a detailed description of the present invention.

It has been confirmed through experiments that the TED type video disc system is extremely effective.

Not only in the case of 3-wire sequential signals as in the case of the TED method, but also in the case of R using an IH ultrasonic delay element.
In various television equipment such as CA video disc systems, unnecessary signals generated by reflected waves that are not converted by the transducer at the output and input ends of the delay element, as described above, are superimposed and output. However, application of the present invention can also be useful in eliminating this.

However, since the amount of unnecessary signals reflected by the transducer of the ultrasonic delay element is small, in order to correct the interference of the unnecessary signals, correction is required if the signal is similar to the signal three horizontal scanning line periods ago. This is possible, and can certainly be effective in this case.

In particular, if the signals reflected twice by transducers 3 and 2 do not necessarily have a smaller amplitude in proportion to the original waveform, but have frequency characteristics, the circuit network in 6 corrects them and interferes with them. can be reduced.

Figure 2 shows the basic configuration, but when designing a specific circuit, the signal propagated through 8 and returned to the input end passes through transducer 2 and appears at the input end of 4. 6
Since there is a possibility that the output will be output through the
A suitable buffer circuit may be provided between the terminals of the transducer 2 and the transducer 2.

[Brief explanation of the drawing]

The drawings are for detailed explanation of the present invention, and the first drawing is for explaining the present invention in detail.
The figure is a line-sequential signal waveform diagram of a standard color par signal, and FIG. 2 is an operation explanatory diagram. 1...Delay element, 2...Input side transducer, 3...Output side transducer,
4...Input terminal, 5...Output terminal, 6
. . . Circuit network, 7 . . . Propagation path for transmission signals, 8, 9 . . . Propagation path for unnecessary signals.

Claims (1)

[Claims] 1 - Determine the phase and amplitude of some signals extracted from similar input signals that are repeated every 3 horizontal scanning line periods and applied to the input transducer of an ultrasonic delay element with a delay time of 1-horizontal scanning line period. Corresponds to unnecessary reflected waves generated by reflection at the output end and input end of the delay element, which are simultaneously output to the output of the circuit network to be adjusted and the output signal of the output side transducer of the delay element. A delay circuit for input signal processing having a linear correlation, characterized in that the delay circuit is added so as to cancel out the output.