JPS61174809A - Signal delay circuit - Google Patents

Abstract

PURPOSE:To separate the output of a comb line filter and that of a one- horizontal period (1H) delay line from each other by taking out two kinds of output of a glass delay line independently of each other. CONSTITUTION:An input signal (a) is converted from an electrical signal to physical oscillation by an input converter 1 and is propagated in a glass delay line 3 and is converted to an electrical signal again by an output converter 2. This signal is added to the input signal (a) by an adding resistance 4, and outputs (b) and (c) are obtained from two positions. That is, a delay circuit 9 from which one output is taken out as the comb line filter output (c) by adding the input (a) in the adding resistance 4 and the other is taken out as the delay output (b) is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a signal delay circuit suitable for application to a magnetic recording/reproducing device, particularly a video tape recorder (hereinafter abbreviated as VTR).

[Background of the invention]

Among video signal edge enhancement methods, a method using a 1H (H is horizontal scanning time) delay line as shown in Japanese Patent Publication No. 55-19551 is known for enhancing the vertical edge of a television screen. This vertical contour enhancement circuit constitutes a feedback system using a 1H delay line, and calculates the input and output signals of the 1H delay line. There was a drawback that it had to be done. In particular, in the contour enhancement circuit for color signals, insufficient phase matching causes deterioration of S/N.

On the other hand, as shown in "Image Electronic Circuit J PP, 504-315, written by Utsunomiya et al., published by Coronasha, a comb filter using a delay line and an addition circuit is generally known. This is shown in FIG. The input v1 and the signal delayed by the delay line 12 are added by the adding circuit 13, and the output V,
I am getting . An example of a comb filter using a glass delay line is shown in FIG. The input signal v, is converted from an electrical signal to a physical vibration by the input transducer 1, propagates through the glass delay line 3, and is converted back to an electrical signal by the output transducer 2. This signal is added to the input v1 by the adding resistor 4 to obtain the output V. The frequency accuracy of the comb filter corresponds to the dimensional accuracy of the glass delay line 3, and highly accurate comb filters are currently available. Since the contour enhancement circuit partially has a configuration of a comb filter, it was thought that it would be effective to apply this comb filter to the contour enhancement circuit in the previous section, but in the configuration shown in Figure 5, the delayed output Since it is not possible to completely separate the filter output V from the filter output V, the comb filter has not been applied to a contour enhancement circuit.

[Purpose of the invention]

An object of the present invention is to obtain a signal delay circuit that solves the problems of the conventional method described above.

[Summary of the invention]

In order to achieve the above object, the present invention has a structure in which the outputs of the glass delay line can be taken out independently in two systems, and are configured so that a comb filter output and an fH delay output can be obtained respectively.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

Components corresponding to those in the conventional example shown in FIG. 5 are given the same reference numerals, and some explanations will be omitted. FIG. 1 shows a first embodiment of the present invention. The difference from the conventional example shown in FIG. 5 is that the output is taken out from two different parts of the same output converter 2, and , a delay circuit 9 in which the input a is added through the addition resistor 4 (rectangular filter output C, and the other is outputted with a delay)
This is what constituted the . By extracting outputs from different parts of the same output converter 2, the comb filter output C and the 1H delayed output can be obtained separately.

FIG. 2 shows a second embodiment of the present invention, and the difference from the conventional example in FIG. 5 and the first embodiment is that two output converters are provided independently, and from one output converter 14, A delayed output is obtained, and the other output converter 5 receives an input a by an adding resistor 4.
The delay circuit 10 is constructed in such a way that the comb filter output C is obtained by adding the above. By using two independent output converters 5 and 14, it is possible to obtain a 1H delay output and a comb filter output with a higher degree of separation than in the first implementation column.

FIG. 3 shows an application of the present invention, which is a color signal contour enhancement circuit or 8/N improvement circuit using the delay element 9 or 10 of the first or second embodiment.

The input 9 of the glass delay line 3 is obtained by subtracting the signal d obtained by multiplying the delayed output by the glass delay line 3 by α (α<1) by an attenuation circuit 6 from the input Vi by a subtraction circuit 8. N.T.
In the case of the SC system, the phase of the color signal is inverted every 1H, so this feedback circuit is busy as a positive feedback circuit. As mentioned above, the output C of the glass delay line 3 is connected to 1H by the addition resistor 4.
Input a is added to the delayed output. Since the phase of the color signal is inverted every 1H, the output CM can be obtained by the difference between the input a and the delayed signal. This difference corresponds to vertical contour components or uncorrelated components between horizontal scanning lines such as noise, and is multiplied by β (β-1) by the attenuation circuit 7 and added or subtracted from the input Vi by the addition/subtraction circuit 11. Output v0 is obtained. When added, an edge enhancement effect is obtained, and when subtracted, an S/N improvement effect is obtained. Furthermore, it is also possible to prevent the waveform response from deteriorating by providing the attenuation circuit 7 with nonlinear characteristics. The delay circuit 9 described above is included in the delay line and the calculation section.
Alternatively, by using 10, the number of adjustment points for phase matching can be reduced, and the performance can be further improved.

〔Effect of the invention〕

As described above, according to the present invention, the 1H delay output and the comb filter output can be obtained independently using the same glass delay line. Furthermore, it is possible to enhance the contour of a color signal or improve the S/N ratio with good performance by using an edge enhancement circuit using a delay element or an S/N improvement circuit.

[Brief explanation of the drawing]

1 and 2 are circuit diagrams showing an implementation of the signal delay circuit of the present invention, FIG. 3 is a circuit diagram showing another implementation of the invention, and FIGS. 4 and 5 are circuit diagrams showing conventional signal delay circuits. It is a circuit diagram of a circuit. b...1H delay output % C...comb filter output, 2...output converter, 5...output converter, 1
4... Output converter, 6, 7... Attenuation circuit, 8...
・Subtraction circuit, 11...Addition and subtraction space.

Claims (1)

[Claims] 1. An input transducer that converts electrical signals into physical vibrations, a glass delay line that propagates and delays the physical vibrations, and an output converter that converts the delayed physical vibrations into electrical signals. The output converter is characterized in that output signals are taken out from two different parts of the output converter, one is used as a delayed output, and the other is added to the input signal using a summing resistor or a summing capacitor, and the comb filter output is taken out independently. signal delay circuit. 2. A plurality of the output converters are provided, the output obtained from one output converter is used as a delayed output, and the output obtained from the other output converter is added to the input signal using an adding resistor or an adding capacitor, and the output is combed. 2. The signal delay circuit according to claim 1, wherein the signal delay circuit independently extracts the output of the shaped filter.